Photoelectrochemical detection of enzymatically generated CdS nanoparticles: Application to development of immunoassay

Abstract

We report an innovative photoelectrochemical process (PEC) based on graphite electrode modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP). The system relies on the in situ enzymatic generation of CdS quantum dots (QDs). Alkaline phosphatase (ALP) catalyzes the hydrolisis of sodium thiophosphate (TP) to hydrogen sulfide (H2S) which in the presence Cd(2+) ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365 nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os-PVP complex on the surface of graphite electrode at applied potential of 0.31 V vs. Ag/AgCl. A novel immunoassay based on specific enzyme linked immunosorbent assay (ELISA) combined with the PEC methodology was developed. Having selected the affinity interaction between bovine serum albumine (BSA) with anti-BSA antibody (AB) as a model system, we built the PEC immunoassay for AB. The new assay displays a linear range up to 20 ngmL(-1) and a detection limit (DL) of 2 ngmL(-1) (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP).

Advanced Functional Electroactive and Photoactive Materials for Monitoring the Environmental Pollutants

“…[ 80 ] Alternatively, alkaline phosphatase (ALP) catalyzes the hydrolysis of sodium thiophosphate to hydrogen sulfide (H 2 S); the subsequently formed CdS in the presence Cd 2+ could then be photoexcited to produce a detectable photocurrent. [ 81 ]…”

Recent Advances in Electrochemical Immunosensors

“…The application of an enzyme-based amplification to a PEC immunoassay has been demonstrated by the use of the in situ generation of an enzymatic hydrolysate as an electron acceptor or an electron donor, which may then trigger the PEC signal chain to assist in signal amplification . Zhao and co-workers recently exploited ALP tagged antibodies on AuNP/TiO 2 nanotube modified electrodes for an amplified PEC immunoassay of protein p53.…”

“…The application of an enzyme-based amplification to a PEC immunoassay has been demonstrated by the use of the in situ generation of an enzymatic hydrolysate as an electron acceptor or an electron donor, which may then trigger the PEC signal chain to assist in signal amplification. 105 Zhao and co-workers 106 recently exploited ALP tagged antibodies on AuNP/TiO 2 nanotube modified electrodes for an amplified PEC immunoassay of protein p53. In such a system, ALP possessed the enzyme activity to specifically catalyze ascorbic acid 2-phosphate to generate in situ ascorbic acid, which was employed as an efficient electron donor in the PEC platform.…”

Specific bioanalytical optical and photoelectrochemical assays for detection of methanol in alcoholic beverages

“…This methodology consists of ramping the potential linearly versus time in cyclical phases in the range between 0 and 0.6 V vs. Ag/AgCl. Final CV revealed redox reversible waves related to the central osmium atom (Barroso et al, 2016). Another aspect of PEC assays is the employment of a reducing agent to neutralize holes generated in CdS QDs upon excitation of electrons by photons.…”