title: Label-free colorimetric detection of cadmium ions in rice samples using gold nanoparticles.
abstract: A simple and label-free colorimetric method for cadmium ions (Cd(2+)) detection using unmodified gold nanoparticles (AuNPs) is reported. The unmodified AuNPs easily aggregate in a high concentration of NaCl solution, but the presence of glutathione (GSH) can prevent the salt-induced aggregation of AuNPs. When Cd(2+) is added to the stable mixture of AuNPs, GSH, and NaCl, Cd(2+) can coordinate with 4× GSH as a spherical shaped complex, which decreases the amount of free GSH on the surface of gold nanoparticles to weaken the stability of AuNPs, and AuNPs will easily aggregate in high-salt conditions. On the basis of the mechanism, we design a simple, label-free colorimetric method using AuNPs accompanied by GSH in a high-salt environment to detect Cd(2+) in water and digested rice samples.
authors.affiliation: Beijing Engineering Research Center for BioNanotechnology, National Center for Nanoscience and Technology , Beijing 100190, China.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Guo
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Huawu
authors.initials: H
authors.lastname: Shao
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
authors.forename: Xuefei
authors.initials: X
authors.lastname: Wang
authors.forename: Xingyu
authors.initials: X
authors.lastname: Jiang
mesh_terms: D002104:Cadmium / Q000032:analysis*; D003124:Colorimetry; D005524:Food Technology / Q000379:methods*; D005978:Glutathione / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007477:Ions; D002104:Cadmium; D012965:Sodium Chloride; D006046:Gold; D005978:Glutathione