Study Of Sensing And Fabricating For Au/hydrogel Micron-Namometer Meterials Using Microfluidic Technology

As the synthesis and fabrication of nanomaterials are improved continuously,more and more nanotechnology has emerged from the laboratory and been used in the factories. Microfluidic technology, originated from electrophoretic separation in the laboratory, is a multidisciplinary science and technology and will be deeply industrialized. Microfluidic chip can produce the uniform microdroplets, which are served as better reactors. The microfluidic chip is referred to "lab or plant in the chip",because this chip can be used for the preparation of materials, such as nanoparticles(NPs), microspheres and crystals. Noble metal NPs possess the Local Surface Plasmon Resonance (LSPR) property and strong electromagnetic coupling features. Tuning nanogaps between NPs is good method of improving these charechters. At present the main methods of tuning the nanogaps are self-assembly, etching, etc, which can prepare the orederd array nanomaterials. However, the nanogaps of these meterials are barely changed after design and preparation, and the LSPR performance of materials is difficult to achieve for human control and adjustment. Therefore, this aim of this study was to flexibly tune the nanogaps between Au NPs using by hydrogel swelling and shrinking properties in the composite materials with Au NPs and hydrogel, which were prepared by microfluidics, and the properties of the optical sensing and the Surface Enhanced Raman Scattering (SERS) of these composite materials were studied.Meanwhile, Au NPs 3D self-assembly and metal alloy NPs preparation have been finished by microfluidics, where the micro-droplets were used as the reactors. And the results are summarized as follows:1. A strategy of fabricating uniform Au NPs/hydrogel microbeads has been presented. The size tunable unifrom micro-droplets of Au NPs and hydrogel monomers were fabricated by microfluidic chip, and then plymeriazated and solidificated to solid-state microspheres by UV-light. The composite microspheres can realize the optical sensing for biochemical molecule because of tunable the nanogaps by hydrogel swelling and shrinkling. Compared with bulk and film shape hydrogel materials, the Au NPs/hydrogel composite microbeads have many advantages, such as simple preparation, conveniention and small-amount detection.2. A new strategy of SERS dynamic measurement is presented. Uniform P(AAm-co-AA) hydrogel microspheres were first fabricated using droplet-based microfluidic technique, and then the Au NPs absorbed on the surface of hydrogel microsphere through electrostatic interaction to form the hydrogel microsphere @ Au NPs. The hydrogel microspheres could be induced to swell by changing the pH value, thereby generating suitable nanogaps between the Au NPs on its surface to obtained high sensitivity SERS property in the semiwet state. Compared with the traditional SERS substrates, the nanogaps can be dynamically tuned by changing certain conditions during testing.3. A new strategy of Au NPs 3D self-assembly is presented. In the microfluidic chip, Au NPs assembly microspheres with uniform shape were prepared through controlling the aqueous dissolution from the mircrodroplet of Au colloid solution to n-butyl alcohol, and the microsphere size was changed by the flow and Au NPs concentration. These assembly microspheres have wide band absorption performance in the visible-infrared spectroscopy, which is great potential in the treatment of cancer,such as thermal therapy.4. A universal strategy of noble metal NPs preparetion is presented. Microdroplet generated in microfluidics can be a reactor, and prepare many noble metal NPs with core-shell structure. Compared with batch reactor, microfluidic technology can apply to small batch experiment research, and large-scale production fabrication as well.