A novel ratiometric molecularly imprinted electrochemical microsensor with synergistic embedded signal and surface reference probes for non-electroactive Aβ42 detection.

Abstract

Ratiometric molecularly imprinted electrochemical sensors (RMIESs) can mitigate electroactive surface area effects, background interference, and signal fluctuations while enhancing anti-interference capability and stability, but reported sensors are mainly suitable for electroactive targets. Herein, a novel RMIES strategy using an acupuncture needle (AN) was demonstrated for the non-electroactive biomarker β-amyloid1-42 (Aβ42). On the AN, an acid chrome blue K-electropolymerized imprinted layer serves as the recognition unit, embedded hemin acts as the Aβ42-modulated signal probe, and surface caffeic acid (CA) serves as the internal reference, forming a common-interface ratiometric system. CA was employed for the first time as an electroactive internal reference probe. The hemin-CA peak potential difference is 600 mV in differential pulse voltammetry, sufficient for ratiometric electroanalysis. This ratiometric microsensor exhibits a wide linear detection range (0.1 ∼ 5 × 106 pg/mL) and a low detection limit (0.0104 pg/mL) for Aβ42. Compared with the single-signal built-in sensor, it shows superior detection performance, anti-interference capability, and reproducibility. Furthermore, an AN-based microelectrode electrochemical system was explored and used on pig brain tissue. This microsensor provides a novel ratiometric electroanalysis strategy for non-electroactive biomarkers and is suitable for integration because it avoids external mediators, enables miniaturization, and allows multifunctional integration with acupuncture.

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