Rapid, direct, visualized and antibody-free bacterial detection with extra species identification and susceptibility evaluation capabilities

Abstract

Bacterial antimicrobial resistance (AMR) driven by the abuse of antibiotics is a global highlight challenge, calling for a rapid, economical and generalizable bacterial detection technology. Here, in case of urinary tract infections (UTIs), a naked-eye, antibody-free and multi-functional bacterial assessment platform was designed, which consisted of concanavalin A modified gold nanoparticles (ConA-AuNPs), vancomycin modified gold nanoparticles (Van-AuNPs), and polymyxin B modified Prussian blue nanoparticles (PMB-PBNPs). Based on the fast agglutination of bacterial cells induced by concanavalin A, ConA-AuNPs could aggregate on bacterial cells of Escherichia coli and Staphylococcus aureus, resulting in a visible color change due to alteration of surface plasmon resonance properties within 30 min. Besides, due to the different affinity of vancomycin and polymyxin B to bacteria, Van-AuNPs preferred to bind to Gram-positive bacteria, generating colorimetric response within 2–3 h; while PMB-PBNPs could be reduced colourless Prussian white (PW) by the prior Gram-negative bacterial metabolization in contrast to Gram-positive bacterial metabolization within 4–6 h. Combining our platform with antibiotics, the minimum inhibitory concentration of bacteria could be determined within 4–8 h, which was proved by incubating Escherichia coli and Staphylococcus aureus with various antibiotics. The feasibility was verified by clinical samples, which was consistent with the classical clinical test within only 1/48 of the process timing. Therefore, this colorimetric nanoplatform orderly realized the rapid detection, species identification (Gram-positive and Gram-negative), and susceptibility evaluation of bacteria, satisfying multiple needs from timely clinical diagnosis to accurate medication guidance.