Fabrication and In Vitro Evaluation of pH-Sensitive Polymeric Hydrogels as Controlled Release Carriers.

Arshad Khan,Pao-Chu Wu,Chih-Wun Fang,Muhammad Usman Minhas,Muhammad Suhail

doi:10.3390/gels7030110

Abstract

The purpose of the current investigation was to develop chondroitin sulfate/carbopol-co-poly(acrylic acid) (CS/CBP-co-PAA) hydrogels for controlled delivery of diclofenac sodium (DS). Different concentrations of polymers chondroitin sulfate (CS), carbopol 934 (CBP), and monomer acrylic acid (AA) were cross-linked by ethylene glycol dimethylacrylate (EGDMA) in the presence of ammonium peroxodisulfate (APS) (initiator). The fabricated hydrogels were characterized for further experiments. Characterizations such as Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), Powder X-ray diffractometry (PXRD), and Fourier transform infrared spectroscopy (FTIR) were conducted to understand the surface morphology, thermodynamic stability, crystallinity of the drug, ingredients, and developed hydrogels. The swelling and drug release studies were conducted at two different pH mediums (pH 1.2 and 7.4), and pH-dependent swelling and drug release was shown due to the presence of functional groups of both polymers and monomers; hence, greater swelling and drug release was observed at the higher pH (pH 7.4). The percent drug release of the developed system and commercially available product cataflam was compared and high controlled release of the drug from the developed system was observed at both low and high pH. The mechanism of drug release from the hydrogels followed Korsmeyer–Peppas model. Conclusively, the current research work demonstrated that the prepared hydrogel could be considered as a suitable candidate for controlled delivery of diclofenac sodium.

Highlights

Morphological analysis was performed by Scanning electron microscopy (SEM) for the purpose of evaluating the structural morphology of chondroitin sulfate (CS)/carbopol 934 (CBP)-co-PAA hydrogels (Figure 1)
A highly porous structure is revealed by the developed hydrogels, which leads to maximum dynamic swelling, loading of drug, and drug release from the developed hydrogels [36]
A 26% reduction in weight is observed within a temperature range of

Summary

Introduction

Hydrogels can hold a high amount of water and cannot be dissolved by water due to the strong linkages (physically or chemically) that formed between the functional groups of the polymer’s chains Both synthetic and natural polymers and their combination are employed for the development of hydrogels by various crosslinking methods [4,5]. The structural and morphological responses of hydrogels—swelling/deswelling, sol–gel transition, or degradation—are altered with the environmental changes. These environmental stimuli can be physical and chemical, such as chemical agents [7], light [8,9], temperature [10,11], and pH [12,13]. This technique has been employed by a number of researchers to improve the mechanical and physical properties of the biodegradable natural polymer-based hydrogels [17,18]

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Conclusion