Fractal aggregation of DNA after thermal denaturation

DNA thermal denaturation was observed by atomic force microscopy (AFM) on the surface of newly cleaved mica. It was found that at temperatures higher than the melting point, denaturation of DNA molecules took place and globular particles with size distribution were formed, and these particles could aggregate together to form fractal structures, which followed the diffusion limited aggregation (DLA) model. At 100 °C, degradation of DNA took place and small particles of about 20 nm in size were formed, and they also aggregated in fractal structures with a lower dimension. Evaporating speed of water affects the fractal dimension.