Photoelectrochemical label-free immunoassay of octachlorostyrene based on heterogeneous CdSe/CdS/Pt/TiO2 nanotube array

TiO2 nanotube arrays decorated with BiOBr nanosheets by the SILAR method for photoelectrochemical sensing of H2O2

The design and construction of a photoelectrochemical (PEC) sensor with excellent photoelectric properties and good photoelectrocatalysis activity is significant for the effective detection of analytes. In this paper, based on a two-step anodic oxidation method and successive ionic layer adsorption (SILAR) method, a TiO2 nanotube array (TNT) photoelectrochemical sensor modified with BiOBr nanosheets was constructed and applied for the detection of H2O2 for the first time. The photocurrent of the photoelectrochemical sensor increases with the increase of the H2O2 concentration under the irradiation of an 8 W UV lamp. Excellent linearity was obtained in the concentration range from 10 nM to 100 μM with a low detection limit of 5 nM (S/N = 3). This excellent photoelectrochemical performance is due to the formation of a p-n heterojunction between BiOBr and TiO2 nanotube arrays, which provides efficient separation of charge carriers and accelerates electron transport. Moreover, it is applied to detect H2O2 in milk samples and it showed a good recovery result ranging from 95.73% to 105.65%, which provides a promising new strategy for the detection of H2O2.

A visible-light-active CuInSe2:Zn/g-C3N4/TiO2 nanowires for photoelectrocatalytic bactericidal effects

A visible-light-active CuInSe₂:Zn/g-C₃N₄/TiO₂ nanowire (NW) photoelectrode was prepared by in situ growth of g-C₃N₄ on the surface of TiO₂ NWs, followed by drop deposition of Zn-doped CuInSe₂ quantum dots (CuInSe₂:Zn QDs).

Quantum-dots-based photoelectrochemical bioanalysis highlighted with recent examples

Photoelectrochemical (PEC) bioanalysis is a newly developed methodology that provides an exquisite route for innovative biomolecular detection. Quantum dots (QDs) are semiconductor nanocrystals with unique photophysical properties that have attracted tremendous attentions among the analytical community. QDs-based PEC bioanalysis comprises an important research hotspot in the field of PEC bioanalysis due to its combined advantages and potentials. Currently, it has ignited increasing interests as demonstrated by increased research papers. This review aims to cover the most recent advances in this field. With the discussion of recent examples of QDs-PEC bioanalysis from the literatures, special emphasis will be placed on work reporting on fundamental advances in the signaling strategies of QDs-based PEC bioanalysis from 2013 to now. Future prospects in this field are also discussed.

Bifunctional polydopamine thin film coated zinc oxide nanorods for label-free photoelectrochemical immunoassay

Photoelectrochemical (PEC) detection is a promising method for label-free immunoassay by reporting the specific biological recognition events with electrical signals. However, it is challenging to rationally incorporate immunosensing components with a photocurrent conversion interface, which generally necessitates multistep fabrication and careful tailoring of various components such as photoactive material and biological probe. For high detection reliability and reproducibility, it is highly desirable to rationally construct an efficient PEC interface with architecture as simple as possible. In this work, a novel yet simple PEC immunosensor based on bio-inspired polydopamine (PDA) thin film-coated zinc oxide (ZnO) nanorods was reported. In this PEC immunosensor, the PDA thin film serves simultaneously as a unique sensitizer for charge separation as well as a functional layer for probe antibody attachment. The photocurrent on this electrode under illumination decreases upon the immunoreaction on the surface, possibly due to the blocking effect of formed immunocomplexes on the access of reducing reagent to the photoelectrode, thus offering a simple and reliable platform for PEC label-free immunoassay. By using an antibody-antigen pair as a model, successful label-free immunoassay was achieved with a detection limit of 10pgmL^-1 and a dynamic range from 100pgmL^-1 to 500ngmL^-1. This work demonstrates intriguing electro-optical property and bioconjugation activity of PDA film and may pave the way toward advanced PEC immunoassays.

Recent advances in the use of quantum dots for photoelectrochemical bioanalysis

Photoelectrochemical (PEC) bioanalysis is a newly developed technique for innovative biomolecular detection. Quantum dots (QDs) with unique photophysical properties are key components in realization of various exquisite PEC bioanalyses. Particularly, significant progress has been made in the QD-based PEC bioanalysis. In this work, we briefly summarize the most recent and important developments in the use of traditional and newly emerging QDs for novel PEC bioanalytical applications. The future prospects in this dynamic field are also highlighted.

Enhanced photocatalytic performances of n-TiO₂ nanotubes by uniform creation of p-n heterojunctions with p-Bi₂O₃ quantum dots

An ultrasonication-assisted successive ionic layer adsorption and reaction (SILAR) strategy was developed for uniform deposition of high density p-type Bi2O3 quantum dots on n-type TiO2 nanotube arrays (Bi2O3@TiO2 NTAs), which were constructed by electrochemical anodization in ethylene glycol containing the electrolyte. Compared with pristine TiO2 NTAs, the Bi2O3 quantum dots sensitized TiO2 NTAs exhibited highly efficient photocatalytic degradation of methyl orange (MO). The kinetic constant of Bi2O3@TiO2 NTAs prepared by an ultrasonication-assisted SILAR process of 4 cycles was 1.95 times higher than that of the pristine TiO2 NTA counterpart. The highly efficient photocatalytic activity is attributed to the synergistic effect between the formation of a uniform p-n heterojunction with high-density for enhancing light absorption and facilitating photogenerated electron-hole separation/transfer. The results suggest that Bi2O3@TiO2 p-n heterojunction nanotube arrays are very promising for enhancing the photocatalytic activity and open up a promising strategy for designing and constructing high efficiency heterogeneous semiconductor photocatalysts.