Colorimetric and photothermal dual-mode aptasensor with redox cycling amplification for the detection of ochratoxin A in corn samples

• Published in: Food chemistry 2024-05, Vol.439, p.137968-137968, Article 137968
• Main Authors: Tang, Jian, Liu, Jiali, Wang, Fupeng, Yao, Yaochun, Hu, Rong
• Format: Article
• Language: English
• Subjects: Aptamers, Nucleotide - chemistry; Biosensing Techniques - methods; Colorimetry - methods; Hemin; Limit of Detection; Ochratoxins - analysis; Zea mays
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2023.137968

Ochratoxin A (OTA) detection is critical for public health safety. This study proposes a G-quadruplex-Hemin/iodide (G4-Hemin/I )-mediated non-enzyme redox cycling amplification (RCA) system for dual-modal (colorimetric and photothermal thermometer) OTA analysis. The proposed aptasensor platform for point-of-care testing employs a common thermometer for quantitative signal readouts. The OTA aptamer folds into a G4 structure, which significantly enhances the catalytic activity in the presence of I after RCA reaction. Moreover, a notable temperature enhancement causes color changes, providing an ultrasensitive and label-free platform for OTA detection. Further, the designed sensor was applied to OTA content determination in corn samples and achieved satisfactory results compared to a commercial enzyme-linked immunoassay kit. The proposed dual-mode aptasensor is simple, highly sensitive (1 pg/mL for colorimetric method, 0.8 pg/mL for photothermal method), selective, and suitable for low-cost instrument-free bioanalysis in low-resource settings.