Phosphorothioate DNA Stabilized Fluorescent Gold and Silver Nanoclusters

Area of Science:

• Nanomaterials Science
• Bioconjugate Chemistry
• Spectroscopy

Background:

• Single-stranded DNA is increasingly used for templating fluorescent noble metal nanoclusters (NCs).
• DNA sequence optimization has yielded bright, stable, and biocompatible NCs.
• The impact of DNA backbone modifications on NC synthesis remains unexplored.

Purpose of the Study:

• To investigate the utility of phosphorothioate (PS) DNA backbone modifications in synthesizing noble metal nanoclusters.
• To explore the templating capabilities of T15 DNA with PS modifications for novel fluorescent emitters.
• To elucidate the formation mechanism of PS-DNA templated nanoclusters, particularly at physiological pH.

Main Methods:

• Synthesis and characterization of gold (Au) and silver (Ag) nanoclusters using unmodified and phosphorothioate (PS) modified DNA templates.
• Evaluation of T15 DNA with PS modifications for templating novel fluorescent emitters at neutral pH.
• Mechanistic studies employing UV-dependent analysis to understand nanocluster formation pathways.

Main Results:

• Successfully synthesized novel fluorescent Au and Ag nanoclusters using PS-modified T15 DNA at neutral pH.
• Identified a distinct UV-dependent formation mechanism for PS-DNA templated nanoclusters, differing from previously known pathways.
• Optimized the positions of PS substitutions on the DNA backbone for enhanced nanocluster synthesis.

Conclusions:

• Phosphorothioate DNA backbone modifications are effective for templating fluorescent noble metal nanoclusters.
• This work presents the first reported use of a T15 DNA template at physiological pH for silver nanocluster (AgNC) synthesis.
• The findings open new avenues for designing advanced DNA-templated nanomaterials with tailored properties.