Cytidine-Directed Rapid Synthesis of Water-Soluble and Highly Yellow Fluorescent Bimetallic AuAg Nanoclusters

Abstract

Fluorescent gold/silver nanoclusters templated by DNA or oligonucleotides have been widely reported since DNA or oligonucleotides could be designed to position a few metal ions at close proximity prior to their reduction, but nucleoside-templated synthesis is more challenging. In this work, a novel type of strategy taking cytidine (C) as template to rapid synthesis of fluorescent, water-soluble gold and silver nanoclusters (C-AuAg NCs) has been developed. The as-prepared C-AuAg NCs have been characterized by UV-vis absorption spectroscopy, fluorescence, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and inductively coupled plasma mass spectroscopy (ICP-MS). The characterizations demonstrate that C-AuAg NCs with a diameter of 1.50 ± 0.31 nm, a quantum yield ∼9%, and an average lifetime ∼6.07 μs possess prominent fluorescence properties, good dispersibility, and easy water solubility, indicating the promising application in bioanalysis and biomedical diagnosis. Furthermore, this strategy by rapid producing of highly fluorescent nanoclusters could be explored for the possible recognition of some disease-related changes in blood serum. This raises the possibility of their promising application in bioanalysis and biomedical diagnosis.

Cytidine-stabilized gold nanocluster as a fluorescence turn-on and turn-off probe for dual functional detection of Ag+ and Hg2+

“…The as-prepared cytidine-stabilized Au nanoclusters were clear, and emitted a weak green fluorescence under a UV lamp (365 nm), which was consistent with the reported literature [51,52]. Fig.…”

DNA-templated fluorescent gold nanoclusters reduced by Good’s buffer: from blue-emitting seeds to red and near infrared emitters

“…24,25 At pH 6, poly-C DNA produced relatively weak fluorescence. The pKa of cytosine is 4.2 and therefore protonation of C is favorable for making fluorescent AuNCs.…”

“…Nanoclusters are typically synthesized by reducing noble metal salts in the presence of a stabilizing agent, such as synthetic polymers, 9,10 proteins, 11 nucleic acids, [12][13][14][15][16][17] or small molecule ligands. [18][19][20][21][22][23][24][25] Amongst these stabilizers, DNA is very attractive due to its excellent programmability, stability and cost-effectiveness. [26][27][28][29][30] Taking advantage of the strong binding interaction between cytosine and Ag + , a wide range of emission colors are obtained by using various cytosine-rich DNA sequences, [12][13][14][15][16][17]31,32 where NaBH4 has been the exclusively used reducing agent.…”

Cytidine Mediated AuAg Nanoclusters as Bright Fluorescent Probe for Tumor Imaging in vivo

“…[24,25] Considering the multiple roles played by glutathione (GSH) in cell survival and metabolic functions, [16] combined with the cytidine as the protectant, in this study we have explored a convenient and efficient synthetic method of fluorescent NCs, the cytidine mediated gold-silver nanoclusters (AuAg NCs). [26] As shown in Figure 1, the facile synthesis of Au NCs could be readily realized and utilized to obtain well dispersible AuAg nanoclusters. It is noted from our studies that after mixing a certain concentration of cytidine and HAuCl 4 , one step hydrothermal reaction assisted the synthesis of Au nanoclusters, where GSH acted as a reductant agent.…”