Exploring the effect of activator topology on CRISPR–Cas12a <i>trans</i>-cleavage activity

The CRISPR-Cas12a system is widely used in nucleic acid detection and biosensing due to its high sensitivity, selectivity, and simple design. However, traditional CRISPR-Cas12a sensors, which rely on linear activators, face challenges such as limited operability and low stability. This study explored the impact of three different activator topologies-linear, planar, and steric-on the trans-cleavage activity of Cas12a. We developed a Cas12a-based switch using a planar activator, which demonstrated superior operability and maintained higher activity compared to linear activators. Using this planar activator, we achieved highly sensitive detection of hypochlorous acid, with a detection limit as low as 88 nM, outperforming chemical probe-based methods. The introduction of topological activators will open new avenues for the development of CRISPR-Cas12a-based biosensors, offering broad potential for diverse applications.