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Potassium niobate (KNbO3) nanocrystals exhibiting good second harmonic generation properties were coated with dextran derivatives containing primary amine groups. The surface modification results from attractive electrostatic interaction between the aminodextran molecules and the negatively charged surface of bare KNbO3 nanocrystals. To avoid flocculation, a suspension of KNbO3 nanocrystals was firstly prepared and then added drop-wise to an aqueous solution of aminodextran. The as-prepared hybrid (AD-coated KNbO3) nanoparticles were then characterized by using various techniques including transmission electron microscopy (TEM), infrared analysis (FTIR), dynamic light scattering (DLS) and zeta potential measurements as a function of pH of the dispersion medium. Then, the prepared AD- coated KNbO3 nanoparticles were evaluated in vitro diagnostic application as biomarker for non-tumor lung-derived human cells. The obtained results showed that the aminodextran-coated KNbO3 nanoparticles were efficiently bound to the non-tumor lung-derived human cells, which was proved by using a commercial Nikon multi-photon imaging platform. In addition, AD-coated KNbO3 nanoparticles showed good optical contrast for the investigated cells, and consequently they can be efficiently used as contrast agents in the bio-imaging diagnostic domain.

A novel bio-photonics approach based on the nonlinear optical process of second harmonic generation by non-centrosymmetric nanoparticles is presented and demonstrated on malignant human cell lines. The proposed method allows to directly interact with DNA in absence of photosensitizing molecules, to enable independent imaging and therapeutic modalities switching between the two modes of operation by simply tuning the excitation laser wavelength, and to avoid any risk of spontaneous activation by any natural or artificial light source.

Matériaux et Outils pour la Santé; International audience; Hydrophobic room-temperature ionic liquids were used to remove KNbO3 and BaTiO3 nanoparticles from water at 25 uC. A very good extraction efficiency was obtained with distribution coefficients as high as 500. After extraction, toxicity of the aqueous phase containing residual amounts of nanoparticles and ionic liquids was assessed using Vibrio fischeri. A preliminary investigation of the toxicity mechanism was carried out with propidium iodide tests. A key result is that the simultaneous presence of a small amount of nanoparticles and ionic liquid in water can result in adverse toxicological effects compared to aqueous solutions containing solely nanoparticles or ionic liquids.

International audience; Background: Harmonic Nanoparticles are a new family of exogenous markers for multiphoton imaging exerting optical contrast by second harmonic (SH) generation. In this tutorial, we present the application of Hyper-Rayleigh Scattering (HRS) for a quantitative assessment of the nonlinear optical properties of these particles and discuss the underlying theory and some crucial experimental aspects. Methods: The second harmonic properties of BaTiO3, KNbO3, KiTiOPO4 (KTP), LiNbO3 and ZnO nanocrystals (NCs) are investigated by HRS measurements after careful preparation and characterization of colloidal suspensions. Results: A detailed analysis of the experimental results is presented with emphasis on the theoretical background and on the influence of some experimental parameters including the accurate determination of the nanocrystal size and concentration. The SH generation efficiency and averaged nonlinear optical coefficients are then derived and compared for six different types of NCs. Conclusions: After preparation of colloidal NC suspensions and careful examination of their size, concentration and possible aggregation state, HRS appears as a valuable tool to quantitatively assess the SH efficiency ofnoncentrosymmetric NCs. All the investigated nanomaterials show high SH conversion efficiencies, demonstrating a good potential for bio-labelling applications.