Vancomycin-conjugated polythiophene for the detection and imaging of Gram-positive bacteria

Bacterial infections can cause serious health problems. The rapid identification of bacteria plays a vital role in the treatment of bacterial infection at an early stage of the disease. In this work, an active polythiophene derivative containing reactive pentafluorophenyl (PFP) ester pendant groups was prepared via Fe³⁺-catalyzed oxidative polymerization. As far as we know, this is the first report of active polythiophene with reactive PFP ester moieties. The active polythiophene derivative was conjugated with vancomycin and α-methoxy-ω-amino poly(ethylene glycol) (mPEG-NH₂) via a reactive ester-amine reaction, resulting in the formation of water-soluble and fluorescent vancomycin-containing polythiophene (PTPVan). Since vancomycin can selectively interact with Gram-positive bacteria and kill them, the antibacterial properties of PTPVan were evaluated. The detection of Gram-positive bacteria was carried out by observing the color change and the fluorescence response of bacteria upon incubation with PTPVan through the naked eye and a fluorescence spectroscope, respectively. The staining of Gram-positive bacteria was observed using a confocal laser scanning microscope (CLSM).