Colloquia & Guest Speakers

Interferometric Microscopy for Detection and Visualization of Biological Nanoparticles

Dr. M. Selim Ünlü, Boston University

Monday, April 23, 2018
3:30 p.m.

Goergen 101

selim unlu


Nearly four hundred years ago, invention of the microscope offered a glimpse into the previously unknown details of insects and minerals. Advent of optical microscopy has provided detailed visualization and study of biological specimens including parasites, fungi, and bacteria.  Today, non-optical microscopes allow us to probe into the once invisible world and it has become possible to visualize the nanoscale biological particles. 2014 Nobel Prize in Chemistry was awarded "for the development of super-resolved fluorescence microscopy" is a testimony to the importance of nanoscale observations in biological world. 

Biological nanoparticles such as viruses and exosomes are important biomarkers for a range of medical conditions, from infectious disease to cancer. Biological sensors that detect whole viruses and exosomes with high specificity, yet without chemical labeling, are promising because they generally reduce the amount and complexity of sample preparation required by molecular amplification methods and may improve measurement quality by retaining information about nanoscale biological structure. Unlike fluorescence-based super-resolution techniques, conventional light scattering microscopy cannot discern details that are closer than half of the wavelength of light. We developed an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS), and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection [1]. In high-magnification modality Single-Particle IRIS (SP-IRIS) has the ability to detect and characterize individual biological nanoparticles. In SP-IRIS, the interference of light reflected from the sensor surface is modified by the presence of particles producing a distinct signal that reveals the size of the particle that is not otherwise visible under a conventional microscope. Using this simple platform, we have demonstrated label-free identification and visualization of various viruses in multiplexed format in complex samples in a disposable cartridge [2]. Recently, our technology was applied to detection of exosomes [3]. We are currently focusing on various biological applications as well as further improvement of the technique using pupil function engineering [4].


M. Selim Ünlü received the B.S. degree from the Middle East Technical University, Ankara, Turkey, in 1986, and the M.S.E.E. (1988) and Ph.D. (1992) degrees from the University of Illinois at Urbana-Champaign, all in electrical engineering.Since 1992, he has been a professor at Boston University. He is currently a Distinguished Professor of Engineering appointed in electrical and computer engineering, biomedical engineering, physics, and graduate medical sciences. He has also served as the Associate Dean for Research and Graduate Programs in engineering. His research interests are in the areas of nanophotonics and biophotonics focusing on high-resolution solid immersion lens microscopy of integrated circuits and development of biological detection and imaging techniques, particularly in high-throughput digital biosensors based on detection of individual nanoparticles and viruses. Dr. Ünlü was the recipient of the NSF CAREER and ONR Young Investigator Awards in 1996. He has been selected as a Photonics Society Distinguished Lecturerfor 2005-2007 and Australian Research Council Nanotechnology Network (ARCNN) Distinguished Lecturer for 2007. He has been elevated to IEEE Fellowrank in 2007 for his “contributions to optoelectronic devices” and OSAFellowrank in 2017 for his “for pioneering contributions in utilization of optical interference in enhanced photodetectors and biological sensing and imaging.”In 2008, he was awarded the Science Award by the Turkish Scientific Foundation. His professional service includes serving as the chair of the Annual Meeting for IEEE Photonics Society and Editor-in-Chief for IEEE Journal of Quantum Electronics.

[1]  O. Avci, N. Lortlar Ünlü, A. Yalcin, and M. S. Ünlü, "Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection," Sensors, Vol. 15 (7), (2015)

[2]  S. M. Scherr, D. S. Freedman, K. N. Agans, A. Rosca, E. Carter, M. Kuroda, H. Fawcett, C. Mire, T. W. Geisbert, M. S. Ünlü, and J. H. Connor, "Disposable cartridge platform for rapid detection of viral hemorrhagic fever viruses," Lab Chip, Vol. 17 (5), (2017)

[3]  G. G. Daaboul, P. Gagni, L. Benussi, P. Bettotti, M. Ciani, M. Cretich, D. S. Freedman, R. Ghidoni, A. Yalcin, C. Piotto, D. Prosperi, B. Santini, M. S. Ünlü, M. Chiari, "Digital Detection of Exosomes by Interferometric Imaging," Nature Scientific Reports, Vol. 6, 37246, (2016)

[4]  O. Avci, M. I. Campana, C. Yurdakul, M. S. Ünlü, "Pupil function engineering for enhanced nanoparticle visibility in wide-field interferometric microscopy," Optica, Vol. 4(2), (2017)

Location:  Goergen 101

Refreshments will be served.