No abstract

A new class of monodisperse water-soluble magnetite nanoparticles was prepared by a simple and inexpensive method based on a polyol process, and their potential as MRI contrast agents was investigated.

No abstract

Monodisperse ZnFe 2 O 4 nanoparticles were synthesized using a simple and low-cost polyol process based on thermal decomposition of the precursors of Fe(acac) 3 and Zn(acac) 2 in triethylene glycol without any surfactant. The as-prepared ZnFe 2 O 4 nanoparticles are highly crystalline, uniform in size, superparamagnetic and can be easily dispersed in aqueous media due to being coated by a layer of hydrophilic polyol ligands in situ. Magnetic study shown that the ZnFe 2 O 4 nanoparticles had a low magnetic anisotropy and low magnetic moment compared to the conventional Fe 3 O 4 nanoparticles. As a result, the as-prepared ZnFe 2 O 4 nanoparticles provide an optimized r 2 /r 1 ratio for T 1 -weighted magnetic resonance imaging (MRI) in the clinical field strength. A preliminary in vitro cytotoxicity test suggests that the zinc ferrite nanoparticles possess a good safety profile. Therefore, the as-prepared ZnFe 2 O 4 nanoparticles have great potential to serve as a novel non-lanthanide T 1 MRI contrast agent.

Bifunctional magnetic-optical Fe 3 O 4 @ZnS microspheres with core-shell heterostructures have been successfully fabricated by a simple chemical deposition method. The adsorption of sodium dodecyl sulfate (SDS) on the preformed magnetite microspheres played an essential role in directing the structure of the composites. The presented materials were characterized by FE-SEM, HRTEM, XRD, FTIR, fluorescence spectrophotometer, and SQUID MPMS. The results showed that spherical Fe 3 O 4 cores were coated by a uniform ZnS layer. The saturation magnetization value of Fe 3 O 4 @ZnS core-shell microspheres is 52.5 emu g -1 at room temperature. Ultraviolet and visible light can be easily obtained by exposing the microspheres to different excitation wavelengths. The combined magnetic and fluorescent properties endow the microspheres with great potential applications in drug targeting, bioseparation and diagnostic analysis.

Although amelogenin comprises the vast majority of the matrix that templates calcium phosphate nucleation during enamel formation, other proteins, particularly enamelin, are also known to play an important role in the formation of enamel's intricate architecture. However, there is little understanding of the interplay between amelogenin and enamelin in controlling processes of mineral nucleation and growth. Here, we used an in vitro model to investigate the impact of enamelin interaction with amelogenin on calcium phosphate nucleation for a range of enamelin-toamelogenin ratios. We found that amelogenin alone is a weak promoter of nucleation, but addition of enamelin enhanced nucleation rates in a highly nonlinear, nonmonotonic manner reaching a sharp maximum at a ratio of 1:50 enamelin/amelogenin. We provide a phenomenological model to explain this effect that assumes only isolated enamelin proteins can act as sites of enhanced nucleation, while enamelin oligomers cannot. Even when interaction is random, the model reproduces the observed behavior, suggesting a simple means to tightly control the timing and extent of nucleation and phase transformation by amelogenin and enamelin.

No abstract

Bifunctional nanoprobes with both magnetic and optical contrast have been developed for ultra-sensitive brain tumor imaging at the cellular level. The nanoprobes were synthesized by simultaneously incorporating a magnetite nanoparticle cluster and fluorescence dyes into silica encapsulation by a sol-gel approach under ultrasonic treatment. The nanoprobes maintain superparamagnetic behavior at room temperature and possess enhanced transverse relaxivity and good photostability. As a glioma targeting ligand, chlorotoxin was covalently bonded to the surface of the nanoprobes. In vitro cellular uptake assays demonstrated that the nanoprobes were highly specific, taken up by human U251-MG glioma cells via receptor-mediated endocytosis. The labeled glioma cells were readily detectable by both MR imager and confocal laser scanning microscopy.