Bovine serum albumin (BSA) was used as a stabilizing agent and biofunctionalized layer for water-dispersed gold nanoparticles (NPs) synthesized from metal precursor HAuCl 4. The BSA binding to gold NPs was characterized qualitatively and quantitatively by transmission electron microscopy, UV-VIS and FTIR spectrophotometers. HER2 (human epidermal growth factor receptor 2) specific phage antibodies were attached to BSA stabilized gold NPs to form a gold–antibody complex. An ELISA (enzyme-linked immunosorbent assay) test was done to confirm the bioactivity of antibodies attached to gold NPs.

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Nano/micro polystyrene (PS) beads have found many applications in different fields spanning from drug delivery, bio-diagnostics, and hybrid plasmonics to advanced photonics. The sizes of the PS beads are an important parameter, especially in plasmonic and photonic experiments. In this work, we demonstrate a quick and straightforward method to estimate the diameters of sub-microspheres (0.2 μm to 0.8 μm) using the transmission spectra of a close-packed monolayer of polystyrene beads on glass or quartz substrates. Experimental transmission spectra of the PS monolayers were verified against finite-difference time-domain (FDTD) simulation and showed good agreement. The effects of the substrates on the transmission spectra and, hence, the accuracy of the method were also studied by simulation, which showed that common transparent substrates only cause minor deviation of the PS bead sizes calculated by the proposed method.

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This paper presents a summary of our results on studies of synthesis and biomedical application of optical nanoparticles. Gold, dye-doped silica based and core-shell multifunctional multilayer (SiO 2 /Au, Fe 3 O 4 /SiO 2 , Fe 3 O 4 /SiO 2 /Au) water-monodispersed nanoparticles were synthesized by chemical route and surface modified with proteins and biocompatible chemical reagents. The particles were conjugated with antibody or aptamer for specific detecting and imaging bacteria and cancer cells. The photothermal effects of gold nanoshells (SiO 2 /Au and Fe 3 O 4 /SiO 2 /Au) on cells and tissues were investigated. The nano silver substrates were developed for surface enhanced Raman scattering (SERS) spectroscopy to detect melamine.

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A simple low-cost system for detection of polycyclic aromatic hydrocarbon (PAH) in solution based on multiphoton ionization configuration is designed using a circulating ionization cell of 0.1 × 2 × 5 mm dimension with quartz optical window. Fourth harmonic emission of Nd:YAG laser (266 nm, 6 ns, 10 Hz, and 2 mJ) and second harmonic generation of distributed feedback dye laser (278 -286 nm, 20 ps, 10 Hz, and 300 μJ) were used as the ionization source. A high voltage of 800 V was applied to separate the ions after ionization. The photocurrent includes a sharp peak and a broad tail indexed to electron and ion currents, respectively. The lowest concentration of anthraxcene (C14H10) in order of few nano-grams per milliliter was detected by this multiphoton ionization configuration.

Spherical gold nanoparticles doped dye solution was used for laser active medium. Fluorescence and absorption spectral shapes of laser dye molecules were modified by the resonance energy transfer between gold nanoparticles due to localized surface plasmon effect. Laser pulse width and tuning range of a distributed feedback dye laser can be controlled by using various gold nanoparticle concentrations. The gold nanoparticles can be considered as a quenching element inside laser cavity to remove relaxation oscillation pulses at high pumping rate above threshold.