A label-free photoelectrochemical immunosensor for prostate specific antigen detection based on Ag2S sensitized Ag/AgBr/BiOBr heterojunction by in-situ growth method.

Prostate cancer is one of the most common cancers in the world, and its early detection is vital to saving the lives of patients. In this research, a novel label-free photoelectrochemical immunosensor was designed for sensitive detection of prostate specific antigen (PSA). Ag2S sensitized on Ag/AgBr/BiOBr heterojunction could effectively inhibit photogenic holes recombination and improve photocurrent response and sensitivity. Ascorbic acid was an effective electron donor, which can effectively eliminate photo-generated holes. The photocurrent reduced linearly with the logarithm of PSA concentration ranged from 0.001 to 50 ng·mL-1 and the limit of detection was 0.25 pg·mL-1. The designed sensor had the advantages of wide linear range, good stability, high reproducibility, and good selectivity. This study not only provided a method for efficient and sensitive detection of PSA, but also provided valuable reference ideas for the detection of other tumor markers.

A label-free photoelectrochemical immunosensor for detection of the milk allergen ß-lactoglobulin based on Ag2S -sensitized spindle-shaped BiVO4/BiOBr heterojunction by an in situ growth method.

Food allergies have become a nonnegligible food safety issue, and milk allergies are one of the most common food allergies, that has attracted large consumer attention. In this work, a novel label-free photoelectrochemical (PEC) immunosensor for the detection of the allergen ß-lactoglobulin (ß-LG) in dairy products was designed that used the specific recognition of allergen ß-LG and antibodies in dairy products in combination with biosensing technology. Here, Ag2S-sensitized spindle-shaped BiVO4/BiOBr heterojunction was fixed on the surface of the ITO electrode as an excellent photoactive substrate and effectively improved the photocurrent responses and sensitivity. Thioglycolic acid (TGA) was used as a linker to immobilize the ß-LG antibody on the surface of the electrode. The photocurrent was detected at different antigen concentrations, which realized the quantitative testing of ß-LG. Under the optimal experimental conditions, the PEC immunosensor proved an ideal linear relationship ranging from 10 pg/mL to 100 ng/mL, with a low detection limit of 3.7 pg/mL. The designed immunosensor showed good stability, a wide linear range, high sensitivity and good reproducibility and could be used for the detection of actual samples. The PEC immunosensor had a strong ability to specifically recognize ß-LG, which was not affected by other proteins in the milk without pretreatment. Meanwhile, the developed immunosensor provided a promising PEC detection platform and reference idea for the detection of other proteins in milk.

Ultrasensitive photoelectrochemical immunosensor of cardiac troponin I detection based on dual inhibition effect of Ag@Cu2O core-shell submicron-particles on CdS QDs sensitized TiO2 nanosheets.

Rapidity and high sensitivity are the critical factors for the diagnoses of heart attacks and cardiac troponin I (cTnI) is used as a gold standard marker for its diagnosis. To realize the accurate detection of cTnI, a novel ultrasensitive photoelectrochemical (PEC) immunosensor for cTnI determination was developed upon dual inhibition effect of Ag@Cu2O core-shell submicron-particles(SPs) toward CdS sensitized the (001) facets of anatase titanium dioxide nanosheets (TiO2/CdS). In this study, the TiO2/CdS composite not only indicated stable and excellent photoelectric signal but also provided abundant functional group to immobilized cTnI antibodies (Ab1). To obtain the high sensitivity, Ag@Cu2O core-shell SPs were used as labels of the secondary antibodies (Ab2), owning to competitive absorption of light and consumption of electron donor, less light energy and electron donors arrived at the TiO2/CdS sensitization structure. Besides, the remarkable steric hindrance effect of Ag@Cu2O core-shell SPs labeled secondary antibodies (Ab2) conjugates obstructed the transfer of electrons and diffusion of the electron donors to the photoelectrode surface, leading to further decrease of photocurrent. Therefore, the constructed immunosensor has an ultrasensitive response to cTnI in a liner range of 0.02 pg/mL to 50 ng/mL with a low detection limit of 6.7 fg/mL, and exhibits good sensitivity and admirable stability. Moreover, the strategy provided an efficient and novel approach for dual inhibition effect in PEC immunoassay development.