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When a metal nanoparticle exhibits its unique dipole plasmon resonance, optical properties can be treated by considering a point dipole. Here we established a strong correlation between the surface-plasmon-induced coupled electric field in nanoparticle arrays and the extinction peak shifts. The model provides an effective way to explain the peak shifts caused by variation of the array structures. The extinction peak shifts of a one-dimensional silver cylinder array with different interparticle distances were predicted, and the results are in good agreement with those obtained by the discrete dipole approximation. [ABSTRACT FROM AUTHOR]

A Ag nanostructure was put forward in this paper. There are two types of Ag nanoparticles, spherical and pyramidal particles. Both of them have the same period, but different height and shapes. The hybrid nanoparticles can produce the localized surface plasmon resonance (LSPR), which couples each other and leads to an extra peak transmission. Our UV-visible-IR spectrophotometer measurement results show that some extra small and sharp peaks appear besides the normal LSPR wave peaks in the transmittance spectrum. The hybrid Ag nanoparticles being used as nanosensors will be more sensitive and selective than the conventional LSPR-based nanosensors. [ABSTRACT FROM AUTHOR]

In this paper, a method is presented for designing the parameters of metallic nanoparticles introduced into ultra-thin film organic solar cells (OSCs) to improve the light absorption. On the basis of Mie theory, a relationship is setup between the scattering efficiency of localized surface plasmon resonance and the size parameter of metallic nanoparticles, by which metallic nanoparticles with optimal size can be designed to realize the highest ratio of resonant scattering to resonant absorption, thus light absorption enhancement of OSCs is maximized. By taking spherical Ag nanoparticles into an OSC system with an active layer of poly(3-hexylthiophene) and [6, 6]-phenyl-C61-butyric acid methyl ester as subject, light absorption increase of 26 % at an average wavelength of incident light is demonstrated. This design method is also applicable to other types of OSCs. [ABSTRACT FROM AUTHOR]

Specific protein detection in multiprotein coexisting environment by localized surface plasmon resonance (LSPR) biosensor is studied. After the surfaces of self-assembly fabricated triangular Ag nanoparticles on the chip are activated, a specific biological molecule layer with \delta-toxic protein identifying function is linked to the chip. Based on the LSPR spectrometer measurement system in our laboratory, \delta-toxic protein in sonicated Bacillus thuringiensis cell fractions (which consists of many kinds of proteins) is detected successfully by measuring the extinction spectrum of the chip. [ABSTRACT FROM PUBLISHER]

Abstract: A triangular hybrid Au–Ag nanoparticles array was proposed for the purpose of biosensing in this paper. Constructing the hybrid nanoparticles, an Au thin film is capped on the Ag nanoparticles which are attached on glass substrate. The hybrid nanoparticles array was designed by means of finite-difference and time-domain (FDTD) algorithm-based computational numerical calculation and optimization. Sensitivity of refractive index of the hybrid nanoparticles array was obtained by the computational calculation and experimental detection. Moreover, the hybrid nanoparticles array can prevent oxidation of the pure Ag nanoparticles from atmosphere environment because the Au protective layer was deposited on top of the Ag nanoparticles so as to isolate the Ag particles from the atmosphere. We presented a novel surface covalent link method between the localized surface plasmon resonance (LSPR) effect-based biosensors with hybrid nanoparticles array and the detected target molecules. The generated surface plasmon wave from the array carries the biological interaction message into the corresponding spectra. Staphylococcus aureus enterotoxin B (SEB), a small protein toxin was directly detected at nanogramme per milliliter level using the triangular hybrid Au–Ag nanoparticles. Hence one more option for the SEB detection is provided by this way. [Copyright &y& Elsevier]

Abstract: Fabrication and characterization of rhombic silver nanoparticles array being used as a localized surface plasmon resonance (LSPR)-based nano-biosensor were reported in this paper. The sensor consists of a rhombic Ag nanoparticles array with single particle dimension of ∼140nm in-plane width and 47nm out-of-plane height. Characteristics of the nanoparticles such as extinction spectroscopy properties, refractive index sensitivity, and concentration of the target molecules were analyzed. The LSPR-based extinction spectra of the antigen or antibody with lower concentration were detected. The detection results from 100nM target molecule indicate a larger peak wavelength shift for the rhombic nanoparticles-based nano-biosensor than that of the reported triangular particles-based biosensor. Using a discrete dipole approximation (DDA) algorithm aided design approach we demonstrated that the refractive index sensitivity is 330nm per refractive index unit for the fabricated rhombic Ag nanoparticles array. [Copyright &y& Elsevier]

A new silver (Ag) nanostructure with a rectangular distribution array composed of rhombic nanoparticles is described here. The structure has an apparent advantage of strong hot spots that have a much higher signal intensity than that of the previously reported traditional triangular structures. It generates a great enhancement of a localized surface plasmon resonance (LSPR) effect. Moreover, an antigen with longer arm length is applied to strengthen the binding signals of both the antigen and antibody. We performed experiments for the LSPR-induced extinction spectra in each step of the surface modification of the Ag nanoparticles in atmosphere environment. A spectrophotometer was used to measure the extinction spectrum of our proposed nanochip. The results obtained indicate a better sensitivity for our current nanochip than that of the other reported LSPR-based nanochips. Theoretical computational numerical simulation is also carried out with a discrete dipole approximation algorithm. Our computational results are in agreement with the corresponding experimental spectrum. This type of nanochip may have potential utility in many applications, including medical science, biological fields and biochemical analysis. [ABSTRACT FROM AUTHOR]

Abstract: A localized surface plasmon resonance (LSPR) nanosensor by using a rhombic Ag nanoparticle array is proposed and developed. The LSPR extinction spectra of the antigen or antibody with lower concentration are detected. The obtained results detected from 100nM target molecule indicate a larger wavelength shift for the rhombic based nanosensor than the triangular based nanosensor. By experimental detection, we demonstrated that the refractive index sensitivity is 266.2nm per refractive index unit for Ag rhombic nanoparticle with in-plane width of ∼140nm and out-of-plane height of 47nm. [Copyright &y& Elsevier]

The modulation of microwave radiation enhanced by gold nanoparticles in graphene antenna is proposed in this paper. In the graphene antenna, the microwave is modulated directly by optical wave based on wideband interaction in the graphene. With the localized optical field absorption enhanced in graphene layer excited by gold nanoparticles, the microwave radiation is enhanced. As gold nanoparticles with the diameter of 200 nm is introduced in the device, the optical absorption is enlarged and the measured modulation of microwave radiation is enhanced about 7.5 times when the optical wave with the wavelength of 532 nm is utilized as the modulating light. • The optical doping of graphene changes the microwave radiation, light signal transfer to microwave signal directly. • Graphene is placed at the radiation region of antenna, strong interaction between microwaves. • Gold nanoparticles enhance the optical doping of graphene by localized resonance, higher modulation depth. • Microwave modulation by optical wave is nonlinear when gold nanoparticle introduced. [ABSTRACT FROM AUTHOR]