Abiotic Fluorescent Probes for Rapid Screening of Membrane-Disrupting Antibiotics

As antimicrobial resistant bacteria become increasingly prevalent, the development of commercial antibiotics has counterintuitively slowed due to their costly and lengthy development timelines. Major bottlenecks in antimicrobial development are related to practical constraints with live, infectious bacteria, which require specialized (BSL 2+) facilities and limit throughput to the timescale of bacterial growth, which can span hours to days. Herein, we address these bottlenecks by developing fluorescent probes which use single-walled carbon nanotubes (SWNT) functionalized with bacteria membrane lipopolysaccharides (LPS) as abiotic proxies to Gram-negative bacteria. LPS form a “corona” phase around SWNT which both solubilizes the otherwise-hydrophobic nanotube and confers surface functionality similar to that of a Gram-negative bacterium. Disruption of this corona phase is transduced by fluorescence quenching, observed in real time. Within sensor response traces, we have also observed distinct kinetic regimes which suggest different mechanisms of disruption such as binding, pore formation, and translocation. Further characterization may allow these sensors to distinguish and multiplex disruption mechanisms. Ultimately, these sensors will reduce barriers to antimicrobial discovery by enabling high-throughput testing in common labs that lack biosafety ratings.