A DNA−Silver Nanocluster Probe That Fluoresces upon Hybridization

Abstract

DNA-templated silver nanoclusters (DNA/Ag NCs) are an emerging set of fluorophores that are smaller than semiconductor quantum dots and can have better photostability and brightness than commonly used organic dyes. Here we find the red fluorescence of DNA/Ag NCs can be enhanced 500-fold when placed in proximity to guanine-rich DNA sequences. On the basis of this new phenomenon, we have designed a DNA detection probe (NanoCluster Beacon, NCB) that "lights up" upon target binding. Since NCBs do not rely on Forster energy transfer for quenching, they can easily reach high (>100) signal-to-background ratios (S/B ratios) upon target binding. Here, in a separation-free assay, we demonstrate NCB detection of an influenza target with a S/B ratio of 175, a factor of 5 better than a conventional molecular beacon probe. Since the observed fluorescence enhancement is caused by intrinsic nucleobases, our detection technique is simple, inexpensive, and compatible with commercial DNA synthesizers.

Highly luminescent silver nanoclusters with tunable emissions: cyclic reduction–decomposition synthesis and antimicrobial properties

“…2,8,9,14,15 Recent studies have shown that luminescent Au and Ag NCs are promising optical probes for bioimaging and biosensing applications. 4,[16][17][18][19][20] This finding has led to the development of various methods for the synthesis of highly luminescent Au and Ag NCs. 2, 21 On the other hand, insofar as nanostructured Ag-based materials are concerned, they are finding an increasing usage for antimicrobial applications owing to the unique chemistry of Ag interfacing with microorganisms.…”

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

“…[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.…”

Correlation of photobleaching, oxidation and metal induced fluorescence quenching of DNA-templated silver nanoclusters

“…[19][20][21][22][23] On the practical side, by rational incorporation of DNA aptamers, the fluorescence signaling of AgNCs has been successfully coupled with the molecular recognition property of DNA to design biosensors and smart imaging probes. [24][25][26][27][28][29][30][31][32][33][34][35][36] An interesting and useful discovery is that the fluorescence of many NCs is strongly quenched by Hg 2+ , allowing its detection at low nM and even sub-nM concentrations. 20,[37][38][39][40][41][42] Despite its importance in analytical chemistry, our fundamental understanding of NCs is still quite limited.…”