Browsing by Author "Tekinay, Ayse Begum"
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Item Open Access Label-free nanometer-resolution imaging of biological architectures through surface enhanced raman scattering(Nature Publishing Group, 2013) Ayas, Sencer; Çınar, Göksu; Özkan, Alper Devrim; Soran, Zeliha; Ekiz, Oner; Kocaay, Deniz; Tomak, A.; Toren, Pelin; Kaya, Yasin; Tunc, I.; Zareie, H.; Tekinay, T.; Tekinay, Ayse Begum; Güler, Mustafa O.; Dana, AykutluLabel free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonstrate the possibility of label-free super-resolution Raman imaging, by applying stochastic reconstruction to temporal fluctuations of the surface enhanced Raman scattering (SERS) signal which originate from biomolecular layers on large-area plasmonic surfaces with a high and uniform hot-spot density (> 10(11)/cm(2), 20 to 35 nm spacing). A resolution of 20 nm is demonstrated in reconstructed images of self-assembled peptide network and fibrilated lamellipodia of cardiomyocytes. Blink rate density is observed to be proportional to the excitation intensity and at high excitation densities (> 10 kW/cm(2)) blinking is accompanied by molecular breakdown. However, at low powers, simultaneous Raman measurements show that SERS can provide sufficient blink rates required for image reconstruction without completely damaging the chemical structure.Item Open Access Selective adsorption of L1210 leukemia cells/human leukocytes on micropatterned surfaces prepared from polystyrene/polypropylene-polyethylene blends(Elsevier, 2014) Atalay, N.; Unal, Hilal Unal; Erbil, H. Y.; Tekinay, Ayse BegumThe objective of this study is to prepare polymeric surfaces which will adsorb L1210 leukemia cells selectively more than that of healthy human leukocytes in order to develop new treatment options for people with leukemia. Chemically heterogeneous and micropatterned surfaces were formed on round glass slides by dip coating with accompanying phase-separation process where only commercial polymers were used. Surface properties were determined by using optical microscopy, 3D profilometry, SEM and measuring contact angles. Polymer, solvent/nonsolvent types, blend composition and temperature were found to be effective in controlling the dimensions of surface microislands. MTT tests were applied for cell viability performance of these surfaces. Polystyrene/polyethylene-polypropylene blend surfaces were found to show considerable positive selectivity to L1210 leukemia cells where L1210/healthy leukocytes adsorption ratio approached to 9-fold in vitro. Effects of wettability, surface free energy, microisland size geometry on the adsorption performances of L1210/leukocytes pairs are discussed.