A portable multimodal electrochemical platform integrating β-cyclodextrin and Pd-Au@ZnO nanostructures for the chiral recognition of valine enantiomers in complex biological matrices.

The development of a straightforward and efficient multimodal electrochemical platform for enantiomeric discrimination is of considerable importance in clinical diagnostics and life sciences. In this study, a compact chiral electrochemical platform was fabricated by modifying a screen-printed carbon nanofiber electrode with β-cyclodextrin and zinc oxide nanostructures decorated with bimetallic Pd-Au nanoparticles, designed for the selective recognition and quantification of valine enantiomers in whole blood samples. The platform integrates two operational modes, linear sweep voltammetry and stochastic sensing, allowing both qualitative and quantitative analysis of the target analyte. A comprehensive characterization of the modified electrode was conducted using scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The platform exhibited high enantioselectivity. A well-defined linear relationship was observed between the anodic peak current and the logarithm of valine enantiomer concentrations in the range of 1.0 × 10-8 to 1.0 × 10-4 M. In stochastic mode, a broader linear dynamic range of 1.0 × 10-14-1.0 × 10-6 M was achieved for L-valine and 1.0 × 10-14-1.0 × 10-5 M for D-valine, with quantification limits as low as 1.0 × 10-14 M. The platform demonstrated excellent reproducibility and stable performance over time. High recovery values (99.3-100.9%) were obtained when applied to real blood samples.