Polydopamine and graphene oxide synergistically modified Prussian blue electrochemical immunosensor for the detection of alpha-fetoprotein with enhanced stability and sensibility

Abstract

In this paper, a simple and highly sensitive amperometric immunosensor for the determination of alpha-fetoprotein (AFP) based on multi-functional gold nanoparticles–polydopamine-Prussian blue–graphene oxide nanocomposites (Au–PDA-PB–GO) was fabricated. GO as a template was employed to situ synthesized PB nanoparticle, then PB–GO surface was functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (PDA) modified reduced PB–GO nanoparticles. Via in situ deposition, the Au NPs deposited on the polydopamine functionalized PB–GO nanocomposites. The Au–PDA-PB–GO nanocomposites not only enhance the stability of Prussian blue and provided a favorable microenvironment to maintain the activity of the immobilized biomolecules due to the excellent biocompatibility of PDA, but also increased the loading capacity of the biomolecules due to the large surface area of nanocomposites, and the present of gold nanoparticles enhanced the conductivity and charge-transport properties of the composites. The dynamic range of the resulted immunosensor for the detection of AFP is from 0.01 ng ml⁻¹ to 80.0 ng ml⁻¹ with a detection limit of 0.007 ng ml⁻¹ (S/N = 3). Moreover, this biosensor displays good selectivity, stability and reproducibility.