Novel conjugation of norvancomycin-fluorescein for photodynamic inactivation of Bacillus subtilis.

A simple and unique conjugation of norvancomycin–fluorescein (VanF) has been achieved. It was characterized by UV–vis and fluorescence spectra and confirmed by MALDI-TOF mass spectrum. The photodynamic assay indicated that VanF effectively inactivated the Gram-positive Bacillus subtilis (ATCC 6633) from clinic with inactivation rate of 30–70% within 1–7.5 μM. In vitro, VanF showed low antimicrobial activity with value of >128 μg/mL, binding affinity with value of 180 nM per 108 cells/mL against the bacteria strains. The fluorescence imaging showed that VanF could label the B. subtilis strain, but not the Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 51299, VanD), and VRE strains from clinic.