Papers by Keyword: Surface Plasmon Resonance (SPR)

Abstract: There are many methods for synthesizing magnetite nanoparticles. Most methods take a long time, and the result is undesirable. In this paper a green method was used to synthesize nanoparticles because it takes a short time and is both straightforward and eco-friendly. It is done by adding : =1:2 molar ratio solution with different amounts of extract and different amounts of NaOH solution for 20 min at different temperatures, in hotplate stirrers, to control their relative size. UV-Vis spectroscopy, vibrating sample magnetometer technique (VSM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the magnetite nanoparticles. The result confirms that the changes in amounts of NaOH and extract led to a change in the pH of a solution and that the increase in amounts of the extract caused the low addition of NaOH. These changes influenced the process of synthesis and characterization. The Uv-vis analysis confirms that the surface plasmon resonance had a highly visible brad peak in the 290–460 nm range, as well as a peak shift to shorter wavelengths (blue shift) with a pH change and a peak shift to longer wavelengths (red shift) with a temperature change. TEM imaging confirms that all the synthesized had a spherical shape with size changed according to a parameter change of within 40–9 nm. Magnetic analysis showed the magnetite nanoparticles synthesized have smaller sizes and are superparamagnetic with the influence of particle size on the magnetic properties, including Hc, Ms, and Mr.

Abstract: The production of a high-sensitivity surface Plasmon resonance (SPR) sensor depends on a few main factors, such as metal thin film types and thicknesses, light coupling techniques and acceptable EM wave polarization modes. This work is carried out to investigate the impact on the SPR characteristics of noble metal thicknesses, namely gold and silver, for optical sensor applications. To excite surface Plasmon polaritons (SPP), a Kretschmann prism coupling was used. The thicknesses of noble metal thin films were varied between t=30nm and 60nm. The characteristics of SPR peaks such as Q-factor and FWHM were studied in SPR signal analyses. In comparison with silver, Q-factor results showed an outstanding optical property of gold at t= 40 nm due to its high Q-factor values, which confirms its ability to produce excellent SPP quantities. In conclusion, gold noble metal at t= 40nm is capable of producing optimum SPR. In the development of the highly sensitive SPR sensor, this excellent criterion put gold as a spectacular candidate for optical sensor applications.

Abstract: The objective of this research is to advance the affectability of Surface Plasmon Resonance (SPR) biosensor utilizing core-shell Fe₃O₄@Ag nanoparticles (Fe₃O₄@Ag NPs) with a variation of Ag concentration (20, 40, 60, 80, 100) mM. Fe₃O₄@Ag NPs were synthesized by the aqueous solution method. The characterization by utilizing X-ray Diffractometer (XRD) depicts that the crystal structure of Fe₃O4 compares to the cubic inverse spinel structure and based on Transmission Electron Microscopy (TEM) estimation, the particle size average of Fe₃O₄@Ag NPs is 14.45 nm. The magnetic properties of Fe₃O₄@Ag NPs were evaluated by Vibrating Sample Magnetometer (VSM), the result appears that the more concentration of Ag increases, the more remanent magnetization (Mr), saturation magnetization (Ms), and coercitivity field (Hc) diminishes. In this research, a Fe₃O₄@Ag NPs, a spherical nanoparticle consisting of a spherical Fe₃O₄ core covered by an Ag shell, was used as an active material to enhance the signal detection of SPR, with a wavelength of 632.8 nm in the Kretschmann configuration. The system consists of a four-layer material, i.e., prism/Au film/ Fe₃O₄@Ag NPs. The results show that the SPR angle shifted to the larger angle of incident light by using Fe₃O₄@Ag NPs. However, the effect of Ag concentration appears that the more concentration of Ag extends, the lower angle of SPR shifts. The addition of a core-shell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity if the fractional volume of the core-shell is large.

Abstract: We have previously reported the surface plasmon resonance (SPR)-based biosensor ability for quantitatively differentiating bovine and porcine gelatin has been done by us before. However, it has some inaccuracies. By improving the method of detection, the results of this study shows that the difference between bovine and porcine gelatin was more distinguishable. The sensor response models acquired were nonlinear as in the previous study. However, they show different characteristics. The sensitivities of the sensor obtained are higher than those of the previous ones, i.e., 3.04^o and 4.29^o for bovine and porcine gelatin concentration change of 0.1%, respectively. And the sensor’s LOD and LOQ towards both gelatin concentrations were 0.22% and 0.74% (w/w), respectively.

Abstract: Weak stimulated emission cross-section of rare earth ions (REIs) as dopants inside various glass hosts are disadvantageous for practical applications and needs improvement. We determine the mechanism of Titania (TiO₂) nanoparticles (TNPs) mediated Surface Plasmon Resonance (SPR) assisted modification in the spectral properties of tellurite glass doped with Erbium (Er³⁺) ions. Transparent and thermally stable glass samples with varying TNPs contents are synthesized using melt-quenching technique. TEM images revealed the existence of TNPs with average size ranged from 16 to 26 nm. Glass containing 0.4 mol% of TNPs displayed an enhancement in the Raman signal by a factor of 2.25, 1.83, 1.98, 1.56 and 3.58 for the bands centered at 388, 495, 673, 758, and 845 cm^-1, which is attributed to the SPR assisted effects. Absorption spectra of TNPs embedded glass (devoid of erbium ions) manifested two surface plasmon (SP) bands at 552 and 580 nm. Up-conversion (UC) PL spectra showed three prominent bands centered at 525, 545, and 660 nm due to the Er³⁺ ion transition from the excited states to the ground state. Furthermore, glass containing 0.4 mol% of TiNPs exhibited an intensity enhancement by a factor of 30, and 28.57 (green bands) and 19.60 (red band), which are ascribed to the generation of strong local electric field mediated by SPR effect of TNPs situated in the vicinity of Er³⁺ ion. The presence of TNPs surface plasmon is asserted to be responsible for the alteration of the Er³⁺ ions absorbance and modification of the UC emission intensity. A correlation between SPR and Surface Enhance Raman Scattering (SERS) is established.

Abstract: Annealing time dependent optical properties of melt-quench synthesized Er³⁺-doped (0.5 mol%) zinc-boro-tellurite (ZBT) glasses containing silver (Ag) nanoparticles (NPs) (1.0 mol%) are reported. Heat treatment (HT) durations are varied to control NPs growth. Reduction of NPs sizes from 12.7 to 6.6 nm for HT time beyond 6 hr at 410 °C is ascribed to their diffusion limited growth. Surface plasmon resonance bands evidenced at 550 and 580 nm are red shifted. Luminescence intensity enhancement is majorly attributed to the local field effect of Ag NPs and quenching is due to the energy transfer from NPs to Er³⁺. Present glass compositions are promising for the development of photonic devices.

Abstract: We present fabrication of silver nanostructures on glass substrates using highly energetic and high fluence material ions generated by one shot of hot, dense and extremely non-equilibrium plasma such as found in modified dense plasma focus (DPF) device. The substrates were first placed at 4.0 cm and 6.0 cm from the top of anode. Nanodots and nanocapsules are observed in the scanning electron microscopy (SEM) images of silver ions deposited with DPF shot on glass. The interparticle distance is found to decrease whereas mean size of nanodots is found to increase slightly when the distance of glass substrate is increased from 4.0 cm to 6.0 cm. The X-ray diffraction (XRD) pattern of the fabricated nanostructures has peaks at 2θ equals 37.90o, 44.24o and 64.20o which correspond to (111), (200) and (220) planes of silver having face-centered cubic structure. The nanostructures obtained on glass placed at 4.0 cm show surface plasmon resonance (SPR) peak at 420 nm whereas nanostructures obtained on glass placed at 6.0 cm has a SPR peak at 428 nm. Redshift of the SPR peak is attributed to increased interaction as a result of decrease in interparticle distance of the nanostructures as well as increase in mean size of nanodots.

Abstract: In this paper, an effective, simple and universal method for cell immobilization was developed. A self-polymerization nanofilm of poly (dopamine) was used to fix yeast cells in microfluidic channels. The surface morphology of the poly (dopamine) film was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Water contact angles (WCA) was also used to characterize the surface property of the poly (dopamine) nanofilm. The WCA on the PDMS substrates rapidly decreased from 105° to 59.8° with an increase in poly (dopamine) coating time. The interfacial process of dopamine self-polymerization and the cell immobilization were measured in a label-free and real-time mode by a surface plasmon resonance (SPR) instrument. Finally the immobilized yeast cells were observed by using a light microscope. From the experimental results, the yeast cells can be easily immobilized on the microfluidic channels modified with the nanofilm of poly (dopamine), which will hold great potential for the immobilization, detection and further analysis of other suspension cells, such as blood cells.

Abstract: We propose a tapered fiber-optic based surface plasmon resonance (SPR) sensor. The plasmonic sensing is designed by coating the waist of tapered fiber-optic with gold. The transmission spectrum of SPR wavelength were investigated by 2D finite element method (FEM). The calculation shows that the dips of the resonance wavelength shift toward long wave direction with the thickness of gold film decreasing. And increasing the diameters of the waist core of tapered fiber-optic also makes the resonance wavelength shift long wave direction. Furthermore, changing the refractive index of the external samples from 1.333 to 1.343 with step of ~0.002, the SPR wavelength shifts linearly from 575.05nm to 472.5nm. Owing to its compact and simple configuration, it also provides a feasible program for the refractive index high sensitivity detection.Keywords: surface plasmon resonance (SPR); tapered fiber-optic sensor; surface plasma; finite element method (FEM); optical fiber sensor

Abstract: The photovoltaic devices with free electrons of nanometal were studied by nanometal scattering and near-field surface plasmon resonance (SPR) enhancing. The results revealed that devices with metal nonoparticles can improve the photoelectric conversion efficiency of solar cells. The metal nanoparticles roughness also reduced the incident light reflection and increased the electrical conductivity of metal characteristics.