Recent advances in split crRNA or activator strategy for disease diagnosis in CRISPR/Cas systems

CRISPR/Cas systems have demonstrated remarkable efficacy in disease diagnosis. In particular, the CRISPR/Cas12a system performs well due to its simple structure and nonspecific trans-cleavage activity. Recent findings have demonstrated that crRNA or activators with appropriate split sites can induce Cas nuclease activity comparable to that of their full-size counterparts. This review primarily focuses on the disease diagnosis integrated with amplification-free strategies, asymmetric systems, logic gates, and signal amplification strategies. Additionally, we discuss its progress in other CRISPR/Cas systems and modification strategies for regulating Cas proteins’ activity. In general, the characteristics and challenges of this method are highlighted. Evidently, the split strategy offers significant advantages, including diverse target accessibility, enhanced base mutation recognition ability, flexible programmability, methodological compatibility, and activity controllability. Future studies are encouraged to explore the application of the split strategy in other CRISPR/Cas systems and to overcome restrictions to advance clinical translation.