Fabrication of NIR-II-Responsive Polydextran Aldehyde/Gelatin/Gold Nanoparticle-Decorated Graphene Oxide Nanocomposite Hydrogels for Antibacterial Applications

Abstract

Near-infrared (NIR)-responsive nanocomposite hydrogels are increasingly utilized in biomedical applications due to their ability to undergo remote-controlled deformation and the deep tissue penetration of NIR light. However, applying highpower lasers may cause skin injuries at the irradiation sites, raising safety concerns for clinical use. Also, the lack of dynamic features (such as self-healing) and processing capability (such as injectability) of the NIR-responsive nanocomposite hydrogels restricts their advanced applications. Here, we enhanced the photothermal efficiency of graphene oxide (GO) by attaching gold nanoparticles (AuNPs), creating a AuNP-decorated GO (GOAu). This GOAu was integrated into a thermoresponsive imine crosslinked hydrogel network made of polydextran aldehyde (PDA) and gelatin (Gel), resulting in PDA/Gel/GOAu nanocomposite hydrogels. The PDA/Gel/GOAu nanocomposite hydrogels were constructed through multiple cross-linking chemistries, including noncovalent chemistry (i.e., coordination, electrostatic interaction, and hydrogen bond) and dynamic covalent chemistry (i.e., imine bond). The structures and properties of the PDA/Gel/GOAu nanocomposite hydrogels were comprehensively investigated in comparison with the PDA/Gel hydrogels and PDA/Gel/GO nanocomposite hydrogels. Adding GOAu to the PDA/Gel network reduced the gelation time of hydrogel formation and improved the rheological and mechanical properties of the PDA/Gel network. The PDA/Gel/GOAu hydrogels exhibited a dose-dependent thermal response to NIR-II light (1064 nm), with the PDA/Gel/GOAu hydrogel containing 4 wt % GOAu achieving the highest temperature among the other hydrogels. The enhanced photothermal properties of the PDA/Gel/GOAu hydrogels were also applied in antibacterial applications based on their capability to perform thermal-induced bactericidal activity and controlled drug release under NIR-II light. Also, with their dynamic properties (i.e., NIR responsiveness, self-healing, and injectability), PDA/Gel/ GOAu nanocomposite hydrogels are promising biomaterials for various applications.