Alain Thorel

Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells

Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm), resonant laser scattering and Raman scattering cross sections are too small to allow single nanoparticle observation. Nanodiamonds can, however, be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time scales. In this work, we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells. By blocking selectively different uptake processes, we show that nanodiamonds enter cells mainly by endocytosis, and converging data indicate that it is clathrin-mediated. We also examine nanodiamond intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule delivery.

Protein-Functionalized Hairy Diamond Nanoparticles

Diazonium salt chemistry and atom transfer radical polymerization (ATRP) were combined in view of preparing new bioactive hairy diamond nanoparticles containing, or potentially containing, nitrogen-vacancy (NV) fluorescent centers (fluorescent nanodiamonds, or fNDs). fNDs were modified by ATRP initiators using the electroless reduction of the diazonium salt BF(4)(-),(+)N(2)-C(6)H(4)-CH(CH(3))-Br. The strongly bound aryl groups -C(6)H(4)-CH(CH(3))-Br efficiently initiated the ATRP of tert-butyl methacrylate (tBMA) at the surface of the nanodiamonds, which resulted in obtaining ND-PtBMA hybrids. The grafted chain thickness, estimated from X-ray photoelectron spectroscopy (XPS), was found to increase linearly with respect to time before reaching a plateau value of ca. 2 nm. These nanoobjects were further hydrolyzed into ND-PMAA (where PMAA is the poly(methacrylic acid) graft) and further decorated by bovine serum albumin through the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling procedure.

High resolution transmission electron microscopy study of interfaces

Abstract The study of interfaces by means of High Resolution Transmission Electron Microscopy (HRTEM) is discussed through selected observations conducted on the Atomic Resolution Microscope (NCEM, Berkeley, USA). The precipitation of germanium into aluminium, the study of interfacial non-crystalline films in silicon nitride, the determination of the chemical nature of twin planes in CuAlO2 and the structure of the ∑3 grain-boundary in aluminium are the examples that serve to illustrate the important problems of relevance in the atomistic study of interface with HRTEM.

Quantitative Analysis of Displacement at 90° Domain Boundaries In BaTiO 3 and PbTiO 3

In this paper we discuss the measurement of long range displacement fields associated with 90° domain boundaries in the ferroelectric ceramics BaTiO 3 and PbTiO 3 . We have calculated displacement fields from high resolution lattice images by two techniques: firstly, measuring the positions of peaks in the images, and secondly, using a geometric phase analysis technique to magnify small lattice distortions. We describe the results and consider the complementary use of Fresnel contrast analysis to characterize local strain and electric fields near the boundaries.

Towards Understanding the Dual Membrane Fuel Cell (IDEAL-Cell) Using a Metallic Central Membrane

This work presents results of a measurement setup which was constructed for understanding the performance contributions of the individual compartments and reactions taking place in the patented concept of IDEAL-Cell (described in detail in(1)). By inserting a third measurement point at the central membrane of an ideal cell it was possible to measure the cell in three different modes corresponding to hydrogen, oxygen compartment and the full cell. Recorded maximum power densities of (~4, ~7, 11, 16) mW/cm² at (600, 650, 700, 750) °C in H2-O2 atmosphere respectively were observed which were similar to the values of proof of concept ideal cell samples tested so far. Moreover in this setup it was possible to record higher maximum power densities for the hydrogen (proton conducting) compartment which was (~14, 22, 33*, ~38*) mW/cm² at (600, 650, 700, 750) °C.