Browsing by Subject "Localized surface plasmon resonance"
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Item Open Access Developing a transducer based on localized surface plasmon resonance (LSPR) of gold nanostructures for nanobiosensor applications(Trans Tech Publications, 2013) Turhan, Adil Burak; Ataman, D.; Çakmakyapan, S.; Mutlu, M.; Özbay, Ekmel; Vlachos, D. S.; Hristoforou, E.In this work, we report the nanofabrication, optical characterization, and electromagnetic modeling of various nanostructure arrays for localized surface plasmon resonance (LSPR) based biosensing studies. Comparison of the experimental results and simulation outputs of various nanostructure arrays was made and a good correspondence was achieved.Item Open Access Influence of gold-silica nanoparticles on the performance of small-molecule bulk heterojunction solar cells(Elsevier BV * North-Holland, 2015) Xu, X.; Kyaw, A. K. K.; Peng, B.; Xiong, Q.; Demir, Hilmi Volkan; Wang Y.; Wong, T. K. S.; Sun, X. W.Light trapping by gold (Au)-silica nanospheres and nanorods embedded in the active layer of small-molecule (SM) organic solar cell has been systematically compared. Nanorod significantly outperforms nanosphere because of more light scattering and higher quality factor for localized surface plasmon resonance (LSPR) triggered by nanorods. The optimum concentration of nanorod was characterized by charge carrier transport and morphology of the active layers. At optimum nanorod concentration, almost no change in the morphology of the active layer reveals that LSPR and scattering effects rather than the morphology are mainly responsible for the enhanced power conversion efficiency. In addition, the preliminary lifetime studies of the SM solar cells with and without Au-silica nanorods were conducted by measuring the current density-voltage characteristics over 20 days. The results show that plasmonic device with nanorods has no adverse impact on the device stabilityItem Open Access LSPR enhanced MSM UV photodetectors(IOP Publishing, 2012-10-18) Butun, S.; Cinel, N. A.; Özbay, EkmelWe fabricated localized surface plasmon resonance enhanced UV photodetectors on MOCVD grown semi-insulating GaN. Plasmonic resonance in the UV region was attained using 36nm diameter Al nanoparticles. Extinction spectra of the nanoparticles were measured through spectral transmission measurements. A resonant extinction peak around 300nm was obtained with Al nanoparticles. These particles gave rise to enhanced absorption in GaN at 340nm. Spectral responsivity measurements revealed an enhancement factor of 1.5. These results provided experimental verification for obtaining field enhancement by using Al nanoparticles on GaN.Item Open Access Nanofabrication and plasma polymerization assisted surface modification of a transducer based on localized surface plasmon resonance of gold nanostructure arrays for biosensor applications(S P I E - International Society for Optical Engineering, 2012-07-31) Turhan, A. B.; Ataman, D.; Sen, Y.; Mutlu, M.; Özbay, EkmelThe nanofabrication and surface modification of a transducer based on localized surface plasmon resonance (LSPR) of gold nanostructure arrays for biosensing was studied. We used electron beam lithography for the nanopatterning technique, which let us choose LSPR sensor properties by providing immense control over nanostructural geometry. A critical step in the utilization of this transducer is to form a selective biolayer over the gold nanostructures. We applied plasma polymerization and wet chemistry techniques for ethylenediamine (EDA) modification and glutaraldehyde immobilization as intermediate layers, respectively. The gold nanostructure arrays were primarily modified using EDA in order to activate the surface with amine groups that are cross-linked with later added avidin molecules by the help of glutaraldhyde layer residing in between. The success of plasma polymerization was validated with x-ray photoelectron spectroscopy measurements. As a last step, we introduced biotin to the surface (biotin has a high affinity for avidin). We were able to detect the LSPR resonance wavelength shift in the transmission spectra at each step of modification, including the avidin-biotin interaction, which acts as a model for specific molecule detection using LSPR. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).Item Open Access Plasmonic nano-bio sensors for detection of E-coli bacteria(IEEE, 2009) Cinel, Neval A.; Bütün, Serkan; Çalışkan, Deniz; Özbay, EkmelBiological sensors, that rely on localized surface plasmon resonance exhibited by metallic nanocylinders fabricated using electron beam lithography and functionalized with the immobilization of biotin conjugated E-coli antibodies are investigated in this study.Item Open Access Plasmonic nanoparticle based nanobiosensors and nanophotodetectors(SPIE, 2013) Cinel, N.A.; Bütün, S.; Özbay, EkmelPlasmonics mainly deals with light-matter interactions in metallic nanostructures. It has gathered interest since its discovery due to the benefits it provides when compared with photonics and electronics. It owes its popularity to the tremendous number of applications it serves for. In this paper, we review how plasmonic nanoparticles can be utilized in applications such as localized surface plasmon resonance based biosensing and enhancing performance of photodetectors. © 2013 SPIE.Item Open Access Plasmonic nanoparticle based nanobiosensors and nanophotodetectors(SPIE, 2013) Cinel, Neval A.; Bütün, S.; Özbay, EkmelPlasmonics mainly deals with light-matter interactions in metallic nanostructures. It has gathered interest since its discovery due to the benefits it provides when compared with photonics and electronics. It owes its popularity to the tremendous number of applications it serves for. In this paper, we review how plasmonic nanoparticles can be utilized in applications such as localized surface plasmon resonance based biosensing and enhancing performance of photodetectors. © 2013 SPIE.Item Open Access SILVER nano-cylinders designed by EBL used as label free LSPR nano-biosensors(SPIE, 2011) Cinel, Neval A.; Bütün, Serkan; Özbay, EkmelLocalized Surface Plasmon Resonance (LSPR) is based on the electromagnetic-field enhancement of metallic nano-particles. It is observed at the metal-dielectric interface and the resonance wavelength can be tuned by the size, shape, and periodicity of the metallic nanoparticles and the surrounding dielectric environment. This makes LSPR a powerful candidate in bio-sensing. In the present work, the size and period dependency of the LSPR wavelength was studied through simulations and fabrications. The surface functionalization, that transforms the surface into a sensing platform was done and verified. Finally, the concentration dependency of the LSPR shifts was observed. All the measurements were done by a transmission set-up. The study is at an early stage, however results are promising. The detection of specific bacteria species can be made possible with such a detection method. © 2011 SPIE.Item Open Access Synthesis of nanoparticles by laser ablation in liquid method and optical applications(Bilkent University, 2023-08) Taylan, UmutPulsed laser ablation in liquids (PLAL) method is a fast, green, and straightforward method that can be used to synthesize pure nanoparticles free of ligands, capping agents, and waste products. Several types of nanoparticles such as metals, oxides, alloys, semiconductors, composite and compound nanoparticles with spherical or complex morphologies can be synthesized with PLAL method. In this thesis, AuCu nanoparticles for photovoltaic application, AgCu nanoparticles for tunable optical properties, CuS/Cu1.8S nanoparticles for photothermal and photoacoustic application, and (Y0.83Yb0.16Er0.01)2O3 nanoparticles for upconversion photoluminescence application are synthesized. The synthesized AuCu nanoparticles are used in organic solar cells and enhanced the photocurrent production, proven by the 21.4% increase in the power conversion efficiency. AgCu nanoparticles show composition and laser fragmentation dependent tunable surface plasmon resonance between 420 nm – 580 nm, giving 160 nm tunability. These nanoparticles also show complex morphologies with Janus nanoparticle and core-shell type configurations. Copper sulphide nanoparticles show a broad absorbance in the NIR region with absorbance peak at 1183 nm. Nanoparticles with 1 mg/mL concentration show a 52.2 °C temperature increase in 3 minutes of 3.23 W/cm2 1080 nm CW laser irradiation. Photoacoustic imaging experiments where copper sulphide nanoparticles are utilized show a significant contrast enhancement compared to ultrasonic imaging at 1 cm depth. The upconversion nanoparticles show an intense red emission at 651 nm from 980 nm laser irradiation and lowered green emission compared to the target material which shows nanoparticles produce more heat compared to the target which can be useful for photoluminescence – photothermal applications.Item Open Access Ultrasensitive electrospun fluorescent nanofibrous membrane for rapid visual colorimetric detection of H2O2(Springer Verlag, 2016-02) Senthamizhan A.; Balusamy, B.; Aytac Z.; Uyar, TamerWe report herein a flexible fluorescent nanofibrous membrane (FNFM) prepared by decorating the gold nanocluster (AuNC) on electrospun polysulfone nanofibrous membrane for rapid visual colorimetric detection of H2O2. The provision of AuNC coupled to NFM has proven to be advantageous for facile and quick visualization of the obtained results, permitting instant, selective, and on-site detection. We strongly suggest that the fast response time is ascribed to the enhanced probabilities of interaction with AuNC located at the surface of NF. It has been observed that the color change from red to blue is dependent on the concentration, which is exclusively selective for hydrogen peroxide. The detection limit has been found to be 500 nM using confocal laser scanning microscope (CLSM), visually recognizable with good accuracy and stability. A systematic comparison was performed between the sensing performance of FNFM and AuNC solution. The underlying sensing mechanism is demonstrated using UV spectra, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The corresponding disappearance of the characteristic emissions of gold nanoclusters and the emergence of a localized surface plasmon resonance (LSPR) band, stressing this unique characteristic of gold nanoparticles. Hence, it is evident that the conversion of nanoparticles from nanoclusters has taken place in the presence of H2O2. Our work here has paved a new path for the detection of bioanalytes, highlighting the merits of rapid readout, sensitivity, and user-friendliness.