A sensitive LSPR sensor based on glutathione-functionalized gold nanoparticles on a substrate for the detection of Pb2+ ions

Abstract

A plasmonic probe based on gold nanoparticles (AuNPs) on a solid substrate for the detection of Pb²⁺ was developed. The AuNPs were self-assembled on a transparent indium tin oxide (ITO) glass using organic PDDA linkers and then calcined to obtain pure AuNPs on the ITO surface (ITO/AuNPs). The probe was fabricated by functionalizing glutathione on the gold surface (ITO/AuNPs/GSH). The strong chelation of Pb²⁺ with GSH resulted in the red-shift of the localized surface plasmon resonance (LSPR) peak due to the change in the refractive index of the environment. The red-shift of the peak wavelength was linearly proportional to the concentration of Pb²⁺ from 10⁻¹⁰ to 10⁻⁵ M with a detection limit of 5 × 10⁻¹¹ M. The sensitivity of the as-prepared sensor was much higher than that of the sensors prepared by the methods based on aggregation strategy. This method offered a new strategy for the determination of Pb²⁺ with satisfactory results.