Searching for colored noise in enhanced diffusion

If claims that chemical reactions can behave as active matter are correct, it should follow that chemical reactions will agitate passive tracers that are suspended in a chemically-reacting solution. We have tested this logic using optical tweezers, trapping colloidal particles in the range 1-4 micrometer diameter, in a homebuilt setup allowing us to resolve fluctuations at frequencies up to 70 MHz. Earlier reports of crossover from ballistic to diffusive motion are confirmed. Focusing on the “click” chemical reaction consisting of copper-catalyzed alkyne-azide cycloaddition, CuAAC, we confirm enhanced fluctuations of the colloidal particle uniformly at all frequencies – which amounts to a shift in the frequency of crossover from ballistic to diffusive motion.