In situ crosslinked hydrogels formed using Cu(I)‐free Huisgen cycloaddition reaction

BACKGROUND: ‘Click’ chemistry, or the 1,3‐dipolar cycloaddition of organic azides with alkynes, has been evaluated for many biomedical purposes; however, its utility in crosslinking hydrogels in situ is limited by the toxicity of the requisite copper(I) catalyst. We report the first use of catalyst‐free Huisgen cycloaddition to generate crosslinked hydrogels under physiological conditions using multivalent azide‐functionalized polymers and an electron‐deficient dialkyne crosslinker. RESULTS: Water‐soluble azide‐functionalized polymers were crosslinked with an electron‐deficient dialkyne crosslinker to form hydrogels at physiological temperature without the addition of copper(I) catalyst. Crosslinking was confirmed using scanning electron microscopy, Fourier transform infrared and ¹H NMR analyses. Flow by vial inversion and dynamic rheological methodologies were implemented to evaluate gelation kinetics at 37 °C of variable polymer compositions, concentrations and stoichiometric ratios. Kinetic studies revealed gelation in as little as 12 h at 37 °C, although strong gels that withstand inversion were observed by 1–8 days. CONCLUSION: The ability to form hydrogel networks under mild conditions demonstrates the potential viability of the catalyst‐free ‘click’ crosslinking chemistry for in situ gelling and other biological applications. Further chemical modifications in the crosslinking moieties, as well as polymer and crosslinker conformations, are expected to enhance gelation kinetics to a more biomedically practical rate. Copyright © 2009 Society of Chemical Industry     

Whey protein concentrate hydrogels as bioactive carriers

Two sets of heat‐induced hydrogels were prepared from whey protein concentrate (WPC), one set at a constant concentration [15% (w/v)] and varying pHs (pH 5.1–10.0) and the other set at a constant pH (10.0) and varying concentrations (12%, 15%, and 18%). At a given pH, the higher the protein concentration, the shorter was the gelation time and the larger were the equilibrium storage modulus (G) and failure stress. For a given protein concentration, the gelation kinetics and mechanical properties of WPC hydrogels were strongly pH dependent. The swelling behavior of WPC gels was studied at 37.5°C ± 0.5°C. The equilibrium swelling ratio (SR) was at the minimum when pH of the swelling medium was close to the isoelectric point (pI) of the whey protein, and when the swelling medium pH was far from the pI (from 6.0 to 10.0), the SR increased. In particular, when the pH was higher than the pI, the swelling was highly pH sensitive. The higher the WPC concentration used in preparing the hydrogel, the lower was the SR. The controlled drug release properties of the WPC hydrogels were studied using caffeine as the model drug. Consistent with the swelling behavior of the gels, release was slower when the pH of the medium was lower (pH 1.8) than when it was higher (pH 7.5). The SR and the drug release rate decreased significantly when the gels were surface‐coated with alginate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Surface patch binding‐induced exfoliation of nanoclays and enhancement of physical properties of gelatin organogels

Nanoclay‐containing organogels were prepared by exfoliating layered silicate nanoclay (Laponite^® and montmorillonite, aspect ratio 30 and 250) in organogels made in glycerol solutions. Zeta potential of the binding profile between clay and gelatin chains in the milieu of glycerol was consistent with a surface patch binding mechanism. To achieve customized thermal and viscoelastic properties, optimum binding of nanoclay to gelatin was probed, and it was noticed that [clay] = 0.03% (w/v) and [glycerol] = 30% (v/v) produced the best results. Gelation temperature T_gel (Laponite organogels) increased from 28 to 34 °C (ca 21% change) with a concomitant increase in gel elastic modulus from 400 to 1200 Pa (ca 300% change). For montmorillonite organogels, it was possible to raise T_gel further to 43 °C (56% change). X‐ray diffraction data and Cole–Cole plots indicated that clay platelets were homogeneously exfoliated in the organogel matrix. Thus, the thermoviscoelastic properties of gelatin organogels could be modulated to raise the gelation temperature to 43 °C, and gel strength to 1200 Pa by the addition of nanoclay whose concentration may not exceed 0.03% (w/v). Considering the wide application of gelatin gels in pharmaceuticals, food preservation and personal care products, the aforesaid enhancement in physical properties is significant. © 2016 Society of Chemical Industry     

Fluconazole release through semi‐interpenetrating polymer network hydrogels based on chitosan,acrylic acid,and citraconic acid

Semi‐interpenetrating polymer network hydrogels with different compositions of chitosan (Cs), acrylic acid, and citraconic acid were synthesized via free‐radical polymerization with ethylene glycol dimethacrylate as a crosslinker. The variations of the swelling percentages of the hydrogels with time, temperature, and pH were determined, and Cs–poly(acrylic acid) (PAA) hydrogels were found to be most swollen at pH 7.4 and 37°C. Scanning electron micrographs of Cs–PAA and Cs–P(AA‐co‐CA)‐1 (Cs‐poly(acrylicacid‐co‐citraconir acid)^?1) were taken to observe the morphological differences in the hydrogels. Although the less swollen hydrogel, Cs–P(AA‐co‐CA)‐1, had a sponge‐type structure, the most swollen hydrogel, Cs–PAA, displayed a uniform porous appearance. Fluconazole was entrapped in Cs–P(AA‐co‐CA)‐1 and Cs–PAA hydrogels, and the release was investigated at pH 4.0 and 37°C. The kinetic release parameters of the hydrogels (the gel characteristic constant and the swelling exponent) were calculated, and non‐Fickian diffusion was established for Cs–PAA, which released fluconazole much more slowly than the Cs–P(AA‐co‐CA)‐1 hydrogel. A therapeutic range was reached at close to 1 h for both hydrogels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Determination of swelling behavior and morphological properties of poly(acrylamide‐co‐itaconic acid) and poly(acrylic acid‐co‐itaconic acid) copolymeric hydrogels

Poly(acrylamide‐co‐itaconic acid) (PAAmIA) and poly(acrylic acid‐co‐itaconic acid) (PAAIA) copolymeric hydrogels were prepared with different compositions via free‐radical polymerization. Ethylene glycol dimethacrylate (EGDMA) was used as an original crosslinker for these monomers. Gelation percentages of the monomers were studied in detail and it was found that addition of IA into the monomer mixture decreased the gelation percentage. The variation in swelling values (%) with time, temperature, and pH was determined for all hydrogels. PAA, which is the most swollen hydrogel, has the swelling percentage value of 2000% at pH = 7.4, 37°C. Swelling behaviors were explained with detailed SEM micrographs, which show the morphologic differences between dry and swollen hydrogels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5994–5999, 2006     

Preparation and characterization by radiation of hydrogels of PVA and PVP containing Aloe vera

In these studies, hydrogels for wound dressing were made from a mixture of Aloe vera, poly(vinyl alcohol) (PVA) and poly(N‐vinylpyrrolidone) (PVP) by freeze‐thaw, gamma‐ray irradiation, or a two‐step process of freeze‐thaw and gamma‐ray irradiation. Physical properties, such as gelation, water absorptivity, gel strength and degree of water evaporation were examined to evaluate the applicability of these hydrogels to wound dressing. The PVA:PVP ratio was 6:4, and the dry weight of Aloe vera was in the range of 0.4‐1.2 wt %. The solid concentration of PVA/PVP/Aloe vera solution was 15 wt %. Mixtures of PVA/PVP/Aloe vera were exposed to gamma irradiation doses of 25, 35 and 50 kGy to evaluate the effect of irradiation dose on the physical properties of the hydrogels. Gel content and gel strength increased as the concentration of Aloe vera in PVA/PVP/Aloe vera decreased and as irradiation dose increased and freeze‐thaw was repeated. Swelling degree was inversely proportional to gel content and gel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1612–1618, 2004     

Kinetics of sol-to-gel transition for poloxamer polyols

Kinetics of gelation for aqueous solutions of poloxamers 407 and 288 were determined using pulse shearometry. The principle of this method for determining the shear modulus of a semisolid was based on generation of a torsional force that is transmitted through the poloxamer sample at discrete time intervals. Three distinct linear phases were observed for the log dynamic shear modulus (G′) vs. time profiles as poloxamer 407 and 288 solutions of varying concentrations were allowed to passively warm at room temperature to a temperature exceeding the sol-to-gel transition temperature, T_m. The beginning of the second exponential phase coincided with the onset of the gelation process as determined by visual observation. Although gelation appeared visually to be complete at the beginning of the third exponential phase of the log G′ vs. time profiles, this last exponential phase may indicate the rate of formation of the polymer network. A comparison of poloxamer 407 [30% (w/w); T_m = 10.9°C] and poloxamer 288 [37% (w/w); T_m = 11.1°C] would suggest that the concentration of poloxamer required to achieve approximately the same gelation temperature for poloxamers having a similar ratio of poly(oxypropylene):poly(oxyethylene) units decreases with increasing molecular weight of the poly(oxypropylene) hydrophobe contained in the copolymer. Results of these preliminary studies suggest that the gelation process was significantly (p < .05) more rapid for poloxamer 407 at a 30% (w/w) concentration compared to a 30% (w/w) solution of poloxamer 288 when the poloxamer solutions were allowed to passively warm at room temperature. In addition, it appears that the rate of gelation for the poloxamer solutions studied was dependent on the rate of heat transfer through the polymer solution.     

Swelling–deswelling kinetics of poly(N‐isopropylacrylamide) hydrogels formed in PEG solutions

A series of poly(N‐isopropylacrylamide) (PNIPA) hydrogels was prepared by free‐radical crosslinking copolymerization of N‐isopropylacrylamide (NIPA) and N,N′‐methylenebisacrylamide (BAAm) in aqueous solutions of poly(ethylene glycol) of molecular weight 300 g/mol (PEG). The amount of PEG in the polymerization solvent, the crosslinker (BAAm) content, and the gel preparation temperature (T_prep) were varied in the gelation experiments. The hydrogels were characterized by the equilibrium swelling and elasticity tests as well as by the measurements of the deswelling–reswelling kinetics of the hydrogels in response to a temperature change between 25 and 48°C. The rate of deswelling of the swollen gel increases while the rate of reswelling of the collapsed gel decreases as the amount of PEG in the polymerization solvent is increased or as the crosslinker content is decreased. The T_prep effect on the swelling kinetics of the hydrogels was only observed if the PEG content of the polymerization solvent is less than 20%, which is explained with the screening of H‐bonding interactions in concentrated PEG solution. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 37–44, 2006     

Acetanilide-loaded injectable hydrogels with enhanced bioactivity and biocompatibility for potential treatment of periodontitis

Chronic periodontitis poses long-term challenges in dentistry, requiring the development of innovative dental composites with biocompatibility, bone regeneration, and antibacterial properties. This study focuses on synthesis of novel injectable thermoresponsive hydrogels composed of chitosan, sodium bicarbonate, bioactive glass (20 and 40% w/w), and acetanilide drug (0.3 and 0.6% w/w). These hydrogels exhibit a sol–gel transition at 37°C, addressing periodontal challenges with reduced gelation time. The smooth flow characteristic was evaluated through 17-22 gauge syringe needles at low temperature. Rheological studies demonstrated pseudoplastic behavior, with viscosity decreasing as shear rate increases. Fourier transform infrared and x-ray diffraction analysis confirmed the bioactivity of hydrogels, forming a bone-like apatite layer in simulated body fluid. The drug-loaded hydrogels demonstrated promising in vitro antibacterial properties against dental pathogens, specifically Staphylococcus aureus and Pseudomonas aeruginosa. Drug dissolution analysis revealed relatively high release rate at 37°C, highlighting its role in rapidly eliminating bacterial colonies at the target site, while the subsequent sustained release contributes to the prevention of infection recurrence. Finally, biocompatibility was assessed with fibroblast, where the cells were observed anchoring into the polymeric chains of hydrogel through extended filopodia.     

Development of dual‐triggered in situ gelling scaffolds for tissue engineering

Hydrogel‐forming materials that mimic the three‐dimensional architecture and properties of tissue are known to have a positive effect on cellular differentiation and growth. A subset of those are in situ gels, which utilise in vivo conditions like pH (e.g. acetate phthalate), temperature (e.g. poloxamer) and ionic concentration (e.g. Gelrite?), and can be used to facilitate the delivery of cells to an affected tissue. Hence, we have developed in situ hydrogels based on gellan and hydroxypropylmethylcellulose (HPMC), which are known to be triggered through ions and temperature, respectively, as matrices to deliver cells. Gellan/HPMC blends had a lower gelation temperature than gellan alone crosslinked with calcium, suggesting the role of the dual trigger. Average storage modulus at a frequency of 10 Hz for gellan crosslinked with 3 mmol L^?1 calcium was 4.53 × 10³ Pa; for 9:1 gellan/HPMC crosslinked with 3 mmol L^?1 calcium was 5.59 × 10³ Pa; and for 8:2 gellan/HPMC crosslinked with 3 mmol L^?1 calcium was 2.13 × 10³ Pa, suggesting tunable stiffness by changing the gellan‐to‐HPMC ratio. Hydrophilicity was confirmed using goniometry with a contact angle much less than 90°, facilitating the passage of cells and electrolytes when using the gels as scaffolds. The gels were also found to be porous and non‐toxic to fibroblast cell line L929 and osteosarcoma cell line MG‐63, which, when encapsulated within the gels, were able to grow and proliferate. These blended hydrogels are suitable as scaffolds to encapsulate cells, with tunable stiffness modulated by varying the concentration of gellan and HPMC. © 2014 Society of Chemical Industry     

Swelling characteristics and in vitro drug release study with pH‐ and thermally sensitive hydrogels based on modified chitosan

The grafting of a poly(ethylene glycol) diacrylate macromer onto a chitosan backbone was carried out with different macromer concentrations. The grafting was achieved by (NH₄)₂Ce(NO₃)₆‐induced free‐radical poly merization. Biodegradable, pH‐ and thermally responsive hydrogels of poly(ethylene glycol)‐g‐chitosan crosslinked with a lower amount of glutaraldehyde were prepared for controlled drug release studies. Both the graft copolymers and the hydrogels were characterized with Fourier transform infrared, elemental analysis, and scanning electron microscopy. The obtained hydrogels were subjected to equilibrium swelling studies at different temperatures (25, 37, and 45°C) in buffer solutions of pHs 2.1 and 7.4 (similar to those of gastric and intestinal fluids, respectively). 5‐Fluorouracil was entrapped in these hydrogels, and equilibrium swelling studies were carried out for the drug‐entrapped gels at pHs 2.1 and 7.4 and 37°C. The in vitro release profile of the drug was established at 37°C and pHs 2.1 and 7.4. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 977–985, 2006     

Equilibrium swelling behavior and elastic properties of polymer–clay nanocomposite hydrogels

Nanocomposite hydrogels were prepared by free‐radical polymerization of the monomers acrylamide (AAm), N,N‐dimethylacrylamide (DMA), and N‐isopropylacrylamide (NIPA) in aqueous clay dispersions at 21°C. Laponite XLS was used as clay nanoparticles in the hydrogel preparation. The hydrogels based on DMA or NIPA monomers exhibit much larger moduli of elasticity compared with the hydrogels based on AAm monomer. Calculations using the theory of rubber elasticity reveal that, in DMA‐clay or NIPA‐clay nanocomposites, both the effective crosslink density of the hydrogels and the functionality of the clay particles rapidly increase with increasing amount of Laponite up to 10% (w/v). The results suggest that DMA‐clay and NIPA‐clay attractive interactions are stronger than AAm‐clay interactions due to the formation of multiple layers on the nanoparticles through hydrophobic associations. It was also shown that, although the nanocomposite hydrogels do not dissolve in good solvents such as water, they dissolve in dilute aqueous solutions of acetone or poly(ethylene oxide) of molecular weight 10,000 g/mol, demonstrating the physical nature of the crosslink points. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and in vitro evaluation of new pH‐sensitive hydrogel beads for oral delivery of protein drugs

New biodegradable pH‐responsive hydrogel beads based on chemically modified chitosan and sodium alginate were prepared and characterized for the controlled release study of protein drugs in the small intestine. The ionotropic gelation reaction was carried out under mild aqueous conditions, which should be appropriate for the retention of the biological activity of an uploaded protein drug. The equilibrium swelling studies were carried out for the hydrogel beads at 37°C in simulated gastric (SGF) and simulated intestinal (SIF) fluids. Bovine serum albumin (BSA), a model for protein drugs was entrapped in the hydrogels and the in vitro drug release profiles were established at 37°C in SGF and SIF. The preliminary investigation of the hydrogel beads prepared in this study showed high entrapment efficiency (up to 97%) and promising release profiles of BSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Swelling dynamics of IPN hydrogels including acrylamide‐acrylic acid‐chitosan and evaluation of their potential for controlled release of piperacillin‐tazobactam

For to be used in controlled releasing of piperacillin‐tazobactam, a series of semi and full IPN type hydrogels composed of acrylic acid (AA), acrylamide (AAm) and Chitosan (CS) were prepared via free‐radical polymerization. Ethylene glycol dimethacrylate (EGDMA) was used for crosslinking of PAAm and PAA chains to form semi‐IPN hydrogels. However, the full‐IPN type hydrogels were prepared by using glutaraldehyde (GA) and EGDMA as cocrosslinkers. Characteristics of the hydrogels were investigated by swelling experiments and SEM and FTIR analysis. Generally, full‐IPN type hydrogels swell much more than the semi‐IPN types. By comparing the full‐IPN type hydrogels in between, it is found that the increasing amount of GA causes the decreasing in S% values from 4860 to 4300%. Releasing of piperacillin‐tazobactam from selected three hydrogels were investigated in phosphate buffer solution at pH = 7.4, 37°C. The kinetic release parameters, n and k were calculated and non‐Fickian type diffusion was established for these hydrogels. The behaviors of the piperacillin‐tazobactam loaded hydrogels in Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) culture suspensions were also studied and the statistically significant differences for the microorganism growth values were determined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Real‐time temperature and photon transmission measurements for monitoring phase separation during the formation of poly(N‐isopropylacrylamide) gels

Phase separation during the formation of poly(N‐isopropylacrylamide) (PNIPA) hydrogels was investigated using real‐time photon transmission and temperature measurements. The hydrogels were prepared by free‐radical crosslinking polymerization of N‐isopropylacrylamide (NIPA) in the presence of N,N′‐methylenebisacrylamide (BAAm) as a crosslinker in an aqueous solution. The onset reaction temperature T₀ was varied between 20 and 28°C. Following an induction period, all the gelation experiments resulted in exothermic reaction profiles. A temperature increase of 6.5 ± 0.6°C was observed in the experiments. It was shown that the temperature increase during the formation and growth process of PNIPA gels is accompanied by a simultaneous decrease in the transmitted light intensities I_tr. The decrease in I_tr at temperatures below the lower critical solution temperature of PNIPA was explained by the concentration fluctuations due to the inhomogeneity in the gel network. At higher temperatures, it was shown that the gel system undergoes a phase transition via a spinodal decomposition process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3589–3595, 2002     

Horseradish peroxidase‐mediated in situ forming hydrogels from degradable tyramine‐based poly(amido amine)s

Horseradish peroxidase (HRP)‐mediated crosslinking of poly(amido amine) (PAA) copolymers was successfully applied in the preparation of in situ forming degradable hydrogels under physiological conditions. PAA copolymers containing different amounts of tyramine residues (termed as pAEEOL/TA) could be synthesized through Michael‐type addition between methylenebisacryamide and amine mixture of 2‐(2‐aminoethoxy) ethanol and tyramine (TA). Depending on the amount of TA residue, the HRP, and H₂O₂ concentration, the gelation times could be varied from about 50 to 350 s. The swelling and degradation experiments indicated under physiological conditions the pAEEOL/TA‐based hydrogels are completely degradable within 6–8 days. Rheological analysis revealed that storage modulus of the hydrogels increased from 2500 to 4100 Pa when increasing HRP concentrations. Importantly, pAEEOL/TA copolymers have low cytotoxicity. Moreover, NIH 3T3 (mouse embryonic fibroblast) cells exposed in the degradation products of pAEEOL/TA‐based hydrogels retained high cell viability, implying that the hydrogels are cyto‐biocompatible. In vitro release of methylene blue and IgG protein from pAEEOL/TA‐based hydrogels could be effectively sustained by encapsulation of the drug in the hydrogels. The results indicate that HRP‐crosslinked, degradable pAEEOL/TA‐based hydrogels are promising for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improvements of electromechanical properties of gelatin hydrogels by blending with nanowire polypyrrole: effects of electric field and temperature

Nanowire‐polypyrrole/gelatin hydrogels were fabricated by dispersion of nanowire‐polypyrrole into a gelatin aqueous solution followed by solvent casting. The electromechanical properties, thermal properties and deflection of pure gelatin hydrogel and nanowire‐polypyrrole/gelatin hydrogels were studied as functions of temperature, frequency and electric field strength. The 0.01%, 0.1%, 0.5%, 1% v/v nanowire‐polypyrrole/gelatin hydrogels and pure gelatin hydrogel possess storage modulus sensitivity values of 0.75, 1.04, 0.88, 0.99 and 0.46, respectively, at an electric field strength of 800 V mm^?1. The effect of temperature on the electromechanical properties of the pure gelatin hydrogel and nanowire‐polypyrrole/gelatin hydrogels was investigated between 30 and 80 °C; there are three regimes for the storage modulus behaviour. In deflection testing in a cantilever fixture, the dielectrophoresis force was determined and found to increase monotonically with electric field strength. The pure gelatin hydrogel shows the highest deflection angle and dielectrophoresis force at an electric field strength of 800 V mm^?1 relative to those of the nanowire‐polypyrrole/gelatin hydrogels. Copyright © 2012 Society of Chemical Industry     

Synthesis and characterization of new methacrylate-type hydrogels containing 2-tert-butylamino ethyl groups for sorption purposes

Crosslinked poly[2-(tert-butylamino)ethyl methacrylate] (PtBAEMA) hydrogels were synthesized by ⁶⁰Co-γ-radiation-initiated simultaneous polymerization and crosslinking of 2-(tert-butylamino)ethyl methacrylate in bulk and in aqueous solutions. The results showed that the gelation percentage decreased with increasing water content. The structural and thermal characterizations of the hydrogels were accomplished with several techniques, including Fourier transform infrared spectroscopy, swelling measurements, thermogravimetry, and differential scanning calorimetry. The effects of time, pH, temperature, and ionic strength on the swelling behavior were also investigated. Swelling equilibrium was attained in 2–3 days. PtBAEMA hydrogels originally swelled to 350% (by volume) in deionized water, but this value reached 3000% around pH 2.0. PtBAEMA hydrogels were reversibly affected by the change in temperature within the temperature range of 4–70°C. The swelling ratios of the gels decreased with increasing ionic strength. As a result, PtBAEMA hydrogels show stimuli-responsive properties depending on the characteristics of the environment, and they are being considered for adoption as some kind of carrying material for separation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Swelling behavior of thermoreversible poly(N‐isopropylacrylamide‐co‐N‐vinylimidazole) hydrogels

Thermoresponsive hydrogels based on N‐isopropylacrylamide and N‐vinylimidazole were synthesized, and their swelling–deswelling behavior was studied as a function of the total monomer concentration. For copolymeric structures with better thermoresponsive properties with respect to poly(N‐isopropylacrylamide‐co‐N‐vinylimidazole) hydrogels, these hydrogels were protonated with HCl and HNO₃, and the copolymer behaviors were compared with those of the unprotonated hydrogels. The temperature was changed from 4 to 70°C at fixed pHs and total ionic strengths. The equilibrium swelling ratio, dynamic swelling ratio, and dynamic deswelling ratio were evaluated for all the hydrogels. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1619–1624, 2004     

A novel gastric release PEG‐enclatherated polymethacrylate‐based memblet system

A novel polymethacrylate‐based membranous system referred to as a “memblet” was developed for potential application in controlled gastric drug delivery. A polymethacrylate‐based latex, Eudragit® E100, was enclatherated with a 60% w/v and a 30% w/v solution of polyethylene glycol 4000 to form hydrogel formulations A and B, respectively. The hydrogels were subsequently compressed into memblets that were characterized for thermal, rheological, morphological, mechano‐chemical properties, and in vitro gastric drug release analysis. Molecular mechanics (MM) simulations were performed to corroborate the experimental findings. Critical yield values of 15.39 and 5.239 Pa were obtained for hydrogel A and B, respectively. The viscoelastic region was found to be <10.67 and 2.542 Pa for hydrogels A and B, respectively. The storage modulus was greater than the loss modulus for hydrogel A while the inverse was true for hydrogel B. Thermal, mechanical, and surface morphology evaluation revealed that the converse was true for the dried membrane structure with hydrogel B having superior characterization profiles than hydrogel A. Notably, the lower PEG concentration (30% w/v) displayed better characterization profiles than a higher concentration (60% w/v). Through MM simulations, desirable agreement between the theoretical and experimental results was achieved over the given concentration range of PEG. Based on the gastric drug release analysis, memblets formulated with hydrogel B displayed superior control of drug release. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013