Journal articles on the topic 'Synthetic Polymer-based mud'

<p><em>Drilling is one of the important things in the drilling process, from the start of drilling to the point of reaching the intended depth, can assist the smooth process of drilling. The potential problems that can arise one of them is the drilling mud reply (loss of circulation). One way to prevent and cope with the discovery of drilling mud is dissolved. At this time Polymers Synthesis and Sago Flour as material for dissolved system. Both materials enter into the colloidal effect. The colloid solution itself is a relatively large, relatively large dispersion system within the dispersing medium.</em></p><p><em>The purpose and objective in collecting these tasks is to determine the effectiveness of Synthetic and Sago Flour Polymer materials in tackling the drilling mud stock problem. Based on the results of the research found, that A sludge system can provide most of the standard specification where the value of physical properties and rheology. While the B sludge system is inversely proportional, most of it does not meet the standard specification. It can be underlined that B system with Sago Flour as LCM is effective in handling dispersion drilling mud.</em></p>

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204763, “Minimization of Ultrahigh-Temperature Filtration Loss for Water-Based Drilling Fluid With β-Cyclodextrin Polymer Microspheres,” by Hanyi Zhong, China University of Petroleum and the University of Oklahoma, and Xin Gao, SPE, and Zhengsong Qiu, China University of Petroleum, et al. The paper has not been peer reviewed. _ Because of the rapid degradation of conventional biopolymer or synthetic polymeric additives at high temperatures (HT) or ultra-HT, effective control of water-based drilling-fluid filtration in these environments remains a major challenge in drilling operations. In the complete paper, β-cyclodextrin polymer microspheres (β-CPMs), generally used for drug release and wastewater treatment, have been evaluated and found to be effective, environmentally friendly ultra-HT filtration reducers. Experimental Methods Sodium bentonite (16 g) and deionized water (400 mL) was homogenized by stirring at 10,000 rev/min for 30 minutes. After hydration for another 24 hours, the suspension, which would be the base mud, was ready for use. β-CPMs were mixed into the base mud and hot rolled under temperatures ranging from 120 to 240°C for 16 hours. After hot rolling, the low-temperature/low-pressure (LT/LP) filtration (ambient temperature/0.7 MPa) and high-temperature/high-pressure (HT/HP) filtration test was carried out according to recommended standards. For the HT/HP filtration test, the pressure difference was set to be 3.5 MPa, while the testing temperature was equal to the hot rolling temperature when the temperature was lower than 200°C, and kept at 200°C when the fluid was thermally aged to rise higher than 200°C. A typical HT-resistant water-based drilling fluid was used as a control sample. Several generally used HT filtration loss agents were added and hot rolled at 220°C to compare their effectiveness in HT filtration control.

Drilling deep holes or drilling to provide access to thermal waters places increasingly high demands on the properties of the drilling muds. Due to the very high temperature, it may be difficult to maintain the appropriate rheology of the drilling fluid during drilling, especially when an inflow of highly mineralized brines occurs. High temperatures significantly reduce the effectiveness of most of the polymeric agents currently used in the drilling muds technology, in extreme cases causing complete and irreversible damage to their structure. Polymers with ether bonds, which include starches and cellulose, are the most vulnerable. Based on the literature data, it can be concluded that the disadvantages of these polymers can be effectively compensated by the addition of synthetic polymers, e.g. sulfonated polymers. Another direction in improving the thermal resistance of drilling muds indicated in the literature is the use of carbon nanoparticles: graphene flakes and nanotubes. The article presents an analysis of the possibilities of improving thermal stability of drilling muds by using chemical agents that allow to maintain appropriate rheological and structural parameters and filtration at temperatures up to 130°C. During the tests, three types of chemicals were added to the polymer-potassium drilling mud at different concentrations. The impact of these modifications on technological parameters of the drilling mud was tested. Then, samples modified by the addition of selected agents were exposed to the temperature of 130°C for a period of 24 hours. After this time, the samples were cooled to 20°C, then their technological parameters were measured and compared with the results obtained before aging at high temperature, and based on the obtained results, the effectiveness of individual agents was assessed. Among the agents tested to protect drilling mud against the adverse effects of high temperature, the most beneficial effect was shown by potassium formate in combination with PoliAMPS.

Geopolymer systems are quite successfully used in such operations as industrial and civil construction, production of fire - resistant concrete, isolation and disposal of radioactive waste, etc. The oil and gas industry was no exception. They are one of the most promising alternatives to Portland cement in insulation operations. They allow achieving sufficiently high performances of well construction strength, corrosion resistance, and in some compositions these parameters significantly exceed those of Portland cement. In recent years, a significant amount of research has been carried out aimed at the development of geo polymer compositions for cementing oil and gas wells, which showed that these systems have strength characteristics comparable to Portland cement, low permeability, resistance to drilling mud and reservoir conditions, and the ability to self-repair. However, despite all the advantages of Geo polymer systems, their most significant disadvantage is poor regulation of rheological properties. Geo polymers (GP) with low ash content do not provide the proper rheological characteristics for the use in insulation operations. Low values of pumpability of solutions are still a serious restriction for wide practical implementation. The use of geopolymer solutions with the correct selection of the compositional composition capable of demonstrating significant improvements in strength and rheological parameters as a result of mixing with anhydrous drilling fluids is a very promising solution to this problem. The paper presents the results of research on the additives of non-aqueous fluids such as oil- based and synthetic-based drilling fluids and inverted emulsion drilling fluids on rheology of geo polymers. The obtained results allow stating that the rheological parameters of geo polymer compositions improve up to comparable values with Portland cement, which considerably extends the range of application of these solutions to use in operations of primary, squeeze cementing and well workover.

This study has endeavored to develop an Al2O3-filled natural fiber reinforced polymer composite which is intended to substitute the most widely used synthetic E-glass fiber material. To attain the desired objective of the work, 0, 5, 10, and 15 wt% Al2O3-filled chopped flax/unsaturated polyester resin composite have been developed by the conventional hand-lay-up method followed by a compression molding process. Consequently, characterization and mechanical property tests are conducted based on the ASTM standard. The results revealed that both tensile and impact strength properties of the base chopped flax/unsaturated polyester resin composite are all affected due to the inclusion and variation of the content of Al2O3 in 15 and 25 wt% fiber loading cases. It has been noticed that a 39.06% increase in the ultimate tensile strength of the composite in 25/UPR-5 composition has been gained. The effect of Al2O3 on the impact strength of the base composite has also been analyzed and a 45% increase has been observed in 15/UPR-10 composition. The findings also witnessed that the newly developed composite can be applied to make automotive parts such as mud guard and engine undercover.

Summary Viscoelasticity plays a significant role in improving the performance of the drilling fluid by manipulating its elastic properties. An appropriate value of the first normal stress difference (N1), extensional viscosity (ηe), and relaxation time (θ) enhance the cutting transportability, hole-cleaning ability, filtration loss, and lubrication behavior. However, the performance of the drilling fluid deteriorates during the drilling of high-pressure and high-temperature (HPHT) wells under acid gas and salt(s) contamination. Therefore, it is a challenging task to synthesize a thermally and rheologically stable drilling fluid, which is acid as well as salt(s) resistant, and maintain its desired properties. Although several water-soluble synthetic polymer-based drilling fluids have been used widely for the drilling of HPHT wells, most of these are limited at less than 200°C. Polyanionic cellulose (PAC) has an excellent heat-resistant stability, salt tolerance, calcium and magnesium resistant, and strong antibacterial activity, and it exhibits exceptional filtration and rheological behavior under HPHT conditions. However, using PAC beyond 200°C is limited because of the presence of the biodegradable cellulose units in it. To use the extraordinary properties of PAC, it is aimed to increase the thermal stability of PAC through appropriate modification. In this study, PAC-grafted copolymers involving acrylamide (a salt-tolerant viscosifying agent), 2-acrylamide-2-methyl-1-propane sulfonic acid (a thermally stable lubricating and fluid-loss control agent), and sodium 4-styrene sulfonate (a high-temperature deflocculant) is synthesized optimally through maximizing the thermal degradation stability of the grafted copolymer and minimizing the filtration loss as well as the coefficient of friction (CoF) of the drilling fluid simultaneously. Optimally synthesized PAC-grafted copolymers are then used to prepare water-based mud (WBM) involving American Petroleum Institute (API)-grade bentonite and alpha-glycol functionalized nano fly ash, and the tests for steady shear viscosity and viscoelasticity are performed to determine the rheological stability of mud beyond 200°C. The amplitude sweep tests for viscoelasticity are performed to determine the linear viscoelasticity range (LVR), structural stability, gel strength, and dynamic yield point (YP), whereas frequency, time, and temperature sweep tests are performed to obtain the elastic modulus (G′), viscous modulus (G″), and complex viscosity under HPHT conditions to check the stability of the drilling fluids under different holding times. Dynamic and static aging tests of the developed drilling fluids are performed at elevated temperature and pressure, and the aged muds are tested by evaluating the rheology, frictional, and filtration-loss behavior as per the API recommended procedure. The stability of the aged muds is also tested by evaluating the N1, ηe, and θ using a cone and plate rheometer. The performance of the proposed drilling fluids is also tested under acidic, sodium chloride (NaCl), and calcium chloride (CaCl2) environments at HPHT bottomhole conditions. The experimental results under HPHT conditions reveal that the performance of the mud (i.e., thermal stability, cutting transportability, hole-cleaning ability, filtration loss, and lubrication behavior) could be considerably improved by increasing the elastic properties of the drilling fluid by manipulating the molecular weight of the proposed PAC-grafted copolymer. Finally, the environmental effect of the developed muds is evaluated by finding the lethal concentration that kills 50% of the shrimp population (i.e., LC50) and the Hg and Cd contamination, and they are found to be environmentally safe.

As the oil and gas drilling industry moves into more technically challenging environments [e.g., drilling ultradeep onshore/offshore wells under extremely high temperature (above 300°F) and pressure (mud specific gravity above 2.0)], companies increasingly come under pressure to stretch technology and improve drilling performance while continuously striving to reduce costs and meet the requirements of stricter environmental regulations. Significant reserves additions may be realized if the risks associated with drilling in such harsh conditions (e.g., pressure control, wellbore instability, lost-circulation, sour gas) can be managed effectively. Design and development of a new generation of drilling fluids able to fulfill all of the attributed functions (e.g., stabilize the wellbore, control formation pressure, transport the drilled cuttings, minimize the fluid loss, and not reduce formation productivity) under such extreme pressure and temperature conditions is one of the key requirements for unlocking these resources. Drilling fluids used under ultrahigh pressures and temperatures need to be thermally stable and able to retain their rheological properties. Traditionally, nonaqueous drilling fluids (NADFs) have been used under these extreme conditions. NADFs, however, have significantly high operational costs with an associated health, safety, and environmental risk. As a result, there has been an increasing demand from operators to use aqueous drilling fluids [water-based muds (WBMs)], which are known to be environmentally benign and relatively less expensive. The use of WBMs under extreme temperatures and pressures, however, faces several challenges, including the breakdown of polymers and other additives used as fluid-loss preventers and rheological stabilizers. Therefore, recent research has focused on design and development of WBM systems meeting the following specifications: - Use of sodium chloride (for barite-laden formulation) and sodium bromide (for barite-free formulation) as base brines to reduce the total solids content for optimal fluid properties and to maximize the quality of wireline logs - Ensure inhibition of reactive shale formations to maintain wellbore stability while drilling intermediate sections - Provide optimal and stable rheological properties for excellent hole cleaning and drilling performance The newly developed ultrahigh-temperature water-based systems used custom-made branched synthetic polymers that exhibit superior rheological properties and fluid-loss control as well as long-term stability above 400°F. These branched synthetic polymers are compatible with most oilfield brines and maintain excellent low-end rheology. Other formulations proposed the use of β-cyclodextrin polymer microspheres (β-CPMs) as an environmentally friendly ultrahigh-temperature filtration reducer. When the temperature rose above 160°C, a hydrothermal reaction occurred for β-CPMs, and, as a result, numerous micro- and nanosized carbon spheres formed, which bridged across micro- and nanopores within the filter cake and reduced the filter cake permeability effectively. Bentonite-hydrothermal carbon nanocomposites also are proposed as nonpolymer additives to solve the ultrahigh-temperature/-pressure challenge in water-based drilling fluid. The nanocomposites are synthesized by a simple hydrothermal reaction in which biomass starch and sodium bentonite are used as the precursor and template, respectively. Such formulations have shown favorable rheology and filtration properties after hot rolling at temperatures as high as 460°F. This section presents selected papers showing examples of design, development, and field applications of the new generation of WBM fluid technologies. Recommended additional reading at OnePetro: www.onepetro.org SPE 206444 - Successful Application of a New Generation of Clay-Inhibitor Polymers While Drilling a Deep Exploration Well in the Astrakhan Region by Petr Leonidovich Ryabtsev, Akros, et al. SPE 205539 - Improvement of Rheological and Filtration Properties of Water-Based Drilling Fluids Using Bentonite-Hydrothermal Carbon Nanocomposites Under Ultrahigh-Temperature and High-Pressure Conditions by Hanyi Zhong, China University of Petroleum East China, et al. SPE 209805 - The Utilization of Self-Crosslinkable Nanoparticles as a High-Temperature Plugging Agent in Water-Based Drilling Fluid by Ming Lei, University of Alberta, et al.

The high-temperature stability and filtration property controlling of ultra-high-temperature water-based drilling fluids is a worldwide problem. To resolve this problem, a high-temperature-resistant quaternary copolymer (HTRTP) was synthesized based on molecular structure optimization design and monomer optimization. The physical and chemical properties were characterized by infrared spectroscopy, thermal weight, and spectrophotometry, and their temperature and salt resistance was evaluated in different drilling fluids, combined with adsorption, particle size analysis, and stability test. The results show that the thermal stability of HTRTP is very strong, and the initial temperature of thermal decomposition is above 320°C. The salt resistance of HTRTP is more than 162 g/L, and the calcium resistance is more than 5000 mg/L, which is equivalent to the foreign temperature-resistant polymer DCL-a, and is superior to the domestic metal ion viscosity increasing fluid loss agent PMHA-II for drilling fluids. It has excellent high-temperature resistance (245°C) and fluid loss reduction effect in fresh water base mud, fresh water weighted base mud, saturated brine base mud, and composite salt water base mud, which is better than foreign DCL-a (245°C) and domestic PMHA (220°C). The adsorption capacity of HTRTP on clay particles is large and firm, and the adsorption capacity changes little under the change of chemical environment and temperature. Both before and after HTRTP aging (245°C/16 h), the permeability of filter cake can be significantly reduced and its compressibility can be improved. By optimizing the particle size gradation of the drilling fluid and enhancing the colloid stability of the system, HTRTP can improve the filtration building capacity of the drilling fluid and reduce the filtration volume. The development of antithermal polymer provides a key treatment agent for the study of anti-high-temperature-resistant saline-based drilling fluid.

Abstract Agricultural reuse of dewatered sludge is a valid route for sludge valorization for small and mid-size wastewater treatment plants (WWTPs) due to the direct utilization of nutrients. A more stringent of German fertilizer ordinance requires the degradation of 20% of the synthetic additives like polymeric substance within two years, which came into force on 1 January 2017. This study assessed the use of starch-based polymers for full-scale dewatering of municipal sewage sludge. The laboratory-scale and pilot-scale trials paved the way for full-scale trials at three WWTPs in Germany. The general feasibility of applying starch-based ‘green’ polymers in full-scale centrifugation was demonstrated. Depending on the sludge type and the process used, the substitution potential was up to 70%. Substitution of 20–30% of the polyacrylamide (PAM)-based polymer was shown to achieve similar total solids (TS) of the dewatered sludge. Optimization of operational parameters as well as machinery set up in WWTPs is recommended in order to improve the shear stability force of sludge flocs and to achieve higher substitution potential. This study suggests that starch-based biodegradable polymers have great potential as alternatives to synthetic polymers in sludge dewatering.

Polymers with a single central point of carboxylic acid functionality were prepared by living radical polymerization methods, RAFT and ATRP. A convenient water-based synthesis of a Y-branched ATRP initiator from 3,5-dihydroxybenzoic acid and 2-bromopropionyl bromide, from which the Y-branched RAFT agent is then subsequently derived, is described. Polymerization occurred uniformly from both of the RAFT groups to give chains of equal length as shown by hydrolysis. ATRP polymerization based on an ester derivative of 3,5-bis(2-bromopropionyloxy)benzoic acid as initiator was well controlled, whereas the free carboxylic acid gave inconsistent performance. The ability to couple functional molecules to the middle of polymers would provide better protection or interaction of the functional molecule with the polymer than conventional end attachment. This would find applications such as in drug delivery where more efficient protection would allow the use of lower molecular weight polymers.

During the exploitation of deep and ultradeep oil and gas resources, the high-temperature problem of deep reservoirs has become a major challenge for water-based drilling fluids. In this study, a novel high-temperature-resistant filtrate reducer (LDMS) with low molecular weight was synthesized using N, N-dimethylacrylamide; sodium p-styrene sulfonate; and maleic anhydride, which can maintain the performance of a drilling fluid gel system under high temperature. Unlike the conventional high-temperature-resistant polymer filtrate reducer, LDMS does not significantly increase the viscosity and yield point of the drilling fluid gel systems. After aging at 210 °C, the filtrate volume of a drilling fluid with 2 wt% LDMS was only 8.0 mL. The mechanism of LDMS was studied by particle size distribution of a drilling fluid gel system, Zeta potential change, adsorption experiment, change of bentonite interlayer spacing, filter cake scanning electron microscope, and related theoretical analysis. The mechanism study revealed that LDMS could be adsorbed on the surface of bentonite particles in large quantities and intercalated into the interlayer of bentonite. Thus, it can improve the hydration degree of bentonite particles and the colloidal stability of the drilling fluid gel system, maintain the content of fine particles in the drilling fluid gel system, form a compact mud cake, and significantly reduce the filtrate volume of the drilling fluid gel system. Therefore, this work will promote the application of a low-molecular-weight polymer filtrate reducer in high-temperature-resistant water-based drilling fluid gel systems.

Synthesis, physicochemical characterization, and the enzymatic degradation of the amphiphilic miktoarm star-shaped polymers is reported herein. First, star-shaped macroinitiators, based on N,N′-dimethylaminoethyl methacrylate (DMAEMA) and glycerol dimethacrylate (GDMA) ((PDMAEMA)n-PGDMA), were synthesized. Due to the presence of hydroxyl groups in the macroinitiator core, polyesters such as poly(ɛ-caprolactone) (P(ɛ-CL)), polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were synthesized using ring opening polymerization (ROP). Comprehensive degradation studies on enzymatic degradation, using a lipase from Pseudomonas cepacia, were performed. Enzymatic degradation was monitored by weight measurements and nuclear magnetic resonance spectroscopy (1H NMR). The fastest degradation rate was observed for the polymer with the lowest molecular weight. Amphiphilic miktopolymers may find application as biomaterials for long- or mid-term period drug-delivery systems.

Summary This paper examines a new class of viscoelastic surfactants (amphoteric) that are used to enhance sweep efficiency during matrix acid treatments. It appears that surfactant molecules align themselves and form rod-shaped micelles once the acid is spent. These micelles might cause the viscosity to significantly increase, and induce viscoelastic properties to the spent acid. The enhancement in these properties depends on the micelle shape and magnitude of entanglement. The effects of acid additives and contaminants [mainly iron (III)] on the rheological properties of these systems were examined over a wide range of parameters. Viscosity measurements were conducted using specially designed viscometers to handle very corrosive fluids. Measurements were made between 25 and 100°C, and at 300 psi at various shear rates from 58 to 1,740 s-1. Acid additives included corrosion inhibitors, inhibitor aids, an iron control agent, a hydrogen sulfide scavenger, an anti-sludge agent, and a nonionic surfactant. Effects of mutual solvents and methanol on the apparent viscosity were also investigated. It is observed that temperature, pH, shear conditions, and acid additives have a profound influence on the apparent viscosity of the surfactant-acid system. The viscosity and related properties are very different from what were observed with both natural and synthetic polymers. The differences in these properties were characterized and correlated with the type and nature of the additives used. Optimum conditions for better fluid performance in the field were derived. Introduction Previous studies (Thomas et al. 1998) highlighted the need for proper diversion during matrix acidizing treatments of carbonate reservoirs. Various systems were introduced to enhance diversion by increasing the viscosity of the injected acid. Depending on the viscosifiying agent, these systems can be divided into two main categories: polymer-based acids and surfactant-based acids. Acid-soluble polymers have been used to increase the viscosity of HCl, and to improve its performance (Pabley et al. 1982; Crowe et al. 1989). As the viscosity of the acid increases, the rate of acid spending decreases and, as a result, deeper acid penetration into the formation can be achieved (Deysarkar et al. 1984). Addition of suitable synthetic or natural polymers to HCl improved acid penetration; however, acid placement did not significantly improve (Yeager and Shuchart 1997). Crosslinked acids were introduced in the mid-70s, as cited by Metcalf et al. (2000). These acids have much higher viscosity than regular acids or acids containing uncross-linked polymers. Two types of crosslinked acids are available The first type consists of a polymer, a crosslinker, and other acid additives [e.g., corrosion inhibitors and iron control agents (Johnson et al. 1988)]. The acid in this case is crosslinked on the surface and reaches the formation already crosslinked. The second type of crosslinked acid consists of a polymer, a crosslinker, a buffer, a breaker, and other acid additives. The acid in this case reaches the formation uncrosslinked, and the crosslinking reaction occurs in the formation (Yeager and Shuchart 1997; Saxon et al. 2000). In-situ gelled acids were the subject of several lab and field studies. In general, lab and field results were positive; however, there were several concerns raised about these acids. Taylor and Nasr-El-Din (2002, 2003) noted that in-situ gelled acids caused loss of core permeability in tight carbonate cores. Permeability loss was attributed to polymer retention in the core and on the injection face of the core. A similar observation was noted by Chang et al. (2001). Lynn and Nasr-El-Din (2001) noted precipitation of the crosslinker (iron) when in-situ gelled acids were used to enhance the permeability of tight cores at high temperatures. Nasr-El-Din et al. (2002) showed that the crosslinker (Fe(III)) may precipitate in sour environments. Mohamed et al. (1999) reported poor field results when large volumes of polymer-based acids were used to stimulate seawater injectors with tight carbonate zones.

One of the challenges for brush synthesis for advanced bioinspired applications using surface-initiated reversible deactivation radical polymerization (SI-RDRP) is the understanding of the relevance of confinement on the reaction probabilities and specifically the role of termination reactions. The present work puts forward a new matrix-based kinetic Monte Carlo platform with an implicit reaction scheme capable of evaluating the growth pattern of individual free and tethered chains in three-dimensional format during SI-RDRP. For illustration purposes, emphasis is on normal SI-atom transfer radical polymerization, introducing concepts such as the apparent livingness and the molecular height distribution (MHD). The former is determined based on the combination of the disturbing impact of termination (related to conventional livingness) and shielding of deactivated species (additional correction due to hindrance), and the latter allows structure-property relationships to be identified, starting at the molecular level in view of future brush characterization. It is shown that under well-defined SI-RDRP conditions the contribution of (shorter) hindered dormant chains is relevant and more pronounced for higher average initiator coverages, despite the fraction of dead chains being less. A dominance of surface-solution termination is also put forward, considering two extreme diffusion modes, i.e., translational and segmental. With the translational mode termination is largely suppressed and the living limit is mimicked, whereas with the segmental mode termination occurs more and the termination front moves upward alongside the polymer layer growth. In any case, bimodalities are established for the tethered chains both on the level of the chain length distribution and the MHD.

OBJECTIVES/SPECIFIC AIMS: This project aims to synthesize an angiogenic decorin mimic (VEGFp-DS-SILY) with varying densities of QK and characterize its angiogenic potential and synergism with VEGF by evaluating (1) endothelial cell (EC) migration and proliferation, (2) EC VEGF receptor activation, (3) EC tubule formation in collagen scaffolds, and (4) angiogenesis from a chick chorioallantoic membrane (CAM assay) growing into the scaffold, reflecting the ability of the collagen scaffold to integrate into existing vasculature. The next main goal is to develop and characterize an MMP-degradable nanoparticle system for controlled release of VEGF. Future work will evaluate in vivo effects of VEGFp-DS-SILY bound to a 3D collagen scaffold on ischemic wound repair in a combined excisional wound/bipedical dorsal skin flap rat model. METHODS/STUDY POPULATION: Peptide hydrazides are conjugated to the free carboxylic acid functional groups on dermatan sulfate using EDC chemistry. We added a 3 amino acid spacer (-Gly-Ser-Gly) to the C-terminus of the established QK sequence before the hydrazide functional group and refer to this modified QK as “VEGFp.” VEGFp, SILY, and N-terminal biotinylated versions were synthesized using standard Fmoc solid-phase peptide synthesis protocols and purified using reverse phase HPLC. Coupling efficiencies of peptides to dermatan sulfate were determined spectroscopically at 280 nm measuring the aromatic residues (Trp or Tyr) using a NanoDrop system. Dermatan sulfate with 1 or 4 VEGFp peptides coupled were termed DSV1 and DSV4, respectively. After further conjugation with SILY, we will blend this VEGFp-DS-SILY with unmodified DS-SILY to a total 10 μM to test increasing densities of VEGFp. To verify that the collagen-binding properties of VEGFp-DS-SILY are not compromised by the addition of VEGFp, we will use a streptavidin-HRP system to detect bound biotinylated VEGFp-DS-SILY on collagen-coated plates by established protocols. DSV1 and DSV4 were tested for their effects on endothelial VEGFR2 phosphorylation using an MSD ELISA-type assay and endothelial proliferation using an MTS assay. Cell migration was monitored using an ORIS assay where cells are grown to confluence around a silicone stopper that is then removed to allow cells to migrate inward. Tubulogenesis was evaluated by examining tubule formation on matrigel. Finally, in vivo angiogenesis will be evaluated using a chorioallantoic membrane assay. For extracellular VEGF release, hollow MMP-degradable thermoresponsive nanoparticles [NIPAM, 5 mol% 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), 1% Acrylic Acid (AAc), 2 mol% MMP-degradable peptide diacrylate, and potassium persulfate initiator] will be synthesized around noncross-linked polymer cores. The cores will then be diffused out through the shell by dialysis prior to drug loading. SILY (and some biotinylated SILY for visualization) will be conjugated with EDC chemistry for targeting nanoparticles to collagen. NPs size and zeta-potential will be measured on a Malvern Zetasizer. VEGF will be loaded into NPs by co-incubating a loading solution of 1 µg/mL VEGF with 1 mg of NPs, incubating overnight at 4°C. VEGF loading and release will be measured by ELISA. Biological activity of the released VEGF from particles will be determined on ECs using assays similar to those outlined previously. RESULTS/ANTICIPATED RESULTS: Preliminary data have verified the synthesis and purification of SILY and VEGFp (QK-Gly-Ser-Gly-hydrazide), as well as an N-terminal biotinylated version, through mass spectrometry and reverse-phase HPLC, respectively. For proof-of-concept, we have verified binding of VEGFp to the VEGF receptor 2 using a ForteBio Blitz interferometry instrument. In addition to support based on published reports showing retained bioactivity of QK after conjugation using other spacers, our preliminary data suggests that VEGFp still binds to VEGF receptor 2, albeit with decreased affinity like QK as compared with VEGF. Circular dichroism also shows that VEGFp has retained its α-helical structure necessary for bioactivity; however it appears that it has some uncoiling when conjugated to dermatan sulfate. We hypothesize that varying densities of VEGFp conjugated to the decorin mimetic (DS-SILY) will modulate the degree of angiogenic activity and synergy with VEGF. We determined that we can achieve ~70% VEGFp conjugation completion to dermatan sulfate after 3.5 hours. We have quantified VEGFR2 phosphorylation after 5 minute treatments by using phospho-specific antibodies and an ELISA-type protocol in a mesoscale discovery system. Preliminary data with human umbilical vein endothelial cells shows that VEGFp exhibits synergism with VEGF at levels similar to QK. DSV1 and DSV4 data suggests synergy with VEGF, although free-peptides and engineered compounds alone did not show effects similar to VEGF in the conditions tested. Prelminary data with 30 minute treatments suggests that the peptides and compounds may require longer exposures to induce activation, as they may have slower binding rates. In contrast, prolonged stimulation with VEGF causes a sharp increase in receptor activation, peaking around 10 minutes and decreasing significantly by 30 minutes. Peptides QK and VEGFp both slightly increased proliferation of dermal microvascular endothelial cells (HMVECs) after 60 hours incubation. However, incubation with dermatan sulfate and DSV caused significant cell death after 24 hours in reduced growth factor media, likely due to sequestering of growth factors. It is possible that VEGFp-DS-SILY may better stimulate proliferation since it would be presented as a surface bound proteoglycan mimic, rather than as a soluble factor. HMVECs migrated farther for all treatment groups (10 µM QK, 10 µM VEGFp, 1 µM DSV4, and 10 µM DSV4) than the 10 ng/mL VEGF positive control, although more cells migrated in response to VEGF. This may be accounted at least in part by the more pronounced proliferation induced by VEGF. Migration will also be tested in 3D culture within a collagen gel. We are currently testing a 2D matrigel system for tubulogenesis. We have found that 10 µM DSV4 forms qualitatively more well-defined tubules than the untreated control on reduced growth factor matrigel. However, we were not able to quantify the improved tubule formation and are still troubleshooting the tubule analysis. After seeding ECs and culturing for 4, 8, and 12 hours, cells will be fluorescently stained with anti-CD31 and imaged for 3D tubule formation. CAM assay angiogenesis growing into a collagen scaffold. In brief, fertilized chicken embryos are incubated for 2 days before exposing the CAM. VEGFp-DS-SILY bound to a collagen gel will be placed onto the CAM. Some treatment groups will receive additional VEGF to investigate synergistic effects. Light microscope images of angiogenesis into the collagen gel coated with VEGFp-DS-SILY, taken every day from days 10 to 13, will reflect the ability of the collagen scaffold to integrate into existing vasculature and 3D angiogenic potential of VEGFp-DS-SILY with or without VEGF. We expect that VEGFp-DS-SILY treatment will increase the number of vessels formed on the CAM. Preliminary data using a Fluoraldehyde assay indicates that loading of ~300 ng VEGF per mg of nanoparticles can be achieved. We expect that using an MMP-degradable peptide diacrylate crosslinker will allow nanoparticles to degrade in protease-rich environments like the chronic wound bed and release VEGF. Adjustments to the formulation, such as crosslinker density, may need to be modified to control the rate of VEGF release. DISCUSSION/SIGNIFICANCE OF IMPACT: We expect that our angiogenic decorin mimetic will lead to a novel treatment to accelerate healing of ischemic diabetic foot ulcers, thereby reducing the need for limb amputation and mortality rate of diabetic patients. We anticipate that the diabetes research and regenerative medicine communities will (1) gain a platform for targeted delivery of growth factors, (2) understand the dependence of vascularization within 3D collagen constructs on VEGFp densities and VEGF receptor activation in controlling the degree of angiogenesis, and (3) gain the benefits of controlled angiogenesis in ischemic diabetic wound healing.

AbstractAmong the more promising approaches to minimizing capacitance in the multilevel interconnect of integrated circuits containing sub-half micron metal spacings is the development of organic polymers which exhibit high performance in key attributes such as thermal stability, low dielectric constant, and low moisture absorption coupled with high outgassing rates of what little moisture may be present. The use of such polymers as the intermetal dielectric can reduce power consumption and cross talk, while increasing signal propagation speed. While polyimides are the most extensively characterized polymer thin film dielectrics, and are in many cases suitable for the intermetal dielectrics in multichip modules, their tendency to absorb significant quantities of moisture, coupled with relatively slow outgas characteristics (presumably due to hydrogen bonding between water molecules and the carbonyls of the polyimide) constitute significant impediments to throughput in the fabrication of IC interconnects.The search for alternative polymers which incorporate the “good” characteristics of polyimides while exhibiting improvements in electrical, moisture, and processing characteristics led us to the development of nominally 1 μm spin-on films derived from a family of noncarbonyl containing aromatic polyethers. Fluorinated poly(arylethers) based on decafluorobiphenyl exhibit thermal stability comparable to polyimides, from ten to forty times lower moisture absorption, dielectric constants in the mid-two's, and good retention of storage modulus above their glass transition temperatures. The precursor spin-on solutions, formulated in low toxicity organic solvents, exhibit excellent shelf life, and can be prepared with extremely low levels of metallic contamination. This paper describes the synthesis and both solution and film properties of this newly developed class of highly processible thermally stable polymers, first reported by Mercer, et. al. [1]. The characteristics of the polymers when spin-coated on silicon wafers is emphasized. Thermal and thermomechanical properties of nominally 10-25 μm free standing films are also described.