Point-of-Care\nDiagnosis of Tuberculosis Using a Portable\nNucleic Acid Test with Distance-Based Readout

Rapid\nand accurate diagnosis of tuberculosis (TB) infection\nin\nresource-limited settings is critically needed to stop the spread\nof the disease but remains difficult to achieve. Herein, we report\na fast, inexpensive nucleic acid test with distance-based readout\n(FINDR) for TB. Based on the unique chromatographic behavior of DNA\nintercalating dye on unmodified cellulose paper, our FINDR platform\nconverted the amplicons of loop-mediated isothermal amplification\n(LAMP) into the migration distance on a paper-based analytical device.\nA suite of innovations were further introduced to enhance the accessibility\nof FINDR, including (1) screening optimal LAMP primers for distance-based\nreadout; (2) developing a chip-on-cover design capable of streamlining\nLAMP amplification and distance-based detection in a fully sealed\nFINDR chip with a simple hand-based swirling for liquid transfer;\nand (3) integrating FINDR with an upstream portable pipetting-free\nDNA extractor and a downstream smartphone app to simplify sample processing\nand data interpretation. With these innovations, FINDR demonstrated\na high clinical sensitivity (96.6%) and specificity (100%) upon validation\nagainst clinical sputum samples. Successful clinical validation was\nalso achieved when FINDR was deployed as a point-of-care test for\ndetecting TB under resource-limited conditions.