Superporous Hydrogel Composites Research Articles

Effect of using high molecular weight crosslinker on the physical properties of super porous hydrogel composite

Superporous hydrogel composite is widely utilized and investigated as a gastro retentive drug delivery system. Materials used in Superporous hydrogel formulation have a profound effect on its properties’, N-methylene bisacrylamide is the crosslinker of choice for the preparation of SPH.
 The purpose of this study is to determine if using a new high molecular weight crosslinker such as polyethylene glycol diacrylate will affect the physical characteristics of SPH and drug release behavior. For the preparation of super porous hydrogel polyvinyl alcohol, acrylamide, polyethylene glycol diacrylate 700, N, N-Methylene bisacrylamide, sodium bicarbonate, and tween 20 were used. Trifluoperazine HCl was used as a model drug. The buoyancy, porosity, density, drug release, drug content, swelling ratio, and swelling time were studied and compared. All the physical characteristics and medication release profiles were impacted by changing the formulation parameters. The formula with the best physical qualities had 300 µl of acrylamide (40 percent w/v), 20 mg of polyvinyl alcohol, 200 µl of Tween 20 (v/v), 5 µl of polyethylene glycol diacrylate 700, 45 µl ammonium persulfate, 45 µl TEMED and 50 mg of sodium bicarbonate. Around 80% of the drug was released over the course of 12 hours according to zero order kinetics. By modifying the formulation parameters using polyethylene glycol diacrylate, Superporous hydrogel was successfully manufactured and has the best properties to be employed as a gastro retentive drug delivery system.

Utilization of clay based super-porous hydrogel composites in atmospheric water harvesting

Current research work reports the synthesis and performance evaluation of solid polymer desiccant materials based on the superporous hydrogel composites (SPHCs) comprising superporous hydrogel (SPHs) of sodium acrylate (SA) and acrylamide (AM) with different clays such as Laponite®, bentonite and palygorskite. Synthesized polymer desiccants were characterized using SEM, XRD, TGA and FTIR techniques. All the polymer desiccants followed type-III isotherm and the experimental data correlated well with Guggenheim, Anderson and Boer (GAB) model and suggested that these desiccants belong to macroporous adsorbents and adsorb water vapors largely via capillary condensation process. Parental SPH (i.e. P(SA-co-AM)-SPH) and different SPHCs i.e. SPHC-Laponite®, SPHC-bentonite and SPHC-palygorskite exhibited maximum adsorption capacities of 0.12, 0.17, 0.15 and 0.14 gw/gads, respectively at 50% relative humidity and 25 °C, however, at 90% relative humidity adsorption capacities increased upto 0.77, 1.05, 0.93 and 0.87 gw/gads, respectively, which suggested that the hydrophilicity of synthesized desiccants increased with increasing relative humidity. Exceptionally high adsorption capacities of these desiccants were because of the combined effects of highly porous structure of SPHs and hydrophilic nature of clays. Furthermore, experimental kinetics data correlated well with linear driving force model and suggested that the diffusion of water within polymer structure was via type-II diffusion mechanism. During multiple cycle adsorption, SPHCs exhibited much better re-use efficiency than SPHs which suggested that the incorporation of clays within the polymer matrix not only improved desiccant performance but also improved re-use efficiency of polymer desiccants.

Zeolites and superporous hydrogels-based hybrid composites as solid desiccants to capture water vapors from humid air

This work reports the synthesis and use of zeolites based super-porous hydrogel composites (SPHCs) as solid polymer desiccants to capture water vapors from moist air. The SPHCs were composed of super-porous hydrogels (SPHs) of acrylic acid and methacrylamide (i.e. P(AA-co-MAM)-SPHs) as polymer matrix and AQSOA type zeolites, i.e. AQSOA-Z01, AQSOA-Z02 and AQSOA-Z05 zeolites as reinforcing materials. Different structural and morphological properties of SPHCs were characterized using techniques like XRD, SEM, FTIR and TGA-DTG. Desiccant properties of P(AA-co-MAM)-SPH and SPHCs were explored in terms of adsorption isotherm and kinetics. All the desiccants exhibited type-III adsorption isotherm, suggesting water vapors’ adsorption via capillary condensation mechanism and correlated well with GAB and FHH isotherm models. P(AA-co-MAM)-SPH exhibited maximum adsorption capacity of 0.72 gw/gads. However, after reinforcing different zeolites, adsorption capacity increased to 0.80, 0.84 and 0.91 gw/gads in SPHC/AQSOA-Z01, SPHC/AQSOA-Z02 and SPHC/AQSOA-Z05, respectively at 90% relative humidity and 25 °C. Further, the adsorption kinetics data correlated well with linear driving force and intraparticle diffusion models and the adsorption equilibrium was achieved much quicker at 70% relative humidity as compared to 90% relative humidity. SPHCs showed much better re-use efficiency as compared to parental SPH, therefore, reinforcement of zeolites improved the re-use efficiency of P(AA-co-MAM)-SPH.

Hybrid super-porous hydrogel composites with high water vapor adsorption capacity – Adsorption isotherm and kinetics studies

Water vapors adsorption capacity of deliquescent salts is very high, but they dissolve in the adsorbed water by forming crystalline hydrates which restricts their use in different water vapor adsorption applications. This limitation can be overcome by incorporating deliquescent salts within a polymer matrix which will keep the salt solution in place. Furthermore, if the polymer matrix used is also capable of adsorbing water vapor, it will further improve the overall performance of desiccant systems. Therefore, in this work, we are proposing the synthesis and use of a highly effective new solid polymer desiccant material, i.e. superporous hydrogel (SPHs) of sodium acrylate and acrylic acid P(SA+AA), and subsequently its composite with deliquescent salt, i.e. calcium chloride (CaCl2), for the adsorption of water vapors from humid air without the dissolution of deliquescent salt in the adsorbed water. Synthesized SPH composite was characterized using different techniques like scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Parental P(SA+AA)-SPHs matrix alone exhibited the adsorption capacity of 1.02 gw/gads which increased to 3.35 gw/gads after incorporating CaCl2 salt in the polymer matrix. For both materials, experimental isotherm data agreed with Guggenheim, Anderson and Boer (GAB) isotherm model and exhibited type-III adsorption isotherm. The adsorption kinetics followed linear driving force model. Furthermore, adsorbents were used successively for ten cycles of adsorption and regeneration. Therefore, the proposed polymer desiccant material overcomes the problem of dissolution of deliquescent salts and purposes a new class of highly effective solid desiccant material.

Formulation, Characterization and Antihelminthic Activity Testing of Nitazoxanide Superporous Hydrogel Tablets

In the pharmaceutical field controlled release products have the ability to maintain desired medicament concentration or a longer period of time. Certain drugs are relatively insoluble in water and have high dose requirements that render unsuitable formulation difficulties in sustained release formulations. Nitazoxanide which is a high dose water insoluble antiprotozoal drug was formulated with the aim. To modulate gastro-retentive dosage form based on the superporous hydrogel composites. Foaming technique was used in the preparation of SPH composites. The superporous hydrogels were extremely sensitive to pH of swelling media and good porosity. Superporous hydrogels tablets of nitazoxanide showed good pre-compressional and post-compressional properties. Formulation X is the best formulation containing chitosan, polyvinyl alcohol, formaldehyde, exhibited good swelling ratio. The compatibility studies were performed by Fourier Transform Infrared (FT-IR) Spectroscopic Studies, Differential Scanning Calorimetry Studies (DSC). All formulations were evaluated for stability, drug content, and kinetic drug release & in-vitro drug release profile. It was concluded that the proposed gastro-retention drug delivery provides a different supply of nitazoxanide directly to the stomach.
 Keywords: Nitazoxanide, Anti protozoal, foaming technique, Chitosan

Implications of superporous hydrogel composites-based gastroretentive drug delivery systems with improved biopharmaceutical performance of fluvastatin

The present research work describes the systematic development and characterization of novel gastroretentive drug delivery system containing superporous hydrogel composites for improving the bioavailability and antihyperlipidemic activity. The superporous hydrogels of fluvastatin exhibited swelling property in presence of the gastric fluid and retains inside the stomach to provide controlled drug release action. These hydrogels were systematically developed and optimized using Box-Behnken design, which includes the concentration of glutaraldehyde (X1), Span 80 (X2) and polyvinyl alcohol (X3) as the independent variables, while swelling ratio (Y1) and in vitro drug release (Y2) were taken as the dependent variables. The prepared hydrogel formulations were also evaluated for density, porosity and void fraction as their physical properties. DSC and FT-IR study was performed to analyze the drug-excipient interactions. SEM imaging was performed for the morphological characterization of the prepared superporous hydrogels. In vivo pharmacokinetic study was conducted for evaluating the drug absorption and elimination parameters, while the pharmacodynamic study was performed for evaluating the antihyperlipidemic activity of the superporous hydrogel formulation. Overall, the studies indicated that optimized superporous hydrogel formulation with improved biopharmaceutical performance.

Adsorption isotherm and kinetics of water vapors on novel superporous hydrogel composites

Abstract A promising and highly efficient new solid desiccant material composted of superporous hydrogel (SPHs) of polyacrylamide (PAM) and AQSOA-Z02 zeolite was fabricated to capture water vapor from moist air. The synthesis method of PAM-SPHs involved the gas blowing and foaming technique which insured a uniform distribution of zeolite particles throughout the polymer matrix. The presence of three dimensional porous structure, interconnected macropores in SPHs and the highly hydrophilic functional groups of AQSOA-Z02 particles enabled the synthesized SPHs composite to exhibit excellent water vapor adsorption capacity. The introduction of AQSOA-Z02 zeolite in the polymer matrix increased the water vapor adsorption capacity from 0.77 gw/gads to 0.89 gw/gads. Both materials exhibited type-III isotherm and followed Frenkel-Halsey-Hill and Guggenheim, Anderson and Boer (GAB) adsorption isotherm models. The high adsorption capacity was attributed to the combined effects of capillary condensation in interconnected macropores and the attachment of water molecules to the hydrophilic functional groups present in the zeolite structure. The water vapor adsorption capacity was found to decrease with increasing temperature. Adsorption kinetics studies suggested that the water vapor adsorption followed first-order kinetics models and the mechanism of water molecules diffusion into the internal structure of SPHs was case-II type of diffusion mechanism.

Superporous Hydrogel Composites of Acrylamide Using Starch-silicone Dioxide Coprecipitate as Composite Agent

Aim: Present study includes the development and evaluation of superporous hydrogel composites of acrylamide using starch silicone dioxide coprecipitate (SSC) as composite agent. Methodology: Gas blowing method was used for synthesis of superporous hydrogels. Different ingredients were mixed in specified amount in test tube and foaming agent was added at last. Simultaneous foaming and gelation lead to formation of porous hydrogel networks. Effect of different treatments (acetone dehydration and simulated gastric fluid (SGF) treatment) and drying conditions on the porous structure was evaluated. The prepared superporous hydrogels were evaluated for density, porosity, equilibrium swelling ratio, equilibrium swelling time, mechanical strength, scanning electron microscopy studies. The pure drug (Verapamil Hydrochloride) mixed with Carbopol 934 (1:0.5 and 1:1 ratio) was loaded into the selected batches of SPHC using in situ method of drug loading Original Research Article British Journal of Pharmaceutical Research, 4(3): 338-351, 2014 339 (drug added directly into the reaction mixture). The in vitro drug release was carried out using USP II dissolution apparatus. Results: Acetone dehydrated superporous hydrogel composites were observed as better floating devices due to least density and maximum porosity values. Maximum swelling ratio was found in case of oven dried conventional superporous hydrogel and superporous hydrogel composites with equilibrium swelling time of more than 25 min. On the other hand, acetone dehydrated SPH showed less equilibrium swelling ratio with equilibrium swelling time of 5-10 min. Minimum swelling ratio was observed in case of SGF treated hydrogels with equilibrium swelling time of 15-19 min. Mechanical strength was improved by addition of starch silicone dioxide coprecipitate as composite agent. SGF treatment also leads to enhanced mechanical strengthbut compromised swelling characteristics. SEM images showed uniformity in pore structure in case of acetone dehydrated hydrogels. Acetone dehydrated SPHC showed sustained drug release behavior with 71.14% and 57.84% of verapamil released in 12 h in the batches with Drug: Carbopol 934ratio of (1:0.5 and 1:1) respectively. Conclusion: Acetone dehydrated SPHC were found to be promising formulations with sufficient swelling and mechanical properties for achieving sustained drug delivery.

Chromium picolinate loaded superporous hydrogel and superporous hydrogel composite as a controlled release device: in vitro and in vivo evaluation

The aim of this work was to develop chromium picolinate (CP) loaded gastroretentive device using superporous hydrogel (SPH) and superporous hydrogel composite (SPHC). The drug was considered as good candidate for such systems owing to its narrow absorption window. Swelling ratio, apparent density, scanning electron microscopy (SEM), drug content and drug release in pH 1.2 were evaluated for hydrogels. SEM of hydrogels showed interconnected pores with extensive capillary insertion. Swelling ratio for CP-SPH was higher than that of SPHC while apparent densities were lower. Both SPH and SPHC retarded drug release as values of half-life attained 3.64 and 2.94 h, respectively, while plain drug 0.22 h. The mechanical strength of SPHC was higher than SPH, so it was selected for in vivo studies in dogs. Radiographic examination in dogs showed that gastric retention persisted for 24 h. Percentage relative bioavailability was 298.8 %. SPHC could be thus considered as good gastroretentive device for CP.

Development of Bioadhesive Chitosan Superporous Hydrogel Composite Particles Based Intestinal Drug Delivery System

Bioadhesive superporous hydrogel composite (SPHC) particles were developed for an intestinal delivery of metoprolol succinate and characterized for density, porosity, swelling, morphology, and bioadhesion studies. Chitosan and HPMC were used as bioadhesive and release retardant polymers, respectively. A 32 full factorial design was applied to optimize the concentration of chitosan and HPMC. The drug loaded bioadhesive SPHC particles were filled in capsule, and the capsule was coated with cellulose acetate phthalate and evaluated for drug content, in vitro drug release, and stability studies. To ascertain the drug release kinetics, the drug release profiles were fitted for mathematical models. The prepared system remains bioadhesive up to eight hours in intestine and showed Hixson-Crowell release with anomalous nonfickian type of drug transport. The application of SPHC polymer particles as a biomaterial carrier opens a new insight into bioadhesive drug delivery system and could be a future platform for other molecules for intestinal delivery.

Microwave-assisted fabrication of chitosan-hydroxyapatite superporous hydrogel composites as bone scaffolds

In this study, a novel scaffold fabrication method was developed by combining microwave irradiation and gas foaming. Chitosan superporous hydrogels (SPHs) and chitosan-hydroxyapatite (HA) superporous hydrogel composites (SPHCs) were prepared by using this method in the presence of crosslinking agent, glyoxal, and a gas-blowing agent, NaHCO3. In order to examine the effect of HA on composite structure and cellular behaviour, two types of HA particles, i.e. spherical beads in 45-80 µm diameter and powder form, were used. While rapid heating with microwave irradiation enhances gas blowing, pH increment, which is accelerated by NaHCO3 decomposition, provides better crosslinking. Thus, interconnected and well-established macroporous hydrogels/hydrogel composites were produced easily and rapidly (~1 min). Cell culture studies, which were carried out under static and dynamic conditions with MC3T3-E1 pre-osteoblastic cells, indicated that chitosan-HA bead SPHCs supported cellular proliferation and osteoblastic differentiation better than chitosan SPHs and chitosan-HA powder SPHCs. In conclusion, simultaneous gas foaming and microwave crosslinking can be evaluated for the preparation of composite scaffolds which have superior properties for bone tissue engineering.

Investigation of Swelling Behavior and Mechanical Properties of a pH-Sensitive Superporous Hydrogel Composite.

The objective of the present study is to develop and investigate the swelling behavior of pH-sensitive Superporous Hydrogel (SPH) and SPH composite (SPHC). A novel superporous hydrogel containing poly (methacrylic acid-co-acrylamide) was synthesized from methacrylic acid and acrylamide through the aqueous solution polymerization, using N,N-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. SPHCs were made in the same way, except for the using of Ac-Di-Sol as a stabilizer. The synthesized SPH and SPHC were characterized by Fourier-transform infrared spectroscopy, swelling kinetics, porosity, mechanical properties and scanning electron microscopy. The swelling of SPH and SPHC was sensitive towards the pH, ionic strength, and temperature stimuli. The study of the surface morphology of SPH using scanning electron microscopy showed a highly porous structure. SPH polymers showed higher swelling ratio but less mechanical stability compared to SPHC polymers, which showed lower swelling ratio but a higher mechanical stability. With a change in pH from acidic to basic, a considerable increase in swelling was observed. Since the prepared SPH and SPHC swell only in the basic pH, it may be concluded that SPH and SPHC can be used as the pH-sensitive drug delivery system.

Preparation and characterization of superporous hydrogel based on different polymers

Introduction:Superporous hydrogel (SPH) swells very rapidly in a shorter period of time to an equilibrium size and contains highly porous structure.Aim:The synthesis of SPH of poly (acrylamide-co-acrylic acid) and its composites viz. Ac-Di-Sol and polyvinylpyrollidone (PVP) was carried out by solution polymerization.Materials and Methods:The SPH and SPH composites (SPHCs) were characterized by measurement of apparent density, porosity, swelling, mechanical strength, and scanning electron microscopy (SEM) studies.Results:FTIR studies confirmed the existence of acrylamide and acrylic acid in SPH. In distilled water SPH showed tremendous increase in equilibrium swelling capacity with conventional SPH as compared to its SPHCs of Ac-Di-Sol and PVP due to the increased in physical cross-linking network, respectively. The presence of Ac-Di-Sol and PVP in SPHCs increased the mechanical strength as compared to conventional SPH which is suitable for gastric retention. SEM pictures clearly indicated the formation of interconnected pores and capillary channels.Conclusion:The amount and type of polymers used affect almost all the characterization parameters of SPHs, and hence, depending upon the applications perspective such polymers could be used in drug delivery systems, successfully.

Novel Scaffolds Based on Poly(2-hydroxyethyl methacrylate) Superporous Hydrogels for Bone Tissue Engineering

In this study, poly(2-hydroxyethyl methacrylate) (pHEMA)-based superporous hydrogels were synthesized by radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in the presence of a gas blowing agent, sodium bicarbonate. These hydrogels are: pHEMA, pHEMA–gelatin, glycerol phosphate (GP) cross-linked pHEMA–gelatin, glutaraldehyde (GA) cross-linked pHEMA–gelatin superporous hydrogels (SPHs) and pHEMA–hydroxyapatite (HA) superporous hydrogel composites (SPHCs). The hydrogels have a structure of interconnected pores with pore sizes of approx. 500 μm. Although the extent of swelling decreased when gelatin and HA were incorporated to the pHEMA structure, the time to reach the equilibrium swelling (approx. 20 s) was not affected so much. In the presence of gelatin and cross-linkers, mechanical properties significantly improved when compared with pHEMA SPH. Among all the synthesized hydrogels, pHEMA–HA SPHC showed great improvement in mechanical strength and its elastic modulus value was 0.027±0.002 N/mm2. Osteogenic activities of pHEMA-based scaffolds were examined by preosteoblastic MC3T3-E1 cell-culture studies. The mitochondrial activity test (MTT) showed that gelatin-containing scaffolds stimulated cell proliferation compared with other scaffolds, while alkaline phosphatase levels (ALP) and mineralization were found highest for the GP cross-linked pHEMA–gelatin SPH. However, pHEMA SPH and pHEMA–HA SPHC did not support cell proliferation and also differentiation. In conclusion, pHEMA–gelatin SPH and GP cross-linked pHEMA–gelatin SPH can be considered as potential scaffolds for bone tissue-engineering applications.

Preparation and In Vitro Evaluation of a Stomach Specific Drug Delivery System based on Superporous Hydrogel Composite.

This study discusses efforts made to design drug-delivery system based on superporous hydrogel composite for sustained delivery of ranitidine hydrochloride. The characterization studies involve measurement of apparent density, porosity, swelling studies, mechanical strength studies, and scanning electron microscopy. Scanning electron microscopic images clearly showed the formation of interconnected pores, capillary channels, and the cross-linked sodium carboxymethylcellulose molecules around the peripheries of pores. The prepared system floated and delivered the ranitidine hydrochloride for about 17 h. The release profile of ranitidine hydrochloride was studies by changing the retardant polymer in the system. To ascertain the drug release kinetics, the dissolution profiles were fitted to different mathematical models that include zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas, Weibull, and Hopfenberg models. The in vitro dissolution from system was explained by Korsmeyer-Peppas model. The diffusion exponent values in Korsmeyer-Peppas model range between 0.48±0.01 and 0.70±0.01, which appears to indicate an anomalous non-Fickian transport. It is concluded that the proposed mechanically stable floating drug-delivery system based on superporous hydrogel composite containing sodium carboxymethylcellulose as a composite material is promising for stomach specific delivery of ranitidine hydrochloride.

Chitosan superporous hydrogel composite-based floating drug delivery system: A newer formulation approach.

Objective:In this study efforts have been made to design a drug delivery system based on a superporous hydrogel composite, for floating and sustained delivery of Ranitidine hydrochloride.Materials and Methods:The characterization studies were performed by the measurement of apparent density, porosity, swelling studies, mechanical strength studies, and scanning electron microscopy studies. The prepared formulation was evaluated for buoyant behavior, in vitro drug release, kinetics of drug release, and stability. The release profile of Ranitidine hydrochloride was investigated by changing the release retardant polymer in the formulation. To ascertain the kinetics of drug release, the drug release profiles were fitted to mathematical models that included zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas, Weibull, and Hopfenberg models.Results:Scanning electron microscopy images clearly indicated the formation of interconnected pores and capillary channels, and cross-linked Chitosan molecules were observed around the peripheries of the pores. The prepared drug delivery system floated and delivered the Ranitidine hydrochloride for about 17 hours. The in vitro drug release from the proposed system was best explained by the Korsmeyer-Peppas model. The values of the diffusion exponent in the Korsmeyer-Peppas model ranged between 0.47 ± 0.02 and 0.66 ± 0.02, which appeared to indicate a coupling of the diffusion and erosion mechanisms, anomalous non-Fickian transport.Conclusion:It was concluded that the proposed floating drug delivery system, based on the superporous hydrogel composite containing Chitosan as a composite material, is promising for stomach-specific delivery of Ranitidine hydrochloride.

Preparation and Characterization of Superporous Hydrogels as pH-Sensitive Drug Delivery System for Pantoprazole Sodium

The objective of the present study is to develop Superporous Hydrogel (SPH) and SPH composites (SPHC) as pH-sensitive drug delivery system for Pantaprazole sodium. In this investigation, Superporous hydrogels containing poly(methacrylic acid-co-acrylamide) with interconnected pores of several hundreds of micrometer were prepared using radical polymerization of methacrylic acid and acrylamide in the presence of N,N-methylene-bis-acrylamide as crosslinking agent. A gas blowing method using bicarbonate as a foaming agent was applied to introduce the porous structure. SPH composite polymers were made in the same way, except for using Ac-Di-Sol as a stabilizer. The structures of the SPH and SPH composites were characterized by FT-IR and Scanning electron microscopy (SEM). Apparent density and swelling ratio studies were also carried out. The swelling properties and mechanical strength of SPHs were affected by the addition of the mechanical stabilizer, Ac-Di-Sol. Results indicated that SPH polymers have more pores and higher swelling ratio but less mechanical stability compared to SPH composite polymers, which have less pores and lower swelling ratio but a higher mechanical stability. With a change in pH from acidic to basic, a considerable increase in swelling was observed for all the formulations. Since the prepared SPH and SPHC swell only in the basic pH, it may be concluded that SPH and SPHC can be used as pH-sensitive drug delivery systems for Pantoprazole sodium.

Preparation and characterization of chitosan-based superporous hydrogel composite

The synthesis of superporous hydrogel composites (SPHCs) with various concentrations of chitosan as a composite material was carried out by solution polymerization. The characterization studies were performed by measurement of apparent density, porosity, swelling studies, mechanical strength studies, and scanning electron microscopy (SEM). In double distilled water, SPHCs showed tremendous increase in their equilibrium swelling capacity. But, when the same SPHCs were placed into simulated gastric fluid for swelling, they showed very less equilibrium swelling capacity. The chitosan altered swelling characteristics in both the swelling media. SPHCs showed improved mechanical strength as the chitosan concentration increased. SEM images clearly indicated the formation of interconnected pore, capillary channels, and the cross-linked chitosan molecules were observed around the peripheries of pores.

Hydroxyapatite containing superporous hydrogel composites: synthesis and in-vitro characterization

The synthesis of an acrylamide-based superporous hydrogel composite (SPHC) with hydroxyapatite (HA) was realized by solution polymerization technique. The characterization studies were performed by FTIR studies, determination of swelling kinetics, measurement of mechanical properties, SEM/EDAX studies and cytocompatibility tests. The FTIR and EDAX studies revealed the incorporation of HA in superporous hydrogel (SPH) structure. The results obtained from swelling experiments showed that, although the extent of swelling was decreased after incorporation of HA in SPH structure, the time to reach the equilibrium swelling was not affected for SPHC. This result indicated that, the presence of HA did not block the capillary channels and the interconnected pore structure was maintained which were consistent with the images obtained from SEM photographs. The results obtained from mechanical tests showed that, in the presence of HA, the compression strength of the hydrogel composite was improved significantly when compared to SPH structure. The compressive modulus for the SPHC increased to 6.59 +/- 0.35 N/mm(2) whereas it was 0.63 +/- 0.04 N/mm(2) for the SPH. The cytocompatibility test which was performed by using L929 fibroblasts showed that both the SPH and SPHC materials were cytocompatible towards fibroblasts. The synthesized superporous hydrogel composite possesses suitable properties especially for bone tissue engineering applications and shall be considered as a novel scaffold.

Synthesis, characterization, mechanical properties and biocompatibility of interpenetrating polymer network–super‐porous hydrogel containing sodium alginate

AbstractIn this investigation an interpenetrating polymer network–superporous hydrogel containing sodium alginate (IPN‐SPHAlg) was synthesized. The morphology of the polymer was characterized using scanning electron microscopy, light images and porosity, and the polymer was further examined by swelling ratio, mechanical strength and biocompatibility. The results indicated that the IPN‐SPHAlg possessed both large numbers of interconnected pores and an interpenetrating network. The swelling ratio of IPN‐SPHAlg was lower than that of the superporous hydrogel (SPH) and it decreased as the sodium alginate/monomer ratio increased. The IPN‐SPHAlg exhibited pH responsiveness and salt‐sensitive properties. Compared to SPH and SPH composites, the mechanical strength of IPN‐SPHAlg was significantly enhanced. Thiazolyl blue assay on AD293 cells, in situ lactate dehydrogenase assay and morphological study of rat intestine showed that the polymer induced no significant cell or mucosal damage. The fast swelling, good mechanical properties, pH sensitivity and biocompatibility of the IPN‐SPHAlg suggested it as a potential candidate in the field of drug‐delivery systems. Copyright © 2007 Society of Chemical Industry