A novel colorimetric immunoassay based on enzyme-regulated instant generation of Turnbull's blue for the sensitive determination of ochratoxin A

• Published in: Analyst (London) Vol. 145; no. 6; pp. 242 - 2424
• Main Authors: Lai, Wenqiang, Guo, Jiaqing, Wu, Qingqing, Chen, Yaomin, Cai, Quanying, Wu, Luxi, Wang, Shuhan, Song, Jun, Tang, Dianping
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 21.03.2020
• Subjects: Chromogenic Compounds - chemistry; Colorimetry; Colorimetry - methods; Enzyme-Linked Immunosorbent Assay - methods; Enzymes; Ferrocyanides - chemistry; Glucose - chemistry; Glucose oxidase; Glucose Oxidase - chemistry; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrolysis; Immunoassay; Iron; Limit of Detection; Ochratoxins - analysis; Oxidation; Potassium ferricyanide; Wine - analysis
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c9an02447f

The aim of this study was to develop a novel colorimetric sensing method based on enzyme-regulated instant generation of Turnbull's blue, serving as a chromogenic agent, for a sensitive immunoassay for the determination of ochratoxin A (OTA). Unlike the traditional enzyme-linked immunosorbent assay (ELISA), the chromogenic reaction reported herein relies on the immediate formation of Turnbull's blue. K 3 [Fe(CN) 6 ] rapidly forms a coordinate bond with iron( ii ), yielding a blue product. Meanwhile, glucose oxidase (GOx) catalyzes glucose hydrolysis to produce hydrogen peroxide (H 2 O 2 ), which was used to inhibit the formation of Turnbull's blue by oxidizing iron( ii ) to iron( iii ). Thus, Turnbull's blue was generated in an enzyme-regulated manner. Accordingly, a competitive-type colorimetric enzyme immunoassay was established using a GOx based nanolabel. Under optimal conditions, the absorbance increased upon increasing the target OTA concentration in the range of 0.01-10 ng mL −1 with a detection limit of 8.3 pg mL −1 estimated at the 3 S blank level. The assay accuracy was validated by analyzing spiked wine samples. The present results potentially provide novel insights into the development of Turnbull's blue-based biological detection methods and colorimetric immunoassay strategies. The aim of this study was to develop a novel colorimetric sensing method based on enzyme-regulated instant generation of Turnbull's blue, serving as a chromogenic agent, for a sensitive immunoassay for the determination of ochratoxin A (OTA).