Cowries derived aragonite as raw biomaterials for bone regenerative medicine.

Carbonate apatites are sought as a bone substitute due to their biocompatibility and excellent resorbability. The present study deals with Cowrie's shell derived powder (CSDP) as natural biomaterial for bone regenerative medicine. Structural and physicochemical analysis showed that Cowrie's shells, presenting brick and mortar microstructures, were mainly composed of aragonite crystals, which were converted into poorly crystalline B-type carbonate apatite once soaked, at 37 °C, in simulated body fluid for 7 days, reflecting bioactive features. Cytotoxic assays showed that CSDP boosted human stem cell proliferation over the study time compared to nacre derived powder (NDP), used as positive control. Human stem cells adopted a flattened morphology and established physical contact with CSDP, signature of a good biocompatibility. Thus, these results suggested that CSDP presents a great interest for bone regenerative medicine, and could be a useful and versatile carrier/scaffold for bone tissue engineering or a raw material for 3D printed orthopedic devices.

Interaction of Aß1-42 peptide or their variant with model membrane of different composition probed by infrared nanospectroscopy.

Toxicity of Aß peptides involved in Alzheimer's disease is linked to the interaction of intermediate species with membranes. Nanoscale Infrared Spectroscopy enhances the study of the morphology and the secondary structure of the peptides as fibers or oligomers interacting with membranes of different compositions, with nanometer scale resolution. Membrane models are used to investigate the role of different lipids in their interactions with Aß peptides. This work clearly brings to light that the presence of cholesterol in membranes is favorable to the interaction with Aß peptides in oligomers or aggregates.

Development of an improved Kelvin probe force microscope for accurate local potential measurements on biased electronic devices.

An improved setup for accurate near-field surface potential measurements and characterisation of biased electronic devices using the Kelvin Probe method has been developed. Using an external voltage source synchronised with the raster-scan of the KPFM-AM, this setup allows to avoid potential measurement errors of the conventional Kelvin Probe Force Microscopy in the case of in situ measurements on biased electronic devices. This improved KPFM-AM setup has been tested on silicon-based devices and organic semiconductor-based devices such as organic field effect transistors (OFETs), showing differences up to 25% compared to the standard KPFM-AM lift-mode measurement method.

Development of a shear-force scanning near-field cathodoluminescence microscope for characterization of nanostructures' optical properties.

An original scanning near-field cathodoluminescence microscope for nanostructure characterization has been developed and successfully tested. By using a bimorph piezoelectric stack both as actuator and detector, the developed setup constitutes a real improvement compared to previously reported SEM-based solutions. The technique combines a scanning probe and a scanning electron microscope in order to simultaneously offer near-field cathodoluminescence and topographic images of the sample. Share-force topography and cathodoluminescence measurements on GaN, SiC and ZnO nanostructures using the developed setup are presented showing a nanometric resolution in both topography and cathodoluminescence images with increased sensitivity compared to classical luminescence techniques.