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

• Published in: Biosensors & bioelectronics Vol. 77; pp. 323 - 329
• Main Authors: Barroso, Javier, Saa, Laura, Grinyte, Ruta, Pavlov, Valeri
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.03.2016
• Subjects: Alkaline phosphatase; Alkaline Phosphatase - chemistry; Assaying; Biosensing Techniques - instrumentation; Cadmium Compounds - analysis; Conductometry - instrumentation; Electrodes; ELISA; Enzyme catalysis; Enzymes, Immobilized - chemistry; Equipment Design; Equipment Failure Analysis; Graphite; Graphite - chemistry; Immunoassay; Immunoassay - instrumentation; Metal Nanoparticles - analysis; Metal Nanoparticles - chemistry; Metal Nanoparticles - ultrastructure; Nanoparticles; Photoelectrochemistry; Photometry - instrumentation; Quantum dots; Selenium Compounds - analysis; Semiconductors; Photoelectrochemistry; Immunoassay; Alkaline phosphatase; Enzyme catalysis; Quantum dots; ELISA
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2015.09.043

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 Cd2+ ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os–PVP complex on the surface of graphite electrode at applied potential of 0.31V 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 20ngmL−1 and a detection limit (DL) of 2ngmL−1 (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP). [Display omitted] •An innovative PEC device was developed for biosensing.•Signal transduction was achieved by Os-PVP complex-modified electrode.•CdS QDs were generated by ALP-catalyzed hydrolysis of thiophosphate.•The PEC immunoassays showed lower detection limit than a standard method.•This method could be extended readily for detecting more analytes labeled with ALP.