#IRON GRIDS WINDOWS AUSTIN TX KEYGEN#
After the reaction mixture was cooled down, the SPIO-embedded silica were separated from the reaction medium by centrifuging at 4000 rpm and redispersed in 100 ml of absolute ethanol. These silica nanoparticles were then treated with 0.04 ml of 3-aminopropyl trimethoxysilane for 6 hr to introduce the amino-terminated silica surface, and then the reaction mixture was refluxed for 30 min to complete the reaction 1.
The functional groups at the surface of these unmodified silica nanoparticles are predominantly silanol (Si-OH) or ethoxy (Si-OEt) groups 1. The reaction was allowed to proceed at room temperature overnight. The clear solution turned to murky suspension in less than 30 min, indicating the formation of silica nanoparticles. An aqueous ammonia solution (30% wt, 7 ml) and tetraethylorthosilicate (0.5 ml) were consecutively added into the SPIO solution at room temperature under continuous mechanical stirring. In a typical procedure, 0.2 ml of water-based SPIO (EMG 304) was diluted with 6 ml of 18 MΩ water and 80 ml of absolute ethanol. The resulting multifunctional nanomaterial, designated SPIO-Au nanoshells, combines the attractive photo-thermal property of gold nanoshells with the magnetic property of SPIO and thus may be useful for targeted photo-thermal therapy mediated through external magnetic field and MRI guidance. In this paper, we describe the synthesis, characterization, and use of nanoparticles with an SPIO core and a gold nanoshell. A magnetic field is then applied to the site externally to concentrate the particles at the target site. drugs or genes) are attached to the magnetic nanoparticles and injected near the target site. In addition, magnetic nanoparticles are being studied to determine whether their use as carriers enhances delivery of therapeutic agents in the presence of external magnetic field 14 - 16. Use of SPIO nanoparticles for imaging of atherosclerotic lesions 11, 12 and for monitoring of the in vivo distribution of cellular trafficking 13 is currently being investigated. SPIO-enhanced MRI has become an established technique for imaging of macrophage activity, in particular for staging of liver tumors and detection of lymph node metastasis several products for SPIO-enhanced MRI have been approved or are being studied in clinical trials 7, 9, 10.
SPIO nanoparticles have a high transverse relaxivity, r 2, which results in negative contrast on T 2-weighted images. These particles not only can be used in biomedical imaging applications but, more important, are potential candidates for localized photo-thermal therapy because they mediate strong plasmon-induced surface heat flux upon absorption of NIR light 4 - 6.Īnother class of inorganic nanoparticles, superparamagnetic iron oxide (SPIO) nanoparticles, have shown great promise in magnetic resonance imaging (MRI) 7, 8. In particular, gold nanoshells exhibit strong absorbance with wavelength tunable in the near-infrared (NIR) region of the electromagnetic spectrum. Nanoparticles derived from gold are an attractive system for diagnostic and therapeutic applications owing to their ease of preparation, ready bioconjugation, good biocompatibility, and unique optical properties 2 - 4. The increasing availability of nanostructures with highly controlled optical properties in the nanometer size range has created widespread interest in the use of nanoparticles in biological systems for diagnostic and therapeutic applications 1. The use of SPIO-Au nanoshells, with their combination of unique magnetic and optical properties, should enhance the efficacy of nanoshell-mediated photo-thermal therapy by making it possible to direct more nanoparticles to tumors through the application of external magnetic field and by permitting real-time in vivo MRI imaging of the distribution of the nanoparticles before, during, and after photo-thermal therapy. Moreover, SPIO-Au nanoshells showed efficient photo-thermal effect when exposed to NIR light. In addition, they exhibited high transverse relaxivity, r 2, and a large r 2/r 1 ratio and therefore could be imaged by MRI to obtain T 2-weighted images. These multifunctional nanoparticles, designated SPIO-Au nanoshells, displayed superparamagnetic characteristics and a significant absorbance in the near-infrared (NIR) region of the electromagnetic spectrum. We describe the synthesis, characterization, and use of hybrid nanoparticles with a superparamagnetic iron oxide (SPIO) core and a gold nanoshell.
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