The evolution of photoelectrochemical (PEC) bioanalysis has resulted in substantial progress in its analytical performance and biodetection applications. The aim of this review is to provide a panoramic snapshot of the state of the art in this dynamically developing field, with special emphasis on PEC DNA analysis, immunoassay, enzymatic biosensing and cell-related detection. The future prospects in this area are also evaluated and discussed. This work will serve as a useful source to inform the interested audience of the latest developments and applications in the field of PEC bioanalysis.

Photoelectrochemical bioanalysis: the state of the art

In the past few decades, researchers have developed lots of artificial enzymes with various materials to mimic the structures and functions of natural enzymes. Recently, nanozymes, nanomaterials with enzyme-like characteristics, are emerging as novel artificial enzymes, and attracting researchers’ enormous interest. Remarkable advances have been made in the area of nanozymes due to their unique properties compared with natural enzymes and classic artificial enzymes. Until now, lots of nanomaterials have been studied to mimic various natural enzymes for wide applications. To highlight the recent progress of nanozymes (especially in bionanotechnology), here we discuss the diverse applications of nanozymes, which range from sensing, imaging, and therapeutics, to logic gates, pollutant removal, water treatment, etc. Finally, we address the current challenges facing nanozyme research as well as possible directions to fulfill their great potential in future.

Nanozymes in bionanotechnology: from sensing to therapeutics and beyond

Photoelectrochemical enzymatic biosensors.

Considerable amount of research has been carried out on designing and improving metal-recognition methodologies in environmental and biological media. The development of fluorescent-based techniques has proven to be an important milestone for non-invasive metal detection and quantification in a multichannel environment. Metals as natural components of the Earth's crust are generally present in trace concentrations in environmental samples, wherein humic substances have a complexation affinity toward them. Iron, zinc and copper are the 1st, 2nd and 3rd most abundant elements that are indispensable to the human body in trace amounts as they play crucial roles in many biological processes. However, unregulated amounts either an excess or deficiency may exacerbate deterioration of the vital organs and trigger the progression of complications. In addition to these three essential elements, mercury is widely considered to be one of the most hazardous pollutants and highly dangerous elements due to its recognized accumulative and toxic effects in the environment and in biological media. In the present study, we attempted to summarize all the recently developed fluorescent signaling materials for the detection of Cu2+, Fe2+/Fe3+, Zn2+ and Hg2+. The spectral shifts in the molecules on metal chelation, the mode of complexation and the stoichiometries of the resulting adducts have been discussed in detail. Furthermore, we highlight molecules that have been reported as an intracellular metal detector via bioimaging, which can be useful for the future design and development of cell-viable and membrane-permeable molecular probes.

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

Photodynamic therapy (PDT) is a light-triggered therapy used to kill cancer cells by producing reactive oxygen species (ROS). Herein, a new kind of DNA nanostructure based on the coordination between calcium ions (Ca2+) and AS1411 DNA G quadruplexes to form nanoscale coordination polymers (NCPs) is developed via a simple method. Both chlorine e6 (Ce6), a photosensitizer, and hemin, an iron-containing porphyrin, can be inserted into the G-quadruplex structure in the obtained NCPs. With further polyethylene glycol (PEG) modification, we obtain Ca-AS1411/Ce6/hemin@pHis-PEG (CACH-PEG) NCP nanostructure that enables the intranuclear transport of photosensitizer Ce6 to generate ROS inside cell nuclei that are the most vulnerable to ROS. Meanwhile, the inhibition of antiapoptotic protein B-cell lymphoma 2 (Bcl-2) expression by AS1411 allows for greatly improved PDT-induced cell apoptosis. Furthermore, the catalase-mimicking DNAzyme function of G-quadruplexes and hemin in those NCPs could decompose tumor endogeno...

G-Quadruplex-Based Nanoscale Coordination Polymers to Modulate Tumor Hypoxia and Achieve Nuclear-Targeted Drug Delivery for Enhanced Photodynamic Therapy.

A new approach to light up the application of semiconductor nanomaterials for photoelectrochemical biosensors: using self-operating photocathode as a highly selective enzyme sensor.

A novel photoelectrochemical sensor based on photocathode of PbS quantum dots utilizing catalase mimetics of bio-bar-coded platinum nanoparticles/G-quadruplex/hemin for signal amplification

A novel strategy for the construction of photoelectrochemical sensors based on quantum dots and electron acceptor: The case of dopamine detection

In situ formation of p–n junction: A novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection

The invention provides a nano material mimic enzyme and application thereof in detecting mercury ions. The mixture of mercury ions and a silver nano material can catalytically oxidate multiple characteristic substrates of horseradish peroxidase in air in the presence of oxygen, thereby being a nano material mimic enzyme. The activity of the mimic enzyme formed by the mercury ions and silver nano material is directly related to the concentration of the added mercury ions, and therefore, the concentration of the mercury ions can be determined according to the spectral signal (absorption spectrum or fluorecence spectrum) of the oxidation product of the characteristic substrate. The invention provides a new mimic oxidase material which can detect the mercury ions simply and sensitively and has favorable selectivity. The linear range of the nano material mimic enzyme for detecting the mercury ions is 1.0*10 mol/L-1.2*10 mol/L, and the detection limit is 20 nM.

Kang-Li Liu

Papers

A new approach to light up the application of semiconductor nanomaterials for photoelectrochemical biosensors: using self-operating photocathode as a highly selective enzyme sensor.

A novel photoelectrochemical sensor based on photocathode of PbS quantum dots utilizing catalase mimetics of bio-bar-coded platinum nanoparticles/G-quadruplex/hemin for signal amplification

A novel strategy for the construction of photoelectrochemical sensors based on quantum dots and electron acceptor: The case of dopamine detection

In situ formation of p–n junction: A novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection

Nano material mimic enzyme and application thereof in detecting mercury ions