Nucleic Acids Research Advance Access published online on May 8, 2007
Nucleic Acids Research, doi:10.1093/nar/gkm237
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Chemistry |
Enhanced oligonucleotide–nanoparticle conjugate stability using thioctic acid modified oligonucleotides
Centre for Molecular Nanometrology, WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral St., Glasgow, Scotland, G1 1XL, UK
*To whom correspondence should be addressed. Tel: 0141 548 4701; Fax: 00 44 141 552 0876; Email: duncan.graham{at}strath.ac.uk
Received March 9, 2007. Revised March 29, 2007. Accepted March 30, 2007.
Metallic nanoparticles of gold functionalized with oligonucleotides conventionally use a terminal thiol modification and have been used in a wide range of applications. Although readily available, the oligonucleotide–nanoparticle conjugates prepared in this way suffer from a lack of stability when exposed to a variety of small molecules or elevated temperatures. If silver is used in place of gold then this lack of stability is even more pronounced. In this study we report the synthesis of highly stabilized oligonucleotide–nanoparticle conjugates using a simple oligonucleotide modification. A modified solid support was used to generate 3'-thioctic acid modified oligonucleotides by treatment with an N-hydroxysuccimidyl ester of thioctic acid. Unusually, both gold and silver nanoparticles have been investigated in this study and show that these disulphide-modified oligonucleotide probes offer significant improvements in nanoparticle stability when treated with dithiothreitol (DTT) compared with monothiol analogues. This is a significant advance in oligonucleotide–nanoparticle conjugate stability and for the first time allows silver nanoparticles to be prepared that are more stable than standard gold-thiol functionalized nanoparticles. This opens up the possibility of using silver nanoparticles functionalized with oligonucleotides as an alternative to gold.