Sticking of magnetite nanoparticles coated with dopamine and polydopamine on gold substrates

Polydopamine can adhere to many materials and this property can by exploited to bind nanoparticles to solid surfaces. Dopamine, the precursor of polydopamine, thanks to catechol and amino groups, is capable to adsorb on metal and oxide surfaces. In the present work, magnetite nanoparticles were functionalized with dopamine and polydopamine and their sticking on gold surfaces was evaluated. Coating of the nanoparticles with polydopamine was achieved by oxidation in air of aqueous dopamine solutions in which nanoparticles were dispersed. DLS, FTIR, XPS, TEM were used for the chemical and morphological characterization of the various types of nanoparticles. Sticking of dopamine and polydopamine coated nanoparticles on gold substrates was monitored by AFM. While magnetite nanoparticles with adsorbed dopamine stick to gold surfaces, adhesion of nanoparticles coated with polydopamine depends on the preparation conditions. The adhesive properties appear to be influenced mainly by the roughness of the coating layer. The electrochemical properties of magnetite NPs coated with DA and PDA deposited on gold electrodes were investigated by cyclic voltammetry.