Molecularly imprinted nanohybrids based on dopamine-modified poly(γ-glutamic acid) for electrochemical sensing of melamine

A voltammetric sensor for melamine (MEL) was prepared from molecularly imprinted nanohybrids (MINBs). A dopamine modified poly-γ-glutamic acid copolymer (γ-PGA-DA) and MEL were self-assembled into MEL/γ-PGA-DA nanoparticles (NPs) in aqueous solution via weak interactions, followed by adding an aqueous AgNO3 solution into the mixture. The Ag+ was adsorbed in the MEL/γ-PGA-DA NPs and spontaneously reduced to Ag NPs by the dopamine moieties of γ-PGA-DA, forming Ag/MEL/γ-PGA-DA MINBs, which were then cast on a gold electrode to form a MINBs film. The MEL was removed by electrolysis via catalysis of Ag NPs at a constant potential of 1.4 V in phosphate buffer saline solution, to obtain a voltammetric sensor for MEL. The sensor responded linearly to MEL in the concentration range of 5×10−18 to 5×10−7 mol L−1. Compared to other published molecularly imprinted polymer sensors for sensing MEL, the prepared MINBs sensor had much wider detection range with lower detection limit.