pH responsive cross-linked polymeric matrices based on natural polymers: effect of process variables on swelling characterization and drug delivery properties

Abstract

Introduction: The current work was aimed to design and synthesize novel crosslinked pH-sensitive gelatin/pectin (Ge/Pec) hydrogels using different polymeric ratios and to explore the effect of polymers and degree of crosslinking on dynamic, equilibrium swelling and in vitro release behavior of the model drug (Mannitol). Methods: The Ge/Pec based hydrogels were prepared using glutaraldehyde as the crosslinker. Various structural parameters that affect their release behavior were determined, including swelling study, porosity, sol-gel analysis, average molecular weight between crosslinks (Mc), volume fraction of polymer (V2,s), solvent interaction parameter (χ) and diffusion coefficient. The synthesized hydrogels were subjected to various characterization tools like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and DSC differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Results:The hydrogels show highest water uptake and release at lower pH values. The FTIR spectra showed an interaction between Ge and Pec, and the drug-loaded samples also showed the drug-related peaks, indicating proper loading of the drug. DSC and TGA studies confirmed the thermal stability of hydrogel samples, while SEM showed the porous nature of hydrogels. The drug release followed non-Fickian diffusion or anomalous mechanism. Conclusion: Aforementioned characterizations reveal the successful formation of copolymer hydrogels. The pH-sensitive swelling ability and drug release behavior suggest that the rate of polymer chain relaxation and drug diffusion from these hydrogels are comparable which also predicts their possible use for site-specific drug delivery.

Influence of gelatin and collagen incorporation on peroxidase-mediated injectable pectin-based hydrogel and bioactivity of fibroblasts

“…In this work, the pH value of the media was more than 4, which caused an increased swelling ratio, and as a result, faster degradation of the Ph-pectin hydrogel matrix due to the ionization of carboxyl groups and electrostatic repulsion of COO-. 42 Inconsistent with results obtained from the mechanical test, the mechanically weakest hydrogels degraded rapidly while the mechanically most robust hydrogels degraded later in both PBS and enzyme-containing solution. In Phpectin/Ph-gelatin, there are a higher number of Ph groups, which makes a larger number of crosslinking sites available.…”

“…41 High cross-linked hydrogels are less acidic since amino groups are covered, which reduces the ionization process. 42 In tissue engineering, excess swelling should be avoided to prevent matrix disintegration. A useful method for diminishing the swelling is to create crosslinks which are not influenced under physiological situations.…”

The Structural, Crystallinity and Thermal Properties of pH responsive Interpenetrating Gelatin/Sodium Alginate Based Polymeric Composites for the Controlled Delivery of Cetirizine HCl

“…The solvent interaction parameter χ was calculated by using the Flory-Huggins theory. 23,24 These parameters were used to determine whether the polymers were compatible with the molecules of the surrounding fluid. According to this theory, the following equation 5was used to determine χ:…”

“…It suggested that M C values were amplified by increasing the swelling ratios of Ge/SA gels. The following relation was used to determine M C : 24,25 (6)…”

Smart Freeze-Dried Bigels for the Prevention of the Sexual Transmission of HIV by Accelerating the Vaginal Release of Tenofovir during Intercourse

“…Pectin is a hydrophilic polysaccharide present in the cell wall of most plants. Its structure is based on a linear chain of poly-α-(1→4)-dextro-galacturonic acid in which the carboxyl groups can be esterified by a variable number of methyl groups [37,38]. These carboxylic groups make pectin a pH-sensitive polymer with an acidic character [36].…”