3D Printing and Pyrolysis of Optical ZrO2 Nanostructures by Two-Photon Lithography: Reduced Shrinkage and Crystallization Mediated by Nanoparticles Seeds.

Two-photon lithography is a potential route to produce high-resolution 3D ceramics. However, the large shrinkage due to the elimination of an important organic counterpart of the printed material during debinding/sintering remains a lock to further development of this technology. To limit this phenomenon, an original approach based on a composite resin incorporating 45 wt% ultrasmall (5 nm) zirconia stabilized nanoparticles into the zirconium acrylate precursor is proposed to process 3D zirconia microlattices and nanostructured optical surfaces. Interestingly, the nanoparticles are used both as seeds allowing control of the crystallographic phase formed during the calcination process and as structural stabilizing agent preventing important shrinkage of the printed ceramic. After 3D photolithography and pyrolysis, the weight and volume loss of the microstructures are drastically reduced as compared to similar systems processed with the reference resin without nanoparticles, and stable 3D microstructures of cubic zirconia are obtained with high spatial resolution. In the case of a patterned surface, the refractive index of 2.1 leads to a diffraction efficiency large enough to obtain microfocusing with linewidths of 0.1 µm, and the demonstration of a microlens array with a period as small as 0.8 µm.

Protein-based medicines analysis by Raman spectroscopy for the detection of counterfeits.

Protein-based medicines, or large molecule medicines, are innovative products used to treat various diseases like hepatitis or cancer. This new generation of molecules are usually expensive, and thus represents an attractive target for the counterfeiters. Due to the complexity of their chemical structure, their analysis for counterfeit detection is more difficult than small molecule medicines. The aim of the article is to demonstrate that Raman spectroscopy and microscopy can be used for the fast analysis of counterfeits of protein-based medicines. Twelve types of medicines, under liquid or lyophilized form, have been analyzed by a Raman spectrometer through their glass packaging and ten of them also by a Raman microscope with drop deposition on a gold plate. The optimization of the acquisition parameters has first been described. Then the identification of the studied products has been presented with the attribution of the protein bands observed on the spectra. Finally the methods were successfully applied to seven counterfeits of these products and their chemical composition identified by spectral analysis. Counterfeits can indeed be detected if the excipient profile differs, if no protein is present, or if the genuine sample has been strongly diluted by the counterfeiters. Raman spectroscopy and microscopy have thus proved efficient for the fast analysis of counterfeits of protein-based medicines.