Colloidal diffusion over complex potential landscapes: From periodic, quasi-periodic and random potentials to live cell membranes

Penger Tong^1*

¹Department of Physics, Hong Kong University of Science and Technology, Hong Kong, Hong Kong

* Presenter:Penger Tong, email:penger@ust.hk

Energy landscape is an important concept in science, which has been widely used in many areas of physics, chemistry, biology and materials science. Applications of the energy landscape concept can be found in the calculation and measurement of the chemical reaction rate, lifetime of single molecular bonds, folding kinetics of proteins, and phase diagram of complex materials. Our general understanding of this type of problem is through the well-known Arrhenius-Kramers equation, which was obtained under an idealized condition for a single energy barrier. For many practical applications, however, one often encounters complex energy landscapes. There are few experimental systems in which one can actually visualize the energy landscape, and thus much of the work done so far is through computer simulations. A physical model system in which one can directly measure the energy landscape and track individual particle trajectories would be extremely valuable in testing different theoretical ideas. In this talk we will present our recent efforts in developing a two-layer colloidal system to study colloidal transport and dynamics over complex potential landscapes [1-4]. This work opens up a whole new realm of investigation at the single-particle level for a range of interesting problems associated with the diffusive and forced barrier-crossing dynamics over complex energy landscapes. Examples of applications of this system will be discussed.

[1] “Colloidal transport and diffusion over a tilted periodic potential: dynamics of individual particles,” X.-G. Ma, P.-Y. Lai, B. J. Ackerson, and P. Tong, Soft Matter, 11, 1182 (2015).
[2] “Colloidal diffusion over a quasicrystalline-patterned surface,” Y. Su, P.-Y. Lai, B. J. Ackerson, X. Cao, Y.-L. Han, and P. Tong, J. Chem. Phys. 146, 214903 (2017).
[3] “Colloidal diffusion over a quenched two-dimensional random potential,” Y. Su, X.-G. Ma, P.-Y. Lai and P. Tong, Soft Matter 13, 4773 (2017).
[4] “Dynamic heterogeneity and non-Gaussian statistics for acetylcholine receptors on live cell membrane,” W. He, H. Song, Y. Su, L. Geng, B. J. Ackerson, H. B. Peng, and P. Tong, Nature Communications, 7:11701 (2016).

This work is done in collaboration with Yun Su, Xiao-guang Ma, Wei He, Bruce J. Ackerson, and Pik-Yin Lai and was supported by the Research Grants Council of Hong Kong SAR.

Keywords: soft matter, biophysics