Diffusion in Nanostructures: Counter-intuitive analytical results and supporting experiments

From Q-bio

Experimentally, we study fluctuations in small, about hundred pA ionic currents through nanopores of biological origin to detect and analyze single molecules of different nature (e.g., Physical Review Letters, 2006, 97:018301). Theoretically, we explore the consequences of interactions between the pore and the translocating molecules within the framework of a continuum diffusion model for the particle dynamics in the channel (Journal of Chemical Physics, 2000, 113:8206-8211 and PRL, 2008, 100:038104 with the references therein). Several of our findings are quite counter-intuitive (Biophysical Journal, 2005, 88:L17-L19; PRL, 2006, 97:020601; JCP, 2007, 127:115101). Three of the examples to be discussed in the talk are: (i) “Sticking” to the channel slows down translocation (a particle spends more time in the channel) but increases the flux; (ii) “Uphill” and “downhill” particle translocation times (and their distributions) are identical; (iii) An optimal channel should exhibit the most pronounced binding on the side that is opposite to the side of the oncoming particles.