Semi-interpenetrating chitosan/ionic liquid polymer networks as electro-responsive biomaterials for potential wound dressings and iontophoretic applications

In this work, electro-responsive chitosan/ionic liquid-based hydrogels were synthetized for the first time, envisaging the development of iontophoretic biomaterials for the controlled release/permeation of charged biomolecules. The main goal was to enhance and tune the physicochemical, mechanical, electro-responsive, and haemostatic properties of chitosan-based biomaterials to obtain multi-stimuli responsive (responsive to electrical current, ionic strength, and pH) and mechanically stable hydrogels. To accomplish this objective, polycationic semi-interpenetrating copolymer networks (semi-IPN) were prepared by combining chitosan (CS) and ionic liquid-based polymers and copolymers, namely poly(1-butyl-3-vinylimidazolium chloride) (poly(BVImCl)) and poly(2-hydroxymethyl methacrylate co-1-butyl 3 vinylimidazolium chloride) (poly(HEMA-co-BVImCl)). Results show that prepared semi-IPNs presented high mechanical stability and were positively charged over a broad pH range, including basic pH. Semi-IPNs also presented faster permeation and release rates of lidocaine hydrochloride (LH), under external electrical stimulus (0.56 mA/cm(2)) in aqueous media at 32 degrees C. The kinetic release constants and the LH diffusion coefficients measured under electrical stimulus were similar to 1.5 and > 2.7 times higher for those measured for passive release. Finally, both semi-IPNs were non-haemolytic (haemolytic index <= 0.2%) and showed strong haemostatic activity (blood clotting index of similar to 12 +/- 1%). Altogether, these results show that the prepared polycationic semi-IPN hydrogels presented advantageous mechanical, responsive and biological properties that enable them to be potentially employed for the design of new, safer, and advanced stimuliresponsive biomaterials for several biomedical applications such as haemostatic and wound healing dressings and iontophoretic patches.

Automated summary

This study synthesized electro-responsive chitosan/ionic liquid-based hydrogels for the first time, aiming to develop biomaterials for controlled release of charged biomolecules. The prepared semi-IPNs showed high mechanical stability and faster permeation and release rates under external electrical stimulus. These hydrogels also exhibited non-haemolytic and strong haemostatic properties, indicating their potential for biomedical applications such as haemostatic dressings and iontophoretic patches.