Electrochemical and radical properties of core-shell structure PDA@SiO2

Radical and electrochemical properties of core-shell polydopamine structures (PDA@SiO2) were studied. We have successfully covered large silica nanoparticles (ca. 960 nm) with a thin layer of polydopamine. The radical's concentration present in PDA is 1.32 x 1015spin/mg and after synthesis in PDA@SiO2 system it is 8.4 x 1013spin/mg. The core-shell structure maintained its radical scavenging properties due to a thin layer of PDA covering silica. Cyclic voltammetry (CV) shows a reduction of peak-to-peak potential separation and an increase of anodic and cathodic current with an increase in the scan rate. Electrochemical impedance spectroscopy shows the electrical connection between PDA and SiO2. PDA@SiO2 core-shell system is electrochemically nondegradable showing a quasi-reversible electrochemical response, which makes it a promising candidate for sensor applications.