Enhanced electrochemical response of structurally related antioxidant at nanostructured hybrid films

In this work, the redox behaviour of structurally related antioxidants, such as catechol, hydroxycinnamic acid and flavonoid derivatives, has been investigated at electrode surfaces modified with different gold nanoparticles (AuNPs)–chitosan films. Our findings demonstrate that the chemical structural features of the antioxidants play a key role in the interaction with modified electrodes that strongly affect the electrochemical response. In particular, a better response was observed for molecules with two hydroxyl groups in ortho position of the catechol ring and with a low steric hindrance. However, the redox behaviour cannot be explained only on these bases, since the nanostructure and surface functional groups of AuNPs–chitosan modified electrodes have also to be considered. The presence of interconnected metal nanoparticles into chitosan film strongly affects the electron transfer properties, whereas the surface functional groups can promote the interaction with selected antioxidants acting as scavenger. The understanding of the key factors that affect the electrochemical response of antioxidants at electrode surface modified with nanostructured hybrid films is a key issue and could significantly contribute to the development of highly efficient electrochemical sensors.