Injectable mesquite gum and carboxymethyl chitosan hydrogel using schiff base crosslinks: a versatile platform for drug delivery in wound care

The novel injectable hydrogel (IH) is developed at 37 ℃ using the dynamic imine bond between mesquite gum with multi-aldehyde groups (MG-CHO) and carboxymethyl chitosan (CMCh). The investigation consists of determining the ideal concentration of an oxidizing agent to maximize the amount of aldehydes in mesquite gum. Then, the oxidized mesquite gum with the optimized aldehyde content (47.6%) determines the minimum gelation time (7 to 2 min.). Structural characterization is conducted through Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). The scanning electron microscopy (pore size = 14 to 34 µm) and rheometer examine surface morphology and rheological properties. The swelling ratio in phosphate buffer saline (PBS) at varying pH levels (5.5, 7.4, and 8.5) is measured for both dry and gel forms, revealing a decrease in the swelling ratio with increasing pH (5.5 to 7.4), followed by an increase at pH 8.5. Ciprofloxacin HCl is employed as a model drug for release experiments, and drug release behavior is compared in PBS at pH 5.5, 7.4, and 8.5, using the Korsemeyer–Peppas model to determine the release mechanism. Biocompatibility of injectable hydrogels is assessed regarding in vitro cytotoxicity using L-929 fibroblast cell lines and hemolysis assay. Additionally, the antibacterial study is analyzed using gram-positive and gram-negative bacteria. Furthermore, the hydrolytic biodegradability of IHs in phosphate buffer saline at pH 7.4 is evaluated.

Graphical abstract

Synthesis of self-healing, biocompatible, and biodegradable injectable hydrogel using mesquite gum and carboxymethyl chitosan crosslinked through Schiff base mechanism utilized for drug delivery application