Controllable Targeted Accumulation of Fluorescent Conjugated Polymers on Bacteria Mediated by a Saccharide Bridge

Current antibacterial systems face challenges associated with limited targeting ability and low antibacterial efficiency. Here, we used a "saccharide bridge" to promote accumulation of fluorescent-conjugated polymer nanoparticles (CNPs) around Pseudomonas aeruginosa (P. aeruginosa). The CNPs contained bifunctional surface groups, including phenylboronic acid (PBA) and quaternary ammonium (QA) salts. Interactions between galactose moieties in lactulose and surface LecA of P. aeruginosa promoted specific binding of lactulose to the surface of P. aeruginosa. Lactulose on the bacterial surface in turn promoted CNP adhesion through CH−π interactions between the PBA group and fructose moieties of lactulose. In addition, the electrostatic interactions between positive QA salts and negative P. aeruginosa was preserved. This dual binding mode promoted the formation of covalent bonds between the CNPs and lactulose. Molecular docking studies have shown that cis-diols in the fructose structures of lactulose provide many binding sites for multivalent covalent bond formation in CNPs. Thus, through the use of lactulose as a saccharide bridge, a large amount of CNPs are actively and tightly bound to the P. aeruginosa surface. This effective accumulation of CNPs on P. aeruginosa was leveraged to efficiently kill the bacteria through reactions with toxic singlet oxygen from photosensitized CNPs. Notably, this killing mode is not subject to drug resistance. Hence, we demonstrate the ability to control the accumulation of antibacterial agents on a bacterial surface at the molecular scale. The saccharide bridge strategy offers a simple approach to improving bacterial disinfection efficiency.