Dynamic light scattering unveils stochastic degradation in large-pore mesoporous silica nanoparticles.

Mesoporous Silica Nanoparticles (MSNs) have been increasingly investigated as versatile drug delivery carriers. A particular challenge for the systemic use of MSNs lies in the control of their degradation, which has not been fully understood until now. We implemented standard dynamic light scattering (DLS) experiments and introduced a novel DLS technique in a confocal volume to track the dynamics of large-pore MSN degradation in situ.

Hybrid CdSe/ZnS Quantum Dot-Gold Nanoparticle Composites Assembled by Click Chemistry: Toward Affordable and Efficient Redox Photocatalysts Working with Visible Light.

A new modular, easy-to-synthesize photocatalyst was prepared by assembling colloidal CdSe/ZnS quantum dots (QD) and gold nanoparticles (AuNP) via their ligands thanks to copper-catalyzed azide to alkyne cycloaddition (CuAAC) click chemistry. The resulting composite (QD-AuNP) photocatalyst was tested with a benchmark photoredox system previously reported by our group, for which QD alone acted as a photocatalyst but with a modest quantum yield (QY = 0.06%) and turnover number (TON = 350 in 3 h) due to poor charge separation.

In Situ Identification of Spherical Ag Monomers and Dimers at Zeptomole Adsorbate Concentrations by Surface-Enhanced Raman Scattering Correlation Spectroscopy.

We have developed a bright optical setup, especially optimized for surface-enhanced Raman scattering (SERS) correlation spectroscopy. We show that the brightness of the experiment combined with the correlation approach permits in situ access to the size and shape of the SERS-active aggregates in solution despite a very weak SERS signal of the adsorbed molecules. As a result, we demonstrate that dimers and larger SERS-active aggregates can be identified through the temporal fluctuations of the SERS signal of only a few hundred of adsorbed molecules, that is, at zeptomole adsorbate concentrations.

Microscope spectrometer for light scattering investigations.

We describe a setup including a microscope to study volumes of a few mum(3) by static and dynamic light scattering (DLS) in a backscattering configuration. Light scattered by individual objects of micrometric size can be analyzed in the 400-800?nm spectral range. This setup can also be employed to study both diluted and concentrated colloidal solutions by DLS measurements.

Plasmon dispersion diagram and localization effects in a three-cavity commensurate grating.

Commensurate gratings of deep-metallic grooves have highly localized cavity resonances which do not exist for purely periodic gratings. In this paper we present the experimental dispersion diagram of the resonances of a commensurate grating with three sub-wavelength cavities per period. We observe selective light localization within the cavities, transition from a localized to a delocalized mode and modifications of the coupling of modes with the external plane-wave that may lead to the generation of black modes.