Adoption of Particle-based Biosensing as a Cost-Disruptive Tool for Diagnosis and Screening Highly Dilute Sample Streams for Bacterial Contamination

Target amplification/ concentration has been a barrier to the realization of LMIC-affordable diagnostic platforms and methods for handling dilute sample streams such as urine or water. The need to amplify targets via nucleic acid amplification, cell culture, and centrifugation increase the complexity and cost of the sample screening process thereby impacting LMIC-adoption and testing rigor. Here, we show, for the first time, the feasibility of detecting 100 bacterial CFU/ mL of water without the need for target amplification. This is enabled by Molecular weightstones (MWS) - a class of non-traditional, particle-based biosensors which signal the presence of bacteria via particle-biomarker aggregation and sedimentation. In this proof-of-concept study, we demonstrated detection and quantification of bacteria in water to a limit of 100 CFU/ mL within 10 minutes. At a cost profile of USD 1 per test(unscaled), MWS is instrument-free, yields visually-discernible results and can be adapted for quantification and concentration of biomarkers of interest.