title: Using L-arginine-functionalized gold nanorods for visible detection of mercury(II) ions.
abstract: A rapid and simple approach for visible determination of mercury ions (Hg(2+) ) in aqueous solutions was developed based on surface plasmon resonance phenomenon using L-arginine-functionalized gold nanorods (AuNRs). At pH greater than 9, the deprotonated amine group of L-arginine on the AuNRs bound with Hg(2+) leading to the side-by-side assembly of AuNRs, which was verified by transmission electron microscopy images. Thus, when Hg(2+) was present in the test solution, a blue shift of the typical longitudinal plasmon band of the AuNRs was observed in the ultra violet-visible-near infrared (UV-Vis-NIR) spectra, along with a change in the color of the solution, which occurred within 5 min. After carefully optimizing the potential factors affecting the performance, the L-arginine/AuNRs sensing system was found to be highly sensitive to Hg(2+) , with the limit of detection of 5 nM (S/N = 3); it is also very selective and free of interference from 10 other metal ions (Ba(2+) , Ca(2+) , Cd(2+) , Co(2+) , Cs(+) , Cu(2+) , K(+) , Li(+) , Ni(2+) , Pb(2+) ). The result suggests that the L-arginine-functionalized AuNRs can potentially serve as a rapid, sensitive, and easy-to-use colorimetric biosensor useful for determining Hg(2+) in food and environmental samples.
authors.affiliation: Dept. of Biological Systems Engineering, Univ. of Wisconsin-Madison, 460 Henry Mall, Madison, WI, U.S.A.
authors.forename: Jiehao
authors.initials: J
authors.lastname: Guan
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Wang
authors.forename: Sundaram
authors.initials: S
authors.lastname: Gunasekaran
mesh_terms: D001120:Arginine / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods; D003124:Colorimetry / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D007477:Ions / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D043942:Nanotubes; D012996:Solutions
chemical_list: D007477:Ions; D012996:Solutions; D006046:Gold; D001120:Arginine; D008628:Mercury
keywords: colorimetric sensor; food safety; green synthesis; heavy metal; surface plasmon resonance; water quality