DNA coronas resist nuclease degradation

Area of Science:

• Biophysics
• Immunology
• Materials Science

Background:

• Cell-free DNA (cfDNA) interactions with particles are implicated in autoimmune diseases like systemic lupus erythematosus.
• Previous work demonstrated that DNA adsorbed onto synthetic particles enhances macrophage immunostimulatory responses, establishing a model for studying DNA-particle interactions in autoimmunity.

Purpose of the Study:

• To investigate the biophysical interactions between DNA of varying lengths and synthetic particles of different sizes.
• To determine how particle-associated DNA is protected from nuclease degradation, specifically DNase 1.
• To elucidate the role of particle size and DNA corona formation in DNA protection and particle aggregation.

Main Methods:

• Characterization of DNA-particle complexes using PicoGreen DNA assay, NanoDrop spectroscopy, dynamic light scattering (DLS), confocal fluorescence microscopy, and transmission electron microscopy.
• Assessment of DNA resistance to DNase 1 degradation in the presence of varying particle sizes and DNA types (double-stranded vs. single-stranded).

Main Results:

• Particle size significantly impacts the protection of adsorbed DNA from nuclease degradation; smaller particles (40, 200 nm) offered less protection compared to larger ones.
• Increased particle aggregation was observed with smaller particles, correlating with reduced DNA protection.
• A single-stranded DNA corona on smaller (200 nm) particles conferred significant protection against nuclease degradation, contrasting with double-stranded DNA on similar-sized particles.

Conclusions:

• The formation of a DNA corona on larger particles provides a protective effect against nuclease degradation.
• Particle aggregation, prevalent with smaller particles, does not confer protection.
• These findings offer a biophysical framework for understanding cfDNA-particle interactions in the context of autoimmune diseases and guide future research.