Two-dimensional correlation localized surface plasmon resonance spectroscopy for analysis of the interaction between metal nanoparticles and bovine serum albumin

Time-resolved extinction spectra assisted with two-dimensional correlation spectroscopy (2DCOS) analysis and principal component analysis (PCA) were employed to investigate the interaction between bovine serum albumin (BSA) and metal nanoparticles (NPs). A series of localized surface plasmon resonance (LSPR) spectra of metal NPs were measured just after a small amount of BSA was added into metal colloids. Through 2DCOS analysis, remarkable changes in the intensities of the LSPR were observed. The interaction process was totally divided into three periods according to the PCA. Transmission electron microscopy, dynamic light scattering, and ζ-potential measurements were also employed to characterize the interaction between BSA and metal NPs. The addition of BSA brings silver NPs to aggregate through the electrostatic interaction between them, but it has less effect on gold NPs. In a gold and silver mixed system, gold NPs can affect the interaction of silver NPs and BSA, leading it to weaken. The combination of 2DCOS analysis and LSPR spectroscopy is powerful for exploring the LSPR spectra of the metal NP involved systems. This combined technique holds great potential in LSPR sensing through analysis of slight, slim spectral changes of metal colloids

Surface-enhanced raman scattering: metal nanostructures coated with langmuir-blodgett films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Optical spectroscopy and frequency upconversion properties of Tm3+ doped tungstate fluorophosphate glasses

Tungstate fluorophosphate glasses of good optical quality were synthesized by fusion of the components and casting under air atmosphere. The absorption spectra from near-infrared to visible were obtained and the Judd-Ofelt parameters determined from the absorption bands. Transition probabilities, excited state lifetimes and transition branching ratios, were, determined from the measurements. Pumping with a 354.7 nm beam from a pulsed laser. resulted in emission at 450 nm. due to transition D-1(2)-->F-3(4) in Tm3+ ions and a broadband emission centered at approximate to 550 nm attributed to the glass matrix. When pumping at 650 nm, two emission bands at 450 nm (D-1(2)-->F-3(4)) and at 790 nm (H-3(4)-->H-3(6)) were observed. Excitation spectra were also obtained in order to understand the origin of both emissions. Theoretical and experimental lifetimes were determined and,the results were explained in terms of multiphonon relaxation. (C) 2003 American Institute of Physics.

The characterisation of the protective film formed by benzotriazole on the 90/10 copper-nickel alloy surface in H2SO4 media

The nature of the protective film formed by benzotriazole (BTAH) on the surface of the 90/10 CuNi alloy in deaerated 0.5 mol L-1 H2SO4 solution containing Fe(III) ions as oxidant was investigated by weight-loss, calorimetric measurements, and by surface-enhanced Raman spectroscopy (SERS). The SERS measurements show that the protective film is composed by the [Cu(I)BTA](n), polymeric complex and that the BTAH molecules are also adsorbed on the electrode surface. A modification of the BET isotherm for adsorption of gases ill solids is proposed to describe the experimental results obtained from weight-loss experiments that suggest an adsorption in multilayers. Electrochemical studies of copper and nickel in 0.5 mol L-1 H2SO4 in presence and absence of BTAH have also been made as an aid to interpret the results. The calculated adsorption free energy of the cuprous benzotriazolate on the surface of the alloy is in accordance with the value for pure copper. (C) 2007 Elsevier Ltd. All rights reserved.

Optical spectroscopy and upconversion luminescence in Nd3+ doped Ga10Ge25S65 glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Optical spectroscopy of Er3+ and Yb3+ co-doped fluoroindate glasses

Optical absorption, Stokes, and anti-Stokes photoluminescence were performed on Er3+-Yb3+ co-doped fluoroindate glasses. For compounds prepared with a fixed 2 mol % ErF3 concentration and YbF3 contents ranging from 0 to 8 mol %, important upconversion processes were observed as a function of temperature and photon excitation energy. Based on the experimental data, two mechanisms for the upconversion (or anti-Stokes photoluminescence) processes were identified and analyzed in detail. At high Yb contents, the upconversion mechanisms are mostly determined by the population of the 2F5/2 levels of Yb3+ ions (or 4I11/2 levels of Er3+ ions, by energy transfer) regardless of the photon excitation energy and temperature of measurement. Moreover, green and red light emission have similar intensities when a large Yb3+ content is present. © 1998 American Institute of Physics.

Surface-enhanced Raman scattering (SERS) applied to cancer diagnosis and detection of pesticides, explosives, and drugs

The inelastic scattering of light, Raman scattering, presents a very low cross section. However, the signal can be amplified by several orders of magnitude, leading to the so-called surface-enhanced Raman scattering (SERS) phenomenon. Basically, the SERS effect is achieved when the target molecule (analyte) is adsorbed onto metallic nanoparticles, usually noble metals. This article presents an overview of the applications of SERS to cancer diagnosis and the detection of pesticides, explosives, and drugs (illicit and pharmacological). SERS is routinely applied nowadays to detect and identify analytes at very low concentrations, including for single-molecule detection. However, the application of SERS as an analytical tool requires reliable and reproducible SERS substrates, in terms of enhancement factors, which depends on the size, shape, and aggregation of the metallic nanoparticles. Therefore, the production of reliable and reproducible SERS substrates is a challenge in the field. Besides, the metallic nanoparticles can also induce changes in the system by possible interactions with the analyte under investigation, which must be taken into account. This review will present work in which, under certain specific experimental conditions, SERS has been analytically applied.

Enhanced optical properties of germanate and tellurite glasses containing metal or semiconductor nanoparticles

Germanium- and tellurium-based glasses have been largely studied due to their recognized potential for photonics. In this paper, we review our recent studies that include the investigation of the Stokes and anti-Stokes photoluminescence (PL) in different glass systems containing metallic and semiconductor nanoparticles (NPs). In the case of the samples with metallic NPs, the enhanced PL was attributed to the increased local field on the rare-earth ions located in the proximity of the NPs and/or the energy transfer from the metallic NPs to the rare-earth ions. For the glasses containing silicon NPs, the PL enhancement was mainly due to the energy transfer from the NPs to the Er3+ ions. The nonlinear (NL) optical properties of PbO-GeO 2 films containing gold NPs were also investigated. The experiments in the pico- and subpicosecond regimes revealed enhanced values of the NL refractive indices and large NL absorption coefficients in comparison with the films without gold NPs. The reported experiments demonstrate that germanate and tellurite glasses, having appropriate rare-earth ions doping and NPs concentration, are strong candidates for PL-based devices, all-optical switches, and optical limiting. © 2013 Cid Bartolomeu de Araujo et al.

Cr+3 distribution in Al1 and Al2 Sites of alexandrite (BeAl2O4: Cr3+) induced by annealing, investigated by optical spectroscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

USE OF THE LINEAR LIGHT SENSOR ILX554 IN OPTICAL SPECTROSCOPY

USE OF THE LINEAR LIGHT SENSOR ILX554 IN OPTICAL SPECTROSCOPY. This technical note describes the construction of a low-cost optical detector. This device is composed by a high-sensitive linear light sensor (model ILX554) and a microcontroller. The performance or the detector was demonstrated by the detection of emission and Raman spectra of the several atomic systems and the results reproduce those found in the literature.

Strategies for detecting DNA hybridisation using surface plasmon fluorescence spectroscopy

Die Anregung und Emission von Fluorophoren nahe planaren Metalloberflächen und schiefen Gittern wurde mittels Oberflächenplasmonen Fluoreszenz Spektroskopie (SPFS) untersucht. Die Fluorophore konnten durch das evaneszente Plasmonenfeld angeregt und die einzelnen Abregungskanäle identifiziert werden.Die Sensorarchitektur für den Nachweis der Hybridisierung bestand aus auf einer Streptavidin-Matrix immobilisierten unmarkierten Sondensträngen. Cy5 markierte Zielsequenzen wurden aus der Lösung hybridisiert und die Adsorptionskinetiken konnten oberflächensensitiv detektiert werden.Ein neues Detektionsschema für unmarkierte Zielstränge wurde mittels fluoreszenzmarkirten Sondensträngen realisiert. Die Hybridisierung führte zu der Bildung von steifen helikalen Bereichen in der Probe und separierte den Farbstoff von der Metalloberfläche. Reduzierte Fluorezenzlöschung zeigte daher das Hybridisierungsereignis an.Die Verwendung eines potentiellen Förster-Paares zur Detektion von DNA Hybridisierung wurde untersucht. Donor und Akzeptor wurden an Ziel- und Sondenstrang immobilisiert und das Hybridisierungsereignis konnte anhand der Auslöschung der Donor-Fluorezenz nachgewiesen werden.Schließlich wurde der Einsatz von einzelstrangbindenden Proteinen (SSB) zur Steigerung der Sensitivität bezüglich Basenfehlpaarungen betrachtet. Verdrängungsreaktionen zwischen Proteinen und markierten Zielsträngen wurden anhand von SPS und Fluorezenzkinetiken studiert.

Nanofabrication of Surface-Enhanced Raman Scattering Device by an Integrated Block-Copolymer and Nanoimprint Lithography Method

The integration of block-copolymers and nanoimprint lithography presents a novel and cost-effective approach to achieving nanoscale patterning capabilities. The authors demonstrate the fabrication of a surface-enhanced Raman scattering device using templates created by the block-copolymers nanoimprint lithography integrated method.