DNA quadruplexes are nucleic acid conformations comprised of four strands. They are prevalent in human genomes and increasing efforts are being directed toward their engineering. Taking advantage of the programmability of Watson–Crick base-pairing and conjugation methodology of DNA with other molecules, DNA nanostructures of increasing complexity and diversified geometries have been artificially constructed since 1980s. In this review, we investigate the interweaving of natural DNA quadruplexes and artificial DNA nanostructures in the development of the ever-prosperous field of biosensing, highlighting their specific roles in the construction of biosensor, including recognition probe, signal probe, signal amplifier and support platform. Their implementation in various sensing scenes was surveyed. And finally, general conclusion and future perspective are discussed for further developments.

Low-dimensional inorganic nanostructures such as quantum dots as well as one- and two-dimensional nanostructures are widely studied and already used in high-performance infrared photodetectors. These structures feature large surface-to-volume ratios, tunable light absorption, and electron-limiting effects. This article reviews the state-of-the-art research of low-dimensional inorganic nanostructures and their application for infrared photodetection. Thanks to nano-structuring, a narrow bandgap, hybrid systems, surface-plasmon resonance, and doping, many common semiconductors have the potential to be used for infrared detection. The basic approaches towards infrared detection are summarized. Furthermore, a selection of very important and special nanostructured materials and their remarkable infrared-detection properties are introduced (e.g., black phosphorus, graphene-based, MoX₂-based, Ⅲ-Ⅶ group). Each section in this review describes the corresponding photosensitive properties in detail. The article concludes with an outlook of anticipated future developments in the field.

Metal chalcogenide solid solution, especially ZnCdS, has been intensively investigated in photocatalytic H₂ generation due to their cost-effective synthetic procedure and adjustable band structures. In this work, we report on the defect engineering of ZnCdS with surface disorder layer by simple room temperature Li-ethylenediamine (Li-EDA) treatment. Experimental results confirm the formation of unusual Zn and S dual vacancies, where rich S vacancies (V_S) served as electron trapping sites, meanwhile Zn vacancies (V_Zn) served as hole trapping sites. The refined structure significantly facilitates the photo charge carrier transfer and improves photocatalytic properties of ZnCdS. The disordered ZnCdS shows a highest photocatalytic H₂ production rate of 33.6 mmol·g⁻¹·h⁻¹ under visible light with superior photocatalytic stabilities, which is 7.3 times higher than pristine ZnCdS and 7 times of Pt (1 wt.%) loaded ZnCdS.

A TiO₂-based multi-color photodetector with controlled photoelectric response to ultraviolet (UV) and visible light is developed by using band regulation technologies such as multi-junction synergy and surface adsorption. This photodetector is manufactured via a continuous process including magnetron sputtering, hydrothermal growth, hydrogen annealing, spin coating and thermal evaporation assembly to form a structure of N-doped TiO₂/hydrogenated-TiO₂/p-Si heterojunction. These synergistic effects form electronic potential wells in the device to control the electrical transport and spectral response of photo-generated carriers. In the air, the device exhibits a controllable photodetection ability that responds to visible light at positive voltages and UV light at negative voltages. But in vacuum (< 0.1 Pa), the photodetection ability of the device at negative voltages is greatly reduced due to the lack of barrier effect caused by surface adsorption. On the contrary, the photodetection ability at positive voltage (e.g., 4 V) has been greatly improved, and the quantum efficiency reaches 206.6% under the 480 nm wavelength light. The device has a controllable ability to detect UV and visible light depending on the environments, which is very useful in the fields of environmental detection, chemical sensing and multi-color communication, etc.