Electrochemical studies of dopamine under stagnant and convective conditions at a sensor based on gold nanoparticles hosted in poly(triaminopyrimidine)

The catalytic activity of surface materials composed of gold nanoparticles (AuNPs) hosted in poly(triaminopyrimidine) (PTAP) towards dopamine (DA) oxidation was studied under static and hydrodynamic conditions. The hybrid composition of the electrode surface (AuNPs·PTAP) shows a pronounced electron transfer capacity estimated from the application of Nicholson model. The electrochemical behavior of dopamine (DA) is diagnosed by the development of reversible peak currents characteristic for the transfer of two electrons. The apparent diffusion coefficient (D_DA ^app) and the heterogeneous rate constant (k_s) for DA oxidation were estimated using cyclic voltammetry (CV) and chronoamperometry (CA) based on well-known relevant electrochemical theories. The D_DA ^app is found to vary significantly with DA concentrations, [DA], and attain a maximum value of 8.65 × 10^− 5 cm² s^− 1 at 60 μM [DA]. A remarkable value of k_s was obtained at low [DA] and approached a steady value of 4.25 × 10^− 2 cm s^− 1 above 50 μM [DA]. The estimated thermodynamic and kinetic parameters of DA were compared concurrently with the reported values for possible validation.