Stomach-Specific Drug Delivery of Clarithromycin Using a Semi Interpenetrating Polymeric Network Hydrogel Made of Montmorillonite and Chitosan: Synthesis, Characterization and In Vitro Drug Release Study.

Purpose: In this study, we aimed to prepare an extended drug delivery formulation of clarithromycin (CAM) based on a semi-interpenetrating polymer network (semi-IPN) hydrogel. Methods: Synthesis of semi-IPN hydrogel nanocomposite made of chitosan (CS), acrylic acid (AA), acrylamide (AAm), polyvinylpyrrolidone (PVP), and montmorillonite (MMT) was performed by free radical graft copolymerization method. Swelling kinetic studies were done in acidic buffer solutions of hydrochloric acid (pH = 1.2), acetate (pH = 4), and also distilled water. Also, the effects of MMT on the swelling kinetic, thermal stability, and mechanical strength of the hydrogels were evaluated. Moreover, in vitro release behavior of CAM and its release kinetics from hydrogels were studied in a hydrochloric acid buffer solution. Results: Fourier transform infrared spectroscopy (FTIR) results revealed that synthesis of semi- IPN superabsorbent nanocomposite and CAM incorporation into hydrogel was performed, successfully. Introducing MMT into hydrogel network not only improved its thermal stability but also increased mechanical strength of the final hydrogel product. Also, in comparison with neat hydrogel (1270 g/g), hydrogel nanocomposite containing 13 wt% MMT exhibited greater equilibrium swelling capacity (1568 g/g) with lower swelling rate. In vitro drug release experiments showed that CS-g-poly(AA-co-AAm)/PVP/MMT/CAM formulation possesses a sustained release character over extended period of time compared with CS-g-poly(AA-co- AAm)/PVP/CAM formulation. Conclusion: In the presence of MMT, the effective life time of drug is prolonged, demonstrating a sustained release property. The reason is that interlinked porous channels within superabsorbent nanocomposite network hinder penetration of aqueous solutions into hydrogel and subsequently cause a slower drug release.

Starch-based semi-IPN hydrogel nanocomposite integrated with clinoptilolite: Preparation and swelling kinetic study.

Semi-interpenetrating polymer network (semi-IPN) of starch-graft-poly(acrylic acid-co-acrylamide)/polyvinyl alcohol/clinoptilolite (starch-g-p(AA-co-AAm)/PVA/clino) superabsorbent nanocomposite was synthesized by free-radical graft co-polymerization technique in an aqueous solution. Taguchi method was used to optimize the synthesis reaction condition based on the equilibrium swelling capacity of the hydrogels. FTIR, XRD, and SEM analyses were used to study the chemical and structural properties of the hydrogel samples. The equilibrium swelling capacity of the semi-IPN superabsorbent nanocomposite (364.82 g/g) was higher than that of neat hydrogel (286.21 g/g) and in both of them water penetration into hydrogel network occurred through non-Fickian diffusion mechanism. Incorporation of clino into the polymeric matrix not only increased the equilibrium swelling capacity of the hydrogel, but also induced a substantial enhancement in its mechanical strength. Semi-IPN superabsorbent nanocomposite showed reasonable water absorbency under different loads, good salt and pH-sensitive swelling behavior, and better water retention capability, which make it potentially useful for hygiene products.

Semi-IPN superabsorbent nanocomposite based on sodium alginate and montmorillonite: Reaction parameters and swelling characteristics.

Semi-interpenetrating polymer network (semi-IPN) superabsorbent nanocomposite based on montmorillonite (MMT) and sodium alginate (NaAlg)-g-poly(acrylic acid(AA))/polyvinylpyrrolidone (PVP) was synthesized. Chemical structure and surface morphology of the hydrogels were characterized by FTIR, XRD, thermogravimetric analysis (TGA), SEM, and TEM techniques. FTIR results revealed that graft polymerization, PVP interpenetration through hydrogel network, and nanocomposite formation have occurred. The coarse surface of the hydrogels was changed into interlinked porous structures in the presence of MMT. The effect of polymerization variables on water absorbency of the hydrogels was assessed and optimized. Semi-IPN superabsorbent nanocomposite presented higher equilibrium swelling capacity (618.92 g/g) compared with neat hydrogel (521.17 g/g). Swelling behavior of the hydrogels strongly depended on pH values of the solution as well as the type and concentration of saline solution. Semi-IPN superabsorbent nanocomposite possessed good reswelling capability, making it as an efficient water reservoir to supply required water to plants in agricultural applications.

Superabsorbent hydrogel made of NaAlg-g-poly(AA-co-AAm) and rice husk ash: Synthesis, characterization, and swelling kinetic studies.

The sodium alginate-g-poly(acrylic acid-co-acrylamide)/rice husk ash (NaAlg-g-P(AA-co-AAm)/RHA) superabsorbent nanocomposite was synthesized by the free-radical graft copolymerization of alginate (NaAlg), acrylic acid (AA), acrylamide (AAm), and RHA in aqueous solution. FTIR spectra revealed that the monomers were grafted onto NaAlg chains, and the nanocomposite was formed successfully. Incorporation of RHA into hydrogel matrix formed porous interlinked channels within hydrogel network. Superabsorbent nanocomposite showed greater equilibrium swelling capacity (1070g/g) compared with neat hydrogel (830g/g). Moreover, water transport mechanism of all hydrogels was non-Fickian diffusion type. Rheological measurements confirmed effective role of RHA in improving gel strength of superabsorbent nanocomposite. The influence of various factors, such as different loads (0.3, 0.6, 0.9 psi), solution pH, saline solution, and temperature on the swelling behavior of hydrogels was also assessed. Superabsorbent nanocomposite exhibited good pH-dependent swelling reversibility and high water retention capability, making it more efficient water-saving material for agricultural and horticultural applications.