No abstract

This review describes hydrogels and their classifications along with the synthesis and properties of biopolymer-dextrin based crosslinked hydrogels towards potential application in controlled drug delivery.

A new class of biodegradable crosslinked hydrogel, consisting of hydrophobic polylactic acid (PLA) and hydrophilic dextrin in presence of crosslinker N,N-methylene bisacrylamide (MBA) has been synthesized by free-radical polymerization technique using potassium persulfate (KPS) as initiator. By variation of crosslinker concentration, a series of hydrogels have been prepared and the optimized grade has been selected on the basis of higher crosslinking efficiency as well as lower equilibrium swelling characteristics, XRD analysis. The hydrogels have been characterized by FTIR spectra, 13 C-NMR spectra, CHN analysis, SEM analysis, swelling characteristics, and toxicity study. In vitro release study of model drugs (ciprofloxacin and ornidazole) from hydrogel matrix has been performed in various buffer solutions at 37 C. The drug release kinetics and mechanism have been studied using zero order, firstorder kinetic models, Korsemeyar-Peppas model, Higuchi model, Hixson-Crowell model, and nonlinear Kopcha model. Hydrogels are physically or chemically crosslinked natural or synthetic 3D polymer network which swell but do not dissolve when added to water or biomedical fluid, maintaining its form until an equilibrium state is achieved. Stimuli-responsive hydrogels exhibit remarkable changes in their swelling behavior, network structure, permeability and mechanical strength in response to a number of external stimuli, including pH, 12 ionic strength, 13 temperature, 14 magnetic field, 15 electric Additional Supporting Information may be found in the online version of this article.

Herein, novel biodegradable, stimulus-responsive, chemically cross-linked and porous hydrogel has been synthesized to evaluate its applicability as an efficient carrier for sustained release of ornidazole and ciprofloxacin. The cross-linked hydrogel (c-Dxt/pAA) has been developed from dextrin and poly(acrylic acid) using N,N'-methylene bis(acrylamide) cross-linker via Michael-type addition reaction. With the variation of reaction parameters, various c-Dxt/pAA hydrogels have been synthesized to optimize the best one. c-Dxt/pAA hydrogel has been characterized using various physicochemical characterization techniques. The hydrogel demonstrates significant pH and temperature sensitivity. Gel characteristics and gel kinetics have been performed through the measurement of rheological parameters. The hydrogel shows noncytotoxic behavior toward human mesenchymal stem cells. Biodegradation study predicts that c-Dxt/pAA is degradable in nature. The in vitro release of ornidazole and ciprofloxacin suggests that the hydrogel released both the drugs in a controlled manner with extensive stability up to 3 months. The results suggest that c-Dxt/pAA is probably a promising candidate for controlled release of ornidazole and ciprofloxacin.

A novel stimulus-sensitive covalently cross-linked hydrogel derived from dextrin, N-isopropylacrylamide, and N,N'-methylene bis(acrylamide) (c-Dxt/pNIPAm), has been synthesized via Michael type addition reaction for controlled drug release application. The chemical structure of c-Dxt/pNIPAm has been confirmed through Fourier transform infrared (FTIR) spectroscopy and (1)H and (13)C NMR spectral analyses. The surface morphology of the hydrogel has been studied by field emission scanning electron microscopic (FE-SEM) and environmental scanning electron microscopic (E-SEM) analyses. The stimulus responsiveness of the hydrogel was studied through equilibrium swelling in various pH media at 25 and 37 °C. Rheological study was performed to measure the gel strength and gelation time. Noncytotoxicity of c-Dxt/pNIPAm hydrogel has been studied using human mesenchymal stem cells (hMSCs). The biodegradability of c-Dxt/pNIPAm was confirmed using hen egg lysozyme. The in vitro and in vivo release studies of ornidazole and ciprofloxacin imply that c-Dxt/pNIPAm delivers both drugs in a controlled way and would be an excellent alternative for a dual drug carrier. The FTIR, powder X-ray diffraction (XRD), and UV-vis-near infrared (NIR) spectra along with the computational study predict that the drugs remain in the matrix through physical interaction. A stability study signifies that the drugs (ornidazole ∼97% and ciprofloxacin ∼98%) are stable in the tablet formulations for up to 3 months.