Synthesis Of Glutathione-Capped Metal Nanoparticles And The Application For Heavy Metal Ions Detection

Heavy metal ions such as Hg²⁺?Ag⁺?Pb²⁺?Cd²⁺?As³⁺ caccumulated in human body through food chains can can induce serious diseases including kidney damage, brain damage, heart disease, cardiovascular disease and lung damage. Therefore, the development of heavy metal ions detection methods receivs considerable attention.Compared with electrochemical and fluorescent methods, colorimetric assays can be easily interpreted by naked eyes.However it is still a challenge to have lower limit of detection. Glutathione?GSH? is chosen as a nucleation template to synthesize GSH-Pt NPs and GSH-Pd NPs, which possesses the high peroxidase-like activity. Nanozymes are employed to explore colorimetric assays of heavy metals.Firstly, Glutathione?GSH? is chosen as a nucleation template to synthesize Pt-based peroxidase nanomimetics ranging from 2.3 to 3.6 nm, of which the surface charge states are greatly associated with the molar ratios of [K₂PtCl₄]/[GSH]. [K₂PtCl₄]/[GSH]=6?GSH-Pt3.3? consisting of 67% Pt0 and 33% Pt²⁺ possesses the highest peroxidase-like activity, while [K₂PtCl₄]/[GSH]=60?GSH-Pt3.6?comprising of 82% Pt0 and 18% Pt²⁺ exhibits the most efficient radical scavenging capability. Owing to the Hg²⁺-induced inhibition of peroxidase mimicking activities, a series of Pt-based nanozymes are employed to explore colorimetric assays of Hg²⁺ in aqueous samples with ultrahigh sensitivity and selectivity. The limit of detection?LOD? can be reached to 0.25 nM by using GSH-Pt with an average diameter of 3.6 nm. GSH-Pt is a promising nanozyme for colorimetric assay of Hg²⁺ in drinking water and biological fluid.Next, Glutathione?GSH? is chosen as a nucleation template to synthesize GSH-Pd NPs. The molar ratios of [Na2PdCl4]/[GSH] =6?GSH-Pd2.6? possesses the highest peroxidase-like activity. [Na2PdCl4]/[GSH] =60?GSH-Pd3.5?consist 72.5% Pd0 and 27.5% Pd²⁺. As decreasing the particle size from 2.6 nm to 1.4 nm, the proportion of Pd0 species decreases significantly from 56.7 % to 30.4 %. GSH-Pd2.6 was used to detection Ag⁺,the detection limit of 1.14 nM with a linear response rage of 0-100 nM.