A fast chiral sensing to DOPA enantiomers via poly-lysine films matrixes

A fast electrochemical sensing to recognize 3,4-dihydroxyphenylalanine (DOPA) enantiomers was proposed based on poly-lysine enantiomers films as matrixes, which were electrodeposited on the surface of glass carbon electrodes via cyclic voltammetry (CV). Differential pulse voltammetry (DPV) and CV were employed to investigate the stereospecific recognition of DOPA enantiomers. The concentration of l-lysine, electro-polymerization cycles, pH and the effect of the temperature on the chiral discrimination were investigated to obtain optimization of the experimental parameters, and the Gibbs' free energy (ΔG) was also discussed. The results showed that not only DOPA enantiomers could be recognized by poly-lysine matrix with the tendency of heterochiral interaction between poly-lysine and DOPA enantiomers, but also the largest discrimination responses were resided in poly-l-lysine matrix (PLL) and d-DOPA with the measurement range of 5.0 × 10−7 M to 8.0 × 10−3 M. The detection limit was 0.17 μM (S/N = 3), and the detection time only spent 75 s. The simple method with rapid recognition, good sensitivity and high stability provided a new perspective to recognize and determine DOPA enantiomers with fast, stabile, selective characteristics.