An Equilibrium Binding-Based Model for LFA Signal Formation in CRISPR-Cas Lateral Flow Assay Design

Recently, CRISPR-Cas lateral flow assay (LFA) has shown promise as a rapid, simple, and sensitive viral testing method; CRISPR-Cas LFA can detect viral nucleic acids with high sensitivity from the color intensity of the detection lines on a test strip in an hour. However, due to a complex reaction process of CRISPR-Cas LFA, it is difficult to find the optimal reaction conditions for testing. In general, CRISPR-Cas LFA design requires conducting experiments with approximately ten conditions for optimization. This is a barrier to efficient research and development of CRISPR-Cas LFA products. Here, we propose a mathematical model to describe LFA signal formation and calculate the color intensity of detection lines from the concentration of substance on a test strip for designing CRISPR-Cas LFA. In this study, we constructed a mathematical model combining three equations. Using parameterized mathematical model, we could find an optimal amount of reporter precursor to include in test strips within a range of a few experimental conditions. Also, it is confirmed that the mathematical model can estimate change of color intensity under positive conditions. We believe that this model provides a useful tool for supporting research and development of CRISPR-Cas LFA.