A built-in signal probe-enhanced molecularly imprinted acupuncture needle sensor for ultrasensitive detection of SARS-CoV-2 spike protein

An integrated, reagent-free sensing platform was constructed based on acupuncture needle and molecular imprinting technology. • 4-mercaptophenylboronic acid, poly(methylene blue), and polydopamine were employed as core functional components for targeted recognition and signal transduction. • High selectivity and sensitive detection of the SARS-CoV-2 spike protein were achieved. • The sensor exhibits excellent reproducibility, stability, and operational simplicity. • Reliability and practicality of the sensor were validated using real human serum samples, laying a foundation for clinical application. Accurate detection of the SARS-CoV-2 spike protein (S-protein) is important for the early-stage investigation and monitoring of COVID-19. We report an integrated electrochemical sensing platform with a reagent-free detection step. A modified acupuncture needle was utilized as the substrate for Au S self-assembly of 4-mercaptophenylboronic acid (4-MPBA), which enabled affinity-based capture and controllable elution of the S-protein template via reversible boronate ester interactions. Poly(methylene blue) (PMB) was electropolymerized as a built-in redox mediator, while a molecularly imprinted polymer (MIP) layer was concurrently fabricated by in situ electrophoretic deposition of polydopamine (PDA). The fabricated biosensor exhibited a linear relationship between the signal response and the logarithm of the S-protein concentration over the range of 0.01 to 10 4  ng/mL, with a detection limit of 0.0033 ng/mL (S/N = 3). It also demonstrated good selectivity, reproducibility, and stability. This work provides a proof-of-concept strategy for developing portable and low-cost electrochemical sensing platforms for protein detection. Download: Download high-res image (216KB) Download: Download full-size image