title: Thiol-directed synthesis of highly fluorescent gold clusters and their conversion into stable imaging nanoprobes.
abstract: Fluorescent gold clusters (FGCs) with tunable emission from blue to red and quantum yields in the range of 6-17% have been synthesized by simple modification of the conditions used for the synthesis of gold nanoparticles, namely by replacing the stronger reducing agent with a controlled amount of thiol. Various functional FGCs with hydrodynamic diameters of 5-12 nm have been successfully synthesized and used as cell labels. The results of our investigations strongly indicate that FGCs composed of Au(0) are more stable imaging probes than commonly reported red/NIR-emitting FGCs with a composition of Au(0)/Au(I), as this combination rapidly transforms into nonfluorescent large clusters on exposure to light. The FGC-based nanoprobes reported herein exhibit stable fluorescence upon continuous light exposure and can be used as imaging probes with low cytotoxicity.
authors.affiliation: Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032, India.
authors.forename: Sharbari
authors.initials: S
authors.lastname: Palmal
authors.forename: S K
authors.initials: SK
authors.lastname: Basiruddin
authors.forename: Amit Ranjan
authors.initials: AR
authors.lastname: Maity
authors.forename: Sekhar C
authors.initials: SC
authors.lastname: Ray
authors.forename: Nikhil R
authors.initials: NR
authors.lastname: Jana
mesh_terms: D005453:Fluorescence; D006046:Gold / Q000737:chemistry* / Q000493:pharmacokinetics; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D015335:Molecular Probes / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D015335:Molecular Probes; D013438:Sulfhydryl Compounds; D006046:Gold