Surface plasmon resonance

About: Surface plasmon resonance is a research topic. Over the lifetime, 24909 publications have been published within this topic receiving 810976 citations. The topic is also known as: Surface plasmon resonance & SPR (technology).

The Synthesis of Size- and Color-Controlled Silver Nanoparticles by Using Microwave Heating and their Enhanced Catalytic Activity by Localized Surface Plasmon Resonance†

Abstract: Silver nanoparticles (Ag NPs) of various colors were synthesized within the mesopore structure of SBA-15 by using microwave-assisted alcohol reduction. The charge density is partially localized on the surface of these Ag NPs owing to localized surface plasmon resonance. This charge localization results in them having enhanced catalytic activity under visible light irradiation compared to Ag NPs obtained by thermal processes.

Electrochemical, Photoelectrochemical, and Surface Plasmon Resonance Detection of Cocaine Using Supramolecular Aptamer Complexes and Metallic or Semiconductor Nanoparticles

Abstract: Metallic or semiconductor nanoparticles (NPs) are used as labels for the electrochemical, photoelectrochemical, or surface plasmon resonance (SPR) detection of cocaine using a common aptasensor configuration. The aptasensors are based on the use of two anticocaine aptamer subunits, where one subunit is assembled on a Au support, acting as an electrode or a SPR-active surface, and the second aptamer subunit is labeled with Pt-NPs, CdS-NPs, or Au-NPs. In the different aptasensor configurations, the addition of cocaine results in the formation of supramolecular complexes between the NPs-labeled aptamer subunits and cocaine on the metallic surface, allowing the quantitative analysis of cocaine. The supramolecular Pt-NPs-aptamer subunits-cocaine complex allows the detection of cocaine by the electrocatalyzed reduction of H(2)O(2). The photocurrents generated by the CdS-NPs-labeled aptamer subunits-cocaine complex, in the presence of triethanol amine as a hole scavenger, allows the photoelectrochemical detection of cocaine. The supramolecular Au-NPs-aptamer subunits-cocaine complex generated on the Au support allows the SPR detection of cocaine through the reflectance changes stimulated by the electronic coupling between the localized plasmon of the Au-NPs and the surface plasmon wave. All aptasensor configurations enable the analysis of cocaine with a detection limit in the range of 10(-6) to 10(-5) M. The major advantage of the sensing platform is the lack of background interfering signals.

Optical biosensors based on ZnO nanostructures: advantages and perspectives. A review

Abstract: This review article highlights the application of beneficial physico-chemical properties of ZnO nanostructures for the detection of wide range of biological compounds. As the medical diagnostics require accurate, fast and inexpensive biosensors, the advantages inherent optical methods of detection are considered. The crucial points of the immobilization process, responsible for biosensor performance (biomolecule adsorption, surface properties, surface defects role, surface functionalization etc.) along with the interaction mechanism between biomolecules and ZnO are disclosed. The latest achievements in surface plasmon resonance (SPR), surface enhanced Raman spectroscopy (SERS) and photoluminescence based biosensors along with novel trends in the development of ZnO biosensor platform are presented.

Size dependence of refractive index of gold nanoparticles

Abstract: The extinction spectra of spherical gold nanoparticles suspended in a homogeneous media were measured and the results were adjusted with Mie's theory together with an appropriate modification of the optical properties of bulk material considering the limitation that introduces the size of nanoparticles on the dielectric function. Usually, the contribution of free electrons to the dielectric function is modified for particle size, while the contribution of bound electrons is assumed to be independent of size. This work discusses the separated contribution of free and bound electrons on the optical properties of particles and their variation with size for gold nanoparticles. The effects of dielectric function and its changes with size on extinction spectra near plasmon resonance are considered. The damping constant for free electrons was changed with size as usual and a scattering constant of C = 0.8 was used. For the bound electron contribution, two different models were analysed to fit the extinction spectra: on the one hand, the damping constant for interband transitions and the gap energy were used as fitting parameters and on the other, the electronic density of states in the conduction band was made size-dependent. For the first model, extinction spectra corresponding to particles with radius R = 0.7 nm were fitted using two sets of values of the energy gap and damping constant: Eg = 2.3 eV and or Eg = 2.1 eV and . For the second model, a simple assumption for the electronic density of states and its contribution to the dielectric function in terms of size allowed to adjust extinction spectra for all samples explored (from 0.3 to 1.6 nm radius). This last model uses only one parameter, a scale factor R0 = 0.35 nm, that controls the contribution of the bound electrons in nanoparticles. Contrast between the maximum and the minimum in the extinction spectra near the resonance at 520 nm or alternatively the broadening of the plasmon band can be used to determine the size of gold nanoparticles with radius smaller than 2 nm.