A DNA tweezer-actuated nanozyme-enzyme hybrid nanoreactor for pesticide detection.

The construction of a nanozyme-enzyme hybrid cascade system is an effective protocol to optimize the performance of biosensors. Yet, the integration has limitations due to the lack of harmonious collaboration between nanozyme and enzyme. Herein, we have constructed an efficient enzymatic cascade system by utilizing the base complementary pairing and the targeting capability of DNA tweezers to combine DNA-regulated copper nanoflowers (CuNFs) with acetylcholinesterase (AChE). The DNA tweezers were immobilized onto the CuNFs undergo regular base complementary pairing, and subsequently employed as aptamer to capture AChE gently, forming CuNFs-Apt-AChE cascade system. This system not only enhanced the spatial proximity of CuNFs and AChE to increase cascade catalytic activity, but also demonstrated excellent stability under harsh conditions. Harnessing the nanoarchitecture and characteristics, the CuNFs-Apt-AChE composites were embedded into the hydrogel to fabricate a sensitive biosensor for on-site detecting carbamate pesticides with a detection limit of 0.19 ng mL. The hydrogel sensor exhibited high specificity for carbamate pesticides and had been successfully applied in water and juice samples for pesticide detection with strong anti-interference ability. This method holds great potential for the on-site detection of pesticides, offering a new strategy for constructing nanozyme-enzyme cascade hybrid systems with accuracy and sensitivity.