Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
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Article Citation - WoS: 5Citation - Scopus: 6Toward Single-Layer Janus Crystals: Off-Balance Materials From Synthesis To Nanotechnology Applications(American Institute of Physics, 2021) Oğuztürk, H. Esra; Sözen, Yiğit; Akyol, Cansu; Özkendir İnanç, Dilce; Yıldız, Ümit Hakan; Şahin, HasanThe existence of things is directly related to their structural symmetry in a broad framework ranging from atoms to crystalline materials and from simple cells to complex organisms like humans. However, structural imbalance that occurs through natural or artificial means can provide completely different advantages. Molecules, crystals, and complex structures with structural imbalance constitute the family of Janus-type materials. This perspective provides a comprehensive discussion on the synthesis techniques of Janus-type materials, their use in fields from biology to materials science, and very recent studies on the family of 2D ultrathin graphene-like structures. We believe that, thanks to the advances in experimental techniques, the few-atom-sized off-balanced materials will be indispensable parts of the nanotechnology products that soon will be used in our daily lives.Article Citation - WoS: 27Citation - Scopus: 28Biocomposite Scaffolds for 3d Cell Culture: Propolis Enriched Polyvinyl Alcohol Nanofibers Favoring Cell Adhesion(John Wiley and Sons Inc., 2021) Bilginer, Rumeysa; Özkendir İnanç, Dilce; Yıldız, Ümit Hakan; Arslan Yıldız, AhuThe objective of this work is generation of propolis/polyvinyl alcohol (PVA) scaffold by electrospinning for 3D cell culture. Here, PVA used as co-spinning agent since propolis alone cannot be easily processed by electrospinning methodology. Propolis takes charge in maximizing biological aspect of scaffold to facilitate cell attachment and proliferation. Morphological analysis showed size of the electrospun nanofibers varied between 172-523 nm and 345-687 nm in diameter, for non-crosslinked and crosslinked scaffolds, respectively. Incorporation of propolis resulted in desired surface properties of hybrid matrix, where hybrid scaffolds highly favored protein adsorption. To examine cell compatibility, NIH-3T3 and HeLa cells were seeded on propolis/PVA hybrid scaffold. Results confirmed that integration of propolis supported cell adhesion and cell proliferation. Also, results indicated electrospun propolis/PVA hybrid scaffold provide suitable microenvironment for cell culturing. Therefore, developed hybrid scaffold could be considered as potential candidate for 3D cell culture and tissue engineering.Article Citation - WoS: 3Citation - Scopus: 4Lipid Bilayer on Wrinkled-Interfaced Graphene Field Effect Transistor(Elsevier Ltd., 2021) Özkendir İnanç, Dilce; Çelebi, Cem; Yıldız, Ümit HakanThis study describes lipid bilayer-based sensor interface on SiO2 encapsulated graphene field effect transistors (GFET). The SiO2 layer was utilized as a lipid compatible surface that drives bilayer formation. The two types of surface morphologies i) wrinkled morphology by thermal evaporation (TE) and ii) flat morphology by pulsed electron deposition (PED) were obtained. The sensing performance of wrinkled and flat interfaced-GFETs were investigated, pH sensitivity of wrinkled interfaced-GFETs were found to be ten fold larger than the flat ones. The enhanced sensitivity is attributed to thinning of the oxide layer by formation of wrinkles thereby facilitating electrostatic gating on graphene. We foresee that described wrinkled SiO2 interfaced-GFET holds promise as a cell membrane mimicking sensing platform for novel bioelectronic applications. © 2020Article Citation - WoS: 7Citation - Scopus: 7Fabrication of a Postfunctionalizable, Biorepellent, Electroactive Polyurethane Interface on a Gold Surface by Surface-Assisted Polymerization(American Chemical Society, 2020) Özenler, Sezer; Sözen, Yiğit; Şahin, Hasan; Yıldız, Ümit HakanThis study describes surface-assisted (SurfAst) urethane polymerization, providing a modular/postfunctionalizable, biorepellent, electroactive similar to 10 to 100 nm-thick polyurethane (PU) interface on a gold surface. SurfAst is a functionalization methodology based on sequential incubation steps of alkane diisocyanates and alkanediol monomers. The gold surface is functionalized by alkane diisocyanates in the first incubation step, and our theoretical calculations reveal that while the isocyanate group atoms (N, C, and O) at one end of the molecule exhibits strong interactions (similar to 900 meV) with surface atoms, the other end group remains unreacted. After the first incubation step, sequential alkanediol and alkane diisocyanate incubations provide formation of the PU interface. The extensive analysis of the PU interface has been conducted via X-ray photoelectron spectroscopy, and the chemical mapping verifies that the interface is made of PU moieties. The topographical analysis of the surface conducted by the atomic force microscopy shows that the PU interface consists of mostly a nanoporous texture with 150 nm total roughness. The adherence force mapping of the PU interface reveals that the nanoporous matrix exhibits an adhesion force of about 14 nN. The electrostatic force microscopy characterizing long-range electrostatic interactions (40 nm) shows that the PU interface has been attracted by positively charged species as compared to negative objects. Finally, it is demonstrated that the PU interface is readily postfunctionalizable by polyethylene glycol (PEG 1000), serving as a biorepellent interface and preserving electroactivity. We foresee that SurfAst polymerization will have potential for the facile fabrication of a postfunctionalizable and modular biointerface which might be utilized for biosensing and bioelectronic applications.