Compact Digital Immunoassay Platform Integrating ELISA with a Lateral Flow Strip.

Background/objectives: On-site diagnosis of infection in their early stages requires assays with high sensitivities that are compact and easy to operate out of the laboratory and hospital environments. However, current assay technologies fall short of these requirements and require highly skilled technicians to set up, operate, and interpret the results.

Methods: To address these challenges, we developed and evaluated a Point-of-Care-Testing (PoCT) immunoassay platform called the D-strip. The D-strip platform combines the capabilities of a digital enzyme-linked immunoassay (ELISA) with a lateral flow assay (LFA). The D-strip sample flow cell is composed of the same components found in conventional LFAs, and its high sensitivity is due to its efficient implementation of ELISA. The fully integrated platform is simple and requires minimal user intervention to operate.

Results: The D-strip exhibited a sample-to-result time of 15 min with a limit of detection (LOD) of 1.7 × 10 copies/mL for severe acute respiratory syndrome coronavirus 2 (SARS-2-CoV) antigen. The LOD of the D-strip is 488-fold higher than that for conventional LFAs and is comparable to a clinical laboratory test.

Conclusions: The D-strip is a compact and highly sensitive immunoassay platform with a strong potential for application as a confirmatory assay outside the clinical laboratory.