Accelerating and breaking adaptive nano-colloids (via push-pull effects

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Conventional colloids exhibit random Brownian motion.
• Active colloids utilize nanomotors for directed movement, but deceleration is challenging.
• Controlling microscale swimmers is established, but nanoscale control requires overcoming rotational diffusion.

Purpose of the Study:

• To investigate the active control of nanoscaled colloids (<100 nm).
• To develop nanoparticles with independent chemical and physical propulsion mechanisms.
• To demonstrate controlled deceleration of active nanoparticles.

Main Methods:

• Fabrication of organosilica nanoparticles with a Janus-type chemical engine.
• Incorporation of a superparamagnetic core for physical locomotion.
• Independent and combined activation of chemical and magnetic propulsion.
• Application of tunable magnetic fields for propulsion control and deceleration.

Main Results:

• Nanoscaled colloids demonstrated directed and anisotropic movement via chemical and magnetic triggers.
• Tuning magnetic forces influenced chemical acceleration angles.
• Parallel magnetic field alignment resulted in superposition and a boost state.
• Antiparallel magnetic field orientation induced rapid deceleration, halting particle motion.

Conclusions:

• Nanoscaled colloids can be actively controlled, addressing challenges posed by rotational diffusion.
• Dual propulsion systems enable both acceleration and precise deceleration.
• This research offers a pathway for advanced nanoscale active matter manipulation.