Synthesis and Surface Functionalization of Water-soluble Quantum Dots
Sonia Bailon-Ruiz, Luis Alamo-Nole and Oscar Perales-Perez
Affiliation: Department of Chemistry, University of Puerto Rico, PO Box 9019, Mayaguez, PR 00681-9019, USA.
Quantum Dots (QDs) for bio-imaging applications need to be water-stable, exhibit high brightness and physico-chemical stability
in order to prevent the leakage of toxic ions. In the present work, the direct synthesis of water-soluble CdSe quantum dots and their
surface functionalization were achieved through a micro-wave assisted approach in aqueous phase. Glutathione, an essential tri-peptide,
was used to functionalize the QDs as an attempt to develop a non-toxic and biocompatible surface. X-ray diffraction analyses suggested
that as-synthesized QDs exhibited an alloy arrangement with an average crystallite size of 3.2 nm. HRTEM measurements suggested a
size of around 4 nm for glutathione-functionalized QDs. Stable aqueous suspensions of QDs showed strong visible emission (551nm and
561 nm for bare and glutathione-functionalized QDs) under 460nm excitation. The presence of glutathione in the QDs’s surface was confirmed
by FT-IR and NRM spectroscopy measurements. Surface characterization of QDs by using FT-IR indicated that glutathione was
chemisorbed onto the surface of the CdSe QDs as carboxylate (vas COO at 1630 cm-1 and vs COO at 1390 cm-1). These water-stable glutathione-
functionalized QDs can be considered a very promising nanomaterial for bio-labeling and imaging.
Keywords: FT-IR, functionalization, glutathione, nanoparticles, NMR, quantum dots
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