Lateral Flow Assay Sensitivity and Signal Enhancement via Laser µ-Machined Constrains in Nitrocellulose Membrane

Abstract

AbstractMultiplex lateral flow assay (LFA) is a handful diagnostic technology that can identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other common respiratory viruses in one strip, which can be tested at the point-of-care without the need for equipment or skilled personnel outside the laboratory. Although its simplicity and practicality make it an appealing solution, it remains a grand challenge to substantially enhance the colorimetric LFA sensitivity. The local flow rate constraints imposed in nitrocellulose (NC) membranes via a number of vertical femtosecond laser micromachined microchannels are important for prolonged specific binding interactions. Porous NC membrane surfaces were structured with different widths and densities μ-channels employing a second harmonic of the Yb:KGW femtosecond laser and sample XYZ translation over a microscope objective-focused laser beam. The influence of the microchannel parameters on the vertical wicking speed was evaluated from the video recordings. The obtained results indicated that μ-channel length, width, and density in NC membranes controllably increased the immunological reaction time between the analyte and the labeled antibody by 950%. Image analysis of the colorimetric indicators confirmed that the flow rate delaying strategy enhanced the signal sensitives by 40% compared with pristine NC LFA.Graphical abstract