Enzyme decorated microbubbles as self-propelling motors

In recent years, enzyme powered micro/nanomotors have emerged as ideal platforms for realizing various biological applications due to their multifunctionality and specificity in operation under complex conditions. However, most motors developed so far suffer from issues pertaining to their integration with biological systems due to retention of their synthetic components. With an aim to design a micromotor completely devoid of non-biological components, we present a proof-of-concept design of a microbubble (MB) motor made entirely from the protein bovine serum albumin. On decorating catalase on the bubble surface, these 'active' motors were found to undergo substrate concentration dependent enhanced diffusion, just like their synthetic counterparts. Interestingly, in presence of passive tracer particles, these MBs were able to transfer energy across a distance 100 times their body length and enhance the diffusions of the tracers as well. We performed Langevin dynamics simulations to find that the estimated average force generated per catalytic turnover on the motor surface is of the order of piconewtons.