A multifunctional electrode interface: A hybrid hexanethiol and polyethylene glycol monolayer for concurrent anti-fouling, stability, and ultrasensitive detection of ochratoxin A.

Integrating antifouling capability, operational stability, and high sensitivity into electrochemical biosensors in a simple and cost-effective manner remains a significant challenge. Herein, we present a multifunctional biointerface based on a hybrid hexanethiol and polyethylene glycol (HT-PEG) self-assembled monolayer (SAM) that concurrently addresses these requirements. The PEG component provides excellent antifouling properties through steric exclusion and hydration effects, while also serving as a dynamic host for spontaneous immobilization of pyrene-modified DNA probes (Py-DNA) via adaptive insertion. Complementarily, the HT monolayer not only enhances interfacial stability but also enables efficient signal amplification by suppressing the electron transfer between [Fe(CN)6]3- and the electrode, thereby overcoming the intrinsic insulation limitation of PEG. The synergistic combination of HT and PEG, co-assembled via straightforward gold-thiol (Au-S) bonding, creates a unified platform that combines antifouling, probe anchoring, signal amplification, and robust performance. As a proof of concept, an aptasensor constructed on this hybrid interface achieved ultrasensitive detection of ochratoxin A (OTA) with a detection limit of 0.68 pg/mL, excellent selectivity, and satisfactory recovery in spiked corn extracts. With its high performance, simplicity, and low cost, this sensing strategy holds great promise for point-of-care monitoring of mycotoxins and other contaminants in real-world samples.