Synthesis and biological evaluation of new bisphosphonate-dextran conjugates targeting breast primary tumor.

Bisphosphonates (BPs) have interesting antitumor effects as well in vitro as in vivo, despite their poor bioavailability in the organism after oral ingestion. To overcome this problem and reduce drug doses and secondary effects, we report the chemical synthesis of new bioconjugates. They were built with a nitrogen-containing BP as the drug covalently coupled to the carboxymethyldextran. This polysaccharide was used as a carrier, in order to increase BP lifetime in bloodstream and to target tumor cells which have a strong affinity with dextran. The efficiency of our vectorization system was biologically proved in vitro and in vivo on mammalian carcinoma models in mice.

Aqueous suspensions of GdPO4 nanorods: a paramagnetic mineral liquid crystal.

Colloidal suspensions of rod-like nanoparticles are well-known to readily form liquid-crystalline phases. Using mineral nanoparticles for this purpose may impart their liquid-crystalline suspensions with original physical properties. We synthesized GdPO(4) nanorods whose aqueous suspensions spontaneously organize in a nematic phase at high concentrations. The nematic phase is very well aligned by small magnetic fields, and the isotropic phase displays a very large field-induced birefringence. Moreover, the nanorods migrate to regions of high magnetic field. On the basis of magnetization measurements, we show that this unusual behavior is due to the fact that GdPO(4) nanorods are actually paramagnetic. Such a paramagnetic mineral liquid crystal, easily synthesized and little sensitive to temperature, may be an interesting alternative to organometallic thermotropic liquid crystals for applications where magnetic field alignment would be more suitable than electric field alignment.