Enhanced oligonucleotide-nanoparticle conjugate stability using thioctic acid modified oligonucleotides

Area of Science:

• Nanotechnology
• Bioconjugation Chemistry
• Oligonucleotide Synthesis

Background:

• Conventional gold nanoparticle-oligonucleotide conjugates utilize terminal thiol modifications, limiting their stability against small molecules and heat.
• This instability is more pronounced in silver nanoparticles, restricting their broader application.
• Existing methods lack robustness for demanding applications requiring enhanced conjugate integrity.

Purpose of the Study:

• To synthesize highly stabilized oligonucleotide-nanoparticle conjugates using a novel oligonucleotide modification.
• To investigate the stability improvements offered by disulphide-modified oligonucleotide probes compared to traditional monothiol analogues.
• To enable the use of more stable silver nanoparticle-oligonucleotide conjugates as a viable alternative to gold.

Main Methods:

• Synthesis of 3'-thioctic acid modified oligonucleotides using a modified solid support and an N-hydroxysuccimidyl ester of thioctic acid.
• Preparation and characterization of both gold and silver nanoparticle-oligonucleotide conjugates.
• Assessment of conjugate stability, particularly in the presence of dithiothreitol (DTT), comparing modified probes with monothiol analogues.

Main Results:

• Disulphide-modified oligonucleotide probes demonstrate significantly improved nanoparticle stability compared to monothiol analogues when treated with DTT.
• This novel modification enhances the stability of both gold and silver nanoparticle conjugates.
• For the first time, silver nanoparticle-oligonucleotide conjugates are prepared with superior stability compared to standard gold-thiol functionalized nanoparticles.

Conclusions:

• The 3'-thioctic acid modification provides a simple yet effective strategy for creating highly stabilized oligonucleotide-nanoparticle conjugates.
• This advancement overcomes the inherent instability issues of conventional thiol-modified conjugates, particularly for silver nanoparticles.
• The enhanced stability opens new avenues for utilizing silver nanoparticles functionalized with oligonucleotides in diverse applications.