A dual-mode vertical flow assay for species-specific identification and total bacteria load assessment from a single urine sample.
basic_science · Level V
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- Record sourced from PubMed, PMID 42300429.
- Also identified by DOI 10.1039/d6lc00265j.
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Abstract
Rapid urine screening would benefit from simultaneous determination of pathogen identity and clinically relevant bacteria burden, yet most paper-based assays provide only one of these outputs. Here, we report a dual-mode vertical flow assay that combines species-specific HRP-antibody/TMB immunodetection with WST-8-mPMS metabolic quantification in spatially separated detection spots within an integrated vertical flow assay device. The device employs a vertically layered membrane stack with graded pore sizes to regulate capillary-driven flow and residence time, enabling efficient analyte transport and signal development. Quantitative analysis is achieved using smartphone-based RGB imaging converted to grayscale intensity. This platform enables simultaneous bacteria identification and quantification from a single urine sample, demonstrating threshold-oriented detection around the clinically relevant bacteriuria level of 10<sup>5</sup> CFU mL<sup>-1</sup> in both tryptic soy broth and urine samples. This work demonstrates a dual-mode vertical flow assay capable of simultaneously identifying bacteria species and estimating bacteria burden, providing a practical strategy for rapid threshold-oriented urine screening at the point-of-care.