Title
Novel blue-emitting gold nanoclusters confined in human hemoglobin, and their use as fluorescent probes for copper(II) and histidine
Author
Mojtaba Shamsipur, Fatemeh Molaabasi, Maryam Shanehsaz, Ali Akbar Moosavi-Movahedi
Year
2015
Journal
Microchim Acta
Abstract
We report on the synthesis and characterization of highly fluorescent gold nanoclusters (Au-NCs) from a gold precursor using a single-step chemical reduction in the presence of human adult hemoglobin (Hb). The conformational changes of Hb before and after cluster formation were studied by various spectroscopic techniques. The Au-NCs in Hb display blue fluorescence with a peak centered at 450 nm (photoexcited at 365 nm) and a quantum yield of 2.8 %. The Au-NCs exhibit excellent photostability and long-term stability, and can be applied in the pH range 5–12 even in the presence of high electrolyte concentrations. The Au-NCs in Hb can act as a highly sensitive and selective fluorescent turnoff probe for Cu(II) ion. The observed reversible fluorescence recovery of Hb-AuNCs/Cu(II) aggregates was exploited to develop a selective and sensitive turn-on fluorescence assay for His. Under optimized conditions, the probe gives a fluorescent response that is linear in the 0.1 to 20.0 μM concentration range of Cu(II), with a limit of detection of 28 nM. The probe for His, in turn, has a linear range in the 1–21 μM concentration range, and the limit of detection is 0.6 μM.
Instrument
J-715
Keywords
Circular dichroism, Secondary structure, Protein folding, Nanostructures, Ligand binding, Biochemistry, Materials