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Construction of Micro/Nanostructures on the Inner Wall of Microchannels and Their Functional Design

Author: HeZhongZuo
Tutor: WangHongZhi
School: Donghua University
Course: Materials Science and Engineering
Keywords: Microfluidic Microchannel Micro-reactor Micro / nanostructures Zinc oxide Semiconductor coupling Core-shell structure Photocatalytic Enrichment Phosphopeptides
CLC: TB383.1
Type: PhD thesis
Year: 2011
Downloads: 178
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Abstract

Microfluidic technology as one of the areas of the world's most cutting-edge science and technology, with its high-throughput, low consumption technology advantages in the field of life sciences and industrial synthesis shows a great prospect. Microchannel as an important part of the microfluidic chip, in the early stages of the field development, its inner surface is just a pure surface micro space, while the with microfluidic technology development, especially microfluidic chip in biological detection specific aspects of a wide variety of applications, will require that the necessary modified to meet the different needs of the inner surface of the microchannel. Compared with the inner surface preparation layer functions film simply on the inner surface of the microchannel geometry modification, fine micro / nanostructures that build in the inner surface of the microchannel and micro / nanostructures grafted functional groups or molecules, can obviously microchannel surface has more features, is to promote the microchannel surface devices and microfluidic technology progress is an important research direction. Currently micromachining (microfabrication) technique with etching techniques, photolithography, soft lithography method, LIGA technology to build a micro / nano-structure in the open surface of the micro-channel, however, these methods are difficult to elongate, almost The microchannel closed, the the open microchannel sealing process will inevitably lead to the destruction of the micro / nanostructure formation. In view of this, the wet chemical method in almost closed quartz capillary microchannel build a specific micro / nanostructures, and build the micro / nanostructure surface modification gives the design microfluidic device specific features The successful design of a micro-channel type light catalytic enrichment with micro-reactors and micro-protein molecules. One-dimensional nanomaterials micro / nanostructures directly integrated into a closed microchannel avoid the traditional micro-channel micro / nano structural modification of the process of sealing bring destruction, but also take advantage of the latest study of one-dimensional nanomaterials device achievements, greatly extends the functionality of the microfluidic device design. Using wet chemical methods, with the help of nanotechnology will be integrated into a controlled ZnO nanorod arrays and the distribution density of ZnO nanorod flower-like clusters on the inner surface of the quartz capillary microfluidic channel. Seed layer of ZnO film prepared ethanol solution of NaOH and Zn (AC) 2.2 H2O on the surface of the microchannel; reverse microemulsion method and high temperature to emulsification caused grain reunion in the inside surface of the microchannel the resulting dispersion controllable ZnO seed crystal. The dispersion of seed crystal on a substrate for the growth of crystals and final morphology is very important. Completely covered with a surface layer of ZnO seed film microchannel vertical growth of ZnO nanorod arrays; decentralized controlled ZnO seed based on the distribution density-controlled growth of ZnO nanorod flower-like clusters . The study found that the water and surfactant, the molar ratio w is the main factors affecting the seed dispersion and nanorods distribution density is changed by changing the value of w is the size of the droplet size, thereby changing the particle size, and then by means of the inner surface of the capillary channel for The adhesion of the different sizes of nanoparticles, to effectively regulate the dispersion density of the seed crystal. With the increase in the value of w, the dispersion density of the seed crystal increases, the more dense the Nanorods distribution obtained, or vice versa. The experimental results only minor entrances sealed long microchannels functional modification or patterned design provides a new method. Pt / ZnO, TiO2/ZnO, ZnO @ ZnS nanorod arrays prepared on the basis of the array of the ZnO nanorods on the inner surface of the micro-channel, and the nanorod arrays modified micro-channel as a photocatalyst with the microreactor devices. Photocatalytic degradation of MB solution and 4 - chlorophenol solution, for example, investigated the photocatalytic performance-based the nanorods array of micro-channel reactor: (a) microchannel reactor based on ZnO nanorod arrays for photocatalytic degradation MB solution of 5 ppm, when the residence time (residence time, RT) for 100s, on the degradation of MB solution was 100%, the residence time continuous photocatalytic 180 h in its degradation of MB remained more than 80% (b) based on the distribution of controlled density ZnO nano rods flower-shaped clusters of micro channel reactor for photocatalytic degradation of 5 ppm MB solution, when the residence time is greater than 110 s, three capillary degradation rate of the MB are close to 100%, while in the short residence time (RT = 25 ~ 110 s), a capillary M (containing medium density ZnO) than H (containing a high density of ZnO) than containing LDL and L (ZnO) exhibits more photocatalytic activity, that on the inner surface of the micro-channel Nanorods distribution density that can affect the performance of the design of the micro device. (C) microchannel reactor based on Pt / ZnO nanorod arrays for photocatalytic degradation of 5 ppm MB solution, when the residence time greater than 35 s, complete degradation of MB solution. Pt on as photogenerated electron capture, and effectively improve the interfacial charge transfer efficiency. (D) Based on the nanorod array microchannel TiO2/ZnO reactor for photocatalytic degradation of 5 ppm MB solution, due to reduced coupling between TiO2 and ZnO semiconductor compound, the light-induced electron and hole The reactor exhibited enhanced photocatalytic activity than pure ZnO nanorod arrays. The TiO2 sol coated the number of TiO2/ZnO of nanorod arrays modified photocatalytic activity of the microchannel TiO2/ZnO-3 (coated for 3 times), showed the strongest photocatalytic activity. When the residence time of 20s, the MB solution was completely degraded, and the residence time for continuous repeating use for MB 100 h after the degradation rate at 90% or more. MB solution (e) nanorod arrays based on ZnO @ ZnS core-shell structure microchannel reactor for photocatalytic degradation of 10 ppm and 10ppm 4 - chlorophenol solution, when the residence time of 120 s, MB solution can be completely degraded 78% of 4 - chlorophenol degradation rate of the solution reached. Comparison TiO2/ZnO nanorod arrays a microchannel reactor showed the strongest photocatalytic activity, and in the continuous repeating use, the array of nanorods exhibit a good stability and resistance to fluid through photocatalytic activity erosion. Continuous flow through the delivery time control Ti02 sol ZnO nanorod arrays microchannel surface a the different coated the extent of TiO2/ZnO of nanorod arrays, in prefabricated. Modified based on TiO2/ZnO nanorod array microchannel microfluidic device for selective enrichment of phosphopeptides from protein digests. In an automated, continuous flow mode of operation to achieve the injection of protein hydrolysates, phosphopeptide enrichment and elution, and the device has a very good selectivity, sensitivity and persistence. 30s phosphate enrichment of the amount of peptide in the residence time is sufficient for the MALDI-TOF MS analysis. For phosphopeptide elution suitable residence time of 60s. In view of the durability of the microfluidic device, and continuous flow mode of operation, may become an effective and economical method for high throughput from a large volume of complex clinical samples, the selective enrichment of phosphopeptides. Similarly, it can be used as a convenient means of rapid and selective enrichment done before the mass spectrometric analysis of phosphorylated peptide. Prefabricated surface micro-channel ZnO nanorod arrays as a source of zinc and in situ template thioacetamide as a sulfur source by in situ synthesis method on the surface of the microchannel has been ordered and ZnO @ ZnS nanorod arrays of core-shell structure, continue to be transported to the microchannel sodium thioglycollate (sodium thioglycollate, ST) solution can be ST-ZnO @ ZnS nanorod arrays, followed by to transport freshly prepared Ag sol prepared containing silver Ag-ST -ZnO @ ZnS nanorod arrays. ST-ZnO @ ZnS nanorod arrays modified micro-channel has a strong adsorption of bovine serum albumin solution (bovine serum albumin, BSA) molecules, and showed good durability. Ag-ST-ZnO @ ZnS nanorod arrays modified micro-channels to achieve the enrichment of trace amounts of BSA molecules in solution, and the use of surface-enhanced Raman spectroscopy (surface-enhanced Raman scattering, SERS) detected by the enrichment to BSA. Nanorod arrays of core-shell structure-based micro-channel device, not only from the large volume of biological samples in continuous high-throughput protein isolate, and proposed a simple method for the enrichment and detection of trace amounts of protein.

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