Smaller Gold Nanoparticles Release DNA More Efficiently During fs Laser Pulsed Optical Heating
David A Hastman1, Eunkeu Oh2, Joseph S Melinger3
1Center for Bio/Molecular Science and Engineering, U.S. Naval Research Laboratory Code 6900, Washington, DC, 20375, USA.
Small (Weinheim an Der Bergstrasse, Germany)
|September 26, 2023
Summary
Smaller gold nanoparticles (AuNPs) unexpectedly accelerate DNA release under laser irradiation. This suggests direct energy transfer, not just heat, is key to DNA denaturation, challenging previous theories.
Area of Science:
- Nanotechnology
- Biophysics
- Materials Science
Background:
- Plasmonic gold nanoparticles (AuNPs) are utilized for laser-induced thermal applications.
- Understanding nanoparticle size effects is crucial for optimizing these applications.
- Oligonucleotide thermal release is a key process in various biotechnologies.
Purpose of the Study:
- To investigate the impact of gold nanoparticle size on oligonucleotide thermal release rates.
- To determine the primary mechanism driving DNA denaturation under femtosecond laser irradiation.
- To reconcile experimental findings with theoretical predictions regarding AuNP heating.
Main Methods:
- Femtosecond (fs)-pulsed laser irradiation of single-stranded oligonucleotides.
- Utilizing varying sizes of plasmonic gold nanoparticles (AuNPs) as heat sources.
- Controlled experiments varying pulse energy fluence, AuNP concentration, DNA loading density, and distance from AuNP surface.
Main Results:
- Smaller AuNPs (25 nm) demonstrated faster double-stranded DNA (dsDNA) denaturation rates compared to larger AuNPs (50-60 nm).
- This finding persisted across controlled experimental conditions.
- Results contradicted theoretical predictions that larger AuNPs would yield greater solution heating and faster DNA release.
Conclusions:
- Solution temperature increase around AuNPs may not solely govern dsDNA denaturation under fs laser pulses.
- Direct energy transfer from AuNPs to DNA, via phonon-phonon coupling, likely plays a significant role.
- The efficiency of this direct energy transfer increases with decreasing AuNP size.
