Dissertations / Theses on the topic 'Localized Drug Delivery System'

Localized drug delivery systems have been widely studied as potential replacements for conventional chemotherapy with the capability of providing sustained and controlled drug release in specific targeted sites. They offer numerous benefits over conventional chemotherapy such as enhancing the stability of embedded drugs and preserving their anticancer activity, providing sustained and controlled drug release in the tumor site, reducing toxicity and diminishing subsequent side effects, minimizing the drug loss, averting the need for frequent administrations, and minimizing the cost of therapy. The aim of this study is to develop a localized drug delivery system with niosomes embedded in a chitosan hydrogel with targeting capabilities. The incorporation of niosomes into a chitosan hydrogel has several advantages over each individually being used. First, embedding niosomes in a chitosan hydrogel can yield control over drug release especially for small molecule drugs. Second, chitosan hydrogel may improve the release time and dosage of drugs from niosomes by protecting them with an extra barrier, resulting in tunable release rates. Third, as a localized delivery system, chitosan hydrogels can prevent the migration of niosomes away from the targeted tumor sites. Finally, chitosan has mucoadhesive property which can be used in the targeting of the tumor cells with the mucin over expression. To enhance the specific targeting, the capacity of chitosan to target MUC1 overexpression in cancer cells will be analyzed. Similarly, the incorporation of chlorotoxin in this system will be achieved and evaluated. Chlorotoxin, a 36-amino acid peptide, is purified from Leiurus quinquestriatus scorpion venom with a distinct characteristic of binding preferentially to neuroectoderma tumors such as glioma, but not to normal tissue. The overexpression of MUC1, a mucin antigen, in certain cancer cells has been used as an attractive therapeutic target in the design of a drug delivery system consisting of chitosan with a distinct mucoadhesive property. To determine the level of MUC1expression in different cell lines, Cell based Enzyme Linked Immunosorbent Assay (Cell ELISA) was developed for the first time. Attenuated Total Reflectance- Fourier Transform Infra-Red (ATR-FTIR) Spectroscopy is used to investigate the possible molecular interaction between chlorotoxin and glioma cells. This study presents a new approach in monitoring the biochemical and biophysical changes in glioma cells after being exposed to CTX. In addition to characterizing the signature spectra of CTX and glioma cells, we evaluated the differences in biochemical compositions of the spectra of the glioma cells treated with and without CTX over different incubation time periods. The results indicate that the proposed localized drug delivery system with the distinct tumor targeting features and extended release profiles would tune and control the specific delivery of chemotherapeutics in tumor sites.

[EN] Nowadays, one of the biggest concerns that permanently keep the attention of main important sectors of human society is health. Modern medical science is compromised with not only providing good adequate treatments but also effective specific solutions for each type of disease or human pathology. In this direction, innovative approaches like tissue engineering or regenerative medicine, controlled drug delivery systems and nanomedicines emerge to bring alternatives to situations hard to solve with conventional treatment and strategies, including the replacement of damaged or diseases tissues and/or organs. Specifically, this research is mainly aimed to design a combined system for controlled, stable and localized release of therapeutic agents that are able to exert their effect selectively on the area that warrants treatment. This construct will have enough versatility to be adapted to almost any kind of treatment, from cancer to tissue regeneration, always that the key requirement of the treatment was the need to provide the treatment of localized, stable and controlled manner. With the purposes of making easier the understanding as well as the design of the system, I was decided, for the proof of concept, to use drugs and materials with known activity applied on tissue regeneration and for the treatment of chronic wounds. The system in question consists of three main elements: 1) The first element is the polymer conjugates of therapeutic agents, which contribute to increasing the selectivity of the therapeutic action of the drug, as well as improved stability, bioavailability and biocompatibility thereof. If the drug is hydrophobic, conjugation contributes to increase its solubility in water, and in the case of proteins used as therapeutic agents, the combination helps reduce the body's immune response, increasing the chance of successful of the treatment. 2) The second element are the biodegradable polymeric microparticles, which in this case act like encapsulation agents for polymeric conjugate , thus allowing to have a second control point in the release kinetics of the therapeutic agents . Simultaneously, the microparticles also play a role in modifying the texture of the final construct, ascribing mechanical and physicochemical properties that help to improve some biological properties of the final material, such as the affinity, adhesion and cell proliferation. 3) The third element consists of a nanoporous membrane made of a biodegradable polymer by electrospinning, which constitute the unifier element of the whole system. This membrane provides manageability to the construct and is itself the last point of control in the release kinetics of the therapeutic agent or agents. Besides, it must be biocompatible and stable at ambient conditions, since this probably is going to be exposed to the environment while protecting the wound, in the case of this kind of application. These three elements, which themselves are complex systems separately, are systematically combined to achieve a synergistic relationship between them so that each one power the qualities of the other two. The resulting construct was characterized and it demonstrated to have characteristic properties that can be used as a control parameter during manufacture of this new material. Also, preliminary biological studies developed "in vitro" indicated that the proposed system may be a good candidate for deeper studies as alternative treatment for chronic wounds and other pathologies that require localized administration for long periods of time.
[ES] Actualmente, una de las mayores preocupaciones que permanentemente laman la atención de los principales sectores de la sociedad humana es la salud. La ciencia médica moderna está comprometida no solo con suministrar tratamientos adecuados, sino más bien ofrecer soluciones efectivas y específicas para cada tipo de enfermedad o patología humana. En este sentido, estrategias innovadoras como la ingeniería de tejidos o la medicina regenerativa, los sistemas de liberación controlada de fármacos y las nanomedicinas, surgen como buenas alternativas para abordar situaciones difíciles de resolver aplicando los tratamientos y estrategias terapéuticas convencionales, como es el caso cuando se hace necesario reemplazar tejidos o incluso órganos dañados por algún traumatismo o enfermedad. Concretamente, el presente trabajo de investigación tiene por objetivo principal diseñar un sistema combinado para la liberación controlada, estable y localizada de agentes terapéuticos que sean capaces de ejercer su efecto de forma selectiva sobre la zona que amerita el tratamiento. Este constructo tendrá la versatilidad suficiente como para poder adaptarse a casi cualquier tipo de tratamiento, desde el cáncer hasta la regeneración de tejido, siempre que el requisito clave del tratamiento sea la necesidad de suministrar el tratamiento de manera localizada, estable y controlada. Para efectos de facilitar la compresión y el diseño del sistema se escogió para la prueba de concepto materiales y fármacos asociados a la regeneración de tejidos, como tratamiento para casos de heridas crónicas. El sistema en cuestión está constituido por tres elementos principales: 1) El primer elemento son los conjugados poliméricos de agentes terapéuticos que contribuirán a aumentar la selectividad de la acción terapéutica del fármaco, así como también a mejora la estabilidad, biodisponibilidad y biocompatibilidad de los mismos. En caso de que el fármaco sea hidrofóbico, la conjugación contribuye a aumentar su solubilidad en agua, y en el caso de usar proteínas como agentes terapéuticos, la conjugación contribuye a disminuir la respuesta inmunológica del cuerpo incrementando las posibilidad de éxito del tratamiento. 2) El segundo elemento son micropartículas poliméricas biodegradables, que en este caso actúan con agentes de encapsulación para los conjugados poliméricos, permitiendo así contar con un segundo punto de control en la cinética de liberación de los agentes terapéuticos. Simultáneamente, las micropartículas también cumplen un papel de modificador de la textura del constructo final, adjudicándole propiedades mecánica y fisicoquímicas que contribuyen a mejorar las propiedades biológicas del material final, como son la afinidad, la adhesión y la proliferación celular. 3) El tercer elemento consiste en una membrana polimérica biodegradable nanoporosa hecha por electrospinning, que constituyen el elemento unificados del sistema, aporta manejabilidad al constructo y es en sí mismo el último punto de control en la cinética de liberación del agente terapéutico. Este último debe ser biocompatible y estable en condiciones ambientales, puesto que probablemente este expuesto al ambiente mientras protege la herida, en el caso concreto de este tipo de aplicación. Estos tres elementos, que en sí mismos constituyen sistemas complejos por separado, se han combinado sistemáticamente para alcanzar una relación sinérgica entre ellos de manera que cada uno potencia las cualidades de los otros dos. El constructo resultante se caracterizó demostrando tener propiedades características que se pueden utilizar como parámetro de control durante la fabricación del mismo. Así mismo estudios in vitro del sistema desarrollado señalan que puede ser un buen candidato para el tratamiento de heridas crónicas entre otras patologías que requieran tratamientos localizados.
[CAT] Actualment, una de les majors preocupacions que permanentment llepen l'atenció dels principals sectors de la societat humana és la salut. La ciència mèdica moderna està compromesa no solament amb subministrar tractaments adequats, sinó més aviat oferir solucions efectives i específiques per a cada tipus de malaltia o patologia humana. En aquest sentit, estratègies innovadores com l'enginyeria de teixits o la medicina regenerativa, els sistemes d'alliberament controlat de fàrmacs i les nanomedicines, sorgeixen com a bones alternatives per a abordar situacions difícils de resoldre aplicant els tractaments i estratègies terapèutiques convencionals, com és el cas quan es fa necessari reemplaçar teixits o fins i tot òrgans danyats per algun traumatisme o malaltia. Concretament, el present treball de recerca té per objectiu principal dissenyar un sistema combinat per a l'alliberament controlat, estable i localitzada d'agents terapèutics que seguen capaços d'exercir el seu efecte de forma selectiva sobre la zona que amirita el tractament. Aquest constructe tindrà la versatilitat suficient com per a poder adaptar-se a quasi qualsevol tipus de tractament, des del càncer fins a la regeneració de teixit, sempre que el requisit clau del tractament sega la necessitat de subministrar el tractament de manera localitzada, estable i controlada. Per a efectes de facilitar la compressió i el disseny del sistema es va escollir per a la prova de concepte materials i fàrmacs associats a la regeneració de teixits, com a tractament per a casos de ferides cròniques. El sistema en qüestió està constituït per tres elements principals: 1) El primer element són els conjugats polimèrics d'agents terapèutics que contribuiran a augmentar la selectivitat de l'acció terapèutica del fàrmac, així com també a millora l'estabilitat, biodisponibilitat i biocompatibilitat dels mateixos. En cas que el fàrmac sega hidrofòbic, la conjugació contribueix a augmentar la seua solubilitat en aigua, i en el cas d'usar proteïnes com a agents terapèutics, la conjugació contribueix a disminuir la resposta immunològica del cos incrementant les possibilitat d'èxit del tractament. 2) El segon element són microparticles polimèriques biodegradables, que en aquest cas actuen amb agents d'encapsulació per als conjugats polimèrics, permetent així comptar amb un segon punt de control en la cinètica d'alliberament de l'agent terapèutics. Simultàniament, les microparticles també compleixen un paper de texturitzant del constructe final, adjudicant-li propietats mecànica i fisicoquímiques que contribueixen a millorar la propietats biològiques del material final, com són l'afinitat, l'adhesió i la proliferació cel·lular. 3) El tercer element consisteix en una membrana polimèrica biodegradable nanoporosa feta per electrospinning, que constitueixen el element unificats del sistema, aporta manejabilitat al constructe i és en si mateix el ultimi punt de control en la cinètica d'alliberament de l'agent terapèutic. Aquest últim ha de ser biocompatible i estable en condicions ambientals, ja que probablement aquest exposat a l'ambient mentre protegeix la ferida, en el cas concret d'aquest tipus d'aplicació. Aquests tres elements que en si mateixos constitueixen sistemes complexos per separat, s'han combinat sistemàticament per a aconseguir una relació sinergètica entre ells de manera que cadascun potencia les qualitats dels altres dos. El constructe resultant es va caracteritzar demostrant tenir propietats característiques que es poden utilitzar com a paràmetre de control durant la fabricació del mateix. Així mateix estudis in vitro del sistema desenvolupat assenyalen que pot ser un bon candidat per al tractament de ferides cròniques entre altres patologies que requeriren tractaments localitzats.
Rodríguez Escalona, GDJ. (2016). DEVELOPMENT OF CONTROLLED DRUG DELIVERY SYSTEMS OF POLYMERIC NANOMEDICINES ASSOCIATED TO SCAFFOLDS FOR TISSUE REGENERATION [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63231
TESIS

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.
Includes bibliographical references (p. 117-120).
There are many potential clinical applications for localized drug delivery and sensing systems, such as cancer, vaccinations, pain management, and hormone therapy. Localized drug delivery systems reduce the amount of drug required for a therapeutic effect and the severity of side effects. Delivery of multiple chemicals has been demonstrated previously from a polymeric microreservoir device. This dime-sized device contains small reservoirs loaded with drug and separated from the outside environment by a degradable polymer membrane. This device was modified to allow minimally invasive implantation with a large-bore needle and has demonstrated in vitro pulsatile release of a model compound after a mock implantation step. A biodegradable sealing method was developed for the polymeric microreservoir device, which makes the device completely resorbable and eliminates the surgical removal step needed with a non-resorbable device. Localized sensing systems will allow early detection of diseases and provide a tool for developing personalized treatment programs. The polymer microchip platform has been combined with magnetic relaxation switch (MRSw) nanoparticle sensors to create an in vivo sensing device. MRSw are magnetic nanoparticles (iron oxide core, crosslinked dextran shell) that can detect a variety of analytes. MRSw are kept in the device by a molecular weight cut-off (MWCO) membrane which allows analytes free access to the nanoparticle sensors.
(cont.) The MRSw aggregate in the presence of the analyte they were designed to detect and this aggregation causes a decrease in the transverse relaxation time (T2), which can be detected with magnetic resonance imaging (MRI) or nuclear magnetic resonance relaxometry. In vitro sensing experiments were used to optimize the device design and characterize its performance. In vivo device-based sensing of hCG, a soluble biomarker that is elevated in testicular and ovarian cancer, has been demonstrated. Cell lines secreting hCG were used to produce ectopic tumors in nude mice. The sensing device was implanted and magnetic resonance imaging (MRI) quantified a T2 decrease in mice with tumors compared to control mice (no tumors). This device may be the first continuous monitoring device for cancer that can be implanted at the tumor site and demonstrates feasibility of MRSw measurements in vivo.
by Karen D. Daniel.
Ph.D.

Localized drug delivery is emerging as an effective technique due to its ability to administer therapeutic concentrations and controlled release of drugs to cancer sites in the body. It also prevents the contact of harsh chemotherapy drugs to healthy regions in the body that otherwise would become exposed to current treatments. This study reports on a model chemotherapy drug delivery system comprising non-ionic surfactant vesicles (niosomes) packaged within a temperature-sensitive chitosan network. This smart packaging, or package-within-a package system, provides two distinct advantages. First, the gel prevents circulation of the niosomes and maintains delivery in the vicinity of a tumor. Secondly, the chitosan network protects the niosomes against fluctuations in tonicity, which affects delivery rates. Tonicity is the sum of the concentrations of the solutes which have the capacity to exert an osmotic force across the membrane. Release rates were monitored from both bare niosomes alone and niosome-embedded, chitosan networks. It was observed that chitosan networks prolonged delivery from 100 hours to 55 days in low ionic strength environment and pH conditions similar to a tumor site. The primary effect of chitosan is to add control on release time and dosage, and stabilize the niosomes through a high ionic strength surrounding that prevents uncontrolled bursting of the niosomes. Secondary factors include cross-link density of the chitosan network, molecular weight of the individual chitosan polymers, dye concentration within the niosomes, and the number density of niosomes packaged within the chitosan network. Each of these factors can be altered to fine-tune release rates. Release rate experiments were conducted with 5,6-carboxyfluorescein, a fluorescent dye and chemotherapeutics paclitaxel and carboplatin. In vitro studies showed a preferential affinity of the smart packaged system to ovarian carcinoma cell line OV2008 as compared to normal epithelial cell lines of Ilow and MCC3. Further, feasibility of the drug delivery system was evaluated in vivo. Toxicity studies revealed that the system was non-toxic and feasible in vivo. The final outcome of this study includes tuning of the variables mentioned above that will contribute to the development of low cost and improved methods for drug delivery with application to intracavitary ovarian cancer treatment and other types of cancer

Methods of guiding magnetic particles in a controlled fashion through the arterial system in vivo using external magnetic fields are explored. Included are discussions of applications, magnetic field properties needed to allow guiding based on particle characteristics, hemodynamic forces, the uniformity of field and gradients, variable tissue characteristics, and imaging techniques employed to view these particles while in transport. These factors influence the type of magnetic guidance system that is needed for an effective drug delivery system. This thesis reviews past magnetic drug delivery work, variables, and concepts that needed to be understood for the development of an in vivo magnetic drug delivery system. The results of this thesis are the concise study and review of present methods for guided magnetic particles, aggregate theoretical work to allow proper hypotheses and extrapolations to be made, and experimental applications of these hypotheses to a working magnetic guidance system. The design and characterization of a magnetic guidance system was discussed and built. The restraint for this system that balanced multiple competing variables was primarily an active volume of 0.64 cm3, a workspace clearance of at least an inch on every side, a field of 0.3T, and a local axial gradient of 13 T/m. 3D electromagnetic finite element analysis modeling was performed and compared with experimental results. Drug delivery vehicles, a series of magnetic seeds, were successfully characterized using a vibrating sample magnetometer. Next, the magnetic seed was investigated under various flow conditions in vitro to analyze the effectiveness of the drug delivery system. Finally, the drug delivery system was successfully demonstrated under limiting assumptions of a specific magnetic field and gradient, seed material, a low fluid flow, and a small volume.
Master of Science

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.
Includes bibliographical references (p. 52-55).
Local drug delivery is a fast expanding field, and has been a center of attention for researchers in medicine in the last decade. Its advantages over systemic drug delivery are clear in cancer therapy, with localized tumors. A silicon microelectromechanical drug delivery device was fabricated for the purpose of delivering chemotherapeutic agents such-as carmustine, a potent brain cancer drug, directly to the site of the tumor. Limitations in the delivery capacity of the device led to the design of a new package. This package is made from thermally bonded Pyrex® 7740 frames that are anodically bonded to the drug delivery chip. It increases the capacity of the chip, is smaller than the previous package and possesses true hermeticity, because of the bonding processes involved. This work describes the fabrication steps of the new package and a problem with the thermal bonding of Pyrex® frames preventing the achievement of a package true to the original design. A temporary solution was devised and the completed package was tested with regards to its intended goals. It managed to increase the load capacity of the chip by a, factor of 10, with potential for more, while decreasing the overall size of the package. Short-term hermeticity was achieved for this package by using a UV-cured epoxy to bond some pieces, which was not in the original design. Future work will focus on finding a permanent solution to the aforementioned problem, and directions for it were suggested.
by Hong Linh Ho Duc.
S.M.

The ultimate aim of this project was to design new biomaterials which will improve the efficiency of ocular drug delivery systems. Initially, it was necessary to review the information available on the nature of the tear fluid and its relationship with the eye. An extensive survey of the relevant literature was made. There is a common belief in the literature that the ocular glycoprotein, mucin, plays an important role in tear film stability, and furthermore, that it exists as an adherent layer covering the corneal surface. If this belief is true, the muco-corneal interaction provides the ideal basis for the development of sustained release drug delivery. Preliminary investigations were made to assess the ability of mucin to adhere to polymer surfaces. The intention was to develop a synthetic model which would mimic the supposed corneal/mucin interaction. Analytical procedures included the use of microscopy (phase contrast and fluorescence), fluorophotometry, and mucin-staining dyes. Additionally, the physical properties of tears and tear models were assessed under conditions mimicking those of the preocular environment, using rheological and tensiometric techniques. The wetting abilities of these tear models and opthalmic formulations were also investigated. Tissue culture techniques were employed to enable the surface properties of the corneal surface to be studied by means of cultured corneal cells. The results of these investigations enabled the calculation of interfacial and surface characteristics of tears, tear models, and the corneal surface. Over all, this work cast doubt on the accepted relationship of mucin with the cornea. A corneal surface model was designed, on the basis of the information obtained during this project, which would possess similar surface chemical properties (i.e. would be biomimetic) to the more complex original. This model, together with the information gained on the properties of tears and solutions intended for ocular instillation, could be valuable in the design of drug formulations with enhanced ocular retention times. Furthermore, the model itself may form the basis for the design of an effective drug-carrier.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, February 2015.
Cataloged from PDF version of thesis. "February 2015."
Includes bibliographical references.
Traumatic joint injuries significantly increase synovial fluid levels of pro-inflammatory cytokines that can initiate cartilage degeneration leading to osteoarthritis (OA). Articular cartilage is a highly negatively charged, avascular tissue, which relies on synovial fluid convection and electro-diffusion to transport proteins and therapeutics to tissue chondrocytes. No OA drug has yet passed the safety criteria of clinical trials due to ineffective intra-articular (i.a.) delivery methods, which require very high drug doses that cause systemic toxicity. There is a need to design local delivery mechanisms that can enable drugs or drug carriers to rapidly diffuse into the cartilage extracellular matrix to achieve intratissue therapeutic levels before these drugs are cleared from the joint space via lymphatics and synovium vasculature. This dissertation investigates the effects of size and charge of solutes on their penetration, binding and retention within negatively charged tissues such as cartilage. Based on this understanding we selected Avidin, a globular protein, as a drug carrier owing to its optimal size and high positive charge (66,000 Da, pI 10.5). Avidin resulted in a six-fold upward Donnan partitioning factor at the synovial fluid-cartilage interface, had a 400-fold higher uptake than its electrically neutral counterpart (Neutravidin), and remained bound within cartilage for at least 15 days. Competitive binding experiments revealed that despite Avidin's weak and reversible ionic binding (dissociation constant, KD ~150 [mu]M) to the negatively charged glycosaminoglycans, its long term retention was facilitated by large intratissue binding site density (NT ~ 2,920 [mu]M). Thus, structures like Avidin are ideal candidates for local i.a. drug delivery into cartilage. In vivo animal studies revealed that Avidin retained inside the joint space for extended time periods resulting half-life of 154h in rabbit cartilage which was 5-6 times longer than that in the thinner rat cartilage. This was confirmed to be consistent with the concept that diffusion-binding kinetics scale as the square of tissue thickness, emphasizing the necessity of using larger animal models for studying joint space transport and pharmacokinetics. Avidin's neutral counterpart (Neutravidin) was completely cleared from the joint space of both rats and rabbits within 24h. We then conjugated Avidin with the glucocorticoid, dexamethasone, using chemical linkers to enable its sustained release. Avidin delivered dexamethasone into cartilage deep zones where majority of chondrocytes reside thereby successfully inhibiting cytokine-induced catabolic activity in cartilage explants in-vitro. A single i.a. injection of Avidin-conjugated drug can thereby enable sustained drug delivery in low doses and therefore has the potential to replace the current clinical practice of using multiple injections of high dose glucocorticoids in patients. The biological efficacy of this system in rescuing degenerative mechanisms of OA is currently being validated in a well-accepted rabbit model of post-traumatic OA as part of a preclinical study.
by Ambika Goel Bajpayee.
Ph. D.

Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 111-117).
Triple negative breast cancer (TNBC) is an aggressive form of cancer that represents 20% of invasive breast cancers, and about 15% are locally advanced at time of presentation. TNBC is negative for estrogen and progesterone receptor, as well as for HER2, and hence it is not treatable with common endocrine treatment such as tamoxifen or Herceptin. Systemic neoadjuvant therapy has been established as the preferred therapeutic approach for locally advanced breast cancer, downstaging the disease and preventing mastectomy. However, complications of systemic chemotherapy are devastating. Local therapy would prevent high concentrations of circulating drug and reduce off-target tissue retention. Yet, the means to attain ideal release kinetics and selective uptake remain elusive. I developed a novel class of biocompatible and biodegradable adhesive materials based on dendrimer and dextran that can coat the tumor and locally release doxorubicin in a controlled manner. Doxorubicin was conjugated to the dendritic component of the adhesive hydrogel to form a pro-drug capable of being released over time as the hydrogel degrades at a pre-programmed rate. The pro-drug was further modified with a ligand capable of sensing and discerning between healthy and cancer cells and facilitating uptake through receptor-mediated endocytosis (RME). The platform developed herein provides a paradigm shift in the way we treat cancer, in a local, selective and targeted manner, to impart optimal clinical outcome.
by Nuria Oliva Jorge.
Ph. D.

The objective of this research was to investigate two important aspects of buccal drug delivery, transport and mucoadhesion. Buspirone was chosen as a model drug for the in vitro buccal transport studies, polyvinyl alcohol and sodium alginate polymer blends were prepared to investigate the mucoadhesive properties through a Lewis acid-base approach and finally, the effect of formulation factors on the force of mucoadhesion, surface energy parameters, release rate and flux was studied. In vitro permeation studies were conducted to investigate the buccal transport pathway of buspirone. Mathematical models were developed to quantify the process of permeation. Permeation enhancement of buspirone across the buccal mucosa was investigated using bile salts (sodium glycocholate and taurodeoxycholate), propylene glycol, propylene. Effect of formulation factors like drug, enhancer, and plasticizer was studied through statistically designed experiments. These experiments aided in characterizing the buccal delivery system. Mathematical models were developed for surface energy parameters, force of mucoadhesion, release rate, and flux. Research conducted in this dissertation focused on two important aspects of transbuccal delivery, drug transport and mucoadhesion by studying a model drug and polymer blends. The results obtained in these investigations can be utilized in the development of other bioadhesive delivery systems with respect to drug transport and mucoadhesion. Polymer blends of polyvinyl alcohol (PVA) and sodium alginate (Alg) were prepared to evaluate their mucoadhesive properties and investigate mucoadhesive mechanism by a Lewis acid-base approach. (Abstract shortened by UMI.)

The work in this thesis has covered three main topics; i) cytotoxic polyamine-conjugates ii) radiation protection polyamine-conjugates iii) polyamine conjugates which probe cellular uptake and DNA binding. The synthesis of these conjugates employed selective protection/deprotection steps, taking advantage of the BOC protecting groups regioselectivity of primary over secondary amines when reacting with naturally occurring polyamines. After promising in vitro and in vivo results of the original spermidine-chlorambucil synthesised by Wheelhouse (1990), attempts were made to improve this compound. The terminal amines were ethylated. The new diethyl derivative showed greater inhibition of [C14] labelled spermidine entry into cultured cells, and improved cytotoxicity. Also a new novel cis-platin polyamine conjugate was synthesised and tested for cellular inhibition of radiolabelled spermidine and cytotoxicity. It failed to recognise the polyamine uptake receptor and gave poor [C14] spermidine inhibition results and subsequently cytotoxicity. Two radiation protection polyamine agents were synthesised and tested against the indirect radiation damage pathway, both N1 and N4 mercaptoethyl spermidine. They both showed very good inhibition of [C14] labelled spermidine entry, the N1 derivative being twice as efficient as the N4. Dilute aqueous solutions of DNA were irradiated with various thiols present. Surprisingly the positively charged thiols protected to a similar extent as the negatively charged thiols, as it was expected that the primary mechanism for protection against the indirect effect was bulk water scavenging of the hydroxyl radical. An EDTA-polyamine conjugate was also synthesised and investigated and it showed moderate [C14] labelled spermidine inhibition and cytotoxicity in preliminary experiments. The cytotoxicity was due to the fact that EDTA chelation to iron (II) produces hydroxyl radicals.

In chapter two, the development of new a nanoparticulate carrier system for gene delivery was described. The new nanocarrier consists of a blend matrix formed by a poly (lactic-eo-glycolic acid) (PLGA) and Poly(ethylene glycol) bis (3-aminopropyl) terminated (also known as JeffamineTM). Nanopartic1es were formulated based on a 50:50 weight ratio of PLGA:Jeffamine using a modified emulsification-solvent diffusion technique. The potential of these blended matrix nanoparticles for encapsulation efficiency of Calf Thymus DNA and release profile were also studied. The achieved encapsulation efficiency of Calf Thymus DNA was approximately 84% for 0.4% theoretical loading with regard to total amount of PLGA. The PLGA: Jeffamine blended nanoparticles provided continuous and controlled release of Calf Thymus DNA. The PLGA:Jeffamine nanopartic1es were also coated with PLGA-PEGMA&75and PDMAEMA-PEGMA block copolymers using a simple physical adsorption method. After surface coating of the nanoparticles, zeta potential value showed significant reduction of surface charges from -38 mV to near zero value, while TEM micrographs showed a well defined core-shell nanoparticle. In chapter three, A facile route to biocompatible poly (lactic acid-coglycolic acid)-co-poly (ethyleneglycol methacrylate) (PLGA-PEGMA) block co-polymers was described utilising a combination of ring-opening polymerisation (ROP) and Radical Addition Fragmentation Transfer (RAFT) methods. A series of PLGA-PEGMA polymers varying in comonomer content and block length were synthesised with low polydispersities. All the block co-polymers formed micelles in aqueous solution as shown by dynamic light scattering, while critical micelle concentrations were found to be in the micromolar range. The polymer micelles were able to encapsulate model drugs(carboxyfluorescein and fluorescein isothiocyanate) and selected copolymer micelles incubated with 3T3 fibroblasts as a model cell line were rapidly taken up as indicated by fluorescence microscopy assays. The combination of the polymer chemistries opens the way to highly flexible syntheses of micellar drug carrier systems. In chapter four, multifunctional and modular block co-polymers prepared from biocompatible monomers and linked by a bioreducible disulphide linkage have been prepared using a combination of ring-opening and atom-transfer radical polymerizations (ATRP). The presence of terminal functionality via ATRP allowed cell-targeting folic acid groups to be attached in a controllable manner, while the block co-polymer architecture enabled well-defined nanopartic1es to be prepared by a water-oil-water double emulsion procedure to encapsulate DNA with high efficiency. Gene delivery assays in a Calu-3 cell line indicated specific folatereceptor-mediated uptake of the nanoparticles, and triggered release of the DNA payload via cleavage of the disulfide link resulted in enhanced transgene expression compared to non-bioreducible analogues. These materials offer a promising and generic means to deliver a wide variety of therapeutic payloads to cells in a selective and tuneable way.

Microcapsules are fast becoming the most successful delivery systems for the oral delivery of drugs and food additives. Since many drugs are proteins and are destroyed in acidic conditions, microcapsules offer protection against the harsh environment of the gastrointestinal (GI) tract. Although the use of microcapsules achieves controlled release of the inner material, many synthetically designed microcapsules lack consistency in their size and morphology. The outer coat (exine) of plant pollen grains and spores is composed of the material sporopollenin. Sporopollenin exines (25µm diameter) were extracted from Lycopodium clavatum and were investigated as a novel drug delivery system that was inexpensive, non-toxic, from a renewable source, and exhibited a large internal cavity for loading of hydrophobic and hydrophilic substances. They showed many advantages over conventional microcapsules, including their constant chemical structure and size within a species, and their ability to offer UV and air-oxidation protection. Previous studies have shown that particles such as pollen, spores and starch migrate into the bloodstream following ingestion by a process termed 'Persorption'. Such findings intrigued many researchers but the phenomenon has not been unanimously accepted. This research is a body of evidence giving unequivocal confirmation that spores of Lycopodium clavatum and their emptied exines were absorbed into the bloodstream of man to the same extent following oral ingestion, with a maximum of 10% (± 2%) of the dose recovered just 15-30 minutes after ingestion. These findings resolve the debate between researchers in support of persorption and those against, whom doubted the transport of particles of micron size into the bloodstream, but did not disprove such a phenomenon. An extensive study was undertaken to investigate the effect of factors such as gender, age, quantity and the method of ingestion on the rate and extent of exine absorption into the bloodstream. In a preliminary in vivo experiment the successful delivery of fish oil into the bloodstream via sporopollenin exines was illustrated. A major breakthrough has formed the foundations of this research. Although sporopollenin exhibits incredible stability to organIc and inorganic solvents, in contrast, this research has shown that exines degrade very rapidly in blood plasma both in vitro and in vivo. In vitro experiments were conducted in an attempt to characterise the specific mechanism responsible for exine degradation. Progression of work has provided much evidence that the conversion of plasminogen to the enzyme plasmin is either partially or wholly responsible for the characteristic degradation of sporopollenin in the blood. Further investigations showed that it was possible to load a sufficient quantity of substances into sporopollenin exines, such as human growth hormone (hGH) , Enfurvitide (an antiretroviral agent used in the treatment of AIDS) and Cyclosporine (an antifungal agent). Their successful release from exines into different media in vitro and in vivo (carried out in Beagle dogs) was shown. These in vivo experiments highlighted the need for extra protection of the drug from the GI tract and additional coatings were applied to sporopollenin exines, including a soluble form of sporopollenin. Exines with coatings were assessed to ensure they were still able to degrade in blood and release the encapsulated substance. Current results are highly indicative that sporopollenin could become a practicable oral delivery system for molecules that are otherwise problematic to administer, such as protein drugs that degrade rapidly in acidic conditions.

The aim of this thesis was to develop biodegradable devices loaded with chemotherapy drug. The system is targeted for advanced ovarian cancer treatment through the intraperitoneal (IP) route of administration. Polylactide-co-glycolide (PLGA) was selected as the model biodegradable polymer to produce drug-loaded microsphere, hollow and solid fibres. Copolymer PLGA with three different lactic:glycolic acids ratios; 50:50, 65:35 and 75:25 were used in order to compare their drug loading capacities and in vitro drug release profiles. Cisplatin, a cytotoxic drug with proven activity against ovarian cancer was selected as the model chemotherapy drug. Intraperitoneal administration is often associated with abdominal pain therefore a local anaesthetic, lidocaine, was selected for the purpose of pain relief.

Phosphorylcholine (PC) based materials have been shown to have increased biocompatibility when compared to more established bio-implantable materials. This has been attributed to the ability of PC to mimic the cell lipid bilayer membrane, resulting in reduced protein adhesion and cellular interaction / activation. PC research has previously focused on the areas of contact lens formulation and medical device coating. This project sought to harness the biomimetic properties of PC to develop novel systems for drug delivery, with the emphasis being focused on microparticulate drug delivery.

It has been demonstrated that 1,25 dihydroxy vitamin D3 (1,25 (OH)2VD3) can inhibit the proliferation of cancer cells including colorectal and hepatocellular cells which are mainly responsible for liver cancer. However, the use of 1, 25 (OH)2VD3 is hampered due to the development of hypercalcaemia. Current treatment using hepatic arterial delivery of drug solution is inconvenient since repetitive invasive treatments are required. This work aims to tackle this problem by utilizing crosslinked microspheres prepared by suspension polymerization as a carrier to control the release of 1, 25 (OH)2VD3 or hydrophobic drug in general at targeted sites over a long period. Poly(vinyl neodecanoate crosslinked ethyleneglycol dimethacrylate) microspheres in the size range of 35 m were prepared via suspension polymerization. Different parameters in suspension polymerization such as temperature, concentration and crosslinker percentage were studied in details. The effect of stabilizer on the formation of spheres was carefully investigated by using RAFT polymerization to produce various structures of the stabilizer, poly (vinyl pyrrolidone). Core- shell microspheres were also produced to enhance the hydrophilicity of the surface of microspheres. Hydrophobic drugs were loaded to these microspheres after reaction by the evaporation method. These microspheres were then used for drug loading and drug release study. Release study has shown that up to 10% of drug was released after 40 days. Cytotoxicity test reveals the suitability of this polymer for application in biomedical field. The MTT assay of Clofazimine loaded microspheres on the colorectal cancer cell lines HT29 has shown that the cell number was decreased about 50% after drug treatment.

Osteoarthritis (OA) is a chronic degenerative disease of the joint. Current treatments for this disease (such as glucocorticoid steroids) aim to reduce pain and increase mobility. Intra-articular injection is used in OA as treatment can be targeted to affected joints only. There is currently a lack of sustained release formulations for intra-articular injection. The aim of this thesis was to produce and characterise an injectable intra-articular drug delivery system capable of providing delivery of the steroid dexamethasone phosphate (DXMP) over 3 months. This would be an injectable hydrogel that contains drug loaded nanoparticles. Initially two systems Pluronic F127 gels and polyelectrolyte complexes between hyaluronic acid (HA) and chitosan, were investigated. The complexes between HA and chitosan were selected for the hydrogel portion of this system as they showed the greatest stability and promise in initial studies. To improve the polyelectrolyte complex properties a modified HA was synthesised. This modified polymer caused faster complex formation and produced stronger, more resilient complexes. DXMP was incorporated into poly(glycerol-adipate) (PGA) nanoparticles. A low but sufficient drug loading was achieved and particles were found to give a sustained drug release over 28 days. Nanoparticles were found to be efficiently incorporated and well retained within complexes. Nanoparticles slightly improved complex formation and properties. Composites were able to be formulated into an injectable form. Drug release from directly loaded complexes was rapid. A full release profile was not determined from composites of nanoparticle loaded complexes, however, over 60% of the loaded drug was recovered after 56 days of release study. Dexamethasone crystals were also incorporated directly into complexes to investigate the necessity of the use of nanoparticles. This gave a sustained drug release over 90 days making this system worthy of further investigation. These results highlight the different responses of these systems using drugs with different hydrophobicities.

The aim of this research was to formulate, characterise and assess the feasibility of a novel drug delivery system known as the in situ gelling matrix (ISGM) where a hydrophilic polymer is suspended in a non-aqueous solvent that converts into a gel when injected subcutaneously or intramuscularly thus giving a controlled release matrix for a drug. Although the concept has been patented with claims that this kind of drug delivery is achievable in theory for a wide variety of candidate substances, actual formulation studies for making a commercially viable product for this technology are completely lacking in practice. The research embodied in this thesis addresses this lack. Initial studies involved conducting a biocompatibility study using the HET-CAM (hens egg test - chorioallantoic membrane) test on a range of possible ingredients for the delivery system. The materials deemed biocompatible were then carried through to a screening process where the physical stability of the hydrophilic polymers in non-aqueous solvents was monitored. It was found that the hydrophilic polymers tested sedimented rapidly in the non-aqueous solvents indicating such a system was not physically stable. Consequently, density-inducing or viscosity-inducing agents were added to the non-aqueous solvents to retard the sedimentation rate. The addition of polycarbophil, a viscosity-inducing agent, clearly increased the viscosity of the system. However, undesirable formation of polycarbophil globules occurred during the manufacturing process, which caused batch-to-batch variations in the viscosity of the continuous phase. Various manufacturing methods were tested before arriving at the optimum procedure to prevent globule formation using a high speed dispersion tool. A final physical sedimentation analysis of candidate continuous phases and hydrophilic polymers was conducted for determining the ideal combination of ingredients to use in the system. These investigations finally led to the adoption of an optimum mix of components consisting of 10% (w/w) hydroxypropyl methylcellulose (HPMC) (the hydrophilic polymer) suspended in a continuous phase of propylene glycol (the non-aqueous solvent) containing 0.67% (w/w) polycarbophil (the viscosity inducing agent). Using this mix of components, the in situ gelling matrix system was then subjected to various characterisation studies including infrared (IR), differential scanning calorimetry (DSC), ultraviolet-visible (UV-Vis) spectrophotometry and redispersion studies. The chemical stability of the hydrophilic polymer and the continuous phase (the non-aqueous solvent and polycarbophil) was monitored and were found to be chemically stable over a 9 month period. The feasibility of the in situ gelling matrix technology as a controlled release device was assessed using the drug propranolol. In vitro drug release studies were conducted using a custom-built dissolution apparatus. The effect of various parameters such as the concentration of the hydrophilic gelling agent on the drug release rate was investigated. Increasing the concentration of the gelling agent in the formulation resulted in a slower rate of release. The drug release data were modelled using the Higuchi relationship and a power law relationship to compare the effects of the various parameters on the release rate Stability studies on the drug in the in situ gelling matrix system were carried out by storing samples in accelerated ageing conditions of 40 C / 75% relative humidity for 4 weeks. During this time, the samples were analysed each week by high performance liquid chromatography (HPLC). These demonstrated that no apparent drug degradation had occurred over the 4-week period. This indicates that the drug propranolol in the in situ gelling matrix system is stable under ambient conditions for at least 4 weeks. The results of this study demonstrated that the in situ gelling matrix technology is potentially viable as a drug delivery system and provide a practical methodology for the commercial development of such systems.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004; and, (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2006.
Includes bibliographical references (leaves 89-90).
The advantages of delivering injections via needle-free methods are numerous. However, conventional methods for needle-free injection lack sufficient control over depth of penetration and shape of injection. Thus, a needle-free injector was designed, constructed, and tested, using a controllable linear Lorentz-force actuator. This actuator allows rapid control of the injection pressure during injections. Using this device, precise control over delivery parameters can be achieved. In addition, several portable power systems for this injector were developed, allowing the energy-intensive needle-free injector to be used in the field. The injector design was tested for repeatability and use for both in-vitro and in-vivo testing on murine tissue using a bacterial collagenase.
by Brian D. Hemond.
M.Eng.
S.B.

The aim of this body of work was to characterise a novel cisplatin drug delivery system and to develop new tools based on biophotonic imaging that could be used to enhance studies of drug delivery in vivo. Cucurbiturils (CB) are macrocycles which are formed by acid catalysed condensation of glycoluril and formaldehyde. The internal cavity of CB[7] encapsulates a single molecule of cisplatin and the hypothesis was that encapsulation would reduce thiol degradation of the drug. Drug sensitivity studies in vitro with the cisplatin-sensitive human ovarian cancer cell line, A2780, and a cisplatin-resistant derivative, A2780/cp70, showed that the CB[7] encapsulated cisplatin retained activity but that this encapsulation drug delivery system was not able to overcome resistance to platinum. However, when these cell lines were grown as subcutaneous xenografts in nu/nu mice, the encapsulated cisplatin was able to reduce the growth of A2780/cp70 tumours which are resistant to the maximum tolerated dose of cisplatin in vivo. One possible explanation of this observation is that encapsulation might alter the pharmacokinetics of cisplatin and a method for the detection of platinum in biological samples by ICP-MS was established and validated. This assay was sufficiently sensitive to detect the low levels of platinum present in mouse plasma 24 hours after administration of either free or encapsulated cisplatin. Plasma and tissue pharmacokinetics show that encapsulation had no effect on the peak plasma concentration of cisplatin but did reduce the rate at which cisplatin was cleared from the plasma. The increased plasma AUC of cisplatin resulted in a non-selective increase in the delivery of cisplatin to both tumour and normal tissues. However, there was no apparent increase in toxicity which could be explained by the fact that encapsulation, unlike an increase in the dose of free cisplatin, had no effect on the peak plasma concentration. Subcutaneous xenografts lack critical features of human tumours. The development of more complex models for use in drug development has been limited due to lack of a method for monitoring tumour growth. Biophotonic imaging was, therefore, investigated to determine whether it is sufficiently sensitive and reproducible to be able to evaluate growth of disseminated tumours in mice. The bioluminescent signal is dependent on the metabolism of luciferin by luciferase. Subcutaneous injection of luciferin was shown to produce a consistent signal in all injected mice. The bioluminescent signal was transient but reached a maximum intensity 6 minutes after injection and remained stable for about 4 minutes which defined the window during which measurements were taken. Sensitivity was shown to be dependent on the level of expression of luciferase by the cells. Injection of commercially available HCT116Luc cells, where the luciferase gene was inserted by a lentiviral system, was shown to allow detection of 10,000 cells in the lungs of mice. This sensitivity was about 10 fold greater than was obtained by lipofectamine based gene transfection. When HCT116Luc cells were grown as subcutaneous xenografts in mice, an exponential growth pattern was easily detected by bioluminescence imaging and the reproducibility between mice was comparable to that routinely obtained by calliper measurements. Activity of encapsulated cisplatin was determined in a model of disseminated ovarian cancer. Rab25, a member of the RAS oncoprotein superfamily, is up-regulated in around 80% of ovarian cancer samples compared to normal ovarian epithelium. Rab25 contributes to tumour progression by enabling the tumour cells to invade the extracellular matrix by altering the trafficking of integrin. Transfection of Rab25 into A2780 cells results in cells that can grow in the peritoneal cavity of mice. A2780-Rab25 cells were 4 fold resistant to cisplatin in vitro which confirms a previous observation that Rab25 expression in A2780 makes them less sensitive to the induction of apoptosis in response to stress. A2780-Rab25 cells that express the luciferase gene (A2780-Rab25Luc) were injected into the peritoneal cavity of mice and growth was measured by biophotonic imaging. Exponential growth was clearly apparent at a stage at which no obvious abdominal distension was apparent. The disseminated A2780-Rab25Luc tumour xenografts were less sensitive to cisplatin than are subcutaneous xenografts of A2780. This is the first study that suggests that Rab25 over-expression results in reduced drug sensitivity in vivo. In contrast, a very significant growth inhibition was observed when mice were treated with an equivalent dose of encapsulated cisplatin regardless of whether it was administered by the intraperitoneal or subcutaneous route. These results are very encouraging since they confirm the enhanced activity of encapsulated cisplatin and also demonstrate the value of biophotonic imaging for measurement of tumour growth in vivo. Pharmacodynamic measures of drug activity in vivo in animal models are often based either on measures of surrogate tissue response or on single measures on tumour tissue removed at the end of the experiment. Biophotonic imaging in vivo allows the translation of reporter assays used in cell lines in vitro to studies of tumour response in vivo. A plasmid was prepared that links the p53 transcriptional response element to the luciferase gene and it was then transfected in to A2780 cells which express wild type p53. Stable transfectants of A2780p53Luc were treated with cisplatin, doxorubicin and paclitaxel and induction of p53 determined by bioluminescence and confirmed by Western blotting. A very low bioluminescent signal was present in untreated cells and a clear dose dependent increase in bioluminescence was seen in response to all three drugs. When A2780p53Luc cells were grown as subcutaneous xenografts the bioluminescent signal was significant in untreated tumours but was markedly increased 24 hours after treatment of the mice with cisplatin. Induction of p53 in the tumours was confirmed by immunohistochemistry and this also confirmed significant expression of p53 in untreated tumours. The possible implications of these findings for the improved delivery of cisplatin are discussed.

PEGylation has become very popular for the generation of nanomedicines with improved protein delivery properties, despite its lack of biodegradability. Researchers usually try to maximise retained protein activity during PEGylation. However, this proof of principle study aimed to create an inactive peptide or enzyme product, using a biodegradable polymer, that would elicit minimal activity/non-specific toxicity on administration. Following triggered site-specific degradation of the polymer, the hypothesis was that protein activity could be slowly regenerated in the general circulation or localised to a specific target site. Model conjugates were synthesised by coupling dextrin degraded by amylase to trypsin and melanocyte stimulating hormone MSH, to test this concept and targeted delivery for both an enzyme and a receptor-binding ligand. Hyaluronic acid HA degraded by hyaluronidase conjugates of trypsin and ribonuclease A were also synthesised. The latter was intended to develop the possibility of designing novel anti cancer conjugates. A higher molecular weight dextrin 47,200 g/mol, 26 mol succinoylation was shown to best mask 34 trypsin activity and reinstate 58 of the activity by addition of amylase. When a HA fraction molecular weight 130,000 g/mol was prepared by acid hydrolysis and conjugated to trypsin 4 w/w, trypsin activity was masked to 6 and immediately re-instated to 24 on addition of hyaluronidase. Similarly, the dextrin-MSH conjugate reduced melanin production to 11 of the control and only restored to 33 on addition of amylase. RNase A alone was not cytotoxic up to 1 mg/mL, whereas, the HA-RNase A conjugate 0.1 mg/mL RNase A equivalent was cytotoxic in B16F10 and CV-1 cells 72 h. This work provides proof of principle for the concept of using biodegradable polymers to mask and reinstate conjugated protein activity in the presence of the appropriate enzyme 'unmasking' trigger.

Aquasomes are nanocarrier systems consist of three distinctive layers; an inner core, a polyhydroxy carbohydrate layer and an outer layer of an API (Kossovsky et al., 1991). Aquasomes have a unique structure and ability to carry active molecules through a non-covalent bounding and provide superior stability, especially for proteins and peptides (Masatoshi and Yongning, 1998; Kim and Kim, 2002; Khopade et al., 2002). Different core and coating materials were used to prepare aquasomes under different conditions to investigate the relationship between preparation conditions and loading efficiency. In terms of loading efficiency, hydroxyapatite aquasomes, with either lactose or trehalose as a coating material, had the highest BSA loading (40%-60%) when compared to DSPA aquasomes. While DCPA aquasomes, with either lactose or trehalose as a coating material, had the lowest BSA loading (8%-16%). To investigate the interaction of the three layers of aquasomes, Surface analysis, docking and MD simulations were performed. Surface analysis performed by Discovery Studio showed that HA and trehalose interact by hydrogen bonding with the later acting as a hydrogen acceptor, while BSA displayed almost complete SAS and that there are numerous targets for trehalose attachments (no specific active site). MD simulations of BSA performed by AMBER 12 showed a stable MD simulation of BSA for 5 ns. Total energy analysis of BSA on the two conditions performed (300K and 280K) support the experimental data of lower BSA loadings of aquasomes prepared at 400C compared to those manufactured at 250C (p < 0.05). This could be related to that BSA might have either started to denature/unfold or breaking up which eventually resulted in low BSA loadings obtained experimentally. The high loading efficiency highlights aquasomes as a promising carrier for the delivery of proteins and peptides. Following formulation Optimisation, two routes of delivery were investigated, pulmonary and oral routes. For pulmonary delivery of aquasomes, BSA-loaded aquasomes were successfully formulated as pMDI and DPI formulations. Both pMDI and DPI formulations were investigated to identify lung distribution of BSA-loaded aquasomes using NGI. In vitro release studies on the selected size fractions from NGI show a sustained release of BSA over a period of 6 hr. In order to complement the in vitro release data, cell culture studies were performed to demonstrate the controlled release effect of aquasomes with BEAS-2B cell lines. The release of salbutamol sulphate (model drug) from aquasomes post 2 hr started to slow gradually until it reached its highest difference at 6 hr (p<0.05) when compared to the control. For oral delivery of aquasomes, BSA-loaded aquasome tablets were successfully formulated with MCC as multifunctional excipient and talc as a lubricant. Various powder blends of varying aquasomes amounts (25, 37.5, 50, 62.5 and 75%) were prepared and compressed at increasing compression forces (0.5, 1, 2 and 3 tons). It was noticed that under high compression forces of 2 and 3 tons, BSA spreads out of BSA-loaded aquasomes as was presented with confocal microscopy images. Tablets compressed under 1 ton of compression force was therefore chosen for coating as it showed desirable tablet characteristics (hardness, disintegration etc.). Acrylic based coating was used to spray coat the tablets. The coated tablets were found to disintegrate in pH >5.5 and steadily release for 6 hr. Cell culture studies were conducted to demonstrate the controlled release effect of aquasomes using Caco-2 cell lines. The release of metronidazole (model drug) from aquasomes post 2 hr started to slow gradually until it reached its highest difference at 6 hr (p<0.05) when compared to the control.

Novel buccal mucoadhesive copolymers of acrylic acid (AA) and poly (ethylene glycol) monomethylether monomethacrylate (PEGMM), (P(AA-co-PEG)), were designed, synthesized, and characterized for systemic delivery of acyclovir across the buccal mucosa. To achieve spontaneous intimate contact between polymer and buccal mucosa, the surface properties of P(AA-co-PEG) were optimized for buccal adhesion by varying the composition of the copolymers. It was found that the mole ratio of the repeat units of PEG, ethylene glycol, to AA is of great importance for mucoadhesion. ATR-FTIR studies revealed that the PEG moiety enhanced intra- and intermolecular H-bond formation. The copolymer films containing 16 mole% PEGMM (PEG MW 400) and 1.3 wt% ethylene glycol dimethacrylate (EGDMA) yielded the most favorable mucoadhesive properties within the investigated range. Factors influencing drug loading included equilibrium hydration, crosslinking density, loading solution medium, and concentration of drug in loading solution. In vitro release studies, performed in isotonic McIlvaine buffer pH 6.8 (IMB), showed a Non-Fickian release behavior. The release of acyclovir from the buccal mucoadhesive films was controlled by a combination of diffusion and macromolecular chain relaxation mechanism. In vitro permeation studies were conducted to determine the buccal transport pathway of acyclovir and to investigate the feasibility of buccal delivery of the drug. The paracellular route was found as the dominant buccal transport route of acyclovir. Permeation enhancement of acyclovir across the buccal mucosa was investigated using 2-100 mM sodium glycocholate (SGC). In the presence of SGC, the drug permeability was enhanced 2 to 9 times. The mechanism of this enhancement was attributed to SGC facilitating the paracellular route. The feasibility of buccal delivery of acyclovir was demonstrated and controlled release was achieved for up to 12 hours from P(AA-co-PEG) devices with a unidirectional design. The rate-limiting barrier to drug delivery from the mucoadhesive device was found to be the buccal mucosa. The target flux for systemic delivery of acyclovir was achieved with the incorporation of SGC into the tailor-made mucoadhesive copolymers of acrylic acid and PEGMM.

As all the physiological processes in our body are controlled by multiple biomolecules, comprehensive treatment of certain disease conditions may be more effectively achieved by administration of more than one type of drug. Thus, the primary objective of this research was to develop a multilayered, polymer-based system for sequential delivery of multiple drugs. This particular device was designed aimed at the treatment of periodontitis, a highly prevalent oral inflammatory disease that affects 90% of the world population. This condition is caused by bacterial biofilm on the teeth, resulting in a chronic inflammatory response that leads to loss of alveolar bone and, ultimately, the tooth. Current treatment methods for periodontitis address specific parts of the disease, with no individual treatment serving as a complete therapy. The polymers used for the fabrication of this multilayered device consists of cellulose acetate phthalate (CAP) complexed with Pluronic F-127 (P). After evaluating morphology of the resulting CAPP system, in vitro release of small molecule drugs and a model protein was studied from both single and multilayered devices. Drug release from single-layered CAPP films followed zero-order kinetics related to surface erosion property of the association polymer. Release studies from multilayered CAPP devices showed the possibility of achieving intermittent release of one type of drug as well as sequential release of more than one type of drug. Mathematical modeling accurately predicted the release profiles for both single layer and multilayered devices. After the initial characterization of the CAPP system, the device was specifically modified to achieve sequential release of drugs aimed at the treatment of periodontitis. The four types of drugs used were metronidazole, ketoprofen, doxycycline, and simvastatin to eliminate infection, inhibit inflammation, prevent tissue destruction, and aid bone regeneration, respectively. To obtain different erosion times and achieve appropriate release profiles specific to the disease condition, the device was modified by increasing the number of layers or by inclusion of a slower eroding polymer layer. In all the cases, the device was able to release the four different drugs in the designed temporal sequence. Analysis of antibiotic and anti-inflammatory bioactivity showed that drugs released from the devices retained 100% bioactivity. Following extensive studies on the in vitro sequential drug release from these devices, the in vivo drug release profiles were investigated. The CAPP devices with different release rates and dosage formulations were implanted in a rat calvarial onlay model, and the in vivo drug release and erosion was compared with in vitro results. In vivo studies showed sequential release of drugs comparable to those measured in vitro, with some difference in drug release rates observed. The present CAPP association polymer-based multilayer devices can be used for localized, sequential delivery of multiple drugs for the possible treatment of complex disease conditions, and perhaps for tissue engineering applications, that require delivery of more than one type of biomolecule.

Controlled release systems offer advantages over conventional therapies by maintaining drug concentrations at therapeutically desired levels whilst simultaneously improving compliance. Intrinsically Conducting Polymers (ICP) are organic materials that have electrical, magnetic and optical properties usually associated with metals, whilst retaining the advantageous mechanical properties and ease of processing usually associated with polymers. A novel drug delivery system, based on the ICP polypyrrole (PPy), has been developed to provide for the controlled release of risperidone. Due to the inherent properties of ICPs, electrical stimulation can be used to alter the redox state of PPy, which in turn can modify the release rate of drug. A validated, specific, stability indicating high performance liquid chromatography (HPLC) analytical method was used to quantify drug release from PPy films. PPy was selected as the platform material for drug delivery due to its inherent conductivity, ease of preparation and apparent biocompatibility. Various anionic dopants were trialled in the preparation of PPy films - p-toluene sulfonate produced the optimal formulation (PPy-pTS). PPy-pTS films were prepared containing risperidone (8.2 % w/w). Drug release profiles could be altered by applying different electrical stimulation. The rate of drug release could be increased or decreased by applying or withholding electrical stimulation. Atomic Force Microscopy was used to investigate changes in PPy film thickness when different stimuli were applied. The highest levels of drug release were observed when PPy was reduced; this was accompanied by expansion of the film. In order to be used clinically, the films must be functional over a defined shelf life. Stability studies suggested polymer morphology altered over time, accompanied by changes in risperidone release. In general, while aging slowed the rate of risperidone release from PPy films, release rates could be altered through electrical signalling in polymer films stored for up to 4 weeks at 40 ��C. This project relied on the multidisciplinary collaboration of pharmaceutical scientists, chemists and clinicians. The described technology could be utilised for implantable drug delivery devices, where the dose could be adjusted by external signalling, optimising patient benefit to side effect ratios while simultaneously ensuring compliance.

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A carbamazepina (CBZ) é um derivado tricíclico do iminoestilbeno com atividade farmacológica antiepiléptica. Entre os problemas deste fármaco está a sua autoindução com a necessidade de administração de até 4 vezes por dia, além da alta incidência de reações adversas, o que provavelmente está relacionado com a sua baixa solubilidade, visto que pertence à classificação biofarmacêutica de classe II. Dessa maneira, a tecnologia farmacêutica auxilia na redução de alguns desses problemas como, por exemplo, através da adsorção da CBZ a um excipiente inovador para que auxilia com a sua solubilidade e altere sua liberação, modulando e prolongando a dissolução do fármaco. Assim, esse trabalho objetivou desenvolver e caracterizar sistemas formados entre a CBZ e uma estrutura organometálica chamada ZIF-8, com a finalidade de ser empregada nos estudos de pré-formulação de forma farmacêutica de liberação prolongada para o tratamento da epilepsia. Os sistemas foram obtidos após agitação do fármaco e da ZIF-8 em diferentes solventes (metanol, etanol, e etanol:H₂O 61%) e proporções molares para que fosse escolhido o melhor meio reacional, através da melhor eficiência de incorporação. As caracterizações dos sistemas desenvolvidos foram realizadas, em seguida, através várias técnicas analíticas para assegurar a obtenção do sistema, procedendo com os ensaios de dissolução in vitro sob condições sink para verificar o comportamento da liberação da CBZ quando adsorvido à ZIF-8 em diferentes pH’s e em meios com presença e ausência de tensoativo. Os perfis de dissolução foram analisados através da área sob a curva (AUC), eficiência de dissolução (ED%), modelo-independente através do fator de similaridade (ƒ2). Por meio do método desenvolvido o escolhido para obtenção foi o realizado com etanol:H₂O 61% como solvente, na proporção molar 1:1 após 3 horas de agitação sem intervalos. Através das análises térmicas pode-se comprovar a obtenção do sistema, indicando que o mesmo também pode influenciar positivamente na estabilidade térmica do fármaco. Os espectros de FT-IR, difratogramas de DR-X e demais análises realizadas, corroboraram com os resultados, confirmando a formação do sistema CBZ-ZIF-8. O estudo de dissolução possibilitou verificar modulação da liberação do fármaco independente do pH utilizado, obtendo resultados de uma liberação máxima de 36,2% em pH 1,2 com 1% de lauril sulfato de sódio (LSS), contra 17,7%, 12,5% e 11,2% quando submetido aos meios sem LSS, com pH 1,2, pH 4,5 e pH 7,6, respectivamente, durante o período de 24 horas. O presente trabalho através dos resultados de liberação prolongada independente de pH, trouxe informações relevantes para o desenvolvimento de formas farmacêuticas de liberação modificada que utilize CBZ como insumo farmacêutico ativo.
Carbamazepine (CBZ) is a tricyclic derivative of iminostilbene with pharmacological antiepileptic activity. Among the problems of this drug is its self-induction with the need to administer up to 4 times a day, in addition to the high incidence of adverse reactions, which is probably related to its low solubility, since it belongs to the class II biopharmaceutical classification. Thus, pharmaceutical technology assists in the reduction of some of these problems, for example by adsorbing CBZ to an innovative excipient, which assists with its solubility and alters its release, modulating and prolonging the dissolution of the drug. Thus, this work aimed to develop and characterize systems formed between CBZ and an organometallic structure called ZIF-8, with the purpose of being used in the preformulation studies of pharmaceutical form of extended release for the treatment of epilepsy. The systems were obtained after agitation of the drug and ZIF-8 in different solvents (methanol, ethanol, and ethanol: H₂O 61%) and molar ratios to the best reaction medium chosen, through the best incorporation efficiency. The characterization of the developed systems was then performed through several analytical techniques to ensure the system was obtained, proceeding with the in vitro dissolution tests under sink conditions to verify the CBZ release behavior when adsorbed to ZIF-8 at different pH's And in media with presence and absence of surfactant. The dissolution profiles were analyzed through the area under the curve (AUC), dissolution efficiency (ED%), model-independent through the similarity factor (ƒ2). Using the developed method the chosen one was obtained with ethanol: H₂O 61% as solvent, in the 1: 1 molar ratio after 3 hours of agitation without intervals. Through the thermal analysis, it is possible to prove the system, indicating that it can also positively influence the thermal stability of the drug. The FT-IR spectra, DR-X diffractograms and other analyzes, corroborated the results, confirming the formation of the CBZ-ZIF-8 system. The dissolution study allowed to verify the modulation of the drug release independent of the pH used, obtaining results of a maximum release of 36.2% in pH 1.2 with 1% of sodium lauryl sulfate (LSS), against 17.7% 12.5% and 11.2% when submitted to the media without LSS, with pH 1.2, pH 4.5 and pH 7.6, respectively, during the 24 hour period. The present work through the results of independent release of pH, has brought important information for the development of pharmaceutical forms of modified release that uses CBZ as active pharmaceutical ingredient.

Total joint replacement (TJR) is commonly used for the treatment of end stage arthritis. The use of Poly-methylmethacrylate (PMMA) bone cement is a gold standard TJR, where it is frequently used for local delivery of antibiotics to provide prophylaxis from prosthetic joint infections (PJI). Currently used antibiotic loaded bone cements have many limitations, including burst release which fall below inhibitory levels leading to the selection of antibiotic resistant strains. This study aims to provide a controlled release for antimicrobial agents from bone cement to provide prophylaxis from postsurgical infections. For this purpose, gentamicin and chlorhexidine were loaded alone or in combination on silica nanoparticles surface using layer-by-layer coating technique (LbL). A novel LbL construct was built using hydrolysable and non-hydrolysable polymers. The nanoparticles were characterised by transmission electron microscopy, thermogravimetric analysis, zeta measurement, and drug release in different media. Then, antimicrobial agents LbL coated nanoparticles were incorporated into PMMA cement and the nanocomposite is characterized for drug release, antimicrobial, mechanical, rheological properties and cytocompatibility. The build-up of LbL coating was confirmed by thermogravimetric analysis and zeta measurements. The release of antimicrobial agents was controlled for > 30 days for different drugs used. The nanocomposite drug release profile also continued > 30 days at concentration higher than the commercial formula t ion containing the same amount of antibiotics, where burst release for few days were observed. Moreover, the nanocomposite showed superior antimicrobial inhibit ion for bacterial growth, without adversely affecting the mechanical properties. Different nanocomposites showed cytocompatibility when tested against Saos-2 cells. Techniques from a variety of disciplines were employed in this study and this interdisciplinary approach has allowed many features of PMMA bone cement to be investigated. The developed nanocomposites can have the potential to reduce PJIs, and the newly developed LbL nano-delivery system may have wider application in a variety of biomaterials.

Skin lesions are traumatic events that lead to the increase of fluid loss, infections, scarring and locally immunocompromised regions. These injuries can be caused by genetic disorders, acute trauma or even surgical interventions. In these situations, a substantial area of skin can be damaged, often without the possibility of being regenerated. Scientists have put a lot of effort in the development of suitable drug delivery systems suitable to release therapeutic molecules that are required for the initials phases of the wound healing process. Cell microencapsulation arises as an alternative approach for sustained in situ cell delivery. This technology is based on the immobilization of cells within a polymeric matrix, surrounded by a semi-permeable membrane, that isolate the encapsulated cells from the host immune system. Nonstanding, the microparticulate matrix still allows the exchange of nutrients, gases, waste and releasing of bioactive molecules, such as extracellular matrix components and growth factors secreted by cells. Nevertheless, the optimization of cell-based therapy demands the development of alternative strategies to improve cell administration. Alginate has been used for cell microencapsulation, due to its simple gelling process, excellent biocompatibility, biodegradability properties and its stability under in vivo conditions. On the other hand, nanoparticulate systems have been widely used in the biomedical field, as drug delivery devices that can improve the efficiency and widening the applications of the microencapsulation systems. Therefore, the present study aimed to develop biodegradable alginate microparticles that were used for human fibroblasts cells and chitosan nanoparticles encapsulation, in order to improve the wound healing process. To do so, two types of microparticles were firstly produced with alginate and a mixture of alginate and collagen. Subsequently, these carriers were characterized according to their size and geometry by scanning electron microscopy. Confocal images were also acquired to confirm cell encapsulation in microparticles. The cytotoxic profile of the carriers was assessed. Cell release from microparticles was observed over time after encapsulation through optical microscopic analysis. In second part of the work, chitosan nanoparticles loaded with a model protein (bovine serum albumin) were produced and were incorporated in microparticles. The encapsulation efficiency of this protein in nanoparticles was determined. Then, both the morphology and size of these nanoparticles were characterized. The results herein obtained showed that the developed microparticles and nanoparticles can be used as systems tailored for sustainable cells and drug release.
As lesões na pele são acontecimentos traumáticos que levam ao aumento da perda de fluidos, a infecções, à formação de cicatrizes e ao aparecimento de regiões imunocomprometidas. Estas feridas podem ser causadas por desordens de origem genética, traumas ou mesmo devido a cirurgias. Deste modo, uma área substancial da pele pode ser danificada, muitas vezes sem a possibilidade de regeneração. Os investigadores têm procurado desenvolver novos sistemas de entrega de drogas, de forma a acelerar o processo de cicatrização. O microencapsulamento celular surgiu recentemente como uma nova abordagem, para entrega controlada e de longa duração de agentes terapêuticos produzidos e secretados pelas próprias células, tais como componentes da matriz extracelular e factores de crescimento, os quais são essenciais para a regeneração. Esta tecnologia tem por base a imobilização de células, dentro de uma matriz polimérica rodeada por uma membrana semi-permeável. Assim, as células não são reconhecidas pelo sistema imunitário do hospedeiro e a membrana permite a difusão de nutrientes e gases para o interior da matriz e a saída das moléculas bioactivas secretadas pelas células e dos resíduos resultantes do metabolismo celular. No entanto, a terapia celular necessita ainda de ser optimizada. O alginato é um polímero que tem sido usado para o encapsulamento celular, devido ao seu fácil processo de gelificação, excelente biocompatibilidade, biodegradabilidade e estabilidade in vivo. Por outro lado, os sistemas nanoparticulados têm sido amplamente utilizados em aplicações biomédicas, por exemplo na produção de dispositivos de entrega direcionada de moléculas bioactivas, uma vez que permitem obter um perfil de libertação controlado. O presente trabalho teve como objectivo o desenvolvimento de micropartículas de alginato para encapsular fibroblastos humanos e nanopartículas de quitosano, com o intuito de futuramente serem usadas como agentes promotores da cicatrização de feridas. Inicialmente, foram produzidos dois tipos de micropartículas, um à base de alginato e outro de alginato com colagénio. As micropartículas produzidas foram caracterizadas quanto ao seu tamanho e geometria por microscopia electrónica de varrimento. Posteriormente, foram também adquiridas imagens de confocal para confirmar o encapsulamento de células nas micropartículas. O perfil citotóxico dos transportadores foi caracterizado através de testes de viabilidade celular, os quais confirmaram a biocompatibilidade dos transportadores. O perfil de libertação das células foi observado por análise microscópica ao longo dos dias. Numa segunda parte do trabalho foram produzidas nanopartículas de quitosano com o objetivo de serem incorporadas nas micropartículas como transportadores de factores de crescimento e, assim, favorecer a cicatrização das feridas. A eficiência de encapsulação das nanopartículas foi avaliada através da incorporação de uma proteína modelo, albumina de soro bovino. Posteriormente fez-se a caracterização da morfologia e do tamanho destas nanopartículas. Os estudos efectuados demonstraram que o sistema desenvolvido é adequado para a libertação de células e moléculas bioativas de forma controlada, prolongada e em concentrações fisiológicas.

Ovarian cancer has the highest mortality rate of all gynecological malignancies, due to inadequate treatment strategies and poor early diagnosis. Intraperitoneal (IP) chemotherapy administered on an intermittent schedule has been pursued for ovarian cancer treatment. However, local toxicities and complications associated with indwelling IP catheters required to deliver the chemotherapeutics have been documented. Furthermore, shortening or completely removing treatment-free periods between each chemotherapy cycle has shown improved efficacy compared to intermittent chemotherapy. The focus of this thesis was to develop and characterize a biocompatible and biodegradable IP injectable depot sustained drug delivery system as a new treatment strategy for ovarian cancer. A polymer-lipid injectable formulation (PoLigel) was developed and used for sustained docetaxel (DTX) delivery. The PoLigel resulted in homogeneous DTX peritoneal distribution and sustained plasma levels in healthy mice, which was in contrast to Taxotere®, the clinically used formulation of DTX. Sustained plasma, tissue, tumor and ascites DTX concentrations were observed in mice bearing IP SKOV3 tumors or ID8 ascites over a 3 week period following IP administration of the PoLigel. The intratumoral distribution and tumor penetration of DTX in subcutaneous (SC) and IP SKOV3 tumors were characterized. DTX distributed more towards the tumor core and diffused 1.5 fold further from blood vessels of the IP tumors compared to the SC tumors. The high efficacy observed in the IP SKOV3 and ID8 models and the SC SKOV3 model was attributed to favorable drug distribution at the whole-body, peritoneal and intratumoral levels in combination with local and systemic sustained drug exposure. Sustained chemotherapy with DTX alone and in combination with a drug efflux transporter inhibitor was investigated in multidrug resistant (MDR) ovarian cancer. In vitro, combination delivery via the PoLigel resulted in more apoptosis, greater intracellular accumulation of DTX, and lower DTX efflux in MDR ovarian cancer cells. Sustained combination chemotherapy was more than twice as efficacious as intermittent Taxotere® treatment in MDR ovarian cancer. Significant anti-tumor efficacy was also observed in the MDR model following sustained DTX chemotherapy compared to intermittent Taxotere®. Overall, results presented here encourage the clinical investigation of IP sustained chemotherapy for ovarian cancer treatment.

The integration of bioactive and biomimetic signals into materials for drug delivery and tissue engineering serves to improve cellular responses and therefore healing by more closely resembling the natural cellular microenvironment. The materials developed in this thesis show promise in delivering therapeutic doses of nitric oxide (NO) to physiological systems and provide novel surfaces for the study of cell adhesion and spatial organization. NO has several biological functions that make it an ideal candidate therapeutic agent for the prevention of the occlusive scarring of blood vessels following treatment of coronary artery disease through procedures such as balloon angioplasty and bypass grafting. The present work incorporates NO donors into polymeric biomaterials, resulting in copolymers that release NO over controllable time frames depending on material design. These NO-generating polymers have proven effective in significantly reducing platelet adhesion and smooth muscle cell proliferation in vitro. Endothelial cells exposed to these materials displayed enhanced proliferation, which is essential in restoring vessel function. Local, sustained release of NO from perivascularly-applied hydrogels reduced unwanted neointimal formation by approximately 90% in an experimental balloon angioplasty model. Novel NO releasing dendrimers have been synthesized to establish the potential for injectible NO therapy and can be targeted to sites of active vascular disease. NO-releasing polyurethane has been synthesized as a candidate material for vascular grafts. The superior mechanical properties of polyurethane combined with the inhibition of platelet adhesion by NO promise increased patency in small diameter vascular prostheses. Bioactive poly(ethylene glycol) (PEG) hydrogels have also been synthesized with covalently bound cell adhesion moieties to elucidate the mechanisms of immune cell adhesion to the vascular wall under shear. Leukocytes perfused over the surfaces of these hydrogels in a parallel plate flow chamber display rolling and adhesion properties like those seen on vascular endothelium in vivo. This work also presents a system of patterning bioactive regions onto hydrogels using transparency masks. This system allows the formation of complex patterns of cell-adhesive regions that closely mimic in vivo cellular arrangement. The intrinsic biocompatibility of PEG and the decreased thrombogenicity that NO affords make these materials ideal for incorporation into blood contacting devices.

碩士
國立清華大學
奈米工程與微系統研究所
101
Hyperpigmentation is a hypermelanosis occurring in all skin types and results from the overproduction of melanin or an irregular dispersion of pigment after cutaneous inflammation. Patients with hyperpigmentation can have a significant psychosocial impact on skin-of-color patients, including Asian. There are a variety of medications and procedures added to photoprotection cream that can safely and effectively treat hyperpigmentation. A fixed triple combination cream, containing 4% Hydroquinone (HQ), 0.05% Tretinoin (Vit. A acid), and 0.01% fluocinolone acetonide (steroids), called Tri-Luma from Galderma Laboratories (Fort Worth, TX), offer maximal efficacy for clinical trial. HQ and Vit. A Acid can inhibit the formation of melanin by inhibiting the tyrosinase in melanocytes in the bottom of epidermis layer. Fluocinolone acetone, the steroids can eliminate the irritation caused by hydroquinone or tretinoin. However, clinical study showed that over 87.5% of patients were noted to have side-effects with cream treatment because of the Hydroquinone cytotoxicity and slow degradation. In this study, we proposed a new design of microneedles patch with different height for different skin layer to treat hyperpigmentation. For the deeper melanocyte in the bottom of epidermis layer, longer microneedle in the center of patch served as a fast released carrier loaded active ingredient HQ and Vit. A Acid for drug localization and fast metabolism to decrease HQ cytotoxicity. The shorter microneedle contained fluocinolone acetonide to dissolve gently in the keratinocytes layer to eliminate the irritation. In vitro and in vivo study showed the feasibility of hyperpigmentation treatment. This approach could be a potential technology enabling direct transcutaneous delivery in clinical applications.

The studies presented in this thesis demonstrate the ability of nitric oxide (NO)-generating hydrogels and YC-1 releasing hydrogels to influence key components of the restenosis cascade both in vitro and in vivo. Using these poly(ethylene glycol) copolymers, which can be rapidly photopolymerized in situ, localized drug delivery can be achieved at the site of vascular injury. PEG-Cys-NO hydrogels inhibited smooth muscle cell proliferation, increased endothelial cell proliferation, and inhibited platelet adhesion in vitro. Moreover, in vivo, PEG-Cys-NO hydrogels inhibited intimal thickening in a rat carotid balloon injury model. The perivascular application of NO-generating polymers post-injury reduced neointima formation at 14 d by approximately 80% compared to controls (I/M: PEG-Cys-NO = 0.20 +/- 0.17, control = 0.84 +/- 0.19, p < 0.00002; intimal thickness: PEG-Cys-NO = 12.7 +/- 10.4 mum, control = 60.4 +/- 18.0 mum, p < 0.00002). Treatment with the PEG-Cys-NO hydrogels caused a significant decrease in the percent of proliferating cell nuclear antigen positive medial cells (28.9 +/- 4.7%) at 4 d as compared to treatment with the control hydrogels (51.3 +/- 0.6%, p < 0.02). Additionally, vessel re-endothelialization at 14 d was slightly enhanced in the presence of the NO-generating hydrogels. Changes in gene expression in response to PEG-Cys-NO hydrogels were characterized both in vitro and in vivo to further elucidate the mechanisms by which NO influenced cell proliferation and neointima formation. YC-1 releasing hydrogels inhibited smooth muscle cell proliferation and platelet adhesion in vitro, and reduced neointima formation at 14 d by approximately 40% compared to controls (UM: YC-1 = 0.41 +/- 0.18, control = 0.65 +/- 0.14, p < 0.05; intimal thickness: YC-1 = 21.0 +/- 6.0 mum, control = 36.7 +/- 9.0 mum, p < 0.05). In addition, delivery of YC-1 in combination with NO from PEG-CYS-NO hydrogels decreased SMC proliferation in vitro to a greater extent than seen for delivery of YC-1 or NO alone. These data indicate that localized delivery of NO and/or YC-1 from poly(ethylene glycol) hydrogels can significantly inhibit neointima formation in a rat carotid balloon injury model and suggest that these materials may be useful in preventing restenosis.