Lateral Flow Assay Sensitivity and Signal Enhancement via Laser Micro-Machined Constrains in Nitrocellulose Membrane
Multiplex 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 -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 -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 O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/593095v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@a6105forg.highwire.dtl.DTLVardef@7cf449org.highwire.dtl.DTLVardef@189fa69org.highwire.dtl.DTLVardef@1973dbb_HPS_FORMAT_FIGEXP M_FIG C_FIG