Hopping and crawling DNA-coated colloids.

Area of Science:

• Colloid and Surface Science
• Biomaterials Engineering
• Nanotechnology

Background:

• Understanding particle motion, particularly DNA-coated colloids, is crucial for biomedical applications and material design.
• Existing studies show seemingly similar particles exhibit different motilities (hopping or rolling), creating ambiguity.

Purpose of the Study:

• To investigate the distinct motion modes of DNA-coated colloids near complementary surfaces.
• To elucidate the factors influencing the switch between hopping and crawling behaviors.

Main Methods:

• Observation of DNA-coated colloids diffusing near surfaces with varying complementary strand densities.
• Analysis of particle trajectories across different temperatures around the melting point.

Main Results:

• Colloids exhibit rapid switching between two distinct modes: hopping (long, fast steps) and crawling (short, slow steps).
• Both modes are observed across various temperatures and coating designs.
• Particle subdiffusion increases with decreasing temperature, correlating with velocity step anticorrelation and trajectory switchbacks.
• Crawling is more predominant and efficient at lower temperatures, while hopping is favored at higher temperatures.

Conclusions:

• The observed motion modes are rationalized by a model where increased strand binding at lower temperatures prevents detachment, favoring crawling.
• Dense surface strands are essential for enabling crawling, a mechanism potentially facilitating long-range self-assembly and particle rearrangement.