KOÇ UNIVERSITY PHYSICS SEMINAR
Speaker : Mustafa Yorulmaz, ASELSAN
Title : Optical Imaging and Spectroscopy of Nanoparticles and Applications in Diagnostics
Date : May 15, 2018
Time : 14:30
Cookie & Tea : SCI 103 14:15
Place : SCI 103
web : https://physics-seminars.ku.
Plasmonic nanoparticles exhibit interesting radiative and non-radiative properties upon interaction with light . Single-particle methods have been utilized to understand the photophysical properties of these nanoparticles. These properties have been widely exploited for a variety of intriguing applications in fields ranging from chemistry to biology and health .
Radiative properties are well-characterized using fluorescence and scattering spectroscopy tools. Photothermal microscopy enables the study of non-fluorescent absorbers, down to single-molecule sensitivity . Correlating the absorption signal with radiative signals, we can gain insight into the photophysical properties of nano-objects, e.g. the effect of size and shape on the quantum yield of individual gold nanoparticles  and strong field enhancements near tips of nanorods .
Absorption measurements have been performed using a single excitation wavelength limiting the knowledge of pure absorption. We introduce the evolution of photothermal imaging toward absorption spectroscopy by incorporating photothermal microscopy with a supercontinuum laser source and a technique that will account for chromatic aberration and different heating efficiencies at different wavelenghts . Absorption spectroscopy paves the way towards making rational designs of the nanoparticles for specific applications .
The majority of biomolecules such as proteins are hardly visible via fluorescence or absorption techniques. Mostly, they are labeled with fluorescent molecules for their detection. Sensitive measurement of scattering signal using interference knowledge can allow direct optical detection of non-fluorescent biomolecules and circumvent the need for labeling. ASELSAN Research Center has launched research efforts in biotechnology and aims to develop an in-vitro point-of-care biosensor that can be used for diagnostic purposes. During the presentation, we will also cover the developments at Biotechnology Laboratory of ASELSAN Research Center and present our recent results on diagnostics applications using Interferometric Scattering Microscopy .
 Gaiduk et al. Chem Phys Chem 12, 1536 (2011); Chang et al. Acc. Chem. Res. 45, 1936 (2012).
 Zijlstra et al. Rep. Prog. Phys. 74, 106401 (2011).
 Gaiduk et al. Science 330, 353 (2010).
 Yorulmaz et al. Nano Lett. 12, 4385 (2012) ; Fang et al. ACS Nano 6, 7177 (2012).
 Yuan et al. Angew. Chem. Int. Ed. 52, 1217 (2013).
 Yorulmaz et al. Nano Lett. 15, 3041 (2015).
 Yorulmaz et al. Nano Lett. 16, 6497 (2016).
 Işıl et al. Appl. Optics 57, 2545 (2018).
Short Bio: Mustafa Yorulmaz received his B.Sc. in Physics at Bilkent University in 2007. He then joined Prof. Dr. Alper Kiraz’s group at Koç University for his M.Sc. study in Materials Science and Engineering. He completed his Ph.D in Physics and studied in Molecular Nano-Optics and Spins Group under the supervision of Prof. Dr. Michel Orrit at Leiden University in 2013. He worked as a post-doctoral researcher in the same group until 2014. He held postdoctoral research position as a Carl and Lillian Illig postdoctoral fellow of Smalley Curl Institute at Rice University and performed research studies in the group of Prof. Dr. Stephan Link until 2015. He joined Biotechnology Research Program Department at ASELSAN Research Center in 2016. He was given the title of Associate Professor in March 2018. His work mainly focuses on the development of nano-imaging and optical spectroscopy tools for investigating the photophysical properties of individual nano-objects and applying the acquired knowledge in physical chemistry, biology, energy and diagnostics.