DropPNA-GO: A Single-cell Uropathogen Sensor Based on PNA Probes and Graphene Oxide in Picoliter Droplets

Rapid, sensitive, and specific methods for pathogen detection and phenotypic antibiotic susceptibility testing (ID/AST) are essential for combating the rise and spread of antimicrobial resistance. Towards this end, peptide nucleic acid (PNA) probes have been used for hybridization-based detection with enhanced sensitivity and specificity. At the same time, graphene oxide (GO) has been shown as a robust quencher for PNA probes with improved sensitivity and minimal cost. Here we report a novel PNA-GO biosensor, which uses GO as a universal quencher for PNA probe-based amplification-free pathogen ID and quantification in 32 min by means of a droplet microfluidic platform (dropPNA-GO). We have optimized GO concentration to maximize sensitivity. We show the dropPNA-GO biosensor enables specific pathogen ID and quantification across 4 orders of magnitude in picoliter droplets. With apparent advantages in simplicity and cost, we foresee further expansion of our dropPNA-GO biosensor for rapid and multiplexed ID/AST applications.