Novel Colorimetric Immunoassay for Ultrasensitive Monitoring of Brevetoxin B Based on Enzyme-Controlled Chemical Conversion of Sulfite to Sulfate

• Published in: Journal of agricultural and food chemistry Vol. 63; no. 7; pp. 1982 - 1989
• Main Authors: Lai, Wenqiang, Zhuang, Junyang, Tang, Dianping
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25.02.2015
• Subjects: Animals; Bivalvia - chemistry; Colorimetry - methods; Glucose Oxidase - chemistry; Immunoassay - methods; Limit of Detection; Marine Toxins - analysis; Oxocins - analysis; Sensitivity and Specificity; Shellfish - analysis; Sulfates - chemistry; Sulfites - chemistry; marine biotoxin; colorimetric immunoassay; brevetoxin B; sulfite-to-sulfate enzyme-controlled chemical conversion
• DOI: 10.1021/acs.jafc.5b00425
• ISSN: 0021-8561

A simple colorimetric immunoassay for quantitative monitoring of brevetoxin B on a functionalized magnetic bead by using glucose oxidase (GOx)/antibrevetoxin antibody-labeled gold nanoparticle as the signal transduction tag was developed. The assay was carried out on the basis of GOx-controlled sulfite-to-sulfate chemical conversion with a silver­(I)–3,3′,5,5′-tetramethylbenzidine [Ag­(I)–TMB] system. Initially, the sulfite was used as an inhibitor of Ag­(I) to hinder the color development of TMB due to the formation of insoluble silver sulfite. Accompanying H2O2 generation with GOx-catalyzed glucose, the sulfite was converted into the sulfate, thus resulting in the colorless-to-blue change. Under the optimal conditions, the absorbance decreased with increasing brevetoxin B from 0.5 to 200 ng/kg with a detection limit of 0.1 ng/kg (ppt). The precision and specificity were acceptable. Furthermore, the methodology gave results matching well with the referenced brevetoxin ELISA kit for monitoring of spiked Musculista senhousia samples.