Bacteriophage and Urease-Conjugated Janus Micromotors for Dynamic Enrichment and Sensitive Detection of Bacteria.

It is highly demanded to establish effective and sensitive method for detecting pathogenic bacteria because of their high morbidity. The conventional molecular recognition-based methods rely on heterogeneous mode, for which the passive diffusion of bacterial cells and signal tracer results in low transport efficiency and unsatisfied sensitivity. Herein, Fe3O4/polydopamine Janus micromotors were prepared and conjugated with bacteriophage acting as capture agent for bacteria and urease acting as propulsion fuel for Janus micromotors. With a bubble-driven approach, this strategy significantly accelerated transport and improved enrichment of bacterial cells onto the Janus micromotors, achieving a capture efficiency over 98%. By using MoS2/Pt conjugated with polymyxin B as the signal tracer, sensitive colorimetry of Pseudomonas aeruginosa was achieved with a dynamic range of 1.0 × 102 to 1.0 × 107 cfu mL-1. The whole procedure including incubation, washing, color development, and signal detection can be accomplished within 17 min. Usage of bacteriophage as capture agent led to satisfied selectivity for the target bacteria even in complex matrixes. The results for detecting Pseudomonas aeruginosa in artificial cerebrospinal fluid and contaminated milk demonstrated its reliability for real application. This work provides an ideal technical tool for dynamic enrichment and sensitive detection of pathogens based on functional self-propulsed micro/nanomotors.