Fabrication, characterization and drug loading efficiency of citric acid crosslinked NaCMC-HPMC hydrogel films for wound healing drug delivery applications

In this study, hydrogel films were prepared from sodium carboxymethylcellulose (NaCMC) and hydroxypropylmethylcellulose (HPMC) using citric acid (CA) as crosslinker. The chemical crosslinking (ester bond) between NaCMC and HPMC was confirmed by FTIR analysis. It was found that swelling degree, crystallinity and water contact angle of hydrogel films based on NaCMC-HPMC (2wt%) decrease with increase in CA from 5% to 20% (by weight). The increase in Tg and decrease in initial decomposition temperature were observed for increasing CA in NaCMC-HPMC films and were confirmed by DSC and TGA analysis, respectively. Tensile strength of hydrogel films decreases while elongation at break (%) increases with increase in CA. Highly interconnected nanoporous network and decrease in average pore diameter from micron to nanosize in cryofixed hydrogel films were found by FESEM and mercury intrusion porosimetry, respectively. The drug loading efficiency of hydrogel films was significantly higher for methylene blue compared to tetracycline. It was observed that hydrogel films release the drugs in sustained manner for 72h. The hydrogel films showed significant antibacterial activity after three days of release at 37°C in PBS (pH7.4). These findings strongly recommend that the prepared hydrogel films can be used as potential wound healing materials.