Low-Powered pH-Stable Nano-electrokinetically Enhanced Lateral Flow Assay for COVID-19 Antigen Test

Lateral flow assay (LFA) is a popular diagnostic system used in point-of-care testing (POCT) due to its low cost and portability. However, LFA has limited sensitivity and detection limits, making it challenging to detect low virus titers. Preconcentration through nano-electrokinetic (NEK) techniques have been proposed as a promising solution to improve the sensitivity of LFA. Nevertheless, the acidic conditions used in NEK operations may reduce the specificity and sensitivity of LFA immunoassays. To address these limitations, an integrated LFA kit, the NEK-enhanced LFA (PcNEK–LFA), has been introduced. This kit features a pH-controlled structure designed to facilitate sample preconcentration. Biomarkers and AuNPs are electrokinetically preconcentrated in the PcNEK–LFA platform to increase the concentration of the test line and Ag–Ab binding events, resulting in enhanced performance. The pH-controlled PcNEK–LFA platform was evaluated using salivary human chorionic gonadotropin beta (β-hCG) and COVID-19 Ag samples, achieving a preconcentrating factor of approximately 10 and a sensitivity enhancement of 55.42%, and a preconcentrating factor greater than 10, respectively. The pH-controlled PcNEK–LFA platform provides an effective solution to overcome the limitations of LFA for POCT. In addition, it improves its sensitivity and detection limit, significantly enhancing the accuracy and reliability of POCT, particularly for COVID-19 screening tests. As a result, this platform may play a pivotal role in addressing current and future healthcare challenges, facilitating rapid diagnosis and treatment of infectious diseases.