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In this review, the research progress of the sensors based on the DNA-nanozymes were summarized.

Polarization of photoactive materials in current photoelectric (PE) systems is difficult to be adjusted, and thus electron-transfer routes of these systems are unchangeable, which limits their performance in photoelectrochemical (PEC) analysis. Herein, we attempted to modulate the polarization of perovskitebased heterostructures by both in situ semiconductor generation and enzyme catalysis. Owing to their band alignments, Cs 3 Bi 2 Br 9 quantum dots (QDs) and BiOBr are confirmed to construct a Zscheme structure, leading to a large anodic photocurrent. In the presence of ascorbic acid 2-phosphate (AAP), BiPO 4 is generated on the surface of the Cs 3 Bi 2 Br 9 QDs/BiOBr heterostructure, reassigning energy bands of BiOBr. Accordingly, polarization of the photoactive materials is converted, and a new Z-scheme structure with a reversed electron-transfer route is constructed, which leads to an evident cathodic photocurrent. Furthermore, abundant electron donors can be obtained by catalyzing AAP with alkaline phosphatase (ALP). In this case, photogenerated holes in BiOBr are preferentially annihilated by electron donors, thereby blocking transfer of photogenerated electrons in the Cs 3 Bi 2 Br 9 QDs/BiOBr/BiPO 4 heterostructure. Consequently, a second polarization conversion is triggered by enzyme catalysis, resulting in the recovery of an anodic photocurrent. Benefited from the polarization conversion, a PEC biosensor with a feature of two-wing signal switch is designed, which remarkably enlarges the range of the signal response and subsequently improves the analytical performance. As a result, ALP in small volume of human serum can be quantified with this method. In this work, polarization of perovskite-based photoactive materials is tuned, proposing an alternative perspective on the design of advanced PE systems.

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Recently, a lot of nanomaterial-based composites have attracted wide interests in the field of electrochemical biosensing. Especially, the nanostructured ZnO (such as nanobelts, nanowires, and nanosheets) has emerged as a unique family of nanomaterials. In this Research Article, the uniform and vertically oriented ZnO nanosheets were electrodeposited on the preobtained MoS2 scaffold via cyclic voltammetry method further as a sensitively sensing platform to detect some molecules containing aromatic or conjugated rings. The morphology and electrochemical behaviors of ZnO-MoS2 nanosheets were investigated by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and some electrochemical methods. Taking the nitro-substituted aromatic explosive 2,4,6-trinitrotoluene (TNT) as an example, the parallel experiments were made to prove that the uniform ZnO-MoS2 nanosheets composite was a worthy electrochemical monitoring platform toward the TNT detection. Compared with individual ZnO and individual MoS2, the ZnO-MoS2 showed the most obvious electrochemical signal, lowest limit of detection, and superior linear relation in the low concentration range. Moreover, the detections of other molecules containing aromatic or conjugated rings, such as 2′-deoxyaguanosine-5′-triphosphate trisodium (dGTP) and riboflavin (Vb), were also investigated.