Enzyme-responsive polycationic silver nanocluster-loaded PCL nanocomposites for antibacterial applications

Infections caused by pathogenic bacteria such as Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa remain a significant healthcare challenge. In this study, we developed an enzyme-responsive antibacterial nanomaterial that delivers antibacterial agents only in the presence of bacterial lipase. This was achieved by first synthesizing highly potent ultra-small silver nanoparticles with an average core size of 1.6 ± 0.2 nm and then embedding them into polycaprolactone nanoparticles ([email protected]) via the water in oil in water approach. The [email protected] nanoparticles had an average diameter of 274.1 ± 60.1 nm and a silver nanoparticle encapsulation efficiency of 15.7 ± 1.3%. We demonstrated that silver released from the [email protected] was selectively triggered by lipase-expressing strains of P. aeruginosa and S. aureus. As expected, there was no antibacterial action observed against E. coli DH5α, which does not express lipase. The [email protected] nanoparticles exhibited minimal cytotoxicity against human fibroblast cells suggesting good biocompatibility. This study resulted in a highly potent on-demand delivery system that can be potentially incorporated into healthcare products and devices to prevent and/or treat infections.