Versatile sensitization of lateral flow assays by integrating a deceleration membrane

Abstract Sensitization of gold nanoparticle-based lateral flow assays (AuNPs-LFAs) will enable them to meet the requirements well across various applications. However, the sensitization of AuNPs-LFA commonly needs complicated operations, which will hinder their practical application. Herein, a novel LFA test strip integrated with a deceleration membrane (DM) was constructed, in which the DM was introduced between the test line and control line. The DM slows down the flow of sample solution in LFA test, thereby providing longer time for the binding between AuNPs-labeled antibody and target. Three types of DMs were prepared by modifying glass fiber membranes with polyvinyl alcohol (PGF), acrylic resin (AGF) and silicone resin (RGF), respectively. A common pesticide, carbendazim (CAR) was selected as a model target, and the analytical performance of the LFA integrated with three DMs (PGF-LFA, AGF-LFA, and RGF-LFA) in competitive format were evaluated. The results demonstrated that their visual detection limits for CAR were 50 ng/mL, 20 ng/mL, and 10 ng/mL, respectively. The limits of detection (LODs) for CAR were 0.38 ng/mL, 0.31 ng/mL, and 0.27 ng/mL using a portable reader, respectively. Compared with traditional AuNPs-LFA strip, their sensitivity had increased by 1.5-fold, 3.5-fold, and 7.5-fold, respectively. When applied to apple samples, the RGF-LFA for CAR achieved recovery rates of 96%–101.5%. In addition, the sensitization of RGF-LFA in sandwich format also was evaluated to be excellent by selecting SARS-CoV-2 N protein as model target, showcasing the versatility of this DM-integrated strategy.