Size-Dependent Optical Properties of Dendronized Perylenediimide Nanoparticle Prepared by Laser Ablation in Water

Fluorescent nanoparticles of dendronized perylenediimide (DPDI) were fabricated by laser ablation in water. We succeeded in the preparation of colloidal nanoparticles of different sizes (150–400 nm) and examined their size-dependent optical absorption and fluorescence properties. The size-dependent extinction spectra can be explained by the effect of light scattering loss, and it was confirmed that their absorption spectrum is similar to that of molecules in solution. The very weak interchromophoric interaction is also confirmed by fluorescence spectral measurement. On the other hand, we found that the fluorescence quantum yield decreases with decreasing of the particle size, and we propose a new mechanism for the size-dependent reduction of emission intensity in organic nanoparticles. On the basis of the size dependent-fluorescence quantum yield and solvent polarity dependence of DPDI fluorescence in organic solvents, we considered that, while the interchromophoric interactions are weak in the nanoparticle, the excited singlet state migrates in a nanoparticle owing to energy hopping and is quenched at the surface, leading to the observed size-dependent fluorescence quantum yield (Φ_f) and a smaller value of Φ_f for nanoparticles than for the molecules in nonpolar solvents

Plasmonic Properties of Aluminum Nanocylinders in the Visible Range

Plasmonic and surface enhanced Raman scattering (SERS) studies have been performed on aluminium nanocylinders arrays of different diameters. We observed sharps localised surface plasmon resonance (LSPR) peaks that can be tuned on the whole visible range and having the same behaviour than gold nanocylinders. The near-field enhancement was measured by SERS on probe molecules as well as on the indium tin oxide (ITO) substrate using two excitation wavelengths: 660 and 785 nm. No SERS signal of the probe molecu

Super-resolution for a dispersive spectrometer using a tilted area sensor and spectrally varying blur kernel interpolation

The grating, lens, and linear sensor determine a spectrometer’s wavelength resolution and measurement range. While conventional methods have tried to improve the optical design to obtain a better resolution, they have a limitation caused by the physical property. To improve the resolution, we introduce a super-resolution method from the computer vision field. We propose tilting an area sensor to realize accurate subpixel shifting and recover a high-resolution spectrum using interpolated spectrally varying kernels. We experimentally validate that the proposed method achieved a hig

Enzyme-Assisted Photoinjection of Megadalton Molecules into Intact Plant Cells Using Femtosecond Laser Amplifier

Femtosecond laser photoporation has become a popular method to deliver various kinds of molecules such as genes, proteins, and fluorescent dyes into single mammalian cells. However, this method is not easily applied to plant cells because their cell wall and turgor pressure prevent the delivery, especially for larger molecules than the mesh size of the cell wall. This work is the first demonstration of the efficient photoinjection of megadalton molecules into a cytoplasm of an intact single plant cell by employing a femtosecond laser amplifier under moderate enzyme treatment conditions. The intense femtosecond laser pulse effectively formed a pore on the cell wall and membrane of Tobacco BY-2, and 2 MDa dextran molecules were introduced through the pore. Along with the pore formation, induced mechanical tensile stresses on BY-2 cells were considered to increase permeability of the cell membrane and enhance the uptake of large molecules. Moreover, the moderate enzyme treatment partially degraded the cell wall thereby facilitating the increase of the molecular introduction efficiency

Quantitative analysis of SERS spectra of MnSOD over fluctuated aptamer signals using multivariate statistics

International audienc

Pulsed-laser-activated impulse response encoder (PLAIRE): detection of core–shell structure of biomimetic micro gel-sphere

Mechanical properties of biological cells and tissues contain important information for further understanding of their function. To estimate mechanical properties of micro-sized biological objects, we developed a system: pulsed-laser-activated impulse response encoder (PLAIRE). In the PLAIRE, femtosecond laser-induced impulsive force is applied to excite elastic waves on a micro-biological object and the excited elastic waves are detected by atomic force microscopy (AFM) as cantilever’s oscillations. In this work, PLAIRE is applied to estimate Young’s moduli of calcium alginate (CaAlg) micro gel-sphere as a biomimetic object. The Young’s modulus calculated from the propagating velocity of surface elastic waves (Rayleigh waves) are 3.7 times larger than that of the entire sphere measured with AFM force curve. The results indicate PLAIRE specifically detects surface mechanical properties of CaAlg which is harder than the inside