Speaker: Dr. Aarat P. Kalra
IIT Delhi

Title: All Wired Up: Harnessing Protein Polymers for Medicine and Nanotechnology

Abstract: The successful interfacing of biochemistry with electronics is one of the grand challenges of nanotechnology. Biodegradable and biocompatible materials with structural integrity, that can perform mixed electronic and ionic roles are required for the development of the next generation of nanodevices. The interface of electronics and biochemistry is also crucial for medicine, with electric and magnetic field-based therapies being used for cancer treatment and wound healing.

Inside the eukaryotic cell, protein polymers such as microtubules and actin filaments play structural roles such as maintaining cell shape and orchestrating cell division. Short intermolecular distances between aromatic amino acids, the presence of a highly negative surface charge, and the structural regularity of the ordered protein ‘lattice’ allow the emergence of interesting properties in both protein polymers. Thus, microtubules and actin filaments are interesting candidates for use in biodegradable nanodevices, while also acting as the potential intracellular targets of electric field-based therapies.

The talk will focus on experiments revealing the nontrivial photophysical and electrostatic properties of microtubules. Our experiments reveal that energy can migrate by diffusive energy transfer over unexpectedly large distances (6.6 nm) in microtubules. We find that conventional Förster theory predicts a diffusion length of only ~2.3 nm; insufficient to explain our observations. Introducing the anesthetics etomidate and isoflurane decreases the observed energy diffusion length. We find significantly higher diffusion lengths when other mechanisms of energy transfer are considered. Collectively, our work shows that it is worth considering protein polymers for ultraviolet light-harvesting systems. Microtubules and actin filaments also have highly negatively charged surfaces, allowing them to store and possibly conduct ions. Our experiments on microtubules in solution show that they lowered their local pH value by as much as one unit on the pH scale and that they increased solution capacitance. This behavior indicates the potential of microtubules as charge storage devices both inside the cell and outside it, within protein-based electronic devices.

About the Speaker: Dr. Aarat Kalra is an Assistant Professor at the Centre for Biomedical Engineering at the Indian Institute of Technology, Delhi, and at the Department of Biomedical Engineering at the All India Institute of Medical Sciences, New Delhi.

He completed his Bachelor of Science (B.Sc. (Hons.) with distinction from Dayal Bagh Educational Institute (Agra, India) in chemistry, a Master of Science (M.Sc.) from McGill University in biology, and a Doctor of Philosophy (Ph.D.) with Prof. Jack Tuszynski at the University of Alberta in physics. Thereafter, he worked as a postdoctoral researcher at Princeton University with Prof. Gregory Scholes, publishing transformative work on microtubule electronics.

During his doctoral work, he was awarded the prestigious Alberta Innovates Graduate Student Scholarship and the micro-nano technology (MNT) Award (two times) over the course of his Ph.D. His work has shown that microtubules are unexpectedly effective light harvesters, changing their photophysical properties upon small-molecule binding. This work has been published by ACS Central Science, on the front cover of the March 2023 issue. He was invited to present a talk at Google in 2022, as part of a conference titled ‘Is Our Brain a Quantum Computer?’ At IIT Delhi, Dr. Kalra is a recipient of the Young Faculty Incentive Fellowship (YFIF).

Dr. Kalra’s work on microtubules has opened several new research directions and has been featured twice in the scientific magazine The New Scientist and recently in the Indian daily Hindustan Times.