Gold Nanoparticles Size Dependence on DNA Damage under X-rays.

Area of Science:

• Nanomedicine
• Radiotherapy
• DNA Damage Mechanisms

Background:

• Gold nanoparticles (AuNPs) combined with X-rays show promise for radiotherapy.
• Nanoparticle size affects cancer tissue penetration and radiosensitization.

Purpose of the Study:

• To investigate the impact of gold nanoparticle size on DNA damage formation after X-ray exposure.
• To elucidate the mechanisms of AuNP-mediated radiosensitization.

Main Methods:

• Exposure of dried gold nanoparticle-oligonucleotide-DNA mixtures to 10-100 keV X-rays.
• Quantification of DNA damage types and yields using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

Main Results:

• Nucleobase release was the predominant DNA damage type (82%).
• Electron-specific damage, including dideoxynucleosides, was observed.
• Smaller AuNPs (5 nm) resulted in 7-10 fold greater DNA damage compared to larger AuNPs (110 nm).
• AuNP presence shifted radiation damage towards electron-mediated pathways.

Conclusions:

• Nanoparticle size critically influences the yield and type of radiation-induced DNA damage.
• Smaller AuNPs enhance radiosensitization more effectively due to emitted electron energy and range.
• Findings support the design of optimized AuNP sizes for improved radiotherapy efficacy.