DNA-stabilized, fluorescent, metal nanoclusters for biosensor development

Abstract

In the past decade, fluorescent silver, gold and copper nanoclusters (Ag, Au and CuNCs) have emerged as a new class of signaling moiety for biosensor development. Compared to semiconductor quantum dots, metal NCs have less toxicity concerns and can be more easily conjugated to biopolymers. Due to their extremely small size, these NCs need a stabilizing ligand. Many polymers, proteins and nucleic acids have been reported to stabilize NCs. In particular, many DNA sequences produce highly fluorescence NCs. Coupling these DNA stabilizers with other sequences such as aptamers has generated a large number of biosensors. In this review, the synthesis of DNA and nucleotide-templated NCs is first summarized; their chemical interactions are also discussed. In the second part, the properties of NCs such as fluorescence quantum yield, emission wavelength and lifetime, structure and photostability are briefly reviewed. In the last part, various sensor design strategies using these NCs are categorized into the following four classes: 1) fluorescence de-quenching; 2) generation of templating DNA sequences to produce NCs; 3) change of nearby environment; and 4) reacting with heavy metal ions or other quenchers. Finally, the future trends in this field are discussed.

Research Update: Density functional theory investigation of the interactions of silver nanoclusters with guanine

“…[1][2][3] Small sized metal nanoclusters (with diameters up to around 2 nm) are considered to be brighter and more photostable fluorophores [4][5][6][7][8][9][10][11] compared to existing organic dyes as well as smaller and less toxic compared to quantum dots. 12 In particular, silver nanoclusters (AgNCs) are of interest, and these systems involve stabilizing ligands to prevent them from oxidation and aggregation.…”

“…[19][20][21][22] Therefore, DNA-AgNCs have been identified as potential candidates to be utilized in various applications such as bioimaging, biolabeling, catalytic reactions, and analyte and ligand sensing. [4][5][6][7]14,[23][24][25][26] The emission tunability can also be altered through experimental conditions, 19,20,27,28 but changing the DNA template itself is considered superior due to the higher functionality in the DNA-AgNCs through emission tuning. 13 Various research groups have conducted extensive experimental investigations on DNA-AgNCs.…”

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

“…[1][2][3][4][5][6][7][8] At the same time, they are important for fundamental nanoscience. 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.…”

Fluorescent Gold Nanoclusters: Promising Fluorescent Probes for Sensors and Bioimaging

“…They reasoned that the great catalytic performance resulted from the low-coordinate Au atoms on the exterior shell of AuNCs which could provide a favorable environment for the adsorption and activation of certain reactants [27]. 6 nanoclusters were capable of catalyzing CO oxidation reaction [28].…”

“…Today, highly fluorescent AuNCs can be fabricated with atomically precise sizes and tunable optical properties. For biomedical applications, AuNCs have been synthesized by using biocompatible capping ligands, including DNA [6], glutathione (GSH) [7], bovine serum albumin (BSA) [8], and other proteins [9]. Such novel properties make fluorescent AuNCs an ideal nanomaterial for promising applications in biosensing [10], imaging [11], and catalysis [12].…”