Optical fiber surface plasmon resonance sensor using electroless-plated gold film for thrombin detection.

This paper describes the simple and label-free detection of thrombin using optical fiber surface plasmon resonance (SPR) sensors based on gold films prepared by the cost-effective method of electroless plating. The plating conditions for simultaneously obtaining gold film on cylindrical core and end surfaces of an optical fiber suitable for measurement were optimized. The fabricated sensor exhibited a linear refractive index sensitivity of 2150 nm/RIU and 7.136 (a.u.)/RIU in the refractive index of 1.3329-1.3605 interrogated by resonance wavelength and amplitude methods respectively and a single wavelength monitoring method was proposed to investigate the sensing performance of this sensor. Polyadenine diblock and thiolated thrombin aptamers were immobilized on gold nanoparticles and gold films respectively to implement a sandwich optical fiber assay for thrombin. The developed optical fiber SPR sensors were successfully used in the determination of thrombin down to 0.56 nM over a wide range from 2 to 100 nM and showed good selectivity for thrombin, which indicated their potential clinical applications for biomedical samples.

Silver-decorated hierarchical cuprous oxide micro/nanospheres as highly effective surface-enhanced Raman scattering substrates.

A facile and simple route to manufacture active surface-enhanced Raman scattering (SERS) substrate based on Ag-decorated Cu2O micro/nanospheres on Cu foil was systematically investigated. Hierarchical Cu2O micro/nanostructure transfers from CuO nanosheets and Cu(OH)2 nanowires by means of thermally reducing the oxides from Cu2+ to Cu1+ at temperature of 500 °Cunder nitrogen atmosphere. The subsequent decoration of Ag on Cu2O nanostructural substrate was carried out by means of thermal evaporator deposition. Using 4-aminothiophenol (4-ATP) as probing molecules, the SERS experiments showed that the Ag-decorated Cu2O micro/nanospheres exhibit excellent detecting performance, which could be used as effective SERS substrate for ultrasensitive detection. Additionally, these novel hierarchical SERS substrates showed good reproducibility and a linear dependence between analyte concentrations and intensities, revealing the advantage of this method for easily scale-up production.

Super-resolution imaging using proximity projection grating and structured light illumination.

This paper addresses optical super-resolution in the far field. We will describe the use of a novel optical component, which we call the proximity projection grating (PPG), that can provide different intensity patterns for sample illumination. These different illumination patterns allow the optical system to perform various modes of imaging, all are capable of resolution beyond the Abbe diffraction limit. Results will be shown to demonstrate the operations of some of these imaging modes. The potential of the PPG unit will also be discussed.

Polarization modulation thermal lens microscopy for imaging the orientation of non-spherical nanoparticles.

In this paper a far field optical technique we call polarization modulation thermal lens microscopy (PM-TLM) is used for imaging the orientation and dichroism of non-spherical nanoparticles. In PM-TLM, the polarization state of a pump beam is periodically modulated which in turn causes morphology related intensity fluctuations in a continuous probe beam, thus allowing high signal to noise ratio detection with using lock-in amplification. Since PM-TLM uses nanoparticle absorption as the contrast mechanism, it may be used to detect and image nanoparticles of far smaller dimensions than can be observed by conventional dark field optical microscopy. The technique, its implementation and experiment results are presented.

Proximity projection grating structured light illumination microscopy.

Structured illumination has been employed in fluorescence microscopy to extend its lateral resolution. It has been demonstrated that a factor of 2 improvement can be achieved. In this paper, we introduce a novel optical arrangement that can further improve the resolution. It makes use of a fine grating held in close proximity to the sample. The fringe pattern thus projected onto the sample contains grating vectors substantially higher than those that are possible with the conventional structured illumination setup. We will present experimental results to demonstrate the principle of the technique, and will show that, theoretically, it can achieve an imaging NA approaching 4.

Terahertz spin-wave waveguides and optical magnonics in one-dimensional NiO nanorods.

The two-magnon (2M) spin waves with a magnon frequency of 43 THz, generated by a polarized laser, were first observed in one-dimensional (1D) NiO nanorods. The 1D NiO nanorods of ∼700 nm length, which have perfectly in-plane antiferromagnetic spins lying on the (200) and (100) faces, are the smallest spin-wave waveguides. Due to the magneto-optical Faraday effect (MOFE), the significant change in the Faraday intensity can show the 2M information in the NiO nanorods. There are only two 2M-on and 2M-off states at various applied alternating-current magnetic fields and laser-incident angles, which make the 1D NiO nanorods excellent optical nanomagnonics.

Thermally activated Cu/Cu2S/ZnO nanoarchitectures with surface-plasmon-enhanced Raman scattering.

Hierarchical Cu/Cu2S/ZnO nanoarchitectures were fabricated via an electroplated ZnO nanorod array in the first step, followed by the growth of Cu2S nanostructures for the application of surface-enhanced Raman scattering (SERS) detection. The Cu/Cu2S nanostructures as grown were thermally treated at 150-300°C under a nitrogen atmosphere to improve the crystalline quality, and, unexpectedly, to induce plasmonic Cu nanoshells on the surface of Cu2S. With 4-aminothiophenol (4-ATP) as probing molecules, SERS experiments showed that the thermally treated Cu/Cu2S/ZnO nanostructures exhibit excellent detection performance, so that they can serve as active and cost-effective SERS substrates for ultrasensitive detection. The enhancement is attributed to the coupling between Cu2S and plasmonic Cu, as confirmed by electromagnetic field simulations. This novel hierarchical substrate shows satisfactory reproducibility and a linear dependence of intensity on analyte concentration, revealing an advantage of this method for easily scaled production.

Impact of cuticle photoluminescence on the color morphism of a male damselfly Ischnura senegalensis (Rambur, 1842).

In this study the damselfly Ischnura senegalensis (Rambur, 1842) was first found to produce strong photoluminescence (PL) emissions from various colored-body portions, such as the eighth abdominal segment of the tail. The colors of the colored-body portions can be enhanced or modified by the PL emissions for assistance in reducing intrasexual and male harassment, and improving mature mating and conspecific identity. Therefore, the PL emissions that contribute to the color modification and coloration are involved in the cuticle evolution of the damselflies. The micro-PL confocal images verify that the PL emissions can strongly influence the surface colors of the cuticle, and demonstrate why the damselfly Ischnura senegalensis is called a bluetail.

Double-grating-structured light microscopy using plasmonic nanoparticle arrays.

Structured illumination increases the spatial bandwidth of optical microscopes. We demonstrate bandwidth extension using a physical grating placed close to the sample. This comprises an array of elongated nanoparticles, whose localized surface plasmon resonance is polarization dependent. By arranging the particle orientation to vary with position the grating can be moved by changing the input polarization. A projected optical grating provides an additional independent mechanism for bandwidth extension. Experimental results showing bandwidth improvement in one direction are presented, and the measures necessary to extend the technique for routine imaging are discussed.