(4bi) Bridging the Protein-Polymer Divide: Designer Protein Materials with Programmed Dispersity

A single macromolecular sample is characterized by a wealth of factors, including molecular weight and distribution, monomer segment distribution, and architecture, which together dictate the macroscopic and microscopic properties. In contrast, proteins have long been lauded as the pinnacle of polymeric materials, in which each individual protein is perfectly sequence-defined, which contributes to their abilities to form complex folded structures and perform unique enzymatic functions. There have been significant synthetic efforts to achieve sequence-defined polymers via organic chemistry, but it remains difficult to bridge the gap between protein- and polymer-based materials physics. My work seeks to develop and use high-throughput biosynthetic tools, such as recombinant DNA cloning techniques, to generate protein materials with well-characterized molecular weight and sequence dispersity. Once synthesized, their properties will be probed with multiscale experimental techniques, including X-ray and neutron scattering and mechanical testing. By harnessing a combination of systematic materials design improvements, I will establish the connection of macroscopic properties to fundamental polymer physics principles with the opportunity for the integration of machine learning-based design to target specific application areas. Initial directions in my research program include development of molecular weight-disperse protein materials, responsive molecular weight-disperse micelles via mixing for biomedical applications, and sequence-disperse gels for transport of small molecules.

Research Experience:

Development of High-Throughput Techniques for Next-Generation Protein Materials Discovery, Department of Chemical Engineering, Massachusetts Institute of Technology (advised by Bradley D. Olsen)

In my postdoctoral research, I have established several high-throughput screening platforms for protein-based materials. Protein materials hold great promise for a wealth of biomaterials applications as a result of their unique combination of binding, enzymatic, and structural properties. However, low protein expression has been a key bottleneck in materials innovation, often costing a researcher months of time optimizing a single expression or requiring high-cost automated screening tools. Here, to overcome this limitation, I have developed an inexpensive, protein expression optimization platform capable of scanning combinations of cell strains and DNA plasmids to identify suitable conditions (in prep, 2021). This platform significantly shortens the time and lowers the costs associated with achieving meaningful protein yields. In several cases, conditions for previously un-expressible proteins have been elucidated.

Concurrently, a high-throughput platform was developed to screen a library of self-assembled streptavidin-binding candidates for biosensors; these recombinant fusion proteins were composed of a series of functional proteins obtained via directed evolution flanked by an elastin-like polypeptide (ELP) and a coiled-coil associative domain to promote self-assembly (in prep. 2021). Proteins were synthesized and purified in high throughput using ELP thermal cycling purification. Despite the functional protein being selected for their streptavidin-binding abilities in the initial directed evolution screening, many candidates performed poorly once integrated into the fusion protein, likely due to inaccessibility of the binding domains. These results highlight the continued requirements to translate the efficiencies of directed evolution techniques to protein material systems. Together, these new platforms present a paradigm-shift in how protein materials can be studied, opening opportunities in materials design and data-driven approaches.

Polymer Electrolyte Designs for Lithium-Ion Batteries, Department of Chemical and Biomolecular Engineering, University of Delaware (advised by Thomas H. Epps, III)

Solid polymer electrolytes are one of the key components of enabling high energy density, safe energy storage solutions, but most current examples sacrifice either the mechanical integrity or ionic conductivity. To connect the morphology of the electrolyte to its macroscopic properties, my dissertation research focused on gaining a greater understanding of the spatial distribution of the mobile lithium salts in the polymer matrix, which is key to designing next-generation electrolytes. Using neutron and X-ray reflectometry techniques, I quantified the distribution of lithium salts and polymer in a solid block copolymer as a function of the lithium salt anion and concentration of salt (Macromolecules, 2018). In further studies, these methods were used to understand a homopolymer-blended block copolymer electrolyte, in which the molecular weight of the homopolymer relative to that of the block copolymer dictated the homopolymer distribution (Macromolecules, 2019). High local salt concentrations in homopolymer-rich domains were found to correlate to higher ionic conductivities, which suggests that these homopolymer additives are powerful tools in achieving realistic ionic conductivities for commercial applications. Additionally, a synthetic platform for self-doped block copolymers that controlled the spatial distribution of salt in the electrolyte was developed (in prep, 2021). Together, this research connected fundamental physics with polymer chemistry to design next-generation electrolyte materials for lithium-ion batteries.

Successful Proposals:

NIST Center for Neutron Research, Off-Specular Reflectometer (May 2017), ORNL Center for Nanophase Materials Sciences (2016-2018)

Selected Publications:

Morris, M.A., Bataglioli, R.A., Mai, D.J., Paloni, J.M., Yang, Y.J., Schmitz, Z., Mills, C.E., Huske, A., Ding, E., Olsen, B.D., “Development of a High-Throughput Screening Platform for Protein Expression,” in preparation.

Morris, M.A.*, Mills, C.E.*, Paloni, J.M, Miller, E.A., Sikes, H.A., Olsen, B.D., “High-Throughput Screening of a Streptavidin Binder Library in Self-Assembled Solid Films,” in preparation. (*equal contribution)

Morris, M.A., Epps, T.H., III, “Design and Development of Self-Doped Block Polymer Electrolytes with Controlled Monomer Segment Distributions,” in preparation.

Yang, Y.J., Mai, D.J., Li, S., Morris, M.A., Olsen, B.D., “Tuning Selective Transport of Biomolecules based on the Site-Mutated Nucleoporin Hydrogels for the Next Generation of Biopurification,” Biomacromolecules, 22 (2), 2021, 289-298.

Morris, M.A., Seung, S.H., Ketkar, P.M., Nieuwendaal, R.C., Dura, J.A., Epps, T.H., III, “Enhanced Conductivity via Homopolymer-Rich Pathways in Block Polymer-Blended Electrolytes,” Macromolecules, 52 (24), 2019, 9682-9692.

Gartner, T.E, III*, Morris, M.A.*, Shelton, C.K.*, Dura, J.A., Epps, T.H., III, “Quantifying Lithium Salt and Polymer Density Distributions in Nanostructured Ion-Conducting Block Polymers,” Macromolecules, 51 (5), 2018, 1917-1926. (*equal contribution)

Morris, M.A., An, H., Lutkenhaus, J.L., Epps, T.H., III, “Harnessing the Power of Plastics: Nanostructured Polymer Systems in Lithium-ion Batteries,” ACS Energy Letters, 2 (8), 2017, 1919-1936.

Morris, M.A.*, Gartner, T.E., III*, Epps, T.H., III, “Tuning Block Polymer Structure, Properties, and Processability for the Design of Efficient Nanostructured Materials Systems,” Macromolecular Chemistry and Physics, 218, 2017, 1600513. (Front cover image) (*equal contribution)

Selected Awards:

Rising Stars in Chemical Engineering, MIT (2020)

Excellence in Graduate Polymer Research, American Chemical Society (2019)

Padden Award Finalist, American Physical Society Division of Polymer Physics (2019)

Frasier and Shirley Russell Teaching Fellowship (2018)

University of Delaware Professional Development Award (2016, 2018)

Oak Ridge Associated Universities Travel Grant (2016)

University of Delaware Robert L. Pigford Teaching Assistant Award (2016)

University of Delaware Laird Fellowship Finalist (2014)

University of Delaware Robert L. Pigford Fellowship (2013)

California Institute of Technology San Pietro Travel Grant (2013)

Larson Scholars Summer Undergraduate Research Fellow (2012)

Teaching Experience:

Fraser and Shirley Russell Teaching Fellow, Chemical Process Dynamics and Control (CHEG 401) (undergraduate core course), University of Delaware, Fall 2018

Guest Lecturer, “Static Light Scattering” Introduction to Polymers (CHEG/MSEG 630), University of Delaware, Fall 2015, 2017, and 2018 (5 lectures total).

Teaching Assistant, Introduction to Polymers (CHEG/MSEG 630), University of Delaware, Fall 2015.

Teaching Assistant, Chemical Engineering Thermodynamics I (CHEG231) (undergraduate core course), University of Delaware, Fall 2014.

Undergraduate Teaching Assistant, Organic Chemistry Laboratory (Ch/ChE9) (undergraduate core course), California Institute of Technology, Spring 2013.

Undergraduate Teaching Assistant, Chemical Engineering Thermodynamics II (ChE63b) (undergraduate core course), California Institute of Technology, Spring 2011.

Teaching Interests:

As a formally trained chemical engineer, I am excited and prepared to teach core courses, including thermodynamics, process dynamics and controls, transport phenomena, and kinetics and reaction engineering, at the undergraduate and graduate levels. At the University of Delaware, I was awarded the Fraser and Shirley Russell Teaching Fellowship, in which I was able to collaborate with Prof. Eric Furst and Prof. Abraham Lenhoff to co-teach Process Dynamics and Controls, a senior-level core chemical engineering class. Together, we designed all aspects of the course; we each prepared and delivered lectures, crafted homework assignments and exam questions, and assigned final grades. My experience as an instructor for a core chemical engineering course taught me how to approach topics students found difficult, which will aid me as I design course curriculum more independently. As a teaching assistant for core undergraduate thermodynamics courses, first at Caltech and later at UD, I discovered how to effectively connect students’ understanding of the course material to the world around them, taking examples from both academic and industrial settings.

In addition to core chemical engineering courses, I will develop and teach electives in polymer science and engineering, advanced characterization techniques in soft matter, soft matter/polymer physics, and/or biomaterials. In my teaching, I aim to implement a combination of teaching tools and assessments, ranging from lectures and exams to research-based design projects and hands-on activities, to reach a diverse student body. I am deeply committed to supporting and encouraging students from underrepresented backgrounds to pursue science and engineering as both a mentor and teacher. I believe it is my responsibility as an educator to continue to push for anti-racism in science and engineering to support the development of early-career researchers from historically-underrepresented backgrounds, and I am dedicated to creating an inclusive and supportive research environment that will allow all students to thrive.