2D-HCR-guided nanobipyramid etching for tri-mode ultrasensitive biosensing of Ochratoxin A

A tri-mode aptasensor for ultrasensitive detection of ochratoxin A (OTA) was developed, based on two-dimensional hybridization chain reaction (2D-HCR)-guided etching to modulate gold nanobipyramid (AuNB) morphology. The OTA aptamer-functionalized magnetic probe (MB@2D-HCR@HRP) integrated the self-assembly 2D-HCR networks, which had loaded with abundant horseradish peroxidase (HRP) for cascade signal amplification. Following OTA recognition, the released 2D-HCR@HRP could induce the generation of hydroxyl radical (·OH), then perform the AuNB etching. The results of AuNB morphological transformation identified through three readouts: (1) visual multicolor (LOD of 100 pg mL −1 ), (2) surface plasmon resonance peak (LOD of 75.3 pg mL −1 ), (3) photothermal response (LOD of 14.7 pg mL −1 ). Thus, the levels of OTA could directly reflect via triple signals, achieving rapid and ultrasensitive detection within 45 min. The aptasensor exhibited high specificity (cross-reactivity less than 7.22 %) and reliability for spiked and authentic agricultural byproduct samples. Furthermore, the highlights of simplified operation visualization and portability had displayed. This aptasensor had handled advanced strategies to improve the detection performance, which might further promote the practicability and accessibility of biosensing.