  Folding and unfolding of biopolymers are often manipulated in experiment by
tuning pH, temperature, single-molecule force or shear field. Here we carry out
Brownian dynamics simulations to explore the behavior of a single
self-attracting chain in the suspension of self-propelling particles (SPPs). As
the propelling force increases, globule-stretch (G-S) transition of the chain
happens due to the enhanced disturbance from SPPs. Two distinct mechanisms of
the transition in the limits of low and high rotational diffusion rates of SPPs
have been observed: shear effect at low rate and collision-induced melting at
high rate. The G-S and S-G (stretch-globule) curves form hysteresis loop at low
rate, while they merge at high rate. Besides, we find two competing effects
result in the non-monotonic dependence of the G-S transition on the SPP density
at low rate. Our results suggest an alternative approach to manipulating the
folding and unfolding of (bio)polymers by utilizing active agents.
