Synthesis of polyhedral gold nanostars as surface-enhanced Raman spectroscopy substrates for measurement of thiram in peach juice

Abstract

Rapid detection of food contaminants using novel analytical methods in combination with nanomaterials has received much attention. This study aimed to synthesize polyhedral gold nanostars (AuNS) with multi-angled corners and develop a surface-enhanced Raman spectroscopy (SERS) method coupled with AuNS to detect pesticide residues in juice products. AuNS are multi-branched three-dimensional metal nanostructures with rough surface features which can induce surface plasmon resonance. A facile synthesis of AuNS was achieved using a two-step method and as-prepared AuNS had much cleaner surfaces than gold nanoparticles. A Raman reporter molecule (4-aminothiophenol) was used to evaluate the performance of the SERS method, yielding fingerprint-like Raman spectra and the sensitivity of the SERS method could reach 10 ppb (μg kg⁻¹). SERS coupled with AuNS was used to detect thiram residues in peach juice and the detection limit was 50 ppb, and is 100 times more sensitive than using normal gold nanoparticles. These results demonstrate that AuNS are excellent substrates for SERS measurement, which has great potential for rapid detection of chemical contaminants in food products.