DNAzyme-integrated plasmonic nanosensor for bacterial sample-to-answer detection

Pathogenic bacteria pose a serious threat to public safety and health, and cause significant losses in the global economy and in lives. The current golden standard, culture-based method, for bacterial detection is often costly, laborious, and time-consuming (even weeks). Thus, there is an urgent need to develop rapid, reliable and easy-to-use approaches for bacterial detection. Herein, we present a new detection strategy termed as 'DNAzyme-Integrated Plasmonic Nanosensor' (DIPNs) that can selectively detect target bacteria in a simple, inexpensive and culture-free process, which combines real-time DNAzyme-based sensor and enzyme-responsive nanoplasmonic biosensor system. The DIPNs platform takes advantage of a bacteria-specific RNA-cleaving DNAzyme probe as the molecular recognition element and enzyme-responsive plasmonic nanoparticles' localized surface plasmon resonance (LSPR) as the signal readout. Using Escherichia coli (E. coli) as a model analyte, we demonstrated that the DIPNs system can provide the fast and low concentration (down to 50 bacteria per mL) quantification of E. coli even in the complex fluids (e.g., milk, serum, juice) with naked eyes, which would be expected for the detection of bacterial pathogens in the simple, low-cost and on-site manner.