Injectable, Self-Healing Hydrogel with Tunable Optical, Mechanical, and Antimicrobial Properties

Injectable self-healing hydrogels, as implanted materials, have received great attention over the past decades. The tunable optical and mechanical properties as well as the ability to lower the risk of inflammatory responses are essential considerations for their applications in diverse bioengineering processes. In this work, we report a novel injectable self-healing hydrogel with tunable optical, mechanical, and antimicrobial properties, fabricated by a multifunctional ABA triblock copolymer gelator, poly{(4-formylphenyl methacrylate)-co-[[2-(methacryloyloxy)ethyl] trime-thylammonium chloride]}-b-poly(N-isopropylacrylamide)-b-poly{(4-for-mylphenyl methacrylate)-co-[[2-(methacryloyloxy)ethyl] trimethylammonium chloride]} and polyethylenimine. The self-healing capability of the hydrogel was demonstrated by rheology tests, and quantitative force measurements using a surface forces apparatus (SFA) provided molecular insights into the self-healing mechanism of Schiff base reaction. Additionally, the optical and mechanical properties of the hydrogel can be fine-tuned in a sensitive temperature-responsive manner because of the local nano-hydrophobic domains formed through the phase transition of the ABA triblock copolymer gelator. The hydrogel also demonstrated multiple sol-gel transitions subjected to pH change. Moreover, the hydrogel can also effectively inhibit the growth of both Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus aureus), while showing low cytotoxicity to both fibroblast and cancer cells (MRC-5 and HeLa). The novel multifunctional injectable self-healing hydrogel with tunable optical, mechanical, and excellent antimicrobial properties shows great potential in various bioengineering applications.