Enantioselective recognition and detection of cysteine using a three-dimensional Mn1/3Zn2/3CO3-rGO/CNT heterostructure-based molecularly imprinted sensor.

Enantioselective recognition of chiral molecules, particularly cysteine enantiomers (L/D-Cys), is crucial in life sciences, drug development, and clinical diagnostics due to their distinct physiological effects. However, conventional methods often lack sufficient selectivity and sensitivity. Herein, a molecularly imprinted electrochemical sensor based on three-dimensional (3D) heterostructured Mn1/3Zn2/3CO3-rGO-CNTs was developed for highly selective detection of cysteine enantiomers. The Mn1/3Zn2/3CO3-rGO microspheres were successfully synthesized via a two-step co-precipitation-hydrothermal strategy, and combined with carbon nanotubes to construct a 3D carrier with high specific surface area and excellent conductivity. XPS, SEM, and TEM characterization studies demonstrated its suitability as an ideal platform for molecular imprinting. Using L-Cys or D-Cys as the template molecule, the chiral recognition sites were constructed on the modified electrode interface via electropolymerized polypyrrole, achieving efficient enantiomer differentiation. Combined with a potential dynamic rapid-switching detection mode, the sensor exhibited significantly enhanced detection efficiency with a response time of 2 s. This proposed sensor demonstrated a wide linear range of 1 × 10-7 to 1 × 10-3 mol L-1 for L-Cys detection, and exhibited significant enantioselectivity at the same concentration (L/D = 4.248 ± 0.01; D/L = 5.033 ± 0.50). This method offers high sensitivity and stability, and applicability for complex biological sample analysis, providing a robust technical platform for chiral recognition and pharmaceutical research.