Synthesis And Assembly Of Functional Micro/nano-Materials For The Bio-application

The main purpose of this thesis is to prepare functional micro/nano-materials and to investigate their possible application in biology. We successfully synthesized several types of gold and magnetic nanoparticles with bio-functional surface. By using the electrospinning and microfabrication techniques, we fabricated the ordered micro-structures of these micro/nano-materials. Furthermore, we tried to applied these micro/nano-materials for bioapplication. The detail of this thesis includes the following six parts:1. A one-step synthetic method has been successfully applied to prepare IgG-capped aqueous colloids of noble metal (Au, Ag and Pt) nanoparticles (NPs), in which IgG is used as the solo stabilizing regent. The produced NPs were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Both Au and Ag NPs prepared from this message show relatively narrow size distribution and form stable suspension in aqueous solution. The IgG-capped AuNPs exhibit much higher stability against high salt concentration than that prepared by conventional ligand-exchange method. The IgG molecules on the Au and Ag NPs can retain their bioactivity, which enables the NPs to bind with specific antigen.2. We report the sonication-assisted synthesis of silica coated gold nanorod (AuNR) nanostructures. By using sonication, the silication reaction occurs rapidly and homogeneously on the poly(vinylpyrrolidone)(PVP) primed AuNRs and the aggregation of AuNRs was significantly inhibited. The obtained core-shell nanoparticles (NPs) were characterized by TEM, UV-vis spectrometer and scanning electron microscopy (SEM). The AuNR@SiO2NPs show uniform size and shape distribution, and strong near infra-red (NIR) absorption property. This sonication-assisted method can also be applied to prepare multifunctional NPs, like AuNR@Fe3O4@SiO2nanostructures.3. Electrospinning was used to produce nanofibers from a magnetic nanoparticles containing polymethylglutarimide (PMGI) precursor solution. After sonication, the fabricated nanofibers were uniformly segmented. We studied the magnetic response of the fiber segments to the external magnetic field. NIH3T3cells were then cultured in a medium containing magnetic fibers, resulting in stable cell-nanofiber hybrids which can be conveniently manipulated with a magnet. 4. Molybdenum disulfide (MoS2) nanosheets were used as nanofillers to fabricate the polymer composite nanofibers by electrospining. The MOS2nanosheets were well dispersed inside the fibers from the TEM and SEM characterization. The incorporation of the MOS2nanosheets changes the polymer nanofibers from round to ribbon-like morphology. Moreover, through TGA and DMA measurements, the MoS2nanosheets additive materials could provide reinforcement of the thermal stability and increase the storage modulus.5. We successfully transferred the electrospun nanofibers on the glass substrate, which show high stability than the nanofibers directed spun on the glass. Combining the electrospinning and microfabrication techniques, we prepared the micropattems of nanofibers by UV-Iithography technique. Nanofiber micropattems were as well fabricated by reactive ion etch without solvent.6. We report a facile self-assembly strategy for fabricating TiO2microlens arrays by localized hydrolysis of TiCl4precursor in water droplets. Micro-contact printing was used to define hydrophilic areas on a substrate for space resolved hydrolytic reaction. The water droplets served as the templates, reactant and microreactors. Both size and shape of the final TiO2microlens can be controlled by the printed chemical pattern and the precursor concentration. The optical application for light focus was investigated by the microscopy imaging process.