Optical absorption of bimetallic nanoclusters complexed with nucleobases

Area of Science:

• Computational Chemistry
• Materials Science
• Biophysics

Background:

• DNA-nanoparticle interactions are key for biosensing and nanomedicine.
• Understanding the optical and structural properties of DNA-metal nanocluster complexes is crucial for their application.

Purpose of the Study:

• To investigate the structural and optical properties of DNA complexes with mono and bimetallic gold (Au) and silver (Ag) nanoclusters (NCs) using Time Dependent Density Functional Theory (TDDFT).
• To examine the electronic transitions and light absorption characteristics of these DNA:NC complexes.
• To determine the binding affinities of different nanocluster compositions with DNA bases.

Main Methods:

• Time Dependent Density Functional Theory (TDDFT) calculations were employed to model DNA:NC complexes.
• Structural and electronic properties were analyzed, focusing on electronic transitions and binding energies.
• Absorption spectra were computed for various Ag n Au m (n + m = 3) nanocluster compositions interacting with DNA.

Main Results:

• Silver-rich nanoclusters bind preferentially to DNA hydrogen bonds, while gold-rich nanoclusters favor cytosine.
• DNA:NC complexes exhibit distinct absorption spectra across the visible and ultraviolet ranges, influenced by nanocluster composition and DNA base pairing.
• Charge transfer from nanoclusters to DNA is a dominant process in the observed absorption transitions.

Conclusions:

• The study provides insights into the stability and optical behavior of DNA:metal nanocluster complexes.
• Findings are valuable for determining nanocluster stoichiometry, DNA base affinities, and the molecular properties of DNA:NC biomarkers.
• The computational approach aids in understanding fundamental interactions for designing novel nanomaterials for biological applications.