Metal-coordinated amino acid hydrogels with ultra-stretchability, adhesion, and self-healing properties for wound healing

Abstract

It is a great challenge to prepare hydrogels with tissue adhesion, ultra-stretchability, and good tensile stress as wound dressings. Here, we reported a poly(acrylamide-histidine methacrylamide) (P(AM-HisMA)) hydrogel polymerized by histidine methacrylamide (HisMA) as a biocompatible amino acid derivative and acrylamide (AM). Since the amino acid HisMA provided physical cross-linking to the P(AM-HisMA) hydrogel, the hydrogel had self-healing properties (tensile strength recovery > 84 %), adhesion (4.1 kPa for porcine skin), and excellent mechanical properties (tensile stress of 77 kPa, tensile elongation of 5800 %, compressive stress of 2.0 MPa) when compared with polyacrylamide (PAM) hydrogels. Moreover, we prepared the P(AM-HisMA)-Fe3+ hydrogel by immersing Fe3+ ions into the P(AM-HisMA) hydrogel. The hydrogel contained histidine-Fe3+ coordination bonds and various non-covalent bonds, which resulted in better physical properties such as reinforced mechanical property (tensile strength of 89 kPa, stretchability of 4900 %), enhanced adhesive strength (11.9 kPa for porcine skin), and better self-healing property (within 5 min). The P(AM-HisMA)-Fe3+ hydrogel showed remarkable biocompatibility and excellent antibacterial property (100 % killing ratio). In vitro wound healing experiments demonstrated that P(AM-HisMA)-Fe3+ hydrogel effectively accelerated the wound healing process. Furthermore, the P(AM-HisMA)-Fe3+ hydrogels have promising application prospects as dressing materials for joint skin wound healing.