Ph.D and final year MS Research Projects

Viscoelasticity of single macromolecules
Single Macromolecules, including unfolded proteins bear rubber-like entropic elasticity and internal friction characterized by finite dissipation coefficient. Direct measurement of this viscoelastic response is important since it plays a significant role, both in polymer physics as well as protein folding dynamics. The viscoelastic response of single polymer chain is difficult to measure and it is prone to artefacts owing to the complications of hydrodynamics of macroscopic probe itself in the liquid environment. Using an interferometer based home-built Atomic Force Microscope we have conclusively shown that the dissipation coefficient of single macromolecule is immeasurably low for current detection limits of the Atomic Force Microscope. The previous reports of dissipation in single unfolded proteins were artefacts of incorrect modelling of dynamics of the probe used to measure the viscoelastic response of macromolecules. We have developed a new magnetic excitation method, which will be fitted onto our home-built AFM. Together, this will push the detection limit of the interferometer based AFM to directly probe dissipation in single macromolecules.

Biomechanics of Hydra somersault and evolution of animal movement
Animal movements on solid substrates involve common mechanical principles emerging from elasticity of tissues. We have unraveled the mechanics governing the somersault of Hydra, one of the earliest multi-cellular organisms to have evolved substratum movement. We measured the local mechanical properties and discovered a specific variation in Young’s modulus of tissues along the body column whose perturbation completely hinders the somersault. Our simulations have revealed that the observed variation in elasticity is optimal for efficient energy transfer, which enables an over-damped system such as Hydra to perform somersault. These results provide mechanistic basis for the evolutionary significance of differential Extra-Cellular-matrix properties and tissue stiffness.

Diffusion in structured electrolytes
The topic is of interest to Lithium Ion Batteries (LIB). The charging capacity and power density of an LIB depends on the diffusion of ions through the carbonate solvents. Little is understood about diffusion laws of ions moving through a structured electrolyte at high ion concentration. Using novel methods in our lab, we suspect that the electrolyte is a glass former with considerable dynamic heterogeneity.