The Waterloo Institute for Nanotechnology (WIN) is pleased to present a seminar talk by Dr. Siddhartha Das, from the Department of Mechanical Engineering at the University of Maryland, College Park.
Water and Ions at Nanoscopic Interfaces
Water and ions are ubiquitous at several nanoscopic interfaces regulating events ranging from the use of nanoporous graphene for water filtration and functionalized nanochannels for current rectification to controlling the electro-physiological responses of plasma membranes for ion signaling and cell apoptosis.
This talk will focus on two very diverse problems of nanoscopic interfaces: nanostructured 2-D, van der Waals solid (e.g., graphene) and nanoscopically thick, electric-double-layer-supporting plasma membranes. The common theme connecting these two vastly different interfaces is the unavoidable significance of water and ions in attributing novel functionalities to these interfaces.
First, the talk will discuss how the presence of nanopillars attributes superhydrophobicity to graphene. Subsequently, the transport in holey grapheme unraveling the breakdown of Darcy’s Law and the generation of highly augmented wateraccessible graphene surface area will be discussed. Finally, this part of the talk will focus on transport of ion-rich drop through holey graphene and the possible corrections needed in the very basic framework to analyze the ion-capillary-wave interactions, which in turn would help to better explain ion-water-graphene interactions.
The second part of the talk will unravel new findings on electrostatics of plasma membranes. Firstly, the conditions that lead to the most improbable situation where the plasma membrane might acquire a positive zeta potential despite having a negative surface charge will be discussed. This will be followed by the discussions on how electrostatics controls (a) the critical receptor-ligand length for specific adhesion of nanoparticles to membranes and (b) the non-specific adhesion of nanoparticles to stiffer membranes.
Dr. Das is an Assistant Professor in the Department of Mechanical Engineering at the University of Maryland. He received his PhD in 2010 from the Indian Institute of Technology Kharagpur in the area of theoretical microfluidics. Following his PhD, Dr. Das joined the Physics of Fluids Group at the University of Twente, as a Postdoc. He worked on surface nanobubbles, capillarity and soft wetting. After his Postdoc in the Kingdom of the Netherlands, Dr. Das completed a Postdoc at the University of Alberta. He was awarded the Banting Postodoctoral Fellowship, one of the most prestigious postdoctoral fellowships in Canada.
Dr. Siddartha Das has authored more than 75 journal publications. His work has appeared in publications such as Advanced Materials, Proceedings of the National Academy of Sciences USA, Nature Communications and Journal of Chemical Physics.
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