The concept of a chemical temperature from optical tweezers experiments

It is fundamental to consider that the random forces giving rise to thermal fluctuations generate both diffusion and dissipation. Our optical tweezer experiments suggest that chemical reaction can also generate such random forces. We have measured the fluctuations of optically-trapped beads that are immersed in aqueous solutions within which the classical click CuAAC chemical reaction system (copper-catalyzed azide-alkyne cycloaddition) is performed. These micrometer-sized beads fluctuate less-and-less rapidly as the chemical reacts moves towards its equilibrium. From the perspective that active matter consists of individual agents that consume energy to move or exert mechanical forces, we conclude that chemical reactions can act as instances of active matter.