You are invited to the New England Society for Microscopy's Virtual Fall Symposium! The meeting will take place on December 10th via Zoom, consisting of four technical talks, and our Annual Business Meeting.
The technical lectures will be delivered by Dr. Heather Clark (Northeastern), Dr. Ayse Asatekin (Tufts University), Dr. Keith Brown (Boston University), and Dr. Jian Zhao (Boston University). The titles and abstracts of the talks are listed below.
Please register (for FREE!) to receive the Zoom link. Log on at 8:45 am, talks will begin at 9 am.
Meeting Schedule, December 10th
8:45 AM – Zoom Meeting will open
9:00 AM – Ayse Astekin (Tufts University)
Next generation membranes through polymer self-assembly
9:40 AM – Jian Zhao (Boston University)
Bond-selective Intensity Diffraction Tomography
10:20 AM – Business Meeting
11:00 AM – Keith Brown (Boston University)
Exploring Smart Fluids from Particles to Emergent Properties
11:40 AM – Heather Clark (Northeastern University)
Nanosensors for Imaging the Chemistry of the Body
12:10 PM - End
ABSTRACTS AND BIOS
Speaker: Ayse Asatekin, (Department of Chemical and Biological Engineering, Tufts University)
Title: Next generation membranes through polymer self-assembly
Abstract:
Asatekin lab focuses on new polymeric materials designed to self-assemble to impart improved and/or new functionality to separation membranes by controlling nano-scale morphology and surface functionality. Our work aims to develop new membranes for generating fresh water, treating wastewater, and process separations. We focus on preventing membrane fouling and controlling membrane selectivity while maintaining high flux and simple, scalable manufacturing methods.
In one research direction, we aim to understand how zwitterion-containing copolymers self-assemble, and utilize their behavior to develop membranes with improved capabilities. Zwitterions, functional groups with equal numbers of positive and negative charges, strongly resist fouling, defined as performance loss due to the adsorption and adhesion of feed components onto the membrane. They also easily self-assemble due to strong intermolecular interactions. We have developed high flux, fouling resistant, size-selective membranes utilizing the self-assembly of random copolymers of zwitterionic and hydrophobic monomers. The effective membrane pore size or ~1 nm closely matches the size of self-assembled zwitterionic nanodomains. These membranes are exceptionally fouling resistant, showing little to no flux decline during the filtration of a wide range foulants and complete flux recovery with a water rinse. We also showed that we can manipulate the selectivity of these membranes through either the inclusion of co-monomers or by cross-linking the copolymer after manufacture to create tighter pores. Using these approaches, we have developed membranes that exhibit subnanometer pores and extremely high sulfate/chloride selectivity.
We also aim to develop membranes that can separate small molecules of similar size based on their chemical properties. For this purpose, we prepared membranes by depositing micelles formed by random copolymers of a highly hydrophobic fluorinated monomer with methacrylic acid on a porous support. The gaps between the micelles act as 1-5 nm nanochannels functionalized with carboxylic acid groups. These membranes show charge-based selectivity between organic molecules. Furthermore, the carboxyl groups can be functionalized to alter the selectivity of the membrane. We used this method to prepare membranes that exhibit aromaticity-based selectivity. We believe these approaches will eventually lead to novel membranes that are capable of new separations and can replace more energy intensive methods such as distillation or extraction.
Biography:
Ayse Asatekin is an associate professor and the Steve and Kristen Remondi Faculty Fellow in the Chemical and Biological Engineering Department at Tufts University. She received bachelor's degrees in chemical engineering and chemistry from the Middle East Technical University in Ankara, Turkey. She went on to receive her Ph.D. in chemical engineering through the Program in Polymer Science and Technology (PPST) at MIT. She pursued her post-doctoral work with Prof. Karen K. Gleason, also at MIT. She co-founded Clean Membranes, Inc., a start-up company that commercialized the polyacrylonitrile-based membrane technology that she began developing during her doctoral research, and worked as its Principal Scientist before joining the Tufts faculty in 2012. Novel membrane technologies developed in her lab are currently being commercialized bt ZwitterCo, Inc., where she serves as the Senior Scientific Advisor. She is the recipient of the NSF CAREER Award, Massachusetts Clean Energy Council's Catalyst Award, and the Turkish American Scientists and Scholars Young Scholar Award. Her research interests are in developing novel membranes for clean water and energy-efficient separations. She is also interested in multi-functional membranes, controlling surface chemistry for biomedical applications, polymer science, and energy storage.
Speaker: Jian Zhao (Boston University)
Title: Bond-selective Intensity Diffraction Tomography
Abstract:
Volumetric chemical imaging is highly desired for investigating biochemical processes at the sub-cellular level. Conventional fluorescence imaging technique plays a central role while suffering from cellular functions perturbations, delivery difficulties, photobleaching, phototoxicity, and lack of endogenous chemical bond information. Nonlinear vibrational spectroscopic imaging techniques, including stimulated Raman scattering (SRS) imaging and mid-infrared photothermal microscopy (MIP), overcome most of these limitations. Especially, MIP techniques demonstrate higher sensitivity than the SRS imaging due to its eight orders of magnitude higher absorption cross-section. Nevertheless, current MIP techniques either lack quantitative imaging capabilities or suffer from complex configurations and slow speed. Here, we report bond-selective intensity diffraction tomography (BS-IDT) based on 3D quantitative phase detection of the mid-infrared photothermal effect. We show that BS-IDT can perform volumetric quantitative phase imaging with molecular specificity in the mid-IR fingerprint region. BS-IDT reaches incoherent diffraction-limited resolution and a high imaging speed up to ~6 Hz per volume. The mid-IR spectrum extracted from BS-IDT shows high fidelity compared with ground truth measured by an FTIR spectrometer. The 3D chemical imaging results from cancer cells and Caenorhabditis elegans validate BS-IDT’s superior performance.
Biography:
Dr. Jian Zhao is a postdoctoral associate with the Department of Electrical and Computer Engineering at Boston University, Massachusetts, United States. He is a member of SPIE and OSA. He received his Ph.D. degrees in optics and photonics from CREOL, the College of Optics and Photonics at the University of Central Florida, USA. Previously, he obtained his B.S. degrees in optics from the School of Physics and Engineering, Sun Yat-sen University, China. His research interests include label-free chemical quantitative phase microscopy based on mid-infrared photothermal effects, deep learning in optics, microstructured optical fiber optics, and ultrafast optics.
Speaker: Keith A. Brown (Boston University)
Title: Exploring Smart Fluids from Particles to Emergent Properties
Abstract:
Smart fluids – or a fluid with suspended particles in which an applied field produces a substantial change in properties – are a fascinating class of soft materials that are widely used in applications ranging from automotive suspension to high performance speakers. However, predicting their performance from first principles remains challenging. Our underlying hypothesis is that a deeper understanding can be gained by studying highly controlled model particles and connecting these to emergent behavior of smart fluids. Here, we explore this approach through the study of electrically-driven assembly of nanoparticles into hierarchical structures. First, we introduce a novel method to measure the polarizability of nanoparticles based upon modest trapping fields and fluorescence microscopy. By using this assay, we determine that nanoparticles can exhibit polarizabilities that are >30 times larger than would be expected based upon simple models, corroborating early theoretical work that includes contributions from space charge in the Debye layer. Next, we find that these particles can assemble into a macroscopic cellular phase under the collective influence of AC and DC voltages. Systematic study of this phase transition shows that it was the result of electrophoretic assembly into a two-dimensional configuration followed by spinodal decomposition into particle-rich walls and particle-poor cells mediated principally by electrohydrodynamic flow. In addition to determining the mechanism underpinning the formation of the cellular phase, we present a method to reversibly assemble microscale continuous structures out of nanoscale particles in a manner that may enable the creation of materials that impact diverse fields including energy storage and filtration. These lessons illustrate that important insights can be gained by combining novel multi-scale characterization strategies and well-characterized particles.
Biography:
Keith A. Brown is an Assistant Professor of Mechanical Engineering, Materials Science & Engineering, and Physics at Boston University. He earned a Ph.D. in Applied Physics at Harvard University under the guidance of Robert M. Westervelt and an S.B. in physics from MIT. Following his doctoral work, he was an International Institute for Nanotechnology postdoctoral fellow with Chad A. Mirkin at Northwestern University. The KABlab studies polymers and smart fluids to determine how useful properties emerge from hierarchical structure. A considerable focus is developing approaches that increase the pace of materials research using autonomous experimentation, scanning probe techniques, and additive manufacturing. Keith has co-authored over 80 peer-reviewed publications, five issued patents, and his work has been recognized through awards including the Frontiers of Materials Award from The Minerals, Metals, & Materials Society (TMS), being recognized as a “Future Star of the AVS,” the Omar Farha Award for Research Leadership from Northwestern University, and the AVS Nanometer-Scale Science and Technology Division Postdoctoral Award. Keith served on the Nano Letters Early Career Advisory Board and currently leads the MRS Artificial Intelligence in Materials Development Staging Task Force.
Speaker: Heather Clark (Northeastern University)
Title: Nanosensors for Imaging the Chemistry of the Body
Abstract:
My group is currently working at the interface of chemistry and biology to develop and apply novel nanoscale probes for biological measurements. In order to fulfill our goal of chemical imaging deep in the body (brain, central nervous system, circulatory system) we are approaching the problem through two directions. First, we are working with fluorescence-based sensors in the peripheral nervous system to understand the capabilities of the sensors for cellular signaling. Second, we are tailoring our sensors to be compatible with advanced imaging techniques (diffuse in vivo flow cytometry, photoacoustics, or MRI) to image deep in the body. Ultimately, we will use the probes to image specific chemical processes and biomarkers in the brain/body, in real-time.
Biography:
Heather Clark is a Professor in the Departments of Bioengineering and Chemistry at Northeastern University. In addition, she is the Founding Director of the Institute for Chemical Imaging of Living Systems and an Associate Editor at ACS Sensors. She received her PhD in Analytical Chemistry from the University of Michigan and completed a postdoc in the Center for Cell Analysis & Modeling at the University of Connecticut Health Center. She is a AIMBE Fellow and has received awards for both research and teaching, including the DARPA Young Faculty Award. Her work has been featured in a live CNN interview, the Wall Street Journal, WIRED magazine and MIT Technology Review.
