Fluorescence turn-on detection of iodide, iodate and total iodine using fluorescein-5-isothiocyanate-modified gold nanoparticles.
Selective turn-on fluorescence detection of I(-) was accomplished using fluorescein isothiocyanate-decorated gold nanoparticles (FITC-AuNPs). FITC molecules, which fluoresce strongly in an alkaline solution, were severely quenched when they were attached to the surface of AuNPs through their isothiocyanate group. Upon the addition of I(-), FITC molecules were detached because of I(-) adsorption on the surface of AuNPs. As a result, released FITC molecules were restored to their original fluorescence intensity. Because I(-) has a higher binding affinity to the surface of Au than do Br(-), Cl(-), or F(-), the FITC-AuNPs obviously have a higher selectivity toward I(-) than toward these other anions. Meanwhile, after IO(3)(-) was reduced to I(-) with ascorbic acid, the detection of IO(3)(-) was successfully achieved using the FITC-AuNPs. Under an optimum pH and AuNP concentration, the lowest detectable concentrations of I(-) and IO(3)(-) using this probe were 10.0 and 50.0 nM, respectively. The FITC-AuNPs provide a number of advantages, including easy preparation, selectivity, sensitivity, and low cost. This unique probe was applied to an analysis of the total iodine in edible salt and seawater.
Chen
Yi-Ming
YM
Department of Chemistry, National Sun Yat-sen University, 70, Lien-hai Road, Kaohsiung, Taiwan 804.
Cheng
Tian-Lu
TL
Tseng
Wei-Lung
WL
D001205:Ascorbic Acid / Q000737:chemistry; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007452:Iodates / Q000032:analysis* / Q000737:chemistry; D007454:Iodides / Q000032:analysis* / Q000737:chemistry; D007455:Iodine / Q000032:analysis* / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D012623:Seawater / Q000737:chemistry; D017673:Sodium Chloride, Dietary / Q000032:analysis; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
D007452:Iodates; D007454:Iodides; D017673:Sodium Chloride, Dietary; D014867:Water; D006046:Gold; D007455:Iodine; D016650:Fluorescein-5-isothiocyanate; D001205:Ascorbic Acid