CRISPR/Cas systems accelerating the development of aptasensors

The clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (CRISPR/Cas) systems, regarded as "God's scissors", have recently received considerable attention in performing genome editing, transcriptional regulation and biosensor construction, benefiting from their adjustable mechanical properties, easy to operate and design, good biocompatibility, and the collateral cleavage activity. Since 2019, aptamers have been becoming an attractive star integrated into CRISPR/Cas systems as newly emerging molecular recognition elements and flexible signal transduction modules, with their significant advantages such as high sensitivity, remarkable specificity, in vitro synthesis, base-pairing, labeling and modification, and programmability capability. In this review, the recent progress of CRISPR/Cas system-based aptasensors (Cas-aptasensors) is comprehensively summarized including their design principles and superior applications. Firstly, we briefly introduce the essential features of aptamers and the CRISPR/Cas system and then outline the composition of Cas-aptasensors involving the Cas proteins, crRNA, reporter probes, as well as the target analytes and their specific aptamers. In detail, we emphasize their fabrication methods, bio-recognition mechanism, as well as the detection evaluation of four major Cas-aptasensors types of fluorescent, electrochemical, colorimetric, and upconversion luminescent resonance energy transfer, and other four novel Cas-aptasensors including inductively light-up RNA aptamer-based sensors coupled plasma mass spectrometry, resonance Rayleigh scattering, and surface-enhanced Raman scattering, along with. Finally, the challenges and future directions are concluded and depicted for aptamers, CRISPR/Cas systems, and their accelerating applications in Cas-aptasensors. This review is expected to inspire more researchers to have insight into Cas-aptasensors and to help to improve the bioanalytical efficiency and probability of success.