Dimethyl Sulfoxide-Induced Transparent Nitrocellulose Membrane for the Lateral Flow Assay

Abstract

Colorimetric lateral flow assays (LFAs) are widely used for detecting analytes through color changes displayed by conjugates on a test strip, typically made of materials such as nitrocellulose (NC) membranes. However, a significant number of conjugate nanoparticles become trapped within the membrane’s porous structure, preventing the full display of color information. Here, gelation of a porous NC membrane is achieved by introducing dimethyl sulfoxide (DMSO) into an LFA strip, resulting in structural changes and high transparency in the NC membrane, exposing red-colored Au nanoparticles within a transparent and portable DMSO/NC membrane. Under optimized conditions (16 μL of 50 vol % DMSO in water and heating the NC strip at 80 °C for 8 min), the membrane becomes highly transparent, achieving 77.42% transmittance while maintaining its capability to effectively perform LFAs for cardiac troponin I (cTnI) in both buffer solutions and clinical samples. We anticipate that this method holds promise for advancing fundamental studies of lateral flow strip materials and has potential applications in healthcare and environmental monitoring.