Multifunctional Magnetic Nanoparticles For Biomedical Photonics Applications

Multifunctional magnetic nanocomposites have potential applications in purification, immunoassay, diagnostic imaging, nano-medicine and advanced photonics. For these applications, how to integrate optical, electrical, magnetic and other functions into monodisperse, high saturation magnetization, and morphology cotrolled nanocomposite is one of key scientific issues. Because different components in multifunctional nanoparticle will interact with each other, their functionalities could be suppressed or weakened to so some extent. For example, researchers find that absorption properties of metal particles and optical properties of quantum dots were influenced or completely disappeard in metal-semiconductor or quantum dots nanocomposite particles, which limited their further application. The susceptibility of magnetic particles decreases as the coated metal shell thickness increases, and so on. These weakened and reduced functions serious impact the responsiveness of materials to environmental stimulies, and thus limit their further applications in biomedical photonics.To solve these above problems, we will foucs on the synthesis and control of novel multifunctional magnetic nanocomposites based on magnetic nanoparticles, and furthermore explore their potential applications in biomedical photonics. The detailed content contains five parts as follows:(1) A uniform, size controlled, high saturation magnetization superparamagnetic nanoparticle was synthesized by using a high-temperature hydrolysis method, and it was then dispersed into photopolymerization resin systems. After UV curing, I succeeded in preparing large size solid Colloidal Photonic Crystals with photonic band gap in the visible spectrum.(2) By using seed adsorption and particle growth methods, superparamagnetic nanoparticle suface was modified with a dense gold shell, and the characteristic plasma peak changes with the gold shell thickness. Induced by the magnetic field, the particles can quickly assembled to be a film. For high density hot spots, enhanced Raman signal strength, stability average enhancement factor, etc.. the particle film can be used as a novel surface-enhanced Raman active substrate (SERS substrate) for trace elements detection.(3) By using seed adsorption and particle growth methods, superparamagnetic nanoparticle suface was modified with upconversion luminescent rare earth nanoshell of different thickness. By changing the reaction parameters, we reduced the fluorescence quenching effect of rare earth materials generated by magnetic nanoparticles. We obtained the composite particle with a dual functional of fluorescence and magnetic resonance imaging (MRI). which thus broaden its biomedical photonics applications.(4) We have developed a new "non-classical controlled nucleation and growth control" approach on preparing a nanoscale exactly controlled magnetic-mesoporous rod-like nanoparticles of asymmetric nature. Janus magnetic-mesoporous nanoparticles. Through the unique suface hydrophobic and hydrophilic properties, the particles assembled at the oil-water interface into a complete shell, strong magnetic response magnetic microcapsules for drug release.By chemical modification. Janus magnetic-mesoporous nanoparticles were modified by fluorescent molecule for fluorescence imaging.(5) By using in situ reduction method, Janus magnetic-mesoporous nanoparticle surface was decorated by small size, large surface area of silver nanoparticles. Experiments show that when silver particles of 9.6μg/ml and 12.5μg/ml can effectively inhibit the growth of Escherichia coli and Bacillus subtilis. respectively. This novel nanocomposite own not only long-lasting antimicrobial ability but also efficient magnetic separation characteristics, which has a wide range of applications in environmental and medical field.