Woodruff School of Mechanical Engineering


Photonic Crystal Enhanced Microscopy for Cell Membrane Imaging and Digital Resolution Biomolecular Sensing


Prof. Brian T. Cunningham


Department of Electrical and Computer Engineering at the University of Illinois at Urbana-Champaign


Thursday, July 28, 2016 at 1:00:00 PM


Love Building, Room 109


Peter Hesketh


New tools are needed that can provide quantitative, long-term, dynamic, and high spatial resolution information about processes that take place in the membrane during cellular adhesion. Tumor invasion, stem cell differentiation, apoptosis, and metastasis all occur while cells are highly engaged with the extracellular matrix of basement membranes, where the interaction of focal adhesion points serve to anchor cells, but where multi-stage processes occur over the bulk membrane, filapodia, and extensions of the cell body. Photonic crystal enhanced microscopy (PCEM) is a newly-demonstrated imaging approach that enables label-free observation of cell-surface interactions through the assistance of a photonic crystal (PC) biosensor surface that forms optical standing waves that penetrate only into cell membrane components in contact with the PC. PCs are inexpensively fabricated from polymer materials onto conventional glass cover slips, and the PCEM instrument is a modification of an ordinary bright field microscope, which we have used to gather quantitative images of shifts in the resonant Peak Wavelength Value (PWV), representing images of the cell membrane-associated mass density. Our approach seeks to take advantage of recent observations achieved via PCEM in which the magnitude of the PC resonant intensity is modulated in a highly localized manner, resulting in the ability to obtain images of the Peak Intensity Value (PIV) of a PC biosensor. We seek to use PCEM to gather dynamic images of localized focal adhesions of live cells, which are comprised of local high density assemblies of cell membrane components, and intracellular membrane-bound protein assemblies. The label-free information from PCEM is complemented by fluorescence microscopy information, in which selective dyes that target cell membrane components are used at label-free experimental endpoints. The comparison of on-resonance and off-resonance illumination is used to estimate the distance of fluorescent emitters from the PC surface with nanometer precision, for a total of five imaging modalities integrated within a single instrument. In addition to cell-surface imaging, we have also demonstrated PCEM’s ability to surface binding of individual dielectric and metallic nanoparticles. When the plasmon resonant wavelength of an adsorbed nanoparticle is selected to match the PC resonant wavelength, the nanoparticle acts as a highly localized efficient quencher of the resonant reflection efficiency, enabling each one to be imaged with high contrast. Nanoparticle PCEM (NP-PCEM) has the potential to be used in the context of sensing biomolecular interactions, with the ability to observe protein-protein or nucleic acid interactions with digital resolution.


Brian T. Cunningham is the Willett Professor of Engineering in the Department of Electrical and Computer Engineering at the University of Illinois at Urbana-Champaign, where he also serves as the Director of the Micro and Nanotechnology Laboratory, and as Director of the NSF Center for Innovative Instrumentation Technology. His research is in the development of biosensors and detection instruments for pharmaceutical high throughput screening, disease diagnostics, point-of-care testing, life science research, and environmental monitoring. He has published 135 peer-reviewed journal articles, and is an inventor on 78 patents. Prof. Cunningham was a co-founder of SRU Biosystems in 2000, and founded Exalt Diagnostics in 2012 to commercialize photonic crystal enhanced fluorescence technology for disease biomarker detection. Acoustic MEMS biosensor technology that he developed at Draper Laboratory has been commercialized by Bioscale, Inc.. Prof Cunningham’s work was recognized with the IEEE Sensors Council Technical Achievement Award and the IEEE Engineering in Medicine and Biology Technical Achievement Award. He is a member of the National Academy of Inventors and a Fellow of IEEE, OSA, and AIMBE.


Refreshments will be served.