Colistin-Functionalized Nanoparticles for the Rapid Capture of Acinetobacter baumannii

Abstract

Gold nanoparticles (AuNPs) were functionalized for rapid binding of Acinetobacter baumannii (A. baumannii), a Gram-negative bacterium. AuNPs were functionalized with colistin (Col), a polycationic antibiotic, using a two-step self-assembly process, in which heterobifunctional polyethylene glycol (PEG) was used as a linker. Colistin was successfully conjugated to the AuNPs (Col-PEG-AuNP), as validated by dynamic light scattering (DLS) and proton nuclear magnetic resonance (H1 NMR). Images taken using a scanning transmission electron microscope (STEM), in combination with x-ray energy dispersive spectroscopy (EDS), confirmed binding of Col-PEG-AuNPs to the cell wall of A. baumannii. Results generated from a rapid binding assay indicated that the reaction rate of Col-PEG-AuNP complexation with A. baumannii reached half-maximum saturation in approximately 7 minutes. Quantitative measurement of the kinetics of Col-PEG-AuNP binding to A. baumannii is essential to inform the design of colistin-functionalized magnetic nanoparticles for magnetic separation of nanoparticle-bound A. baumannii.