(6fi) Microfluidics for Polymer Self-Assembly in Confined Quasi-2D Geometries and Enzyme Design towards Plastic Recycling and Biofuel Production

My postdoctoral work with Prof. David Weitz (Harvard University, 2010-present) involves high throughput microfluidics for performing chemical reactions and biochemical assays in picoliter drops. Taking advantage of material behaviors at liquid-liquid interfaces, enables me to engineer complex materials of hierarchical orders with novel functionalities. For example, I created triggered-release systems using stimuli responsive polymers and enzyme-based functional materials in collaboration with Advanced Energy Consortium and BASF companies. Additionally, in collaboration with New England BioLabs, I genetically engineered proteins and also performed single molecule assays using DNA templates and an in vitro transcription-translation system. Moreover, part of my duties as a postdoc included mentoring and supervising the research of undergraduates, graduates and postdocs on a large number of projects.

Thus, I believe that my training and expertise position me advantageously for becoming a faculty member.

As a new faculty member, my first thrust is to take advantage of confinement to engineer novel structures that otherwise are unattainable in bulk. It has been demonstrated that confinement is a powerful tool to break symmetry on the scale of single molecules, allowing polymers to form new phases that are not possible using bulk self-assembly. However, the phase behavior of polymer blends under confinement has not been characterized experimentally in detail due to the lack of available techniques. We recently developed a novel microfluidic method for fabricating monodisperse double emulsions with ultra-thin polymer shells, less than 100 nm in thickness. Due to the quasi-two dimensional physical confinement this method offers exquisite control over the phase behavior of the polymer blend enabling non-equilibrium assembly to create membranes with controlled porosity and permeability. In addition, I will synthesize new polymers and investigate how changing their molecular structure affects self-assembly to obtain quantitative structure-function correlations rules. Applications range from encapsulation and controlled release to membranes for separation and purification.

My second thrust addresses the huge environmental challenges arising from plastic waste and energy production. The current approach for dealing with plastic waste is incineration, which releases large amount of CO₂. In contrast, enzymatic degradation is a possible solution for efficient transformation into high-value fine chemicals without significant greenhouse gas emissions. However, naturally occurring enzymes are inefficient at processing plastic substrates. To increase their efficiency for plastic degradation controlled mutations can be utilized; this approach necessitates generating an enormous library of enzyme mutants. However, developing reliable high-throughput screening platforms to screen for functional variants in libraries with large size is very challenging.

I will use drop-based microfluidics to develop a high-throughput screening platform to overcome these difficulties by using new assays based on in vitro transcription and translation (IVTT) system. I will adapt this approach to engineer enzymes and enzyme-polymer conjugates through mutagenesis and study their interaction with natural and non-natural substrates. The results of this study will be applied to the design of enzymes for new applications: such as the biochemical recycling of plastics and production of renewable energy through degradation of cellulose.