1. Insulin Sensing by 2D-SPR Observation of Rat Myoblast Cells upon Insulin Stimulation

   Yuki SHIRAISHI, Hiroaki SHINOHARA, and Minoru SUGA

   Graduate School of Innovative Life Science, University of Toyama, 930-8555, Toyama City Japan.
   

   Abstract: In this paper, we applied a two dimensional surface plasmon resonance (2D-SPR) system for insulin sensing by label-free observation of individual rat L6 myoblast cells (L6 cell) upon insulin stimulation. The L6 cells were cultured on a gold thin layer-coated glass chip. Individual L6 cells on the sensor chip were observed with a 2D-SPR sensor upon insulin stimulation. Insulin was detected in the concentration range from 5 to 100 μM by reflection intensity change after 50 min from insulin injection. We further considered the SPR response mechanism for insulin. The SPR signal response for insulin decreased in the presence of staurosporine or cytochalasin B. From these inhibitor experiments, we considered SPR response might reflect the insulin-induced initial kinase aggregation and following intracellular reactions such as actin-movement near the cell-bottom membrane. This L6 cell-based 2D-SPR system showed the usefulness of SPR observation for the label-free, simple, rapid, biosensing to various hormones with mammalian cells as sensing element and for the consideration of the intracellular reaction mechanism.

   Keywords: 2D-SPR, Insulin sensing, Rat myoblast, Intracellular reactions, Label-free observation techniques

   Pages: 23 – 31 | Full PDF Paper

2. Synthesis of Fluorescent Silica Hollow Nanoparticles Using Coumarin Fluorphore

   Min Min Yee¹, Yusuke Koyanagi ², Shin-ichi Yusa³ and Kenichi Nakashima⁴

   1. Department of Chemistry, University of Mandalay, Mandalay Region, Myanmar.
   2. Department of Chemistry, Graduate School of Science & Engineering, Saga University, 1 Honjo, Saga ,840-8502, Japan.
   3. Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji 671-2280, Japan.

   Abstract: There have been a lot of studies on fluorescent silica nanoparticles as a bioimaging reagent. Almost all of them, however, are based on dense silica nonoparticles. Recently, increasing number of studies have been directed to fluorescent silica hollow nanoparticles, because hollow nanoparticles can be employed as theranostic (therapeutic + diagnostic) particles. In this study, the fluorescent silica hollow nanoparticles (FSHN) have been synthesized by labelling coumarin dye on the surface of silica hollow nanoparticles (SHN). SHN has been prepared by utilizing the triblock copolymeric micelles of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) (PS–PVP–PEO) as a template and tetramethyoxysilane (TMOS) has been added as a precursor. The micelles exhibit a core–shell–corona (CSC) structure in aqueous solutions. The prepared SHN has been thoroughly characterized by transmission electron microscopy (TEM) and X- ray diffraction spectroscopy (XRD). According to TEM results, the size of the silica hollow nanoparticles is about 33 nm, the size of the cavity part is about 10 nm, and the size of the shell is about 12.5 nm. The SHN is amorphous in nature. FSHN has been synthesized by labelling silane coupling reagent, 4-methyl-7-trimethylsiloxycoumarin (MTSC) on SHN. The synthesized FSHN has been examined by transmission electron microscopy (TEM). The size of the synthesized hollow silica nanoparticles is 35±1 nm and the size of the cavity part is 10±1 nm, and the size of the shell is 12.5±1 nm. Fluorescence properties of FSHN are elucidated by observing various fluorescence parameters such as intensity, fluorescence lifetime and quantum yield. The fluorescence life time is 2.08 ns and the quantum yield is 0.637. The results demonstrate that the FSHN can be successfully prepared.

   Keywords: Fluorescent, hollow, silica, nanopartilcles, coumarin

   Pages: 32 – 39 | Full PDF Paper