Figure 4

Analytical sensitivity improvement of LFA by different contact angles of liquid on the sponge. The detection limit of unmodified LFA is 1 nM (A), 23.5° (30% Tween 20) of contact angle is 0.5 nM (B), 50° (20% Tween 20) of contact angle is 0.25 nM (C) and 68.5° (10% Tween 20) of contact angle is 0.01 nM (D). (E) The optical density of LFA test line under different contact angles of liquid on the sponge. (F) The wicking distance on the NC membrane with time at different contact angles sponge shunt. (G) The relationship between the experimental data and simulation data. Three replicates were performed for the optimization experiments for high concentrations in the range of 2.5–50 nM (N = 3), while eight replicates were performed for lower concentrations in the range of 0.05–1 nM (N = 8).