Functionalization of small rigid platforms with cyclic RGD peptides for targeting tumors overexpressing αvß3-integrins.

Gadolinium based Small Rigid Plaforms (SRPs) have previously demonstrated their efficiency for multimodal imaging and radiosensitization. Since the RGD sequence is well-known to be highly selective for αvß3 integrins, a cyclic pentapeptide containing the RGD motif (cRGDfK) has been grafted onto the SRP surface. An appropriate protocol led to the grafting of two targeting ligands per nano-object. The resulting nanoparticles have demonstrated a strong association with αvß3 integrins in comparison with cRADfK grafted SRPs as negative control. Flow cytometry and fluorescence microscopy have also been used to highlight the ability of the nanoparticles to target efficiently HEK293(ß3) and U87MG cells. Finally the grafted radiosensitizing nanoparticles were intravenously injected into Nude mice bearing subcutaneous U87MG tumors and the signal observed by optical imaging was twice as high for SRP-cRGDfK compared to their negative analogue.

Chemical and in vitro characterizations of a promising bimodal AGuIX probe able to target apoptotic cells for applications in MRI and optical imaging.

Different studies on AGuIX nanoparticles have been achieved in the biomedical domain, showing that they allow us to combine multimodal and theranostic properties in oncology. The targeting of apoptotic cells presents a wide range of biomedical applications, including the monitoring of antitumoral therapy and the diagnosis of diseases related to this process, such as atherosclerosis, ischemia, chronic inflammation or autoimmune disorders. AGuIX nanoparticles functionalized with a peptide that recognizes apoptotic cells and with organic fluorophores were characterized by several physicochemical and biological methods such as HPLC, relaxometry and photon correlation spectroscopy, which attested to their potential as bimodal tracers detected by optical imaging and MRI. An increase of relaxivity and stability of AGuIX nanoparticles is also observed after their vectorization. The biological efficiency of this novel bimodal probe to target apoptotic cells was evaluated by fluorescence microscopy, relaxometry, MRI and flow cytometry on a lymphoblastic human T-cell line. In vitro cell apoptosis was chemically induced by incubation with camptothecin. Our in vitro experiments showed a significant specificity of vectorized AGuIX nanoparticles for camptothecin-treated cells that suggests their potential efficiency as probes to target apoptosis. Copyright © 2016 John Wiley & Sons, Ltd.