07/06/2023
By Kwok Fan Chow

The Kennedy College of Science, Department of Chemistry, invites you to attend a Ph.D. Dissertation defense by Subrata Chandra entitled “Physicochemical Investigation and Electrical Measurement of Biomolecular Interactions at the Single-Molecule Level."

Location: Olney, Room 518
Date: Tuesday, July 18, 2023
Time: 12:30 p.m.

Committee Chair:
Prof. Juan ArtesVivancos, Department of Chemistry, University of Massachusetts Lowell

Committee Members:
Prof. Marina Ruths, Department of Chemistry, University of Massachusetts Lowell
Prof. James Whitten, Department of Chemistry, University of Massachusetts Lowell
Prof. Michael Ross, Department of Chemistry, University of Massachusetts Lowell

Abstract:
The interactions between biomolecules and their binding kinetics at a molecular level are key research domains in biochemistry and biophysics. Understanding complex biological processes, including DNA long-range communications (like signaling, damage detection, and repair) and charge transport in biomolecules at the nanoscale, is a complex challenge still underexplored. Here in this thesis, we primarily focus on single-molecule electrical measurements to obtain insights into those phenomena and compare them with bulk measurements.

Biomolecular electronics is the study of the charge transport process in biomolecules. RNA has become the focus of intensive biophysical and biochemical research because RNA is the primary carrier of genetic information for many pathogens and the basis for many vaccines and therapeutic approaches. We propose to use the Scanning tunneling microscope-assisted break junction method (STM-BJ) to study charge transport in biomolecules and biomolecular complexes by measuring reproducible conductance histograms. Herein, we measure, for the first time, the conductance of individual double-stranded (ds) RNA molecules and compare it with the conductance of identical DNA:RNA hybrids. Then we demonstrated base-mediated charge transport in specific single-stranded (ss)RNA oligonucleotide sequences and compare that with equivalent DNA and dsRNA molecules. In our final study, we obtain an electrical fingerprint of RNA-protein (Argonaute) interactions in the RISC (RNA-induced silencing complex) and compare those single-molecule results with bulk electrochemical techniques. Investigating those interactions with electrical and electrochemical signals in RISC reveals unknown factors related to gene expression at the individual complex level.

Successful outcomes from these studies are a motivating starting point for the biophysical characterization of several other biomolecular interactions at the single biomolecule complex and in biologically relevant liquid-liquid phase-separated systems. With our experiments, we established that single-molecule conductance measurements can be valuable methods for studying biomolecular interactions. Finally, these fundamental results can be the basis for designing next-generation innovative biomaterials and biosensors.


All interested students and faculty members are invited to attend.