Interrupted DNA and Slow Silver Cluster Luminescence.

Area of Science:

• Nanomaterials Science
• Biophysical Chemistry
• DNA Nanotechnology

Background:

• DNA-silver cluster conjugates act as hierarchical chromophores.
• The DNA backbone and nucleobases influence silver cluster properties.
• Specific DNA sequences can spectrally tune silver clusters.

Purpose of the Study:

• To investigate how DNA backbone integrity affects silver cluster luminescence.
• To explore the role of thymine as a placeholder in DNA-silver conjugates.
• To compare the luminescence properties of contiguous vs. broken DNA scaffolds.

Main Methods:

• Synthesis of DNA-silver cluster conjugates with interrupted sequences.
• Spectroscopic analysis of luminescence properties (prompt and sustained).
• Oxygen quenching studies to assess luminescence stability.

Main Results:

• The (C2A)2-T-(C2A)4 sequence forms Ag10 6+ with dual green and red luminescence.
• Removing thymine results in two separate fragments, (C2A)2 and (C2A)4, also forming Ag10 6+.
• The broken scaffold exhibits weaker red luminescence, faster relaxation, and quicker O2 quenching compared to the contiguous sequence.

Conclusions:

• A break in the DNA phosphodiester backbone can regulate scaffold conformation.
• Scaffold wrapping and protection of the silver cluster adduct are influenced by backbone integrity.
• These findings offer insights into controlling the optical properties of DNA-silver nanostructures.