Fluorescent Radiosensitizing Gold Nanoparticles.

Ultrasmall polyaminocarboxylate-coated gold nanoparticles (NPs), Au@DTDTPA and Au@TADOTAGA, that have been recently developed exhibit a promising potential for image-guided radiotherapy. In order to render the radiosensitizing effect of these gold nanoparticles even more efficient, the study of their localization in cells is required to better understand the relation between the radiosensitizing properties of the agents and their localization in cells and in tumors. To achieve this goal, post-functionalization of Au@DTDTPA nanoparticles by near-infrared (NIF) organic dyes (aminated derivative of cyanine 5, Cy5-NH2) was performed. The immobilization of organic Cy5-NH2 dyes onto the gold nanoparticles confers to these radiosensitizers fluorescence properties which can be exploited for monitoring their internalization in cancerous cells, for determining their localization in cells by fluorescence microscopy (a common and powerful imaging tool in biology), and for following up on their accumulation in tumors after intravenous injection.

Improving bioassay sensitivity through immobilization of bio-probes onto reactive micelles.

An antigen probe (HIV-1 p24) immobilized onto N-succinimidyl ester based micelles was used as a solid phase coating in ELISA test, and induced a significant improvement in antibody detection sensitivity as compared to the standard free antigen coating. The relevance of this straightforward approach to improve the bioassay sensitivity was confirmed by using biotin as a generic probe.

Preclinical evaluation of gold-DTDTPA nanoparticles as theranostic agents in prostate cancer radiotherapy.

AIM: Gold nanoparticles have attracted significant interest in cancer diagnosis and treatment. Herein, we evaluated the theranostic potential of dithiolated diethylenetriamine pentaacetic acid (DTDTPA) conjugated AuNPs (Au@DTDTPA) for CT-contrast enhancement and radiosensitization in prostate cancer. MATERIALS & METHODS: In vitro assays determined Au@DTDTPA uptake, cytotoxicity, radiosensitizing potential and DNA damage profiles. Human PC3 xenograft tumor models were used to determine CT enhancement and radiation modulating effects in vivo. RESULTS: Cells exposed to nanoparticles and radiation observed significant additional reduction in survival compared with radiation only. Au@DTDTPA produced a CT enhancement of 10% and a significant extension in tumor growth delay from 16.9 days to 38.3 compared with radiation only. CONCLUSION: This study demonstrates the potential of Au@DTDTPA to enhance CT-image contrast and simultaneously increases the radiosensitivity of prostate tumors.

Preparation and in vitro evaluation of imiquimod loaded polylactide-based micelles as potential vaccine adjuvants.

PURPOSE: Activation of immune cells through pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs) or NOD-like receptors (NLRs), has been identified as a key issue in the development of new efficient vaccine adjuvants. We report here on the elaboration and immunostimulatory potential of polylactide (PLA)-based micelles core-loaded with imiquimod TLR7 ligand and able to be further surface-functionalized with antigenic protein (HIV-1 Gag p24) for antigen delivery purpose. METHODS: Micelles prepared from poly(D,L-lactide)-b-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) amphiphilic copolymer were incubated in the presence of imiquimod, leading to 1.2 wt% loading, and further conjugated to p24 antigen through reaction of p24 lysines and N-terminal amine with the N-succinimidyl pendant groups of the micelle corona. The impact of imiquimod encapsulation in the micelles on its immunostimulatory properties was investigated in vitro, by monitoring: (i) the NF-κB and mitogen-activated protein kinases (MAPK) pathways through experiments with RAW-Blue™ cells, a mouse macrophage cell line encoding an NF-κB/AP-1-inducible reporter construct; (ii) human dendritic cells (DCs) maturation markers by flow cytometry. RESULTS: RAW-Blue™ cells based experiments showed that imiquimod encapsulated in the micelles was much more efficient to activate the NF-κB and MAPK pathways than free imiquimod. Furthermore, encapsulated imiquimod was found to induce much higher maturation of DCs than the free analog. Finally, these immunostimulatory properties of the loaded imiquimod were shown to be conserved when the p24 antigen was coupled at the micelle surface. CONCLUSIONS: Taken together, these data regarding improved immunostimulatory efficiency suggest the strong potential of our micelle-based nano-system for vaccine delivery.