Looking at Ultrafast DNA Dynamics and Particle Diffusion in Solution using Fluorescence-based Time-Resolved and Correlation Spectroscopy

by Prof. Sobhan Sen (Jawaharlal Nehru University, New Delhi)

Tuesday, January 10, 2012 from 14:30 to 15:30 (Asia/Kolkata)
at Colaba Campus ( AG-80 )

TIFR, Colaba Mumbai 400005

Description

Fluorescence-based time-resolved and correlation spectroscopy are widely used to study ultrafast dynamics in complex biomolecules and diffusion of (single) particle in solution, respectively. However, the power of these techniques has not been tested to its best to unravel the intricate details of dynamics of complex molecular systems. In this talk, I will focus on how time-resolved fluorescence spectroscopy, combined with molecular dynamics simulation, can be used to understand the ultrafast DNA dynamics in femtoseconds to nanoseconds time-scale [1, 2]. The results will be discussed to show how the structure and dynamics of DNA are inter-related, and how water and ion motions in the vicinity of DNA affect the dynamics. In a separate section, I will discuss on how Fluorescence Correlation Spectroscopy (FCS) can be used to monitor particle diffusion, and thus, the size and size distribution of nanometer-sized supramolecular assemblies (viz. microemulsion droplets;MEDs) in dilute solution [3]. In particular, it will be shown how one can use FCS to measure accurate size-parameters of particles, bypassing the Optical Matching point problem in light scattering techniques (e.g., DLS and SLS) that are used often for particle-size measurements. It will be shown how FCS, as a technique, can become advantageous over light scattering techniques, in occasions, when one measures the size of particles in dilute solution [3]. (1) Pal, N.; Verma, S. D.; Sen, S. J. Am. Chem. Soc. 2010, 132, 9277.
(2) Sen, S.; Andreatta, D.; Ponomarev, S. Y.; Beveridge, D. L.; Berg, M.
A. J. Am. Chem. Soc.2009, 131, 1724.
(3) Pal, N.; Verma, S. D.; Singh, M. K.; Sen,
S. Anal. Chem. 2011, 83, 7736.