Academic literature on the topic 'Mesoporous Materials - Drug Delivery -'

Mesoporous materials, which exhibit great potential in the control of polymorphs and delivery of poorly water-soluble drugs, have obtained considerable attention in the field of pharmaceutical science. The physical properties and release behaviors of amorphous or crystalline drugs may be affected by formulating them into mesoporous drug delivery systems. In the past few decades, an increasing amount of papers have been written about mesoporous drug delivery systems, which play a crucial role in improving the properties of drugs. Herein, mesoporous drug delivery systems are comprehensively reviewed in terms of their physicochemical characteristics, control of polymorphic forms, physical stability, in vitro performance, and in vivo performance. Moreover, the challenges and strategies of developing robust mesoporous drug delivery systems are also discussed.

Fused deposition modelling (FDM) is the most extensively employed 3D-printing technique used in pharmaceutical applications, and offers fast and facile formulation development of personalized dosage forms. In the present study, mesoporous materials were incorporated into a thermoplastic filament produced via hot-melt extrusion and used to produce oral dosage forms via FDM. Mesoporous materials are known to be highly effective for the amorphization and stabilization of poorly soluble drugs, and were therefore studied in order to determine their ability to enhance the drug-release properties in 3D-printed tablets. Celecoxib was selected as the model poorly soluble drug, and was loaded into mesoporous silica (MCM-41) or mesoporous magnesium carbonate. In vitro drug release tests showed that the printed tablets produced up to 3.6 and 1.5 times higher drug concentrations, and up to 4.4 and 1.9 times higher release percentages, compared to the crystalline drug or the corresponding plain drug-loaded mesoporous materials, respectively. This novel approach utilizing drug-loaded mesoporous materials in a printed tablet via FDM shows great promise in achieving personalized oral dosage forms for poorly soluble drugs.

The physicochemical properties of many drugs have a decisive impact on their bioavailability, as well as the pharmacokinetic efficiency in various disease therapeutics. That is why mesoporous materials have attracted a special interest in the drug delivery field, facilitating the loading of drugs into their pores due to their high surface area and porosity. The interfacial interactions established with drug molecules represent the driving force for efficient drug loading and controlled release kinetics. Moreover, these materials offer an optimal design for implantable local-delivery devices or for improving the accuracy of imaging techniques in clinical diagnosis. Their use is validated by improvements in therapeutic outcome and prevention of side effects. This review discusses the role of mesoporous materials in different biomedical applications.

Interest in the use of mesoporous materials as carriers of medicinal substances has been steadily increasing in the last two decades. Mesoporous carriers have application in the preparation of delivery systems for drugs from various therapeutic groups; however, their use as the carriers of anti-inflammatory agents is particularly marked. This review article, with about 170 references, summarizes the achievements in the application of mesoporous materials as the carriers of anti-inflammatory agents in recent years. This article will discuss a variety of mesoporous carriers as well as the characteristics of their porous structure that determine further use of these materials in the field of medical applications. Special attention will be paid to the progress observed in the construction of stimuli-responsive drug carriers and systems providing site-specific drug delivery. Subsequently, a review of the literature devoted to the use of mesoporous matrices as the carriers of anti-inflammatory drugs was carried out.

This study evolved to its last form primarily around the development of a hybrid material is the core of the work. This hybrid material is then further explored for two different applications which are catalysis and drug delivery. A nanoassembly was established around a mesoporous silica support. SBA-15 was picked as this support among the other mesoporous silica dueto its well-defined pore structure and accessible pore volume. The silica framework was doped with Zr-atoms and the pores partly infiltrated with Cu nanoparticles resulting in a hybrid material with tunable properties. SBA-15 was synthesized by a sol-gel method where a micellar solution was employed as a template for the silica framework. To achieve the doped version, a Zr precursor was added to the synthesis solution. The effects of different synthesis conditions on the final material were investigated. lt was observed that changes in these synthesis conditions yielded different particle morphology, pore size, and specific surface area. The infiltration method is based on functionalizing the (Zr-) SBA-15 support surfaces before the Cu ion attachment whereas EIWI is based on slow evaporation of the liquid from the (Zr-)SBA-15 - Cu aqueous suspension. Both methods are designed to yield preferential growth of Cu NPs in the pores with a diameter smaller than 1O nm and in oxidized form. However, depending on the infiltration method used different chemical states of the final material is achieved, i.e. Zr content and porous network properties are different. Cu-Zr-SBA-15 nanoassembl ies were used for the catalytic conversion of C02 into valuable fuels such as methanol and dimethyl ether (DME). The effect of different chemical states of the catalyst was investigated. lt was found that the Si precursor had a considerable impact on the overall performance of the catalyst whereas the Cu loading method (lnf or EIWI) changed the catalytic selectivity between DME and methanol. The activity of the catalyst was further investigated in a time-evolution study where the accumulation of each product in the gas phase and the molecular groups attached to the catalyst surface were recorded over time. Accordingly, thermodynamic equilibrium was achieved on the 14th day of the reaction under 250ºC and 33 bar. The resulting total C02 conversion was 24%, which is the thermodynamically highest possible conversion, according to theoretical calculations. lt was also concluded from the experimental results that, DME is formed by a combination of two methoxy surface groups . Additionally, the formation of DME also boosts the total C02 conversion to fuels, which otherwise is limited to 9.5%. The design of Cu-Zr-SBA-15 was also investigated for drug delivery applications, dueto its potential as a biomaterial, e.g. , a filler in dental composites, and the antibacterial properties of Cu. Also, the bioactivity of Si02 and Zr02 was considered to be an advantage . With this aim, Cu infiltrated Zr doped SBA-15 material was prepared by using TEOSas the silica precursor and the lnf-method to grow Cu NPs. The performance of the final material as a drug delivery vehicle was tested by an in-vitro delivery study with chlorhexidine digluconate. The nanoassemblies show a drug loading capacity of 25-40% [mg drug 1 mg (drug+carrier)] . The drug release was determined to be composed of two steps. The presence of Zr and Cu limits the burst release and beneficially slows down the drug release process. The effect of pore properties of SBA-15 was explored in a study where the antibiotic doxycycline hyclate was loaded in SBA-15 materials with different pore sizes. lt was observed that the pore size is directly proportional to the drug loading capacity [mg drug 1 mg (drug+carrier)] and the released drug % (the released drug amounUtotal amount of loaded drug). The release profile was fast, dueto its weak interactions with the SBA-15 and smaller size molecule compared to chlorhexidine digluconate.
Los sistemas de materiales híbridos poseen propiedades multifuncionales. En este trabajo se desarrolló un nanoensamblaje alrededor de un soporte de sílice mesoporoso. Como soporte se seleccionó SBA-15 debido a su estructura de poro bien definida y volumen de poro accesible. La matriz de sílice fue dopada con átomos de Zr y los poros se infiltraron parcialmente con nanopartículas de Cu dando como resultado un material híbrido con propiedades ajustables . La síntesis de SBA-15 se realizó mediante un método de sol-gel en el que se empleó una solución micelar como plantilla para el sílice. Para lograr la versión dopada, se añadió un precursor de Zr a la solución de síntesis. Se investigaron los efectos de diferentes condiciones de síntesis, como el catalizador así como la fuente de Si en las características del material final. Los cambios en estas condiciones de. síntesis dieron lugar a partículas con distinta morfología, tamaño de poro (11-15 nm) y área superficial específica (400-700 m2/g). Las nanopartículas de Cu (NP) se hicieron crecer en el sustrato (Zr-) SBA-15 usando los métodos de infiltración (lnf) o de impregnación húmeda inducida por evaporación (EIWI).Dependiendo del método de infiltración utilizado, se logran diferentes propieddes químicas del material final, es decir, el contenido de Zr y las propiedades de red porosa son diferentes. Los nanoensamblajes de Cu-Zr-SBA-15 producidos bajo diversas condiciones de síntesis se usaron para la conversión catalítica de C02 en combustibles valiosos tales como metanol y dimetil éter (DME). El precursor de Si (TEOS o SMS) tuvo un impacto considerable en el rendimiento global del catalizador mientras que el método de carga de Cu (lnf o EIWI) cambió la selectividad catalítica entre DME y metanol. Por otra parte, la actividad del catalizador se investigó evaluando la acumulación de cada producto en la fase gaseosa y los grupos moleculares unidos a la superficie del catalizador a lo largo del tiempo. Se llegó al equilibrio termodinámico en el día 14 de la reacción a 250 ºC y 33 bar. La conversión total resultante de C02 fue del 24%, que es la conversión termodinámicamente más alta posible, según los cálculos teóricos . El material híbrido sintetizado Cu-Zr-SBA-15 también se investigó para aplicaciones de administración de fármacos, debido a su potencial como material de relleno en compuestos dentales y las propiedades antibacterianas del Cu. Por otra parte, la bioactividad de SiO2 y ZrO2 podría ser ventajosa para esta aplicación. El rendimiento del material final como vehículo de administración de fármacos se probó mediante un estudio de liberación in vitro con digluconato de clorhexidina . Los materiales desarrollados muestran una elevada capacidad de carga de fármaco (25-40%). Los perfiles de liberación del fármaco muestran dos etapas: una primera etapa de liberación rápida de las moléculas del fármaco unidas con interacciones más débiles al sustrato mesoporoso, seguida por la difusión de las moléculas del fármaco que están unidas a la superficie del portador. La presencia de Zr y Cu limita la liberación inicial y reduce la velocidad de liberación del fármaco . En otro estudio se evaluó el efecto del tamaño de poro de SBA-15 en la liberación del antibiótico hiclato de doxiciclina. Se observó que el tamaño de poro es directamente proporcional a la capacidad de carga de fármaco, el porcentaje y la cantidad de fármaco liberado . En resumen, este trabajo demuestra el carácter multifuncional de una nanomatriz diseñada a medida que proporciona información valiosa para dos aplicaciones en catálisis y liberación de fármaco.
Hybridmaterial består av minst två komponenter, vilket ger dem mångfacetterade egenskaper. Detta har gjort att denna typ av material attraktiva sedan länge. Det är dock inte enkelt att tillverka dessa materialsystem. Ett enkelt och effektivt tillvägagångssätt behövs för att tillvara ta de önskade egenskaperna hos varje komponent och få dem att samverka. Denna avhandling bygger huvudsakligen på utvecklingen av ett hybridmaterial.Ett hybridmaterial med en sammansättning bestämd på nanonivå, tillverkades med mesoporös kiseldioxid, SBA-15, som stomme. SBA-15 valdes framför andra typer av mesoporös kiseldioxid på grund av dess väldefinierade porstruktur och stora, tillgängliga porvolym. Kiseldioxiden dopades med zirkoniumatomer och porerna fylldes delvis med kopparnanopartiklar, vilket resulterade i ett hybridmaterial med egenskaper som kunde varieras. SBA-15 tillverkades via en våtkemisk metod där en micellösning används som mall för kiseldioxidens struktur. Vid dopningen tillsätts en zirkoniumkälla till synteslösningen. Effekterna av olika tillverkningsparametrar, till exempel salter med katalytiska egenskaper (salter med F- eller Cl-), olika kiselkällor (tetraetyl ortosilikat eller natriummetasilikat), på materialens egenskaper studerades. Variationer av dessa parametrar ger material med olika form, porstorlekar (11 – 15 nm) och specifik yta (400 – 700 m2/g). Kopparnanopartiklar växtes i (Zr-)SBA-15-stommarna med två metoder: infiltration (Inf) eller indunstningsinducerad våtimpregnering (EIWI). Inf baseras på funktionalisering av (Zr-)SBA-15-stommen innan kopparjoner fick reagera med ytan. EIWI bygger på en blandning av (Zr-)SBA-15 och kopparsalt i en lösning där vätskan långsamt får avdunsta. Båda metoderna är designade för framställning av oxiderade kopparnanopartiklar, mindre än 10 nm i diameter, som ska växa i stommens porer. Dock påverkar infiltrationsmetoden den kemiska sammansättningen hos det slutliga materialet då Zr-koncentrationen och porositeten i stommen ändras. Cu-Zr-SBA-15-sammansättningar, tillverkade med varierande syntesparametrar, användes som katalysatorer för omvandling av CO2 till bränslen såsom metanol och dimetyleter (DME). Resultaten visar att valet av kiselkälla har en stor inverkan på katalysatorns prestanda, samt att metoden för att introducera koppar ändrar den katalytiska selektiviteten mellan DME och metanol. Katalysatorns aktivitet undersöktes även över tid. Ackumuleringen av varje produkt, både i gasfas och på katalysatorns yta, registrerades över tid. Termodynamisk jämvikt nåddes efter att reaktionen fortgått i fjorton dagar vid 250 °C och 33 bar. Den totala CO2-omvandlingen var 24 %, vilket, enligt teoretiska beräkningar, är den termodynamiskt högsta möjliga omvandlingen. Det observerades att DME bildas genom en kombination av två metoxygrupper på katalysatorns yta, samt att bildandet av DME ökar den totala omvandlingen av CO2 till bränsle, vilken annars är begränsad till 9.5 %. Cu-Zr-SBA-15-sammansättningen användes även i läkemedelstillämpningar. De kan användas som biomaterial, e.g., fyllnadsmaterial i tandkompositer, och koppar har antibakteriella egenskaper. Dessutom kan kiseldioxid och zirkoniumdioxid vara bioaktiva vilket ses som en fördel. För denna tillämpning tillverkades Cu-Zr-SBA-15 med TEOS som kiselkälla och Inf-metoden för att växa kopparnanopartiklar. Cu-Zr-SBA-15 lämplighet som bärare av läkemedelet klorhexidindiglukonat testades in vitro. I detta fall uppvisar bäraren en laddningskapacitet [massa laddat läkemedel/(massa laddat läkemedel +massa bärare)] på 25 – 40 %. Frisättningen av läkemedel skedde i två steg. Först frisattes en stor mängd läkemedelsmolekyler. Dessa var löst placerade i håligheter i de mesoporösa stommarna. Därefter frisattes läkemedel via diffusion av molekyler som bundit till stommens yta. De två stegen representerar växelverkan mellan läkemedel – läkemedel- och läkemedel – bärare. Närvaron av zirkonium och koppar begränsar den första frisättningen och förlänger den aktiva tiden, vilket är fördelaktigt ur tillämpningsperspektiv. Effekten av porstorlek hos SBA-15 vid läkemedelsfrisättning undersöktes också i en studie där SBA-15 fylldes med doxycyklinhyklat. Laddningskapaciteten och mängden frisatt läkemedel och andelen av laddat läkemedel som frisätts var båda direkt proportionella mot porstorleken där frisättningen av doxycyklinhyklat dominerades av läkemedel – läkemedelsväxelverkan. Doxycyklinhyklat är en mindre molekyl jämfört med klorhexidindiglukonat och växelverkar svagare med SBA-15 på grund av sin mer anjoniska natur. Sammanfattningsvis visar arbetet den multifunktionella karaktären hos en skräddarsydd nanosammansättning, vilket ger värdefulla insikter i två användningsområden: katalys och läkemedelstransport Materialet testas sedan i två olika tillämpningar: katalys och läkemedelstransport.

Parmi les récentes découvertes dans le monde des matériaux, les silices mésoporeuses ordonnées (SMO) ont suscité un intérêt considérable, notamment grâce à leurs perspectives d’application dans de nombreux domaines tels que le biomédical ou les technologies de séparation. Un tel engouement s’explique par la nature unique de leurs propriétés. En effet, les SMO possèdent en général de grandes surfaces spécifiques, de grands volumes poreux, des tailles de pores ajustables, des surfaces aisément modifiables, ainsi que des tailles et morphologies de particules adaptables. L’objectif principal de ce doctorat est donc d’utiliser au mieux ces propriétés pour synthétiser et caractériser de nouveaux systèmes ayant un potentiel d’application en imagerie par résonnance magnétique (IRM) et en relargage contrôlé de médicaments par voie orale. Les premières et secondes parties de ce travail (chapitres 4 et 5) portent sur l’étude des paramètres de synthèse des SMO de type SBA-15 et KIT-6 ainsi que sur leurs effets sur les propriétés poreuses obtenues après calcination. Les résultats présentés montrent toute l’importance de bien contrôler cette porosité afin de caractériser correctement les différentes structures et topologies poreuses accessibles. La troisième et la quatrième partie de cette thèse (chapitres 6 et 7) visent à concevoir et évaluer le potentiel de nouveaux agents de contraste (AC) positifs pour l’IRM basés sur des nanoparticules (Nps) de MCM-41 et MCM-48 fonctionnalisées avec des ions paramagnétiques tels que le gadolinium (Gd) ou le manganèse (Mn). Les résultats de ces études démontrent la supériorité des réseaux poreux 3-D comme supports pour l’insertion d’atomes paramagnétiques, utilisés pour bonifier le signal en IRM. Les Nps de MCM-48 dopées avec du Gd ou du Mn améliorent significativement la relaxivité des protons d’hydrogène dans l’eau tout en conservant un rapport r2/r1 proche de l’unité (1.5 – 2), confirmant leur performance en tant qu’AC positifs. Par ailleurs, l’utilisation de nombreuses techniques de caractérisation et de tests in vitro ont permis de délimiter clairement le potentiel effectif ainsi que les limitations de ces Nps pour des études de traçage cellulaire. La dernière partie de ce travail (chapitre 8) se concentre sur le greffage d’une protéine succinylée, la β-lactoglobuline, sur des Nps de MCM-48 fonctionnalisées afin de développer une nouvelle plateforme de relargage contrôlé de médicaments par voie orale. Les résultats obtenus avec ce système nano-conjugué et nutraceutique montrent un bon contrôle du relargage en fonction du pH ainsi qu’une bonne biocompatibilité et une excellente stabilité colloïdale dans un milieu physiologique. L’utilisation de cette protéine bon marché représente une alternative potentielle à l’utilisation des bio-polymères classiques.
Among recent discoveries in material science, ordered mesoporous silica (OMS) have been in the limelight and attracted considerable attention because of their prospects of application, especially in the biomedical field and separation technologies. Such growing interest is explained by their unique physico-chemical properties. Indeed, OMS usually exhibit high specific surface areas, high pore volumes, adjustable pore sizes, ease of surface functionalization and customizable particle size and shape. The main objective of this Ph.D. thesis is to use these properties in order to design and characterize novel systems with potential applications in magnetic resonance imaging (MRI) and/or oral drug delivery. The first and second parts of this project (chapters 4 and 5) deal with SBA-15 and KIT-6 materials and the effects of the different synthesis parameters on the porosity features of the structures, obtained after calcination. The results showed that it is of prime interest to thoroughly and accurately characterize the porosity of these silicas in order to correctly assess their porous topologies. Such knowledge could be of substantial importance for high-tech applications of OMS. The third and fourth part of this thesis (chapters 6 and 7) are aimed to design, characterize and evaluate the potential of novel positive contrast agents (CA) for MRI based on MCM-41 and MCM-48 nanoparticles (Nps) functionalized with paramagnetic ions such as gadolinium (Gd) or manganese (Mn). The results reported in these studies demonstrate the superiority of 3-D pore networks as a host for the insertion of paramagnetic atoms used to enhance the signal in MRI. Also Gd and Mn loaded MCM-48 Nps provide a significant increase in 1H proton longitudinal relaxivity while maintaining low r2/r1 ratio (1.5 – 2) in water. Furthermore, various modern techniques and in vitro tests were used to clearly delineate the true potential and limitations of these inorganic contrast agents for cellular and in vivo tracking studies. The last part of this work (chapter 8) is focused on the binding of a succinylated protein, the β-lactoglobulin, onto functionalized MCM-48 Nps for the development of a new oral drug delivery platform. This nutraceutical nano-conjugate system reveals promising features such as high biocompatibility, efficient pH-responsive properties for both hydrophilic and hydrophobic drugs/dyes and excellent colloidal stability. The use of this low-cost protein could represent an alternative over classical biopolymers.

A range of mesoporous materials based on SBA-15, KIT-6 and FDU-12 have been prepared using neutral block copolymers Pluronic P123 and F127 and characterised using methods including electron microscopy and nitrogen adsorption. Typically the materials have a hexagonal (p6mm) or cubic (Fm3m and Ia-3d) symmetry and pore geometry and are rendered porous by either calcination or solvent extraction. Organic functional groups were incorporated into the silica walls of the materials by co-condensation in the form of propyl thiols and additives in the form of alkanes were added to control pore size and geometry. The effects of temperature, additives, organic functionalisation, synthesis time and sol-gel composition were investigated and the resulting materials were tested as supports for protein adsorption, enzyme immobilisation, and drug delivery. Two FDU-12 materials of differing entrance and cavity sizes were used to adsorb a range of proteins with molecular weight 17 to 160 kDa to determine if there was a size exclusion effect. It was seen that the larger pore material was able to adsorb proteins of a larger size (molecular weight 105 kDa) and an exclusion effect was observed when the dimension of the proteins became too great (larger than 130 kDa). There was no clear trend for the smaller pore material where each protein was adsorbed to some extent by the material but apart from the smallest protein, myoglobin, mainly on the surface and not within the pores. The adsorption of the lipase B from Candida Antartica, CALB, was studied on a range of mesoporous supports with their templates removed by either calcination or extraction. The effect of pore size and functionalisation was investigated in terms of maximum loading and rate of loading. By functionalising the KIT-6 material the maximum loading of CALB was reduced from 45.5 to 32 mg/g whereas functionalising the FDU-12 material increased the maximum from 33 to 42.5 mg/g. The activity of the immobilised CALB was measured by enantioselective transesterification of (R)-1-phenylethanol in methyltetrabutyl ether (MTBE). The effect of loading, surface functionalisation and reusability in organic media were investigated. Functionalisation with propyl thiol was seen to increase the rate of conversion after 30 minutes for both KIT-6 and FDU-12 materials. Selected FDU-12 and KIT-6 materials with window sizes from 6 to 12 nm and with and without functionalisation were used to carry out a drug release study using Bovine serum albumin (BSA). BSA was loaded onto the material and the uptake quantified using nitrogen adsorption, elemental analysis, and thermogravimetric analysis. The release of BSA into simulated body fluid at 37 ºC was measured using HPLC. Functionalisation was seen to have little effect. The type of cubic morphology controlled the rate at which the BSA was released. The KIT-6 3D channel material exhibited a burst release initially followed by a steady release of BSA whereas the mesocage FDU-12 material had a slower and more linear release profile, closer to that desired.

The aim of this PhD work was to develop and characterize all physicochemical aspects of this new CRT for CTZ and AKS using OMS until the introduction onto the market. The first part comprehends the characterization of different OMS synthesized and commercially available; the study of different incorporation techniques based on hydrophilicity/hydrophobicity of API; the characterization of the new impregnated OMS. Consequently, the work is oriented on the interaction details of API on silica surfaces. A closer look is given to the big questions of OMS-drug phenomena: mobility, solubility, bioavailability, etc. Therefore, all the scCO2 incorporation parameters have been studied, highlighting the differences between OMS and the spatial assembly of drug inside the mesoporous channels. Thus, the patented CRT has been developed for AKS describing all the main aspect of the innovative semisolid formulation. In-vitro and ex-vivo release test has been produced and characterized, revealing the functionality of the OMS reservoir effect. Finally, the same DDS have been developed for CTZ. Both the DDS have been compared with commercially available creams.

A literature review of medical implant applications of mesoporous silica films was written, highlighting the advantages and limitations of different film synthesis methods. Both films synthesized through the EISA sol-gel method and particulate films, including those synthesized through the direct growth method, were reviewed and discussed. All films were found to have their strengths and weaknesses, however, the films synthesized through the direct growth method was found to be the most promising type for coating implants. In addition to the literature review, copper-doped mesoporous silica films were synthesized on titanium grade 2 substrates. SEM shows that particles grown on all the films and EDX elemental analysis confirms the presence of copper in the material. Nitrogen physisorption measurements show that particles with incorporated copper have a higher specific surface area, and pore volume compared to un-doped particles. No copper content could be confirmed through FTIR. The particles grown on titanium substrates were more rod-like compared to the ones grown on the silicon substrates as control.

The idea of utilizing nanomaterials in bio-related applications has been extensively practiced during the recent decades. Magnetic nanoparticles (MPs), especially superparamagnetic iron oxide nanoparticles have been demonstrated as promising candidates for biomedicine. A protective coating process with biocompatible materials is commonly performed on MPs to further enhance their colloidal and chemical stability in the physiological environment. Mesoporous hollow silica is another class of important nanomaterials that are extensively studied in drug delivery area for their ability to carry significant amount of guest molecules and release in a controlled manner. In this study, different synthetic approaches that are able to produce hybrid nanomaterials, constituting both mesoporous hollow silica and magnetite nanoparticles, are described. In a two-step approach, pre-synthesized magnetite nanoparticles are either covalently conjugated to the surface of polystyrene beads and coated with silica or embedded/enclosed in the porous shell during a nanosized CaCO3 templated condensation of silica precursors, followed by acid dissolution to generate the hollow structure. It was demonstrated that the hollow interior is able to load large amount of hydrophobic drugs such as ibuprofen while the mesoporous shell is capable of prolonged drug. In order to simplify the fabrication procedure, a novel in-situ method is developed to coat silica surface with magnetite nanoparticles. By refluxing the iron precursor with mesoporous hollow silica nanospheres in polyamine/polyalcohol mixed media, one is able to directly form a high density layer of magnetite nanoparticles on silica surface during the synthesis, leaving reactive amine groups for further surface functionalization such as fluorescence conjugation. This approach provides a convenient synthesis for silica nanostructures with promising potential for drug delivery and multimodal imaging. In addition to nanoparticles, nanowires also benefit the research and development of instruments in clinical diagnosis. Semiconductive nanowires have demonstrated their advantage in the fabrication of lab-on-a-chip devices to detect many charge carrying molecules such as antibody and DNA. In our study, In2O3 and silicon nanowire based field effect transistors were fabricated through bottom-up and top-down approaches, respectively, for ultrasensitive bio- detection of toxins such as ricin. The specific binding and non-specific interaction of nanowires with antibodies were also investigated.

Mesoporous silica nanocomposite (MSNC) with a wall thick of around 10 nm were created using Fe3O4 nanoparticles as the inorganic template. In accordance with the results of SEM and BET analysis, MSNC were homogenous spherical particles with good dispersion, and their specific surface area it possible that Ibuprofen will become stuck within the MSNC carrier. Loading of drug shows a decline in a surface area from 225.08 to 69.25 m2 g-1, pore volume from 0.56 to 0.13cm g-1 and the pore diameter from 7.96 to 6.74 nm correspondingly. The amount of Ibuprofen entrapped in the carrier was measured by UV spectroscopy and total glycerol (TG) measurement, respectively. It was determined pore size distribution of MSNC changed before and after Ibuprofen entrapment. The release profile of Ibuprofen from MSNC was characterised by a three-stage pattern with an influence on the time between each stage.