Department of
Physics

Shivprasad Patil obtained his PhD in University of Pune (year 2003). His carried out postdoctoral research at the Wayne State University, USA (2003-2005) and at IMM-CSIC in Madrid, Spain (2005-2008) before joining as a faculty member at IISER Pune.

Research

Nanomechanics of soft and living matter, Diffusion measurements in structured liquids

Diffusion under nanoconfinement

Prior to 2014, Dr. Shivprasad Patil's group showed intriguing flow properties of water confined between solid walls, which are separated by less than 5 nm. They observed that pure nanoconfined water exhibits rheological properties such as shear thinning and viscoelasticity. To understand physical processes responsible for this phenomenon, the group decided to probe diffusion of tracer dye molecules in the confinement below 5 nm. It required development of a novel instrument as well as data analysis methods. Over last five years, they have been successful in this endeavour and have reported this development in a recent Review of Scientific Instruments publication. They have interesting new result using the instrument, which indicates that there is coexistence of two phases in confined liquids and it is responsible for different time-scales for a diffusing tracer molecules.

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, the group has 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. They 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. The group has unraveled the mechanics governing the somersault of Hydra, one of the earliest multi-cellular organisms to have evolved substratum movement. They 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. Simulations 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 the lab, they suspect that the electrolyte is a glass former with considerable dynamic heterogeneity.

Selected Publications

Ahlawat V., Rajput S.S., and Patil S. (2021) Elasticity of single flexible polymer chains in   good and poor solvents. Polymer. 630:124031.

Rajput S.S., Deopa S.P.S., Ajith V.J. kamerkar S.C. and Patil S. (2021) Validity of point-   mass model in off-resonance dynamic atomic force microscopy. Nanotechnology. 32:405702.

Rajput S.S., Deopa S.P.S., Yadav J., Ahlawat V., Talele S. and Patil S. (2021) The nano-scale viscoelasticity using atomic force microscopy in liquid environment. Nanotechnology. 32:085103.

Joseph E., Rajput S.S., Patil S., and Nisal A. (2021) Mechanism of Adhesion of Natural Polymer Coatings to Chemically Modified Siloxane Polymer. Langmuir. 37 :2974–2984.

Naik S., Unni M., Sinha D.,  Rajput S.S., Reddy P.C., Kartvelishvily E., Solomonov I., Sagi I., Apratim Chatterji A.,  Patil S. and Galande S. (2020) Differential tissue stiffness of body column facilitates locomotion of Hydra on solid substrates. J Exp Biol 223 : jeb232702.