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Beyazkilic P.,National Nanotechnology Research Center | Beyazkilic P.,Institute of Materials Science and Nanotechnology | Tuvshindorj U.,National Nanotechnology Research Center | Tuvshindorj U.,Institute of Materials Science and Nanotechnology | And 7 more authors.
RSC Advances | Year: 2016

This article describes a facile method for the preparation of two-dimensionally patterned superhydrophobic hybrid coatings with controlled wettability. Superhydrophobic coatings were deposited from nanostructured organically modified silica (ormosil) colloids that were synthesized via a simple sol-gel method. On the defined areas of the superhydrophobic ormosil coatings, stable wetted micropatterns were produced using Ultraviolet/Ozone (UV/O) treatment which modifies the surface chemistry from hydrophobic to hydrophilic without changing the surface morphology. The degree of wettability can be precisely controlled depending on the UV/O exposure duration; extremely wetted spots with water contact angle (WCA) of nearly 0° can be obtained. Furthermore, we demonstrated high-throughput biomolecular adsorption and mixing using the superhydrophilic patterns. The proposed superhydrophilic-patterned nanostructured ormosil surfaces with their simple preparation, robust and controlled wettability as well as adaptability on flexible substrates, hold great potential for biomedical and chemical on-chip analysis. © The Royal Society of Chemistry 2016.

Yunusa M.,National Nanotechnology Research Center | Yunusa M.,Institute of Materials Science and Nanotechnology | Ozturk F.E.,National Nanotechnology Research Center | Ozturk F.E.,Institute of Materials Science and Nanotechnology | And 9 more authors.
RSC Advances | Year: 2017

We demonstrate a rice leaf-like hierarchically textured polymer fiber array for anisotropic non-wetting surfaces. To provide superhydrophobicity in addition to the anisotropic behavior, fiber surfaces are spray coated with organically modified silica nanoparticles. The resulting micro/nano hierarchically structured fiber surfaces demonstrate anisotropic non-wetting properties. We designed various fiber architectures for droplet transportation, mixing, and guiding exploiting the scalability of the fiber texture during thermal drawing; optional nanoparticle surface modification; and inherent flexibility of the fibers. © The Royal Society of Chemistry.

He T.,Shenzhen University | Gao Y.,Nanyang Technological University | Lin X.,Shenzhen University | Chen R.,South University of Science and Technology of China | And 8 more authors.
Macromolecular Chemistry and Physics | Year: 2016

Nanocomposites with organic-inorganic properties represent a new field of basic research and offer prospects for many novel applications in extremely diverse fields, due to their remarkable emerging new properties and multifunctional nature. However, controllable manipulation of their fluorescent properties in different phases is still challenging, which seriously limits the related applications of nanocomposites. In this work, a convenient protocol to fabricate organic-inorganic nanocomposites composed of stilbene chromophores and CdZnS/ZnS quantum dots (QDs) pairs, with controllable fluorescent properties is presented. It is found that stable white-light emission can be achieved only in solution phase, with negligible energy transfer or reabsorption between chromophores and QDs pairs. By contrast, when the nanocomposites are deposited as blended films, they cannot give rise to white-light emission, no matter what donor/acceptor volume ratios are used. However, the blended films can exhibit near-unity efficiency (94%) of Förster resonance energy transfer from QDs to chromophores. The underlying physical mechanisms are revealed through comprehensive steady-state and time-resolved spectroscopic analysis. This work suggests that the CdZnS/ZnS QDs/stilbene nanocomposites can be directly used for fluorescence sensors and probes in biological system as well as fundamental investigation of light-harvesting, and also sheds light on developing other new materials for artificial photosynthesis and optoelectronics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Perkgoz N.K.,Institute of Materials Science and Nanotechnology | Toru R.S.,Institute of Materials Science and Nanotechnology | Unal E.,Institute of Materials Science and Nanotechnology | Sefunc M.A.,Institute of Materials Science and Nanotechnology | And 6 more authors.
Applied Catalysis B: Environmental | Year: 2011

We propose and demonstrate photocatalytic hybrid nanocomposites that co-integrate TiO2 and ZnO nanoparticles in the same host resin to substantially enhance their combined photocatalytic activity in the near-UV and visible spectral ranges, where the intrinsic photocatalytic activity of TiO2 nanoparticles or that of ZnO nanoparticles is individually considerably weak. For a comparative study, by embedding TiO2 nanoparticles of ca. 6nm and ZnO nanoparticles of ca. 40nm in the sol-gel matrix of acrylic resin, we make thin film coatings of TiO2-ZnO nanoparticles (combination of TiO2 and ZnO, each with a mass ratio of 8.5%), as well as the composite films of TiO2 nanoparticles alone (17.0%), and ZnO nanoparticles alone (17.0%), and a negative control group with no nanoparticles. For all of these thin films coated on polyvinyl chloride (PVC) polyester, we experimentally study photocatalytic activity and systematically measure spectral degradation (recovery obtained by photocatalytic reactions). This spectral characterization exhibits photodegradation levels of the contaminant at different excitation wavelengths (in the range of 310-469nm) to distinguish different parts of optical spectrum where TiO2 and ZnO nanoparticles are individually and concurrently active. We observe that the photocatalytic activity is significantly improved towards the visible range with the use of TiO2-ZnO combination compared to the individual cases. Particularly for the excitation wavelengths of photochemical reactions longer than 400nm, where the negative control group and ZnO nanoparticles alone yield no observable photodegradation level and TiO2 nanoparticles alone lead to a low photodegradation level of 14%, the synergic combination of TiO2-ZnO nanoparticles achieves a photodegradation level as high as 30%. Investigating their scanning electron microscopy (SEM), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HRTEM), we present evidence of the heterostructure, crystallography, and chemical bonding states for the hybrid TiO2-ZnO nanocomposite films, in comparison to the films of only TiO2 nanoparticles, only ZnO nanoparticles, and no nanoparticles. © 2011 Elsevier B.V.

Yildirim A.,National Nanotechnology Research Center | Yildirim A.,Institute of Materials Science and Nanotechnology | Ozgur E.,National Nanotechnology Research Center | Ozgur E.,Institute of Materials Science and Nanotechnology | And 3 more authors.
Journal of Materials Chemistry B | Year: 2013

Although numerous mesoporous silica nanoparticle (MSN) drug carriers and theranostic agents with various surface functionalities have been designed in the last decade, their biocompatibility remains a matter of intensive debate. Here, we systematically evaluated interactions of a series of MSNs possessing different surface functional groups (ionic, polar, neutral, and hydrophobic) with blood constituents, in terms of their hemolytic activity, thrombogenicity, and adsorption of blood proteins on their surfaces. Using a hemolysis assay we showed that surface functionalization can reduce or even completely prevent the hemolytic activity of bare MSNs. We investigated thrombogenicity of MSNs by measuring prothrombin time (PT) and activated partial thromboplastin time (aPTT). We observed that none of the MSNs used in this study exhibit significant thrombogenic activity. Lastly, we examined non-specific protein adsorption on MSN surfaces using human serum albumin (HSA) and gamma globulins (γGs) and found that surface functionalization with ionic groups can greatly reduce protein adsorption. Demonstration of the surface functionalization having a crucial impact on blood compatibility might serve as a guideline for further investigation related to the design of mesoporous silica systems for biomedical applications, and shed light on research towards the ultimate goal of developing smart theranostic systems. This journal is © The Royal Society of Chemistry 2013.

Yildirim A.,National Nanotechnology Research Center | Yildirim A.,Institute of Materials Science and Nanotechnology | Budunoglu H.,National Nanotechnology Research Center | Budunoglu H.,Institute of Materials Science and Nanotechnology | And 7 more authors.
ACS Applied Materials and Interfaces | Year: 2011

One-pot synthesis of fluorinated mesoporous silica nanoparticles (FMSNs) is reported. Uniform mesoporous nanoparticles are prepared by condensation of tetraethyl orthosilicate (TEOS) and fluoroalkyl containing organotriethoxy silane monomers, respectively. The method enables selective deposition of fluorine atoms on the surface of the particles. FMSNs are used to prepare stable liquid marbles with water. An organo-modified silica sol is used with FMSNs to prepare mechanically stable superhydrophobic surfaces (water contact angle of 161°). The mechanical stability of the surface is investigated with water dripping and adhesive tape tests. The prepared FMSNs are promising building blocks for robust, large-area, and multifunctional self-cleaning surfaces. © 2011 American Chemical Society.

Erdem T.,Institute of Materials Science and Nanotechnology | Demir H.V.,Institute of Materials Science and Nanotechnology | Demir H.V.,Nanyang Technological University
Nanophotonics | Year: 2013

Colloidal nanocrystals of semiconductor quantum dots (QDs) are gaining prominence among the optoelectronic materials in the photonics industry. Among their many applications, their use in artificial lighting and displays has attracted special attention thanks to their high efficiency and narrow emission band, enabling spectral purity and fine tunability. By employing QDs in color-conversion LEDs, it is possible to simultaneously accomplish successful color rendition of the illuminated objects together with a good spectral overlap between the emission spectrum of the device and the sensitivity of the human eye, in addition to a warm white color, in contrast to other conventional sources such as incandescent and fluorescent lamps, and phosphorbased LEDs, which cannot achieve all of these properties at the same time. In this review, we summarize the color science of QDs for lighting and displays, and present the recent developments in QD-integrated LEDs and display research. First, we start with a general introduction to color science, photometry, and radiometry. After presenting an overview of QDs, we continue with the spectral designs of QD-integrated white LEDs that have led to efficient lighting for indoor and outdoor applications. Subsequently, we discuss QD color-conversion LEDs and displays as proof-of-concept applications - a new paradigm in artificial lighting and displays. Finally, we conclude with a summary of research opportunities and challenges along with a future outlook. © 2013 Science Wise Publishing.

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