Luminescent quantum clusters of gold in bulk by albumin-induced core etching of nanoparticles: metal ion sensing, metal-enhanced luminescence, and biolabeling.
The synthesis of a luminescent quantum cluster (QC) of gold with a quantum yield of approximately 4 % is reported. It was synthesized in gram quantities by the core etching of mercaptosuccinic acid protected gold nanoparticles by bovine serum albumin (BSA), abbreviated as Au(QC)@BSA. The cluster was characterized and a core of Au(38) was assigned tentatively from mass spectrometric analysis. Luminescence of the QC is exploited as a "turn-off" sensor for Cu(2+) ions and a "turn-on" sensor for glutathione detection. Metal-enhanced luminescence (MEL) of this QC in the presence of silver nanoparticles is demonstrated and a ninefold maximum enhancement is seen. This is the first report of the observation of MEL from QCs. Folic acid conjugated Au(QC)@BSA was found to be internalized to a significant extent by oral carcinoma KB cells through folic acid mediated endocytosis. The inherent luminescence of the internalized Au(QC)@BSA was used in cell imaging.
Habeeb Muhammed
Madathumpady Abubaker
MA
DST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai 600 036, India.
Verma
Pramod Kumar
PK
Pal
Samir Kumar
SK
Retnakumari
Archana
A
Koyakutty
Manzoor
M
Nair
Shantikumar
S
Pradeep
Thalappil
T
D000818:Animals; D002412:Cations / Q000737:chemistry; D002417:Cattle; D006046:Gold / Q000737:chemistry*; D006801:Humans; D049449:Luminescence; D053768:Metal Nanoparticles / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*
D002412:Cations; D012710:Serum Albumin, Bovine; D006046:Gold