  Active transport of biomolecules assisted by motor proteins is imperative for
the proper functioning of cellular activities. Inspired by the diffusion of
active agents in crowded cellular channels, we computationally investigate the
transport of an active tracer through a polymer grafted cylindrical channel by
varying the activity of the tracer and stickiness of the tracer to the
polymers. Our results reveal that the passive tracer exhibits profound
subdiffusion with increasing stickiness by exploring deep into the grafted
polymeric zone, while purely repulsive one prefers to diffuse through the
pore-like space created along the cylindrical axis of the channel. In contrast,
the active tracer shows faster dynamics and intermediate superdiffusion even
though the tracer preferentially stays close to the dense polymeric region.
This observation is further supported by the sharp peaks in the density profile
of the probability of radial displacement of the tracer. We discover that the
activity plays an important role in deciding the pathway that the tracer takes
through the narrow channel. Interestingly, increasing the activity washes out
the effect of stickiness. Adding to this, van-Hove functions manifest that the
active tracer dynamics deviates from Gaussianity, and the degree of deviation
grows with the activity. Our work has direct implications on how effective
transportation and delivery of cargo can be achieved through a confined medium
where activity, interactions, and crowding are interplaying. Looking ahead,
these factors will be crucial for understanding the mechanism of artificial
self-powered machines navigating through the cellular channels and performing
in vivo challenging tasks.
