An exceptional and universal DNA walker amplified "one-to-many" CRISPR/Cas12a-mediated fluorescent biosensor for ultrasensitive detection of non-DNA biomarkers

Although the recently found CRISPR/Cas12a system is a promising choice to significantly enhance the analytical accuracy and the construction flexibility of fluorescent biosensors, the traditional "one-to-one" mediation type and the short of effective target transduction routes can lead to a difficulty in improving sensitivity and detecting non-DNA analytes, respectively. In response to these challenging problems, we present here an exceptional and universal DNA walker amplified "one-to-many" CRISPR/Cas12a-mediated fluorescent biosensor. For this design, a nicking endonuclease is selected as the energy supply to drive an efficient walking process on the surface of a small size magnetic nanosphere. With the release of abundant activators, many CRISPR/Cas12a systems will be activated and finally trans-cleave a large number of reporters to actualize signal amplification. To extend the sensing species, a strand displacement and an aptamer competition triggered target transduction strategies are conceptually proposed. After using a photonic crystal coated biochip to further amplify the fluorescence emission, the newly-raised assay method can be successfully employed to severally determine a liver injury associated biomarker (microRNA-122) and a broad-spectrum tumor biomarker (carcinoembryonic antigen) by just a simple smartphone assisted imaging in an ultrasensitive and highly-specific manner. Moreover, our approach is capable of precisely measuring these targets in clinical human plasmas and also offer useful diagnostic information for drug-induced liver injury and lung cancer, greatly boosting the practical application ability of CRISPR based biosensors.