Synthesis of DNA-templated fluorescent gold nanoclusters

Guiying Liu,Shujuan Xu,Yong Shao,Kun Ma,Fei Wu,Qinghua Cui

doi:10.1007/s13404-012-0049-6

Abstract

Water-soluble and red-emitting gold nanoclusters (Au NCs) were synthesized with single-stranded DNA as a promising biotemplate and dimethylamine borane as a mild reductant. The fluorescent Au NCs can be formed in a weakly acidic aqueous solution that is free from the simultaneous formation of large nanoparticles. The cluster feature of the formed Au species has been revealed by fluorescence spectra, absorption spectra, and transmission electron microscopy. Additionally, DNA sequences could be used to tune the Au NCs' emissions. The as-prepared Au NCs display high stability at physiological pH condition, and thus, wide potential applications are anticipated for the biocompatible fluorescent Au NCs serving as nanoprobes in bioimaging and related fields.

Highlights

Decreasing the size of noble metal nanostructures down to less than 2 nm will produce nanoclusters (NCs) and restrict the motion of their free electrons in a very confined space that results in discrete electronic band structures
Fluorescent Au NCs have been widely synthesized in a bottom–up manner by reduction of gold precursors that are associated with various biotemplates [10] such as bovine serum albumin [11], horseradish peroxidase [18], lysozyme [12], and transferrin protein [20]
Synthesis of Au NCs templated by DNA has rarely been reported maybe because of the weak association between the negatively charged DNA and commonly used precursor AuCl4−

Summary

Introduction

Decreasing the size of noble metal nanostructures (mainly Au and Ag) down to less than 2 nm will produce nanoclusters (NCs) and restrict the motion of their free electrons in a very confined space that results in discrete electronic band structures. The freshly prepared dimethylamine borane (DMAB, Sigma Chemical Co., St. Louis, USA) solution was added to the aged HAuCl4/DNA solution, which was followed by another 36-h reaction at room temperature in the dark to produce fluorescent Au NCs. The resulting solutions were examined at room temperature (22±1 °C).

Results

Conclusion