Collagen hydrogel with multiple antimicrobial mechanisms as anti-bacterial wound dressing.

Wound infection by multidrug-resistant bacteria seriously threatens human life. Chronic wounds, with necrosis, persistent inflammation, and covered by hypoxic tissue, seriously hinder anti-infection treatments. Herein, we have developed a multifunctional hydrogel dressing with antibacterial activity in the hypoxia environment to promote wound healing. The hydrogel comprises Cypate-conjugated antimicrobial peptides (AMP-Cypates), liposome-encapsulated perfluorodecalin, and recombinant type III collagen. AMP-Cypates exhibited outstanding antibacterial activity, jointly achieved through antimicrobial peptide (AMP) activity, photothermal therapy (PTT), and photodynamic therapy (PDT). The perfluorodecalin liposomes act as the oxygen carrier to mitigate wound hypoxia condition and enhance the efficacy of PDT. The recombinant type III collagen in the hydrogel further promoted the healing of the wounds together with the eradication of bacterial infection. Taken together, the hydrogel dressing provides a platform for integrating multiple antimicrobial mechanisms for the rapid removal of bacterial infection and the healing of chronic wounds.

Gelatinase Responsive Nanogel for Antibacterial Phototherapy and Wound Healing.

The unique bactericidal mechanism of metal nanoparticles (MNPs) is considered to be an effective strategy to deal with antibiotic resistance, but the oxidative stress damage caused by excessive accumulation of MNPs to normal cells cannot be ignored. Achieving on-demand release of nano-drugs in specific infection environments is highly attractive. Herein, we constructed a "core-shell" nanogel (G@CuS) based on a copper sulfide (CuS) antimicrobial agent and gelatin for targeted drug release and bacterial clearance in a gelatinase infected microenvironment. G@CuS produced heat and reactive oxygen species (ROS) under the irradiation of a laser, which together with the released Cu2+ cause irreversible and efficient physical damage to the bacteria. Moreover, the encapsulation of gelatin not only limits the biotoxicity of CuS nanodots (NDs), but also effectively promotes the proliferation of mammalian cells. Under the synergy of multiple mechanisms, G@CuS eradicated the colonized bacteria in the wound of mice infected with Staphylococcus aureus (S. aureus) and accelerated wound healing. The proposed application strategy of nanogel is expected to provide a new idea for clinical transformation.