Digital Counter: A Microfluidics and Computer Vision-Based DNAzyme Method for the Isolation and Specific Detection of from Water Samples.

Biological water contamination detection-based assays are essential to test water quality; however, these assays are prone to false-positive results and inaccuracies, are time-consuming, and use complicated procedures to test large water samples. Herein, we show a simple detection and counting method for in the water samples involving a combination of DNAzyme sensor, microfluidics, and computer vision strategies. We first isolated into individual droplets containing a DNAzyme mixture using droplet microfluidics. Upon bacterial cell lysis by heating, the DNAzyme mixture reacted with a particular substrate present in the crude intracellular material (CIM) of . This event triggers the dissociation of the fluorophore-quencher pair present in the DNAzyme mixture leading to a fluorescence signal, indicating the presence of in the droplets. We developed an algorithm using computer vision to analyze the fluorescent droplets containing in the presence of non-fluorescent droplets. The algorithm can detect and count fluorescent droplets representing the number of present in the sample. Finally, we show that the developed method is highly specific to detect and count in the presence of other bacteria present in the water sample.