Signal-on photoelectrochemical immunoassay for salivary cortisol based on silver nanoclusters-triggered ion-exchange reaction with CdS quantum dots

Abstract

Nowadays, the epidemic, employment, and academic pressures are seriously affecting our physical and mental health. Herein, we designed a magneto-controlled photoelectrochemical immunosensor for noninvasive monitoring of salivary cortisol regarded as a pressure biomarker. A competitive immunoassay model was established by coupling bovine serum albumin-cortisol modified magnetic beads (MB-BSA-cortisol) with silver nanoclusters (Ag NCs)-labelled anti-cortisol antibody, and quantity analysis was operated by photoelectrochemical measurement of the CdS/Au electrode as an ion-exchange platform. Accompanying the formation of immune complexes, the carried Ag NCs were readily dissolved with nitric acid to produce abundant silver ions, which transferred to the electrode for ion-exchange reaction with CdS quantum dots to produce Ag 2 S, a new electron–hole capture site, leading to a decrease in the photocurrent intensity. The photocurrent signal gradually recovered with the increase of concentration of target cortisol, acquiring the signal-on mode competitive immunosensing system, which is propitious to the detection of small molecules. Within optimal conditions, this sensor had a satisfactory linear relationship in the range of 0.0001–100 ng mL −1 with favorable repeatability, specificity, and acceptable method accuracy. The detection limit was as low as 0.06 pg mL −1 . In addition, this strategy provided new thought for the test of other small-molecule analytes and immunosensor applied in the complex biological system. Supplementary Information The online version contains supplementary material available at 10.1007/s00216-022-03893-z.

Advancements in Cortisol Detection: From Conventional Methods to Next-Generation Technologies for Enhanced Hormone Monitoring

“…As a step up from electrochemical bioanalysis, PEC possesses fast response times, good signal-to-noise ratio and high sensitivity . A competitive assay based on PEC immunosensing was developed with an extremely low LoD of 0.06 pg/mL . This type of “signal-on” immunoassay could become routine as PEC based reactions become more commonplace.…”

“… 90 A competitive assay based on PEC immunosensing was developed with an extremely low LoD of 0.06 pg/mL. 91 This type of “signal-on” immunoassay could become routine as PEC based reactions become more commonplace. As supramolecular techniques grow more refined, with further understanding of coupling reactions, sensitive and discerning assays for cortisol can be developed for rapid cortisol detection.…”

Self-Powered Photoelectrochemical Assay for Hg2+ Detection Based on g-C3N4-CdS-CuO Composites and Redox Cycle Signal Amplification Strategy

“…These results demonstrate that the GSH could specifically recognize Ultraviolet-visible diffuse reflection spectroscopy (DRS) was used to study the electronic orientation of the composite materials. The band gap of the three semiconductors was calculated according to the equation (αhν) 2 = C (hν-Eg) (where α, hν, C, and Eg are the absorption coefficient, photoenergy, the constant, and band gap energy, respectively) [42] and extrapolated the intercept of the linear part of (αhν) 2 vs. hν plot to the x-axis shown in Figure S1A. The band gaps (E g ) of g-C 3 N 4 , CdS, and CuO are 2.84 eV, 2.10 eV, and 1.38 eV, respectively.…”

Colorimetric and Photocurrent-Polarity-Switching Photoelectrochemical Dual-Mode Sensing Platform for Highly Selective Detection of Mercury Ions Based on the Split G-Quadruplex–Hemin Complex

“…In order to overcome these shortcomings, several methods with low cost including colorimetric, electrochemical, and photoelectrochemical (PEC) techniques were developed for the detection of Hg 2+ . − Thereinto, PEC method has received much attention with many advantages including low background signal, easy operation, miniaturization, and so forth. − However, the current PEC methods for detecting mercury ions are still limited because many excellent photoactive materials (such as CoSx@CdS, ZnS@Ag 2 S, CdS, etc − which results in false-negative or false-positive results. In the last few years, the photocurrent-polarity-switching strategy was developed as a highly selective way to effectively avoid the false-negative or false-positive signals, , implying that a new sensing platform based on the photocurrent-polarity-switching strategy may be constructed for the selective assay of Hg 2+ .…”