A new contrast agent, LipImage™ 815, has been designed and compared to previously described indocyanine green (ICG)-loaded lipid nanoparticles (ICG-lipidots®). Both contrast agents display similar size (50-nm diameter), zeta potential, high IC50 in cellular studies, near-infrared absorption and emission wavelengths in the "imaging window," long-term shelf colloidal and optical stabilities with high brightness (>106 L mol-1 cm-1) in ready-to-use storage conditions in aqueous buffer (4°C in dark), therefore being promising fluorescence contrast agents for in vivo imaging. However, while ICG-lipidots® display a relatively short plasma lifetime, LipImage™ 815 circulates in blood for longer times, allowing the efficient uptake of fluorescence signal in human prostate cancer cells implanted in mice. Prolonged tumor labeling is observed for more than 21 days.
Fluorescence-enhanced diffuse optical tomography is expected to be useful to the collection of functional information from small animal models. This technique is currently limited by the extent of tissue heterogeneity and management of the shape of the animals. We propose an approach based on the reconstruction of object heterogeneity, which provides an original solution to the two problems. Three evaluation campaigns are described: the first two were performed on phantoms designed to test the reconstructions in highly heterogeneous media and noncontact geometries; the third was conducted on mice with lung tumors to test fluorescence yield reconstruction feasibility in vivo.
This study reports on the dynamics of droplets in the capillary regime induced by electrowetting-ondielectric actuation. The configuration investigated allows for comparing the experimental results with respect to the predictions of Brochard's theoretical model (Brochard in Langmuir 5:432-438, 1989). Firstly, side-view observations using stroboscopic recording techniques were used to measure and analyse droplet deformations as well as the front and rear apparent contact angles during motion. Secondly, the influence of viscosity on the droplet velocity as a function of the applied voltage was studied. This has revealed that low Reynolds number droplet motion can be described by the simple laminar viscous model of Brochard. Finally, the influence of the dielectric thickness on the droplet dynamics was studied. It is shown that droplet velocity is limited by a saturation effect of the driving electrostatic force and that this phenomenon is very similar to that occurring in static experiments.
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