Title: Topological Freezing of Macromolecular Diffusion

Speaker: Prof. M. Muthukumar, University of Massachusetts, Amherst

Abstract: Diffusion of macromolecules in solutions at non-zero temperatures is of common occurrence, in accordance with the Einstein law of diffusion. The magnitude of the non-zero diffusion coefficient depends on the characteristics of the system such as the size and concentration of the macromolecules, and the extent of environmental confinements. As a drastic departure from the law of diffusion, we have recently discovered [1-4] a non-diffusive Topologically Frustrated Dynamical State (TFDS), at intermediate concentrations and confinements. We attribute the origin of TFDS to extreme metastability arising from cooperative action of multiple deep entropic traps on a single confined macromolecule. We will discuss the magnitude of the extreme metastability in terms of its effective entropic barrier preventing its diffusion, escape from TFDS into diffusion, and implications of the TFDS.

1. D. Jia and M. Muthukumar, Nature Communications, 9, 2248 (2018).

2. D. Jia and M. Muthukumar, Phys. Rev. Lett. 126, 057802 (2021).

3. K. Chen and M. Muthukumar, Proc. Natl. Acad. Sci. (USA), 118, e2106380118 (2021).

4. K. Chen, S-F. Li, and M. Muthukumar, ACS Macro Lett. 11, 699 (2022).