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There are a number of lipophilic cations that can be chosen; the triphenylphosphonium (TPP) ion is particularly unique for mitochondrion targeting, mainly due to its simplicity in structure and ease to be linked to the target molecules. In this work, mitochondrion-targeted AB

The reflections of today's world's dizzying technical and technological developments make it feel almost every way. From communication technology to defense industry, service production to healthcare technologies, the concept of technology that is in every conceivable area makes it feel intensely in lighting systems, as predicted. By the time the fire was found, humanity sought to escape the darkness, along with the invention of fire, to provide visual comfort and convenience to individuals in the lighting field, as well as warm-up or cooking. The lighting used in the past as a key lighting element provides visual contributions to ensure a wide range of psychological and perceptual interactions today, and is particularly rich in building facades.1 The accelerated development of lighting technology has contributed a great deal to the creation of structural fiction that is also exciting in architecture, and in particular, the lighting of historical structures gives an identity to both the structure and the area of the structure. Modern lighting technologies, on the other hand, enable the creation of authenticity in structures, while front lighting, which is unanalyzed without good analysis, can also cause considerable damage to the visual texture and historical values of structures. In this respect, it is important to select the architectural lighting criteria to be applied on the construction front. As a result of serious developments in technology since the last century, variations in lighting concepts have also begun. The lighting is implemented in conjunction with modern lighting luminaires placed on historical sites and contributes to both urban silhouette and urban fabric. Modern lighting elements provide identity to the city, as well as the creation of a warm urban space atmosphere2 The creation of attractive atmospheres also has positive results on human perception, thus opening the way for the development of such living areas in the tourism economy. With the lighting of historical sites, increasing the appeal of these structures is helping to develop social interactions and trade in these areas. In this respect, lighting designsshould not only be satisfied with the standards in this area, but should be well analyzed in social, economic and environmental factors, particularly esthetic elements. The lighting of structures in the status of cultural presence itself is an especially important design problem, while the historical structures of those structures symbolize the cities, they are in make lighting designs that will be implemented on these structures much more critical. The lighting architecture of historical structures, especially in cities that are in the forefront of historical identity, and in the landmark state of the city, is an increasingly common building practice in both our country and around the world. The study covers the principles of lighting designs of historical structures and reflections of the principles of practice in the individual psychology and visual perception

Impurities in trioctylphophine (TOP) strongly affect nanocrystal synthesis. 1-Octanol among other contaminants in TOP is identified for the first time as a functional impurity by H-1 NMR. The deliberate addition of 1-octanol into trioctylphosphine reduced particle size and modified photophysical properties of ZnCdSSe/ZnS colloidal nanocrystals. NMR analysis furthermore revealed that 1-octanol is bonded to the nanocrystal surfaces. The ratio of integrals for the O-CH2 protons of 1-octanol, which is the lowest compared to the other ligands, suggests that 1-octanol plays a critical role to tune the particle size of nanocrystals. The increased amount of 1-octanol added into TOP reduces the particle size from 9.8 to 7.2 nm, causing a progressive blue shift in the UV-vis and PL spectra but leaving the alloy composition unaffected. The rate of nonradiative processes is enhanced with the amount of 1-octanol added into TOP, correlating with higher dislocation density observed in the nanocrystals. As a conclusion, 1-octanol is proposed as a functional impurity that varies particle size and nonradiative photophysical processes in the ZnCdSSe/ZnS colloidal nanocrystals.

Counterfeiting is a growing issue and causes economic losses. Fluorescent inks containing In(Zn)P/ZnS/DDT colloidal nanoparticles are formulated and combined with a convenient optical device for authentication. The particle size and fluorescent colors of the colloidal nanoparticles were tuned by adjusting the reaction temperature. The particle stability and brightness were improved by the addition of dodecanethiol, coating the particle surface with an organic shell. Security patterns were printed on various substrates by applying the screen-printing technique. The patterns were invisible under daylight but observable under UV-light illumination, displaying five different emission colors. By adjusting the concentration of the nanoparticles in the ink, the security patterns were made almost not observable under UV-light illumination but clearly identified by a commercial fiber optics-based spectrometer and a handheld optical device, called a Quantag sensor that was developed in-house. Furthermore, the spectral signatures of barely noticeable patterns are unambiguously validated by the Quantag sensor. Accordingly, low cost and easily applicable anticounterfeiting technology powered by custom-formulated fluorescent inks and a handheld optical instrument are developed to authenticate valuable documents and products.

Strongly concentrated optical fields around a metal nanoparticle in the close vicinity of a dipole noticeably facilitate dramatic changes in the localized density of states due to hybrid photonic–plasmonic mode couplings as compared to that of the pure cavity mode fields. Significant variations of the field intensity in the presence of the metal nanoparticle elucidate enhanced light–matter interaction in a hybrid structure. The enhancement factor of the light–matter interaction is studied through the single-atom cooperativity parameter, which is directly proportional to the ratio of the fluorescence lifetimes of the off-resonant and on-resonant emission. A compact and cost-effective hybrid device, which includes a microfiber cavity, supporting whispering gallery modes, and a well-defined solid nanostructure, consisting of a gold nanoparticle core, overcoated by a silica shell, and decorated with CdS/CdSe quantum dots, is demonstrated to offer an outstanding potential for the enhancement of light–matter interaction. Surface plasmons of a gold nanoparticle, placed inside a hollow cylindrical nanostructure at the surface of a microfiber, are activated upon excitation of the dipoles of the quantum emitters, which are on-resonance with the whispering gallery mode. Time-resolved experiments demonstrate that the single-atom cooperativity parameter of the quantum dots is enhanced by a factor of about 4.8 in the presence of the gold nanoparticle being simultaneously in strong interaction with the cavity mode field and the metal nanoparticle’s surface plasmons.

In this paper, CdTe quantum dots (QDs)-doped single electrospun polymer nanofibers are partially coated with gold nanoparticles to form distinct hybrid photonic-plasmonic nanoresonators to investig...

In this study heteroleptic A

Engineered silica nanoparticles (SiNP) are emerging materials for medical applications. Evaluating biological responses of specific cells treated with engineered silica nanoparticles is however essential. We synthesized and characterized the physicochemical properties of silica nanoparticles with two different sizes of 10 and 100 nm (10SiNP and 100SiNP) dispersed in cell culture medium. HuH-7, an epithelial-like human hepatoblastoma cell line and SK-HEP-1, a liver sinusoidal endothelial cell line (LSEC) are employed to evaluate their biological responses for the SiNP treatment. Primary human lymphocytes are used to assess genotoxicity recommended by OECD guidelines while erythrocytes are used to assess hemolytic activity. The engineered silica nanoparticles are not able to produce radical species, to alter the mitochondrial membrane potential, and induce any adverse effects on cell proliferation. The colony formation ability of HuH-7 hepatoblastoma cells was not affected following the SiNP treatment. Furthermore, SiNPs do not induce hemolysis of red blood cells and are not genotoxic. These findings suggest that SiNPs regardless of the size, amount, and incubation time are biologically safe vehicles to deliver drugs or genes to the liver. © 2020 Elsevier B.V., İzmir Yüksek Teknoloji Enstitüsü, İYTE: 2012IYTEBAP06, This work was supported by the Izmir Institute of Technology [grant number 2012IYTEBAP06 ].

Green light-emitting CdSe@ZnS/ZnS (QD) nano-particles were synthesized; the photophysical and morphological properties of their films, which were prepared by spin coating from six different concentrations, corresponding to absorbance values of 0.6, 1.1, 1.6, 2.1, 2.8, and 4.0, were determined. Increasing the absorbance value from 0.6 to 4.0 did not change the photophysical properties of QD films to a large extent, whereas it resulted in an increment in QD film thickness from 20 to 110 nm. The films were utilized as an emissive layer in QD light-emitting diodes with poly(9-vinylcarbazole) (PVK), PVK:2-(4-biphenyllyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), and PVK:1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene (OXD-7) hole-transport layers (HTLs). The presence of PBD or OXD-7 in PVK reduced the efficiency values but played a positive role in the color purity and efficiency roll off. The maximum color temperature and electroluminescence wavelength shifts obtained with applied potential were 109, 50, and 50 K and 11, 5, and 5 nm for pure-PVK, PVK:PBD, and PVK:OXD-7-based devices, respectively. Hole mobility, capacitance (at 10(3) Hz), and charge-transfer efficiency values were 9.0 x 10(-7), 6.8 x 10(-7), and 4.2 x 10(-7) cm(2) V s(-1), 1.7, 1, and 1 nF, and 6.90%, 15.50%, and 16.10% for pure-PVK, PVK:PBD, and PVK:OXD-7-based devices, respectively. Enhanced color purity and lowered efficiency roll off obtained with PVK:PBD and PVK:OXD-7 HTLs were attributed to decreased capacitance, increased charge-transfer efficiency, and reduced Joule heating.

In this paper, a hybrid photonic-plasmonic resonator, which comprises an electrospun polymer fiber with a micrometer diameter and a core/shell nanostructure with a gold nanoparticle core, is constructed to investigate the dynamics of the coupled spontaneous emission of CdS/CdSe quantum dots (QDs). The gold nanoparticle core; covered with a silica shell, anchored with individual CdS/CdSe QDs, is placed inside a hollow cylindrical nanocavity formed on the surface of the microfiber to enable integration of the optical mode with the plasmonic effect, which is induced by the localized surface plasmons of the metal nanoparticle being present in the vicinity of the dipoles. The spontaneous emission rate of the QDs, coupled into the hybrid photonic-plasmonic mode, is measured to enhance by a factor of 23 via a time-resolved experimental technique. This result suggests that the regeneration of the optical mode-field inside the photonic-plasmonic resonator through the interaction of the dipoles with the localized surface plasmons of a metal nanoparticle strongly enhances the density of the electromagnetic states of the quantum emitters to facilitate an enhanced spontaneous emission within the host medium of the proposed polymer based-photonic structure.

Becer, C. Remzi/0000-0003-0968-6662; Ozcelik, Serdar/0000-0003-2029-0108; Geyik, Caner/0000-0002-8382-2186; Guler Celik, Emine/0000-0003-2381-9775; YILMAZ, GOKHAN/0000-0002-1803-5397; Odaci Demirkol, Dilek/0000-0002-7954-1381, WOS: 000424988400014, Over the past decade, there has been a great deal of interest in the integration of nanotechnology and carbohydrates. The advances in glyconanotechnology have allowed the creation of different bioactive glyconanostructures for different types of medical applications, especially for drug delivery and release systems. Therefore, the use of more efficient biocompatible nanocarriers with high loading capacity, low overall toxicity and receptor-mediated endocytosis specificity is still in focus for the enhancement of the therapeutic effect. Conjugation of sugar derivatives onto gold nanoparticles presents unique properties that include a wide array of assembling models and size-related electronic, magnetic and optical properties. Here, pH-responsive drug-conjugated glycopolymer-coated gold nanoparticles were prepared by functionalization of gold nanoparticles with thiol-terminated glycopolymers and then subsequent conjugation of doxorubicin (DOX). Among the four different glycopolymers, their drug release, physicochemical characterization (spectroscopy, particle size and surface charge) and in vitro bioapplications with four different cell lines were compared. As a result, pH-sensitive drug delivery via sugar-coated AuNPs was performed thanks to hydrazone linkages between glycopolymers and DOX. Comparative viability tests also demonstrated the efficiency of glycopolymer-DOX conjugates by fluorescence cell imaging. The obtained results reveal that AuNP homoglycopolymer DOX conjugates (P4D) have significant potential, especially in human neuroblastoma cells in comparison to cervical cancer cells and lung cancer cells.

Counterfeiting is a growing economic and social problem. For anticounterfeiting, random and inimitable droplet/fiber patterns were created by the electrospinning method as security tags that are detectable under UV light but invisible in daylight. To check the authenticity of the original security patterns created; images were collected with a simple smartphone microscope and a database of the recorded original patterns was created. The originality of the random patterns was checked by comparing them with the patterns recorded in the database. In addition, the spectral signature of the patterns in the droplet/fiber network was obtained with a simple and hand-held spectrometer. Thus, by reading the spectral signature from the pattern, the spectral information of the photoluminescent nanoparticles was verified and thus a second-step verification was established. In this way, anticounterfeiting technology that combines ink formula, unclonable security pattern creation and two-level verification is developed.

PubMed: 31334629, This letter describes formation of single chain cationic polymer dots (Pdots) made of poly[1,4-dimethy1-1-(34(2,4,5-trimethylthiophen-3-yl)oxy)propyl)piperazin-1-ium bromide] conjugated polyelectrolyte (CPE). The single chain Pdot formation relies on a simple process which is a rapid nanophase separation between CPE solution of ethylene glycol and water. Pdots show narrow monodisperse size distribution with a 3.6 nm in diameter exhibiting high brightness and excellent colloidal and optical stability. It has been demonstrated that photoluminescent Pdots provide selective nuclear translocation to hepatocellular carcinoma cells as compared to healthy liver cells. The Pdot labeling effectively discriminates cancer cells in the coculture media. Pdots hold great promise as a luminescent probe to diagnose cancer cells in histology and may guide surgeons during operations to precisely separate out cancerous tissue due to augmented fluorescence brightness.

Radiation therapy aims to kill or inhibit proliferation of cancer cells while sparing normal cells. To enhance radiosensitization, we developed 40 nm-sized gold nanoparticles targeting the nucleus. We exploited a strategy that combined RGD and NLS peptides respectively targeting cancer cell and the nucleus to initiate cell-death activated by x-ray irradiation. We observed that the modified gold nanoparticles were either translocated in the nuclei or accumulated in the vicinity of the nuclei. We demonstrated that x-ray irradiation at 225 kVp energy reduced cell proliferation by 3.8-fold when the nuclear targeted gold nanoparticles were used. We determined that the radiation dose to have a 10% survival fraction was reduced from 11.0 Gy to 7.1 Gy when 10.0 µg ml-1 of the NLS/RGD/PEG-AuNP was incubated with A549 cancer cells. We conclude that the peptide-modified gold nanoparticles targeting the nucleus significantly enhance radiosensitization.

WOS: 000336525400031, An ultraviolet photodetector with an active layer of solution processed polymer:quantum dot hybrid is introduced. Poly[9,9-di-(2-ethylhexyl)-fluoreny1-2,7-diy1] represents the polymer and ZI10.71 Cdo.29S is the quantum dot used for the device. Photophysical studies showed that an electron transfer from the polymer to the ternary quantum dot is thermodynamically favored. Quenching experiments performed between the polymer and quantum dot indicates the formation of a non-fluorescent complex with an association constant of 4.6 x 10(4)M(-1). The device structure of ITO/PEDOT:PSSIADS231BE: 50 wt% ZI10.71 Cd0.29S/A1 yielded a photoresponsivity value of 324 mAIIN at -4 V under 1 mIN/cm(2) illumination at 365 nm at room temperature and this value is further increased to 380 mAIIN as a result of annealing at 75 degrees C. (C) 2014 Elsevier B.V. All rights reserved., funds of Ege UniversityEge University [13GEE003]; state planning agencyTurkiye Cumhuriyeti Kalkinma Bakanligi, We acknowledge the project support funds of Ege University (PC #: 13GEE003) and funds provided by the state planning agency for SO.

CdSe0.75S0.25 nanoalloys were blended with asymmetric triblock copolymer of polystyrene-b-polyisoprene-b-polystyrene(PS-SIS) in tetrahydrofuran. The fraction of styrene block varies from 14 to 22% with respect to isoprene by mass. The morphology of the copolymer cast film experiences a phase change from cylinder to lamella. CdSe0.75S0.25 nanoalloys were prepared by two-phase method. The surface of the nanoalloys was capped by either oleic acid (OA) or n-tri-octylphosphonic acid (TOPO) in situ. The mean diameter of the alloyed particles is around 12 nm in both systems. The chemical nature of the nanoalloy surface was found to influence the dispersion of the particles over polymer volume. The size of the nanoalloy domains in PS is 50 nm, on average, consisting of approximately 0.7 wt% nanoalloys. However, the size of the nanoalloy domains is smaller when they are loaded into PS-SIS. The structure formation is predominantly determined by enthalpic compatibilization. Atomic force microscopy results suggest that the nanoalloys capped with TOPO sequester into PS-rich domains and enlarge the domain. On the other hand, the ones capped with OA prefer to locate in polyisoprene domains. The increase of particles over 1.0 wt% distorts the lamella structure., Turkish Academy of Sciences (TUBA-GEBiP)

Ozcelik, Serdar/0000-0003-2029-0108; Zafer, Ceylan/0000-0002-8407-2452; Varlikli, Canan/0000-0002-1081-0803 WOS: 000259133500029 We report optical and electrochemical properties of polyether derivatives of perylenediimides (PDIs) thin films formed in various materials (semiconductor, insulator, amorphous and self-assembly). Perylenediimides adsorbed on nanocrystalline TiO2 (NT) nanocrystalline alumina (NA), amorphous silicon (PS) and neat self-assemblied (SA) films were prepared and characterized based on spectroscopic, electrochemical, spectro-electrochemical techniques. The absorption and fluorescence spectra of PDIs in chloroform exhibit vibronic features. The fluorescence quantum yields (Phi(f)) of PDIs with end amino substituents in chloroform solutions are over 0.95, while the quantum yield of triethoxyphenyl substituted PDI Phi(f) value is 0.024 in solution. Optical spectroscopy proves that PDIs in metal oxide thin films form aggregated type complexes. An electrochromism, a color change from red to blue/violet, is observed on metal oxide films, that indicates existence of mono and dianion forms of PDIs. Reversibility of electrochemical reductions in NT film depends on the scanning rate. However, electrochromism in NA films is stable and reversibility is independent from scanning rate. Stable mono and diaionic species are formed on NA films. SA films show broad absorption peaks during the voltammetric scan. On the other hand. the first reduction onset potentials of PDIs are almost equal to the onset potential of capacitive current of TiO2 which lead to low efficiency in dye-sensitized solar cells. (C) 2008 Elsevier B.V. All rights reserved. European CommissionEuropean CommissionEuropean Commission Joint Research Centre [SES-CT-2003-502783]; Scientific and Technical Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Alexander von Humbolt Foundation of GermanyAlexander von Humboldt Foundation; State Planning Organization of Turkey (DPT). We acknowledge partial funding by the European Commission (FP6 MOLYCELL project-SES-CT-2003-502783), Scientific and Technical Research Council of Turkey (TUBITAK NATO A-2 support funds) and Alexander von Humbolt Foundation of Germany. We appreciate the project support funds of the State Planning Organization of Turkey (DPT).

The flow of information through the epidermal growth factor receptor (EGFR) is shaped by molecular interactions in the plasma membrane. The EGFR is associated with lipid rafts, but their role in modulating receptor mobility and subsequent interactions is unclear. To investigate the role of nanoscale rafts in EGFR dynamics, we used single-molecule fluorescence imaging to track individual receptors and their dimerization partner, human epidermal growth factor receptor 2 (HER2), in the membrane of human mammary epithelial cells. We found that the motion of both receptors was interrupted by dwellings within nanodomains. EGFR was significantly less mobile than HER2. This difference was likely due to F-actin because its depolymerization led to similar diffusion patterns between the EGFR and HER2. Manipulations of membrane cholesterol content dramatically altered the diffusion pattern of both receptors. Cholesterol depletion led to almost complete confinement of the receptors, whereas cholesterol enrichment extended the boundaries of the restricted areas. Interestingly, F-actin depolymerization partially restored receptor mobility in cholesterol-depleted membranes. Our observations suggest that membrane cholesterol provides a dynamic environment that facilitates the free motion of EGFR and HER2, possibly by modulating the dynamic state of F-actin. The association of the receptors with lipid rafts could therefore promote their rapid interactions only upon ligand stimulation.

We report the photophysical properties of 3,3′-diethyl-5,5′-dichloro-9-phenylthiacarbocyanine (DDPT) in methanol-in-oil (m/o) reverse micellar systems which form methanol droplets stabilized with anionic surfactant aerosol-OT (AOT) in n-heptane. The fluorescence quantum yield of DDPT is enhanced by a factor of 17 in the methanol droplet in comparison with bulk methanol. The fluorescence lifetimes of DDPT in m/o reverse micelles are prolonged up to 2.2 ns with increasing molar ratio of methanol to surfactant (w0=[MeOH]/[AOT]), whereas the fluorescence lifetime of DDPT in bulk methanol is 75 ps. The non-radiative rate constants of DDPT in the droplets are decreased by a factor of 40, resulting in a remarkable enhancement in quantum yields, indicating that internal motions of DDPT in the droplets are significantly reduced due to strong electrostatic interactions between the positively charged DDPT and the negatively charged sulfonate head-groups of AOT and the spatial confinement induced by the reverse micellar structure., TBAG-1939

We have performed femtosecond pump-probe spectroscopy measurements in 1,1’-diethyl- 3,3’-bis(4-sulfobutyl)-5,5’,6,6’-tetrachlorobenz imidazolocarbocyanine (also known as TDBC) J aggregates adsorbed onto silver colloidal surfaces. We show that the dependence on probe power and wavelength of the induced emission band dynamics, intensity, and position can only be explained by assuming stimulated emission from the one-exciton state. The stimulated emission originates from the amplification of the one-exciton state emission by an induced transition from the two-exciton state to the one-exciton state. One of the key causes of the stimulated emission is the formation of coherently coupled TDBC molecules on colloidal silver surfaces.

WOS: 000341457500028, A folic acid (FA) modified poly(epsilon-caprolactone)/clay nanocomposite (PCL/MMT-(CH2CH2OH)(2)-FA) resulting in selective cell adhesion and proliferation was synthesized and characterized as a cell culture and biosensing platform. For this purpose, first the FA modified clay (MMT-(CH2CH2OH)(2)-FA) was prepared by treating the organo-modified clay, Cloisite 30B [MMT-(CH2CH2OH)(2)] with FA in chloroform at 60 degrees C. Subsequent ring opening polymerization of 3-caprolactone in the presence of tin octoate (Sn(Oct)(2)) using MMT-(CH2CH2OH)(2)-FA at 110 degrees C resulted in the formation of MMT-(CH2CH2OH)(2)-FA with an exfoliated clay structure. The structures of intermediates and the final nanocomposite were investigated in detail by FT-IR spectral analysis and DSC, TGA, XRD, SEM and AFM measurements. The combination of FA, PCL and clay provides a simple and versatile route to surfaces that allows controlled and selective cell adhesion and proliferation. FA receptor-positive HeLa and negative A549 cells were used to prove the selectivity of the modified surfaces. Both microscopy and electrochemical sensing techniques were applied to show the differences in cell adherence on the modified and pristine clay platforms. This approach is expected to be adapted into various bio-applications such as 'cell culture on chip', biosensors and design of tools for targeted diagnosis or therapy., Ibidi GmbH, Ibidi GmbH is acknowledged for their supports to the cell culture studies.

WOS: 000331596100013, PubMed ID: 24176888, We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Antihuman epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MIT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved., Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109T573]; Federal Ministry of Education and Research (BMBF)Federal Ministry of Education & Research (BMBF) [01DL12013]; Ege UniversityEge University [2012/FEN/0071], This work is supported by Scientific and Technological Research Council of Turkey (TUBITAK, project number 109T573) and Federal Ministry of Education and Research (BMBF, project number 01DL12013). Also it was partially funded by Ege University Scientific Research Project (2012/FEN/0071). We are grateful to Michael Meyer (Gottfried Wilhelm Leibniz University of Hannover, Institute for Technical Chemistry) for his knowledge and time spent carrying out flow cytometry experiments. In addition our thanks go to F. B. Barlas (Ege University, Faculty of Science, Biochemistry department) for taking fluorescence microscope images.

Proceedings of the 16th International Conference on Dynamical Processes in Excited States of Solids, Reaching a control on the mesoscopic morphology and internal molecular arrangement of cyanine aggregates is an important step for realization of devices with tailor-made optical properties. Despite a wealth of research, understanding of the relationship between molecular organization, excitonic states and dynamics of aggregates is still preliminary. To this end, we have employed polarized absorption spectroscopy to investigate the relationship between internal molecular organization and excitonic states of J-aggregates in 1,1′,3,3′tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine (TTBC) thin films in poly-vinyl alcohol (PVA). Angular dependence of the UV-vis spectra has been measured at 11 different orientations between the electric field polarization and the macroscopic alignment axis. Aggregate spectral response consisted of an asymmetrically split Davydov pair of bands exhibiting opposite polarization: an H-band (505 nm, Lorentzian-like, polarized along the macroscopic film axis) and a J-band (594 nm, one-dimensional J-aggregate like band shape, polarized perpendicular to the macroscopic film axis). The polarized absorption observations were found to be consistent with a herringbone model for which the internal molecular arrangement, the excited state structure and dynamics have recently been detailed by us upon interpretation of isotropic absorption data in ionic aqueous solution., TÜBİTAK–NSF Joint Grant TBAG U-12

We have conducted Raman investigations on the cyanine dye 3,3‘-dimethyl-9-phenyl-4,5:4‘,5‘-dinaphthothiacarbocyanine (NTC) for which an enhanced Raman scattering occurs that is concomitant with the formation of aggregates, and for which resonance Raman and surface-enhanced Raman scattering can be excluded. The formation of aggregated molecules is determined through characteristic changes in absorption and fluorescence spectra. Also, fluorescence lifetime measurements for monomeric and aggregated NTC are reported and independently confirm aggregate formation. Off-resonance Raman measurements for NTC in various physical states confirm that molecular aggregation leads to an enhancement of Raman scattering of vibrational modes of the monomeric species (i.e., intramolecular modes) and an even greater relative enhancement of certain modes of the molecules involved more intimately with formation of the aggregate (i.e., intermolecular modes). Additionally, we make empirical band assignments for NTC from which we ...

We report molecular aggregate formation of TTBC (1,1′,3,3′- tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine) in submicrometer-sized PVA (poly(vinyl alcohol)) fibers by electrospinning. The formation of the molecular aggregate is examined by solution and instrumental parameters of electrospinning. The precursor solution of PVA/TTBC, in the range of 0.016-0.065 wt % is subjected to electrospinning under an electrical field ranging from 0.95 to 1.81 kV cm-1. Both randomly deposited and uniaxially aligned fibers are achieved by using two parallel-positioned metal strips as counter electrode. Photoluminescence and polarized Fourier transform infrared spectroscopies are employed to determine spectral properties of the fibers. H-aggregates are formed within the electrospun fibers, regardless of their alignment, and H- and J-type aggregates coexist in the alternative spin-coated and the cast films. A strongly polarized photoluminescence emission is observed in the direction of uniaxially aligned fibers as a result of the orientation of the H-aggregates along the fiber axis. We demonstrate that electrospinning is a process capable of forming and orienting TTBC aggregates during the structural development of the polymer/dye nanofibers. These fibrous films may potentially find applications in optics and electronics., TÜBİTAK TBAG-107T795

The solvatochromic and spectral properties of oxazolone derivatives in various solvents were reported. Fluorescence spectra clearly showed positive and negative solvatochromism depending on substituents. The solvatochromic plots and quantum chemical computations at DFT-B3LYP/6-31 + G(d,p) level were used to assess dipole moment changes between the ground and the first excited singlet-states. The electron accepting nitro substituent at the para-position increased the pi-electron mobility, however, the 3,5-dinitro substituent decreased the pi-electron mobility as a result of inverse accumulation of the electronic density as compared with that of its ground state. Experimental and computational studies proved that the photoinduced intramolecular electron transfer (PIET) is responsible for the observed solvatochromic effects. We demonstrate that PIET can be finely tailored by the position of the electron accepting and donating substituents in the phenyl ring of the oxazolone derivatives. We propose that the photoactive CPO derivatives are new molecular class of conjugated push-pull structures using azlactone moiety as the pi-conjugated linker and may find applications in photovoltaic cells and light emitting diodes.

Spherical silica nanoparticles of various particle sizes (∼10 to 100 nm), produced by a modified Stoeber method employing amino acids as catalysts, are investigated using Dynamic Nuclear Polarization (DNP) enhanced Nuclear Magnetic Resonance (NMR) spectroscopy. This study includes ultra-sensitive detection of surface-bound amino acids and their supramolecular organization in trace amounts, exploiting the increase in NMR sensitivity of up to three orders of magnitude via DNP. Moreover, the nature of the silicon nuclei on the surface and the bulk silicon nuclei in the core (sub-surface) is characterized at atomic resolution. Thereby, we obtain unique insights into the surface chemistry of these nanoparticles, which might result in improving their rational design as required for promising applications, e.g. as catalysts or imaging contrast agents. The non-covalent binding of amino acids to surfaces was determined which shows that the amino acids not just function as catalysts but become incorporated into the nanoparticles during the formation process. As a result only three distinct Q-types of silica signals were observed from surface and core regions. We observed dramatic changes of DNP enhancements as a function of particle size, and very small particles (which suit in vivo applications better) were hyperpolarized with the best efficiency. Nearly one order of magnitude larger DNP enhancement was observed for nanoparticles with 13 nm size compared to particles with 100 nm size. We determined an approximate DNP penetration-depth (∼4.2 or ∼5.7 nm) for the polarization transfer from electrons to the nuclei of the spherical nanoparticles. Faster DNP polarization buildup was observed for larger nanoparticles. Efficient hyperpolarization of such nanoparticles, as achieved in this work, can be utilized in applications such as magnetic resonance imaging (MRI)., Deutsche Forschungsgemeinschaft of the DIP program; Deutsche Forschungsgemeinschaft (DFG); State Planning Organization

Fluorescence decay dynamics and structure of a meso-tetrakis(p-sulfonatophenyl)porphyrin, referred to herein as either H2TSPP4- or TSPP, which aggregates in highly acidic homogeneous solution, are discussed. The fluorescence lifetime of the aggregate is found to depend on whether electronic excitation is to the B (Soret) state or the Q state. This finding is interpreted as indicating that the aggregate's effective size differs in the two cases. Also, a discussion is provided of possible nonradiative pathways that might affect measured fluorescence lifetimes. Specific structural changes that occur within the porphyrin upon N-protonation and incorporation within the aggregate are also discussed. Additionally, vibrational frequencies are assigned to specific bonds of the porphinato macrocycle, and comparisons are made between bond lengths in the aggregate environment and those of the monomeric dianion.

In this study, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS): cadmium sulfide selenide quantum dots (CdS0.75Se0.25 QDs) nanocomposites based OLEDs were fabricated. By the addition of CdS0.75Se0.25QDs into the polymer active layer, a considerable enhancement was observed in terms of hole and electron injection in devices. Additionally, the presence of QDs reduced the interchain interaction of polymer that resulted in narrower electroluminescence (EL) spectrum. The device structure of ITO/PEDOT: PSS/MEH-PPV-POSS: 25 wt% CdS0.75Se0.25/Ca (40 nm)/Al demonstrated the best performance with a brightness of 8672 cd/m 2 at 10 V, current efficiency of 2.5 cd/A at 8 V, and an EQE of 0.55% at 150 mA/cm2 .

We report a facile method for systematic tuning the hydrodynamic diameter of uniformed fluorescent silica particles in the size range from 12 to 465 nm. Dynamic light scattering and electron microscopy studies demonstrate that the hydrodynamic size distribution of the silica particles is uniform. We show that the initial amounts of ethanol and ammonia are essential to tune the size of these particles. The hydrodynamic diameter of such a particle increases as the amount of ammonia is increased. On the other hand, an increase in the amount of ethanol leads to the formation of smaller particles. Higher initial amount of ethanol yield an increase in the concentration of ethoxide ions and a decrease in the concentration of hydroxide ions. Such control over the concentration of hydroxide ion, which is responsible for the formation of siloxane bonds, causes a controlled-growth of the silica particles, resulting in precise tuning the hydrodynamic size. We confirm that a linear relationship exists between size and brightness of particles, demonstrating that the amount of dye molecules in such particles can be regulated by the presented method. We prove that the silica network provides protection for dye molecules encapsulated in particles against solvents, fluorescence quenchers, and unfavorable pH of environments. Moreover, the fluorescent silica particles with the size of 12, 50 and 250 nm were found to not be cytotoxic against the epithelial cell lines of MCF7 and PC3 even when the dosage levels up to 1.0 mg/ml and incubation periods up to 72 hours were applied.

Microwave-assisted synthesis, photophysical and electrochemical properties of thermal-stable naphthalene benzimidazoles and naphthalimides are studied in this paper. Microwave-assisted synthesis of naphthalene benzimidazoles provide higher yields than the conventional thermal synthesis. Comparative photophysical properties of naphthalene benzimidazoles and naphthalimides are revealed that conjugation of electron-donating group onto naphthalimide moiety increases fluorescence quantum yields. Fluorophore-solvent interactions are also investigated using Lippert-Mataga equation for naphthalimides and naphthalene benzimidazoles. Thermal stabilities of naphthalene benzimidazoles are better than naphthalimides due to increased aromaticity. The experimental E(LUMO) levels of naphthalene benzimidazoles are found to be between 3.15 and 3.28 eV. Therefore, naphthalene benzimidazole derivatives consisting of anchoring groups are promising materials in organic dye sensitized solar cells.

Composites of poly(glycidyl methacrylate) (PGMA) and L-lysine-coated silica nanoparticles with varying contents were prepared by in situ bulk polymerization using benzoyl peroxide (BPO) as free radical initiator. Silica nanoparticles covered by L-lysine molecules were synthesized using emulsion method. Dynamic light scattering measurements confirmed that the particles are highly monodisperse with the diameter of 10 nm and free of aggregates in the monomer (glycidyl methacrylate, GMA). Upon polymerization of the homogeneous particle/monomer dispersion, aggregates of individual silica nanoparticles are observed by tapping mode atomic force microscope (AFM). Amine and/or carboxylic acid sites on particle surface covalently react with the oxirane groups of the polymer backbone. The aggregation was substantially suppressed by using a difunctional comonomer divinyl benzene (DVB) in polymerization. A three-dimensional polymer network, P(GMA-DVB), forms throughout the system. This structure leads to significant progress in particle dispersion, therefore in physical properties of the resulting composite. We demonstrated that the composites prepared by crosslinked chains are thermally more stable and mechanically stiffer than those prepared by linear ones., TÜBİTAK TBAG-109T905; TÜBİTAK TBAG-108T446; State Planning Organization (DPT-2003K120690-6)

Submicrometer diameter, light emitting fibers of poly(vinyl alcohol) (PVA) doped with pseudoisocyanine (1, 1'-diethyl-2,2'-cyanine bromide, PIC) dye were prepared by electrospinning. A horizontal setup was employed with a stationary collector consisting of two parallel-positioned metal strips separated by a void gal). Formation of uniaxially aligned and randomly deposited fibers in electrospun films was confirmed by microscopy. Photoluminescence (PL) spectroscopy is used to evaluate spectral properties of both types of fibers doped with PIC. While PIC molecules were individually dispersed in PVA Solution, they assemble into J-aggregates upon electrospinning when the weight fraction of PIC molecules is above 2.5 wt%. The formation of J-aggregates was observed in both randomly deposited and Uniaxially aligned electrospun fibers. Moreover, the fibers aligned uniaxially showed a high degree of polarized emission (PL(parallel to)/PL(perpendicular to) = 10), arising from the orientation of J-aggregates along the fiber axis. On the other hand, isotropic emission of J-aggregates was observed from the fibers deposited randomly. As a conclusion, electrospinning was found to be an efficient and a practical method to form highly oriented J-aggregates dispersed into polymer fibers. To the best Of Our knowledge, it is the first time formation of J-aggregates (a bottom-up approach) and electrospinning (a top-down approach) is successfully combined.

2009 14th National Biomedical Engineering Meeting, BIYOMUT 2009; Balcova, Izmir; Turkey; 20 May 2009 through 22 May 2009

Luminescent fibrous composite films consisting of submicrometer diameter fibers were prepared by electrospinning of segmented polycarbonate urethane (PCU) in dimethyl formamide and tri-n-octylphosphine oxide (TOPO)-capped CdSe nanocrystals (5 nm in diameter) in toluene. Using a pair of conductive electrodes separated with an air gap, we successfully produced randomly deposited and uniaxially aligned electrospun fibers. The surface structure of the electrospun fibers was studied using atomic force microscopy (AFM) and was compared to the corresponding film prepared by casting. In cast film, tapping mode AFM imaging suggests that hard urethane segments organize into rodlike morphology dispersed in soft polycarbonate. When PCU/ CdSe dispersions were subjected to electrospinning, copolymer domains were forced to arrange into lamella along the fiber axis due to elongational flow and high stretching. Molecular orientation in the domains of the composite fibers was confirmed by polarized infrared spectroscopy. We demonstrated that formation of the oriented domains by electrospinning develops a hierarchical structure, which consequently modifies spectral properties because new multiple sharp lines appeared in the photoluminescence (PL) spectra of the fibers. In contrast to randomly deposited fibers, the PL intensity of uniaxially aligned fibers was found to be angle dependent. We propose that the elongated internal structure within the fibers controls the spontaneous emission of CdSe nanoparticles dispersed throughout the electrospun mat. A discussion on the nature of the controlled spontaneous emission is provided.

The structure–spectroscopy–function relationship of 1,1′,3,3′-tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine (TTBC) aggregates is studied using a combination of experimental and theoretical techniques. The aggregates are macroscopically aligned in poly-vinyl-alcohol thin films by vertical spin coating. Angular dependence of the UV–Vis spectra is measured at eleven different orientations between the electric field polarization and the macroscopic alignment axis. The aggregates are characterized by a pair of Davydov split bands with opposite polarization behaviors: an H-band (505 nm) and a J-band (594 nm) polarized respectively, close to being parallel and perpendicular to the alignment axis. Spectral response is interpreted via simulations within the Frenkel exciton formalism. TTBC aggregates are shown to assume very similar internal molecular packing (herringbone) and dynamics of excited states (phonon-assisted intraband and interband relaxations) in ionic aqueous solution and in thin films. The general conclusions on the structure–spectroscopy–function relationship are expected to hold for other cyanine aggregates with the same generic spectral features.

Proceedings of the 16th International Conference on Dynamical Processes in Excited States of Solids, We argued against the current spectral assignment for absorption spectrum of monomeric PIC which is widely accepted since the pioneering works of Scheibe and Jelley [G. Scheibe, Angew. Chem. 49 (1936) 563; E.E. Jelly, Nature 138 (1936) 1009]. A new spectrum is presented along with its conceptual basis. The hypothesized spectrum attributes the previous 0-0 (≈525 nm) and 0-1 (≈490 nm) assignments, respectively, to intermediates acting as the precursor of J-aggregates and to the 0-0 transition of monomeric PIC and brings the spectrum in accord with the seemingly universal spectral fingerprint of cyanines. The hypothesis is used to analyze and interpret the temperature dependence of the UV-vis absorption of PIC aggregates in saline aqueous solution by incorporating the J-band simulations within frenkel exciton formalism. Its implications for aggregate formation kinetics are given on the basis of current spectroscopic evidence. The hypothesis readily answers several long-standing questions: Why compared to many other cyanines at least an order of magnitude higher dye concentration is needed to form J-aggregates of PIC? Why are there no precursors, since aggregation is expected to be a consecutive process? A large number of observations on steady-state and time-resolved spectral properties, and aggregation kinetics in solution/thin films are likely to find reasonable explanations within this hypothesis.

Strong experimental and theoretical evidence was provided on the controlled formation of the two-dimensional J-aggregates that were assembled in the herringbone morphology. The exciton-band structure formation of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachlorobenzimidazolocarbocyanine (TTBC) J-aggregates was investigated in ionic (NaOH) aqueous solution at room temperature. The control was achieved by changing the [TTBC] at a given [NaOH], or vice versa, and was monitored through the changes in the absorption, fluorescence excitation, and emission spectra. Specific attention was paid to expose the excited-state structure and dynamics through simulations of the excitonic properties, which included diagonal energetic disorder and phonon-assisted exciton relaxation. Aggregates were characterized by an asymmetrically split Davydov pair, an H-band (approximately 500 nm, 1300 cm(-1) wide, Lorentzian-like) and a J-band (approximately 590 nm, 235 cm(-1) wide, with a band shape typical of a one-dimensional J-aggregate), whose relative intensities showed a strong dependence on the [TTBC]/[NaOH]. The H-band is favored by high [TTBC] or high [NaOH]. An explanation of the control on the aggregate formation was given by correlating the changes in the absorption with the structural modifications and the subsequent changes in the dynamics, which were induced by variations in the dye and NaOH concentrations. The J-band shape/width was attributed to disorder and disorder-induced intraband phonon-assisted exciton relaxation. The intraband processes in both bands were estimated to occur in the same time scale (about a picosecond). It has been suggested that the wide energetic gap between the Davydov split bands (3000 cm(-1)) could get bridged by the excitonic states of the loosely coupled chains, in addition to the monomeric species at low [TTBC]. Phonon-assisted interband relaxation, through the band gap states and/or directly from the H- to the J-band, are suggested for accounting the difference between the bandwidths and shapes of the two bands. Energy transfer between the H-band and the monomeric species is suggested as crucial for tuning the relative strengths of the two bands.

An extremely low threshold for lasing from a specially formulated system involving self-assembled, aggregated molecules enables the system to function as a mirrorless laser. Superradiant energy states created in coherently coupled aggregated molecules emit photons that stimulate emission from other spatially distributed superradiant states. This study focuses on a cyanine dye (specifically, 1,1′-3,3′-tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine iodide) adsorbed onto silica colloid on which the dye aggregates, forming excitonic states involving coherent domains in which a finite number of molecules act cooperatively in the process of emitting photons. It is found that lasing from such a system is induced at a threshold of ca. 39 pJ/pulse, which corresponds to a factor of 3×10+4 times smaller than the lowest lasing threshold reported in the literature.

Overexpression of HER2 alters the cellular behavior of EGF receptor (EGFR) and itself,with great implications on cell fate. To understand the molecular interactions underlying these alterations, we quantified the association between the two receptors by looking at efficiency changes in fluorescence resonance energy transfer (FRET) between a small number of molecules at the membrane of living cells. Human mammary epithelial (HME) cells expressing varying degrees of HER2 were studied, to identify and compare the degree of receptors interactions as a function of HER2 overexpression. A high resolution wide-field laser microscope combined with a high sensitivity cooled CCD camera was used to capture simultaneously donor and acceptor emissions. Alternating between green and red lasers every 80 msec, donor, FRET, and acceptor images were acquired and were used to calculate FRET efficiency. Automated image analysis was developed to create FRET efficiency maps from overlapping donor, acceptor and FRET images, and derive FRET efficiency histograms to quantify receptorreceptor interactions pixel by pixel. This approach enabled us to detect subtle changes in the average distance between EGFR molecules, and between EGFR and HER2. We found pre-existing EGFR homoassociations, and EGFR-HER2 heteroassociations in cells overexpressing HER2, and identified the changes in these interactions with ligand stimulation. These observations demonstrate the power of FRET measurements between small numbers of molecules in identifying subtle changes in molecular interactions in living cell.

Cataloged from PDF version of article. We report the steady-state and the excited state properties of 1, 3, 1', 3' -tetraethyl-5, 6, 5', 6' -tetrachlorobenzimidazolocarbocyanine iodide (TTBC) in various solvents. The magnitude of the Stokes shift and the average transition energy proves that the structure of the fluorescent state should be very similar to that of the ground-state structure. The fluorescence lifetimes and quantum yields indicate that non-radiative processes are collectively much more effective than the radiative processes. It is therefore suggested that the non-radiative processes, which are driven by the medium around the TTBC molecule control the excited state dynamics. r 2002 Elsevier Science B.V. All rights reserved.

Emission lifetime and steady-state spectral measurements of aggregated and monomeric 3,3′-diethyl-5,5′-dichloro-9-phenylthiacarbocyanine (DDPT) in methanol and aqueous solutions at room temperature have been conducted. We deduce that in aqueous solution DDPT molecules that maintain their monomer emission lifetime and spectral properties exist intimately with molecules that are coherently interconnected in the excitonic structure. Simultaneous superradiance and monomer fluorescence from DDPT molecules occur and allows for a direct comparison of superradiance emission properties of aggregated molecules to the emission properties of the single molecule. We have found that the fluorescence lifetime of the aggregate is excitation wavelength dependent, and are led to conclude that superradiance by aggregated molecules and energy transfer from monomeric species to the aggregate play important roles in determining the optical dynamics of the aggregated system. We also report some of the photophysical properties of DDPT.

We report a facile method to synthesize highly luminescent colloidal CdSxSe1-x ternary nanoalloys. The synthesis is achieved exactly in one-step, one-pot and at low temperature, by applying the two-phase thermal approach. The optical and structural properties of the nanoalloys were characterized by various techniques. Photoluminescence of the nanoalloys is tunable from 435 to 545 nm by either the size or the composition of the nanoalloys. Highly luminescent nanoalloys having quantum yields up to 90% were prepared. The hydrodynamic size of the nanoalloys can be varied from 1.4 to 10.0 nm by the reaction time. DLS measurements showed that the size distribution of the nanoalloys is monodispersed. TEM images confirmed the size and the size distribution of the nanoalloys. The sulfur fraction in the nanoalloy composition, measured by XRD and verified by EDX, is modulated from 0.17 to 0.95 by increasing the amount of thiourea in the chalcogenide mixture. The sulfur-rich nanoalloys are formed when the initial mole ratio of the chalcogenide (S : Se) is equal or higher than eleven-fold. The gradient and homogeneous internal structures are revealed by analysis of the alloy composition as a function of the growth time. We propose that the two-phase approach, a non-injection technique, is a facile and versatile method to develop highly luminescent CdSxSe1-x nanoalloys without an inorganic coating layer.

The picosecond time-resolved emission spectrum of the cyanine dye 1,18-diethyl-3,38- bis-~3-sulfopropyl!-5,58,6,68-tetrachlorobenzimidazolocarbocyanine ~also known as BIC! adsorbed onto colloidal silver was examined as a function of laser pulse energy at room temperature. BIC is found to aggregate on colloidal silver, and the number of coherently responding molecules involved in the one-exciton state ~i.e., the coherence length! was estimated to involve 8–9 molecules. Lasing at a remarkably low incident pulse energy threshold was found for this system and explained in terms of a mechanism involving superradiant states created in coherently coupled adsorbed molecules that emit photons which stimulate emission from other spatially distributed superradiant states. © 1998 American Institute of Physics.