The synthesis of small-size dendrons and their grafting at the surface of iron oxide nanoparticles were achieved with the double objective to obtain a good colloidal stability with a mean hydrodynamic diameter smaller than 100 nm and to ensure the possibility of tuning the organic coating characteristics including morphology, functionalities, physico-chemical properties, grafting of fluorescent or targeting molecules. Magnetic resonance and fluorescence imaging are then demonstrated to be simultaneously possible using such versatile superparamagnetic iron oxide nanocrystals covered by a dendritic shell displaying either carboxylate or ammonium groups at their periphery which could be further labelled with a fluorescent dye. The grafting conditions of these functionalized dendrons at the surface of SPIO NPs synthesized by co-precipitation have been optimized as a function of the nature of the peripheral functional group. The colloidal stability has been investigated in water and osmolar media, and in vitro and in vivo MRI and optical imaging measurements have been performed showing encouraging biodistribution.
This chapter discusses the synthesis, functionalization, characterization, and imaging applications of iron-oxide-nanoparticle-based contrast agents. By reducing the size from bulk to the nanometer scale (<20 nm), ferrimagnetic iron oxide acquires a magnetic property called superparamagnetism, which is key to the potential of these particles as MRI contrast agents. This chapter describes the theory governing the relaxivity of nanoparticle-based contrast agents. The different syntheses, coatings, and functionalization approaches are then discussed, including how these syntheses affect the properties of the nanomaterial. Different techniques for the characterization of the cores and coatings of nanoparticles, including their size and composition, are then discussed. Particular attention is given to characterization of the magnetic properties of iron oxide nanoparticles. Finally, the acquisition of MRI phantoms is presented.
The biodistribution of dendronized iron oxides, NPs10@D1_DOTAGA and melanin-targeting NPs10@D1_ICF_DOTAGA, was studied in vivo using MRI and planar scintigraphy through [177Lu]Lu-radiolabeling. MRI experiments showed high contrast power of both dendronized nanoparticles (DPs) and hepatobiliary and urinary excretions. Little tumor uptake could be highlighted after intravenous injection probably as a consequence of the negatively charged DOTAGA-derivatized shell which reduces the diffusion across the cells’ membrane. Planar scintigraphy images demonstrated a moderate specific tumor uptake of melanoma-targeted [177Lu]Lu-NPs10@D1_ICF_DOTAGA at 2 h post intravenous injection, and the highest tumor uptake of the control probe [177Lu]Lu-NPs10@D1_DOTAGA at 30min pi, probably due to the enhanced permeability and retention (EPR) effect. In addition, ex vivo Confocal microscopy (EVCM) studies showed a high specific targeting of human melanoma samples impregnated with NPs10@D1_ICF_Alexa647_ DOTAGA.
We report herein the synthesis of biocompatible small-sized phosphonated monomers and dendrons used as functional coatings of metal oxide nanoparticles, more specifically superparamagnetic iron oxides (SPIOs) for magnetic resonance imaging (MRI) and therapy through hyperthermia. The molecules were engineered to modulate their size, their hydrophilic and/or biocompatible character (poly(amido)amine versus oligoethyleneglycol), the number of anchoring phosphonate groups (monophosphonate versus phosphonic tweezers) and the number of peripheral functional groups for further grafting of dyes or specific vectors. Such a library of hydrophilic phosphonic acids opens new possibilities for the investigation of dendronized nanohybrids as theranostics.
Nanomedicine can take advantage of the recent developments in nanobiotechnology research areas for the creation of platforms with superior drug carrier capabilities, selective responsiveness to the environment, unique contrast enhancement profiles and improved accumulation at the disease site. Colloidal inorganic nanoparticles (NPs) have been attracting considerable interest in biomedicine, from drug and gene delivery to imaging, sensing and diagnostics. It is essential to modify the NPs surface to have enhanced biocompatibility and reach multifunctional systems for the in vitro and in vivo applications, especially in delivering drugs locally and recognizing overexpressed biomolecules. This paper describes the rational design for dendrimer-nanoparticle conjugates elaboration and reviews their state-of-the-art uses as efficient nanomedicine tools.