Scientists found that sticking the natural antimicrobial peptide LL‑37 onto tiny titanium‑dioxide particles makes them stick to bacterial toxins (LPS and LTA) much better. When you shine UV light on these coated particles, they still make reactive oxygen that breaks down the toxins, and the broken‑down pieces are captured by the particles. This combo also calms down immune cells that would normally react to the toxins, without being toxic itself.

In this study, we report the degradation of smooth and rough lipopolysaccharides (LPS) from Gram-negative bacteria and of lipoteichoic acid (LTA) from Gram-positive bacteria by peptide-coated TiO₂ nanoparticles (TiO₂ NPs). While bare TiO₂ NPs displayed minor binding to both LPS and LTA, coating TiO₂ NPs with the antimicrobial peptide LL-37 dramatically increased the level of binding to both LPS and LTA, decorating these uniformly. Importantly, peptide coating did not suppress reactive oxygen species generation of TiO₂ NPs; hence, UV illumination triggered pronounced degradation of LPS and LTA by peptide-coated TiO₂ NPs. Structural consequences of oxidative degradation were examined by neutron reflectometry for smooth LPS, showing that degradation occurred preferentially in its outer O-antigen tails. Furthermore, cryo-TEM and light scattering showed lipopolysaccharide fragments resulting from degradation to be captured by the NP/lipopolysaccharide coaggregates. The capacity of LL-37-TiO₂ NPs to capture and degrade LPS and LTA was demonstrated to be of importance for their ability to suppress lipopolysaccharide-induced activation in human monocytes at simultaneously low toxicity. Together, these results suggest that peptide-coated photocatalytic NPs offer opportunities for the confinement of infection and inflammation.