Simultaneous Bacteria Sensing and On-Demand Antimicrobial Peptide Release

A material that was able to simultaneously sense a bacterial presence and to release antimicrobial peptides (AMP) on demand in a tunable amount was developed. Simultaneous sensing and release were achieved by the combination of a bacteria-sensing hydrogel with antimicrobial-peptide-carrying mesoporous silica particles or coatings. The mesoporous silica with a mesopore diameter of 22 nm was functionalized with a covalently grafted green light-sensitive linker, to which antimicrobial peptides were covalently attached. The gelatin-based hydrogel, which contains C14R-functionalized mesoporous silica particles, is designed to respond to bacterial presence as it may occur, e.g., in a wound's microbiological environment. In the presence of bacteria and 0.1% trypsin, a protease enzyme simulating bacterial presence, the hydrogel, deposited in a donut shape, undergoes a shape loss as the bacteria cleave cross-linking bonds within the hydrogel. When observing hydrogel shape loss after 2 h as a readout of a bacterial infection, subsequent irradiation triggers the release of antimicrobial peptides on demand with adjustable concentration-time profiles. The sensing and on-demand release are integrated into commercially available wound dressing fabrics, demonstrating an application proof-of-concept. Characterization using ATR-IR spectroscopy, TGA, and BCA validates the successful fabrication and release. The H1.6P composite released antimicrobial agents, reaching concentrations of up to 298 μg/mL at pH 7.4 from a 300 μL sample. The efficacy of the released C14R against E. coli BL21(DE3) is illustrated. Overall, the multifunctionality of this approach presents a promising step toward on-demand wound care and thus for reducing side effects and antibiotic resistance.