Synthesis and Characterization of Slow-Release Fertilizer Hydrogels Based on Hydroxy Propyl Methyl Cellulose, Polyvinyl Alcohol, Glycerol and Blended Paper as Second Layer

In this study, a slow-release urea fertilizer hydrogel was synthesized from hydroxyl propyl methyl cellulose, polyvinyl alcohol and glycerol blends with paper (blended paper) as second layer. The fertilizer hydrogel was characterized by SEM, XRD and FTIR. Its retention in sandy soil, swelling behavior in distilled and tap water as well as slow-release behavior to urea were investigated. The results indicated that the fertilizer had good slow-release properties and ability to retain water in soil. However, the addition of blended paper as a second layer matrix was found to help improve the release properties of the fertilizer. The swelling kinetic of the hydrogel followed the Schott’s Second order model. The release kinetics of urea in water was best described by the Zero order model signifying that the release behavior was independent of fertilizer concentration

Semi-Crystalline Copolymer Hydrogels as Smart Drug Carriers: In Vitro Thermo-Responsive Naproxen Release Study

In this study, poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate) hydrogels were synthesized using free radical initiated copolymerization method. Four hydrogels with different cross-linker concentrations were prepared. Semi-crystalline, cross-linked copolymer networks were confirmed by FTIR, SEM and XRD analysis. Variation of swelling behaviour was monitored gravimetrically and thermo-responsiveness has been noticed. An application of synthesized thermo-responsive hydrogels as carriers for the modulated release of anti-inflammatory model drug was investigated. Moreover, naproxen loading into these hydrogels was also determined using FTIR, SEM and XRD techniques and release was analyzed using HPLC method at simulated physiological conditions. Swelling kinetic and mechanism of water transport, as well as diffusion of naproxen through the hydrogels were analyzed. Thus, the aim of this work was to study various compositions of obtained hydrogels and their possibility of application as a thermo-responsive carrier for prolonged naproxen release in order to evaluate as a potential candidate for drug carrier in future pharmaceutical applications.

Investigation of Gel Properties of Novel Cryo-Clay-Silica Polymer Networks

Several methods to increase the mechanical and swelling properties of Poly(N-isopropylacrylamide) gels are known. In this study different methods were combined to systematically alter the gel properties. The combination of nanocomposite and cryo gels as well as silica post modification was used to modulate the gel strength. This new cryo-clay-silica gel based on N-isopropylacrylamide was investigated in respect to degree of swelling, kinetic of thermo responsive behavior and tensile strength. Here, the properties of new cryo-clay-silica gel were compared with properties of clay-, silica-clay and cryo-clay gels.

Stomach-Specific Drug Delivery of Clarithromycin Using aSemi Interpenetrating Polymeric Network Hydrogel Made ofMontmorillonite and Chitosan: Synthesis, Characterization and InVitro Drug Release Study

Purpose: In this study, we aimed to prepare an extended drug delivery formulation ofclarithromycin (CAM) based on a semi-interpenetrating polymer network (semi-IPN) hydrogel.Methods: Synthesis of semi-IPN hydrogel nanocomposite made of chitosan (CS), acrylicacid (AA), acrylamide (AAm), polyvinylpyrrolidone (PVP), and montmorillonite (MMT) wasperformed by free radical graft copolymerization method. Swelling kinetic studies were done inacidic 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 strengthof the hydrogels were evaluated. Moreover, in vitro release behavior of CAM and its releasekinetics 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 stabilitybut also increased mechanical strength of the final hydrogel product. Also, in comparisonwith neat hydrogel (1270 g/g), hydrogel nanocomposite containing 13 wt% MMT exhibitedgreater equilibrium swelling capacity (1568 g/g) with lower swelling rate. In vitro drug releaseexperiments showed that CS-g-poly(AA-co-AAm)/PVP/MMT/CAM formulation possesses asustained 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 asustained release property. The reason is that interlinked porous channels within superabsorbentnanocomposite network hinder penetration of aqueous solutions into hydrogel and subsequentlycause a slower drug release.