Highly Efficient Visual Detection of Trace Copper(II) and Protein by the Quantum Photoelectric Effect

Abstract

This work presented a photocurrent response mechanism of quantum dots (QDs) under illumination with the concept of a quantum photoelectric effect. Upon irradiation, the photoelectron could directly escape from QDs. By using nitro blue tetrazolium (NBT) to capture the photoelectron, a new visual system was proposed due to the formation of an insoluble reduction product, purple formazan, which could be used to visualize the quantum photoelectric effect. The interaction of copper(II) with QDs could form trapping sites to interfere with the quantum confinement and thus blocked the escape of photoelectron, leading to a "signal off" visual method for sensitive copper(II) detection. Meanwhile, by using QDs as a signal tag to label antibody, a "signal on" visual method was also proposed for immunoassay of corresponding protein. With meso-2,3-dimercaptosuccinic-capped CdTe QDs and carcino-embryonic antigen as models, the proposed visual detection methods showed high sensitivity, low detection limit, and wide detectable concentration ranges. The visualization of quantum photoelectric effect could be simply extended for the detection of other targets. This work opens a new visual detection way and provides a highly efficient tool for bioanalysis.

Ultrasensitive photoelectrochemical immunoassay through tag induced exciton trapping

“…Owing to the separation of excitation signal and detection signal, PEC sensing strategy has plenty of advantages such as low background, low potential different from electrochemiluminescence analysis, which leads to a good analytical performance. Moreover, this strategy can be very easily combined with general immunosensing methods for highly sensitive immunoassay of biomarkers [22][23][24].…”

“…Based on the quantum photoelectric effect of quantum dots (QDs), a "signal on" visual method has been proposed for immunoassay of protein via the formation of insoluble reduction product of nitro blue tetrazolium by the photoelectron escaped from the QDs labeled to the secondary antibody under light excitation [24], and a "signal off" PEC method has also been reported for selective sensing of trace Cu 2 þ by the analyte-induced formation of exciton trapping [25]. This work further combined the "signal off" PEC method with sandwichtype immunosensing strategy to develop a simple and sensitive PEC immunoassay method by using CuO NPs to label the secondary antibody.…”

Reprint of "Cathode photoelectrochemical immunoassay based on analyte- induced formation of exciton trapping for carcinoembryonic antigen detection"

“…Owing to the separation of excitation signal and detection signal, PEC sensing strategy has plenty of advantages such as low background, low potential different from electrochemiluminescence analysis, which leads to a good analytical performance. Moreover, this strategy can be very easily combined with general immunosensing methods for highly sensitive immunoassay of biomarkers [23][24][25].…”

“…Based on the quantum photoelectric effect of quantum dots (QDs), a "signal on" visual method has been proposed for immunoassay of protein via the formation of insoluble reduction product of nitro blue tetrazolium by the photoelectron escaped from the QDs labeled to the secondary antibody under light excitation [25], and a "signal off" PEC method has also been reported for selective sensing of trace Cu 2+ by the analyte-induced formation of exciton trapping [26]. This work further combined the "signal off" PEC method with sandwich-type immunosensing strategy to develop a simple and sensitive PEC immunoassay method by using CuO NPs to label the secondary antibody.…”

Characterization and separation of semiconductor quantum dots and their conjugates by capillary electrophoresis

“…Due to their quantum confinement, QDs show unique optical properties, such as sharp and symmetrical emission spectra, high quantum yield, good chemical and photostability compared to fluorescent dyes. When QDs are linked with biorecognition molecules, such as ligands, proteins, peptides and DNA, they can be widely used in biological and medical fields, such as immunoassay , DNA hybridization , cell imaging , and so on.…”