Development of a Motorized DNAzyme Assay for Enhancing the Performance of Electrochemical Biosensors for Bacterial Detection

Abstract

Early detection of bacteria plays a crucial role in preventing the spread of infectious diseases and strengthens infection control measures. High-affinity biorecognition molecular probes (e.g., antibodies, aptamers, DNAzymes) that selectively bind to bacterial proteins enable the creation of practical biosensors for on-site testing and point of-care diagnostics. The growing integration of colloidal micromotors in biosensing has unlocked exciting possibilities, paving the way for innovative diagnostic platforms with enhanced sensitivity and efficiency. A simple bath-based biosensing system was developed for detecting Legionella pneumophila in crude culture, utilizing DNA enzymes (i.e., DNAzymes) as biorecognition probes grafted onto micromotors. This assay eliminates the multi-step handling of reagents and uses a single step of dipping and readout for target detection. Using this assay, cultured protein target from Legionella pneumophila was detected with a limit-of-detection of 2×104 CFU mL−1 under self-fluidic mixing condition, while a limit-of-detection of 1×106 CFU mL−1 was achieved under static/non-mixing condition. This application shows the improvement in limit-of-detection due to the mixing effect induced by micromotors and serves as a user-friendly platform for on-site detection and point-of-care use.