Determination of Cr(III) ions based on plasmonic sensing and anodic stripping voltammetry with amplification of Ag nanoparticles

Abstract

In this paper mercapto succinic acid (MSA) capped gold nanoparticles (AuNPs) upon indium tin oxide (ITO) glass strips (ITO/AuNPs/MSA) have been used as platform for detection of Cr(III) ions. Cr(III) ions can be immobilized on the surface of AuNPs through formation of complex with MSA, allowing the development of plasmonic and electrochemical methods in assays. The plasmonic sensing is based on the formation of complex between ITO/AuNPs/MSA-Cr(III) and BSA as the second complexant, resulting the red-shift of plasmonic AuNP peak due to the change of environmental refractive index. The concentration of Cr(III) ions could be detected in the linear range of 10 nM–1 mM. On the other hand, the electrochemical method is based on the formation of complex between ITO/AuNPs/MSA-Cr(III) and MSA capped silver nanoparticles (MSA/AgNPs), in which Ag can be detected by anodic stripping voltammetry. With the amplification of AgNPs, the sensitivity of the Cr(III) detection was further improved. The stripping current was found to be linearly proportional to the concentration of Cr(III) ions from 0.1 to 10 nM with detection limit of 0.05 nM. The proposed both methods have great potential in the design of chemical sensors for detection of metal ions in field analyses.