Enhancement of surface plasmon resonance signals using a MIP/GNPs/rGO nano-hybrid film for the rapid detection of ractopamine.

A novel surface plasmon resonance (SPR) sensor that uses molecular imprinted polymers (MIPs) coated with gold nanoparticles (GNPs) and reduced graphene oxide (rGO) as a sensing nano-hybrid film was developed for detection of ractopamine. The MIPs were synthesized by precipitation polymerization and characterized by scanning electron microscopy and Scatchard analysis. The GNPs/rGO composite was synthesized by a single-step reduction of graphene oxide and HAuCl4 solution. The MIP/GNPs/rGO nano-hybrid film was immobilized onto a bare sensor chip and exhibited remarkable sensitivity and stability by the “grafting to” method with the assistance of ionic liquid (IL) as a binder. The prepared sensor showed class-specific selectivity for ractopamine (RAC) and its analogs under optimized conditions. The novel SPR sensor had a wide linear range over an RAC concentration from 20 to 1000 ng/mL with a detection limit of 5 ng/mL (S/N=3). The results demonstrated that the MIP/GNPs/rGO nano-hybrid film was suitable as the recognition element of the SPR sensorfor rapid screening and detection of beta-agonists such as RAC.