The Application of Poly(Glutathione Disulfide)-poly(L-lysine) Multilayer Films for the Enantioselective Interaction with Ascorbic Acid and Isoascorbic Acid

Poly(glutathione disulfide)-poly(L-lysine) (PGSSG-PLY) multilayer films prepared by electropolymerization via cyclic voltammetry were constructed as a new chiral interface for recognition of ascorbic acid (AA) and isoascorbic acid (IAA). The morphology of the films was characterized by scanning electron microscopy (SEM), the electrochemical behaviors of the films were studied via chemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Meanwhile, differential pulse voltammetry (DPV) was used to study the interactions between PGSSG-PLY modified glassy carbon electrodes and AA or IAA. A strong interaction with AA was observed on the chiral interface. The results proved that PGSSG film could amplify eletrochemical signal, while PLY film could provide more recognition sites to discriminate AA and IAA enantiomers with satisfying recognition efficiency. The possible formation of the films on the electrode surface was described. And the influences of electropolymerization cycles and pH to the recognition process were explored. Under the optimum conditions, the method showed an acceptable linear response to AA and IAA in a range from 1.0 × 10−7 to 5.0 × 10−3 M with a low detection limit of 3.3 × 10−8 M (S/N = 3). The modified electrodes also displayed good stability and reproducibility.