At the most fundamental level, membrane transport simply involves movement of a particle through a confining quasi-one-dimensional geometry. Yet biological systems employ a wide variety of different pores and channels that display highly efficient and exquisitely selectivity transport .
We exploit the ability to visualise, tune and directly manipulate colloidal suspensions to create ideal toy systems with which to understand the underlying mechanisms behind this selectivity . In particular we design microfluidic devices that act as confining channel structures and use microscopy to visualise the dynamics of colloidal particles in this environment. The complexity of the system can be rapidly increased by the addition of range of driving forces (pressure, electric and magnetically driven flows) and the use of holographic optical tweezers to impose controlled energy landscapes.
These experiments uniquely allow for full resolution of translocation dynamics in systems with controlled channel structure, controlled particle structure and controlled interactions. Combined with the possibility of acquiring large statistics through experimental automation this truly allows for unprecedented insight into the key factors governing molecular transport.
Alice L. Thorneywork, Jannes Gladrow, Yujia Qing, Marc Rico-Pasto, Felix Ritort, Hagan Bayley Anatoly B. Kolomeisky and Ulrich F. Keyser, ‘Direct detection of molecular intermediates from first passage times’, Sci. Adv., 6, 18, eaaz4642, (2020)