Target-Specific Electrochemical Sensing of Pipecolic Acid via Molecular Imprinting.

Pipecolic acid (PA) is an important biomarker associated with peroxisomal and neurological disorders, necessitating the development of rapid, selective, and cost-effective detection methods beyond conventional chromatographic techniques. In this study, a molecularly imprinted electrochemical sensor (PA-MIP/Au) was developed for the selective determination of PA. The sensor was fabricated by electropolymerizing pyrrole on a gold electrode in the presence of PA as a template, followed by template removal to create specific recognition cavities. The electrochemical behavior and analytical performance were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a ferri/ferrocyanide redox system. The sensor exhibited a linear response over 5-100 µM, with a detection limit of 1.05 µM. This range covers the reported physiological plasma concentrations of pipecolic acid (0.7-2.6 µM) and extends to elevated levels observed in pathological conditions, thereby demonstrating its suitability for clinical and biochemical monitoring applications. The sensor also demonstrated high selectivity against structurally similar amino acids, good repeatability, reproducibility, and stability, retaining over 87% of its initial response after 28 days. Recovery studies in spiked artificial plasma samples yielded values between 97.2% and 98.4%, confirming its applicability in complex matrices. Overall, the proposed sensor offers a simple, rapid, and cost-effective alternative for PA determination with potential for clinical and point-of-care applications.