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The delivery of drugs by nanoparticles within cells holds promise for the treatment of cancer, but also raises a number of questions. Do these nanoparticles aggregate before they even reach their destination? Can they easily penetrate into target cells and remain there? Are they toxic? The limitless variety of these nanovectors, as well as the difficulty of probing their behavior in situ, is a barrier to the effective optimization of these therapies.
The Iramis researchers therefore decided to study a set of model nanoparticles that all have the same structure, differing only in their surface properties. They selected gold cores – gold being radiosensitizing – onto which different crowns of polymers and polymethacrylate copolymers (CH2=C(CH3)COO-) are grafted. A modulation in the polymer chemistry is used to modify the properties of the nanoparticles without altering their structure, thus making it possible to establish a reliable comparison. To make their observations, they use small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) tools.
Their results show that copolymerization between hydrophobic, positively charged monomers contributes to a significant reduction in the toxicity of nano-objects while maintaining a good cellular "capture". On the other hand, negative charges promote diffusion in the extracellular matrix.
This work was conducted in collaboration with the LLB (Laboratoire Léon-Brillouin).