Vancomycin dimer formation between analogues of bacterial peptidoglycan surfaces probed by force spectroscopy.

Functionalised thiols presenting peptides found in the peptidoglycan of vancomycin-sensitive and -resistant bacteria were synthesised and used to form self-assembled monolayers (SAMs) on gold surfaces. This model bacterial cell-wall surface mimic was used to study binding interactions with vancomycin. Force spectroscopy, using the atomic force microscope (AFM), was used to investigate the specific rupture of interfacial vancomycin dimer complexes formed between pairs of vancomycin molecules bound to peptide-coated AFM probe and substrate surfaces. Clear adhesive contacts were observed between the vancomycin-sensitive peptide surfaces when vancomycin was present in solution, and the adhesion force demonstrated a clear dependence on antibiotic concentration.