Pb(II) inhibits CRISPR/Cas12a activation and application for paper-based microfluidic biosensor assisted by smartphone

A simple and low-cost paper-based microfluidic biosensor has been developed for on-site detection of Pb(II) by using CRISPR-Cas12a assisted smartphone device. Pb(II) induced G-quadruplex can inhibit the activation of the CRISPR-Cas12a system and subsequently prevent the cleavage of single-stranded DNA around gold nanoparticles. Thus, the resultant dispersed gold nanoparticles will flow into the detection zone and be subsequently captured by DNA nano-flowers in the detection zone of the paper-based microfluidic chip, resulting in the corresponding color change. The R/G values analyzed through our established SmartIons APP, correlate well with Pb(II) concentrations with a linear detection range of 0.1 μM - 10 μM and a lowest detection limit of 18.3 nM. The paper-based microfluidic biosensor exhibits high specificity, good anti-interference ability, stability and applicability. In view of low cost, easy customization and multiple channel, paper-based microfluidic biosensor has great potential for the on-site detection of Pb(II).