AB - An iron and gadolinium-containing bimetallic polynuclear complex was used as a single source precursor in the synthesis of gadolinium-doped magnetite nanoparticles (Gd:Fe3O4). The synthesis produces well defined octahedral particles (12.6 ± 2.6 nm diameter) with a gadolinium content in the region of 2 mol%. The nanoparticles showed a value of the specific absorption rate of 3.7 ± 0.6 W gFe -1 under low-amplitude radiofrequency magnetic field excitation, and moderate biocompatibility, suggesting that these particles are viable candidates for magnetic hyperthermia applications.
In recent decades engineered magnetic nanoparticles and related nanoconstructs have attracted extensive research and development in the field of nanomedicine.[-] Because their biocompatibility and toxicity are extensively investigated and better understood, magnetic nanoparticles, especially iron oxide nanoparticles (IONPs) composed of maghemite or magnetite nanocrystals, are proper choices for various in vivo biomedical applications. Among them, magnetic resonance imaging (MRI) contrast enhancement for molecular imaging takes advantage of superb and tunable magnetic properties of engineered magnetic nanoparticles, while a range of surface chemistry offered by nanoparticles provides multifunctional capabilities for image-directed drug delivery. In parallel with the fast growing research in nanotechnology and nanomedicine, the continuous advance of MRI technology and the rapid expansion of MRI applications in the clinical environment further promote the research in this area.
"A Green and Facile Approach for Synthesis of Magnetite ..
This paper presents a facile, rapid and green method to prepare magnetite (Fe3O4) nanoparticles in one step reaction. In this method, an aqueous solution of ferric chloride hexa hydrate, ferrous chloride tetra hydrate (2/1 molar ratio) was mixed with carob leaf extract and heated for 5 minutes at 80℃. The magnetite nanoparticles were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). XRD analysis showed that the magnetite nanoparticles are well-monodisperse with 8 nm of average diameter. A possible synthesis mechanism of magnetite nanoparticles was presented at the same time.
Size Controlled Synthesis of Nanoparticles 3.2.1 Magnetite 3 ..
Because one of the major limitations of MRI is its relative low sensitivity, the strategies of combining MRI with other highly sensitive, but less anatomically informative imaging modalities such as positron emission tomography (PET) and NIRF imaging, are extensively investigated. The complementary strengths from different imaging methods can be realized by using engineered magnetic nanoparticles via surface modifications and functionalizations. In order to combine optical or nuclear with MR for multimodal imaging, optical dyes and radio-isotope labeled tracer molecules are conjugated onto the moiety of magnetic nanoparticles.[-] Xie et al. demonstrated the multifunctionalizations of magnetic nanoparticles via dopamine-human serum albumin (HSA) procedure. After exchanging the existing oleic acid/oleic amine, the dopamine modified magnetic nanoparticles can be easily encapsulated in HSA molecules for further functionalizing. In addition to MRI contrast enhancement from the core of the iron oxide nanoparticle, the covalent binding and absorption of 64Cu-DOTA and Cy5.5 provide PET/NIRF imaging capabilities. The application of multimodality MRI/PET/NIRF imaging using this novel probe was demonstrated in the U87MG glioma tumor model bearing mice. Due to the prolonged circulation time, the multifunctional HSA-IO nanoparticles specifically accumulated in the tumor site through passively targeting based on the tumor growth associated enhanced permeability and retention (EPR) effect. Histological examinations and analyses showed that the nanoconstructs were distributed intra-vascularly at the tumor section and not related to the uptake of macrophages.
Synthesis, Characterization and Magnetic Properties of …
As an expansion from the molecular imaging for MRI based diagnosis, engineered magnetic nanoparticles have been also developed for the MRI-guided delivery of therapeutic agents. For example chemotherapeutic drug noscapine (Nos) was attached on the human ATF (hATF) peptide conjugated IONPs to target uPAR expressed prostate cancer, so that the MRI contrast generated from IONPs can be used to follow Nos-hATF-IO nanoparticles for MRI-directed prostate cancer therapy. The drug carrying uPAR targeting magnetic nanoparticles showed specific binding to uPAR expressing PC-3 cells. While these Nos-hATF-IO nanoparticles with drug molecules embedded in the hydrophobic coating layers of IONPs demonstrated a ~6-fold improvement in drug efficacy, compared to free drug, they also retained the MRI contrast effect from the IONPs cores. Besides small drug molecules, some specific antibodies or small interfering RNA (siRNA) which can inhibit the tumor growth have been also conjugated onto the magnetic nanoparticles for MRI-guided therapies. Hadjipanayis et al. crosslinked EGFRvIII antibodies to IONPs functionalized with carboxyl groups through the EDC/NHS reaction. Significant decrease in glioblastoma cells survival was observed after the treatment by EGFRvIII-IONPs. MRI-guide convection-enhanced delivery of EGFRvIII-IONPs increased the survival of animals bearing glioblastoma xenografts.