Preparation of gold core and silver shell substrate with inositol hexaphosphate inner gap for Raman detection of trace Penicillin G

Abstract

The abuse of Penicillin G (PG) in the feeds of livestock resulted in health risk for human being via the food chain. It is urged to develop the rapid and sensitive method for monitoring PG residue in food products. In this work, silver shell was formed on the core gold nanoparticles protected with inositol hexaphosphate (IP6), designated as Ag@IP6@AuNPs, which is used as surface enhanced Raman scattering (SERS) substrate. Thanks to the presence of IP6 between silver shell and core gold, Ag@IP6@AuNPs show high storage stability. The great surface plasmon resonance of hot spot field generated in the molecular gap between core-shell extends to nanoparticle surface results in synergistic enhancement of Raman scattering effect. Ag@IP6@AuNPs-based SERS assay is employed to successfully detect trace PG residue in milk with a wide linear quantitative range from 10−5 to 10-11 mol/L and the limit of detection at 10-12 mol/L. The sensitivity of such Raman protocol meets the requirement for the maximum residue limit (MRL, 4 μg/kg or 1.2 × 10−8 mol/L) of PG in milk products set by the European Union. Additionally, the detection recoveries in the range from 92.18 % to 101.4 % mean the acceptable robustness of such SERS method. The proposed SERS method could be advanced to realize the on-field determination of PG in milk for guarantee of food safety.