Aptamer-tagged green- and yellow-emitting fluorescent silver nanoclusters for specific tumor cell imaging

Aptamer-functionalized fluorescent silver nanoclusters (Ag NCs) possessing specific recognition ability of aptamer and fluorescence emissions have been developed for applications in biorelated areas. However, only one color emission hampered their further use in multiplexed analysis. To address this issue, AS1411 aptamer-tagged Ag NCs with green color emissions and MUC 1 aptamer-tagged Ag NCs with yellow color emissions were synthesized by one-pot approach in this work. With the rational design of the DNA template and optimization of the synthetic buffer, as well as the NaBH4-to-Ag+ ratio, the growth time and purity of the obtained aptamer-functionalized Ag NCs were improved. Under the optimal conditions, the quantum yields of AS1411 aptamer-functionalized green Ag NCs and MUC 1 aptamer-functionalized yellow Ag NCs were 20.33% and 8.65% with 9,10-diphenyl anthracene and fluorescein as the reference standards, respectively. The green and yellow emission properties of Ag NCs were related to the surface oxidation states of the Ag NCs. Furthermore, the binding ability of AS1411 aptamer and MUC 1 aptamer to cancer cells enabled specific cellular imaging. Aptamer-functionalized Ag NCs with multicolor emissions could broaden the applications of Ag NCs in multiplexed analysis and multicolor imaging of tumor cells, especially with the selection of more targeted aptamers.