Effect of the nanoparticle synthesis method on dendronized iron oxides as MRI contrast agents

Abstract

Aqueous suspensions of dendronized iron oxide nanoparticles (NPs) have been obtained after functionalization, with two types of dendrons, of NPs synthesized either by coprecipitation (leading to naked NPs in water) or by thermal decomposition (NPs in situ coated by oleic acid in an organic solvent). Different grafting strategies have been optimized depending on the NPs synthetic method. The size distribution, the colloidal stability in isoosmolar media, the surface complex nature as well as the preliminary biokinetic studies performed with optical imaging, and the contrast enhancement properties evaluated through in vitro and in vivo MRI experiments, have been compared as a function of the nature of both dendrons and NPs. All functionalized NPs displayed good colloidal stability in water, however the ones bearing a peripheral carboxylic acid function gave the best results in isoosmolar media. Whereas the grafting rates were similar, the nature of the surface complex depended on the NPs synthetic method. The in vitro contrast enhancement properties were better than commercial products, with a better performance of the NPs synthesized by coprecipitation. On the other hand, the NPs synthesized by thermal decomposition were more efficient in vivo. Furthermore, they both displayed good biodistribution with renal and hepatobiliary elimination pathways and no consistent RES uptake.

Tailored biological retention and efficient clearance of pegylated ultra-small MnO nanoparticles as positive MRI contrast agents for molecular imaging

“…Indeed, peak shoulders were observed at 1045 cm À1 and 938 cm À1 respectively. This is in accordance with previous results, 40,47,49 and conrms the involvement of the phosphonate group in the chelation. However, the band at 993 cm À1 was not fully attenuated aer complexation with MnO, suggesting that a certain fraction of unreacted phosphonate groups is still present aer reaction with MnO.…”

A bisphosphonate tweezers and clickable PEGylated PAMAM dendrons for the preparation of functional iron oxide nanoparticles displaying renal and hepatobiliary elimination

“…Previously 6b, 15 and currently reported studies clearly highlight that the dendritic organic coating impacts the aggregation state of the nano-objects, thus influencing the bioelimination speed and importance of the hepatobiliary versus urinary elimination pathway: NPs covered with small dendrons (this study) are more rapidly and completely eliminated within 24 hours post-IV, predominantly by urinary elimination.…”

“…14 X-ray and selective area electron diffraction (SAED) measurements showed that they display the typical iron oxide spinel structure. 15 The NP@OA were in situ coated with oleic acid and formed a monodisperse and stable hexane suspension as observed in Fig. 1b.…”

Nanoparticle-cored dendrimers: functional hybrid nanocomposites as a new platform for drug delivery systems

“…71,72 In vivo and in vitro MRI measurements showed that the contrast enhancement properties of the dendronized NPs were higher than those obtained with commercial polymer-coated NPs (Figure 3). 22 Figure 3: a) Synthetic scheme of NCDs, b) Spin echo T2 weighted axial images sequentially acquired before and after an injection of 650 µl of NCDs at 7T with a small animal dedicated MRI (Biospin -Brücker®). Reproduced from Ref.…”