(4ht) Investigating Electrochemical Mechanisms in Biophysics and Bioseparations

Microscopic biomolecular interactions give rise to macroscopic order, from the scale of a single cell to an entire organism. I am fascinated by the emergence of biological organization from cooperative biomolecular interactions because organization can determine biological function. In my future research, I seek to quantitatively understand the multi-scale mechanisms of biological organization, and then to harness these same biological design principles for engineering process development. Since nearly all biological interfaces are charged at microscopic scales, I am particularly interested in the often-overlooked electrochemical dynamics that leads to biomolecular-scale and cellular-scale behavior, especially driven by interfacial physics at phase boundaries. My career goal is to connect quantitative models to applications in (i) understanding the physical principles governing living matter and disease states, and (ii) designing and optimizing separations for pharmaceuticals and other societally important chemicals and materials.

My current research is focused on understanding biophysical phenomena and engineering applications by constructing physics-based mathematical models. During my chemical engineering PhD at MIT working with Martin Bazant, I studied the structure and transport of electrolytes near interfaces to understand membrane separations, colloidal stability, and electrochemical energy storage. Now, as a Princeton Bioengineering postdoctoral fellow, I am working across disciplines with Howard Stone (mechanical engineering) and Sabine Petry (molecular biology), using theory and experiments to investigate biomolecular phase separation for processes related to cell division. Some key contributions I have made in these research areas include:

1. Biopolymer Phase Separation: I discovered an analytical solution for phase coexistence within the Flory-Huggins model, the most widely used model for interpreting polymeric phase separations. The model describes phase separation in diverse applications, from biological systems to the chemicals industry.

2. Fluid Structure at Electrochemical Interfaces: I derived formulas describing the charge and orientational structuring of polar liquids (such as water) at interfaces, which were verified by comparison to molecular dynamics simulations. The models are relevant for understanding electrochemical reactions at interfaces and hydration-mediated interactions between biomolecules or other colloids.

3. Capillary Forces from Biomolecular Condensates: I carried out atomic force microscopy experiments and applied a theoretical model to elucidate the role of electrostatics on biomolecular condensation, wetting, and capillary forces. The experiments quantify the strength of capillary forces for microtubule bundling and nucleation factor recruitment by condensed phases of proteins. The theory explains the strong electrostatic driving forces in the bulk and interface of condensed phases.

4. Colloidal Interactions: I explored the role of electrostatics for colloidal interactions, including attractive electrostatic interactions between like-charged surfaces from bridging multivalent counterions, relevant for cement cohesion. Working with collaborators, I applied related models to the interactions of ions and proteins with an ion exchange resin.

Based on these foundations, my future research group will study electrochemical phenomena in biophysics and biomolecular separations building from physics-based models to applications. Starting from a strong theoretical foundation, we will design and execute experiments to test hypotheses at a quantitative and mechanistic level. My group will investigate molecular-level mechanisms of cellular function or dysfunction connected to disease and explore similar mechanisms for the design and optimization of biopharmaceutical separation unit operations. Specifically, we will answer open questions about (i) the maintenance of electrochemical cellular homeostasis with biomolecular phase separation, (ii) the microscopic mechanisms of neurodegenerative diseases driven by protein aggregation, and (iii) the design of effective routes for biological separations and downstream processing using ion exchange chromatography or precipitation-based separations.

Teaching Interests:

I am passionate about STEM education and training the next generation of engineers and scientists. Given my chemical engineering background, I am prepared to teach any course in the chemical engineering curriculum from undergraduate to graduate levels. I taught graduate-level Transport Phenomena at MIT, both as a teaching assistant and later as an instructor. I find it especially fulfilling to teach the mathematical foundations of engineering, since I believe the tools of model-building empower students to tackle any engineering problem.

Beyond formal teaching positions, I participated in numerous teaching opportunities to serve the broader community. At Princeton, for four semesters, I instructed and tutored basic mathematics courses for non-traditional, incarcerated students as part of the Princeton Prison Teaching Initiative. Further, during my time at MIT, I helped create an open, online graduate-level course in transport phenomena on EdX, reaching a diverse set of students from around the world. I also contributed materials to an online math course for entering MIT graduate students, to bring them up to speed on mathematical foundations for graduate school. As a faculty member, I plan to seek similar opportunities to share my passion for mathematical sciences and their applications—a core goal of my career.

I look forward to teaching courses while creating an inclusive environment for all my students to learn. I hope to develop new courses that emphasize electrochemical foundations broadly for energy, environmental, and biological applications, while maintaining a deep connection to applied mathematics fundamentals that underlie the discipline of chemical engineering. Further, I strongly believe in academic research as a tool for scientific education that may also contribute to broader societal outcomes. Therefore, I will be strongly invested in the training of my future undergraduate and graduate students to be effective scientists, communicators, and educators as a part of my group’s research mission.

Selected Awards:

Princeton Bioengineering Institute - Innovator (PBI2) Distinguished Fellow, 2022

National Science Foundation Graduate Fellow, 2016-2021

MIT ChE Best Graduate Student Seminar, Fall 2019

MIT Presidential Fellow, 2016-2017

UT Austin Chemical Engineering Publication of the Year Award, 2015 (co-first author)

Selected Publications: (3 of 27)

1. J. P. de Souza, H. A. Stone. Exact Analytical Solution of the Flory-Huggins Model and Extensions to Multicomponent Systems. J. Chem. Phys. In press. (2024).

2. K. Pivnic^†, J. P. de Souza^†, M. Urbakh, M. Z. Bazant, A. A. Kornyshev. Orientational Ordering of Confined Polar Liquids. Nano Letters 23, 12, 5548-5554 (2023).

3. J. P. de Souza, Z. A. H. Goodwin, M. McEldrew, A. A. Kornyshev, M. Z. Bazant. Interfacial Layering in the Electric Double Layer of Ionic Liquids, Phys. Rev. Lett. 125, 116001 (2020).