Dissertation > Excellent graduate degree dissertation topics show

Functionalization of Planar Surface Si (111)-H with Covalently Bound Molecular Monolayers and Polymer Brushes and Their Chemical Conversions to Immobilize Biomolecules

Author: LiuXiang
Tutor: XiaoShouJun
School: Nanjing University
Course: Inorganic Chemistry
Keywords: Planar silicon Covalently coupled Monolayers of Polymer brushes Biomolecules
CLC: O613.72
Type: PhD thesis
Year: 2011
Downloads: 126
Quote: 0
Read: Download Dissertation

Abstract

In recent years, the people of planar silicon surface chemical modification of the various methods, in order to meet the requirements of the special properties of the planar silicon interface in the field of bio-chip, molecular devices, microelectronics: silicon surface by chemical methods chemical modification, you can give it a new physical and chemical properties, and can use it to prepare biosensors, protein and DNA detection chip. Chemical modification method can be used in the reaction of the silane coupling agent with the surface Si-OH role as well as the Grignard reagent with the surface Si-Cl or Si-Br is achieved, the former easily in alkaline solution, but the resulting Si-O-Si bond, easy to further cleavage: the latter requires relatively harsh reaction conditions, and due to the limited types of Grignard reagent, and can not satisfy a variety of actual requirements. The actual application process, the required stable covalent bonds can be generated in the silicon surface can be subjected to a different chemical environment, the different functions of a functional group can be easily introduced. Si-C bond is stable chemical properties, the planar silicon material itself can be resistant to a variety of organic solvents, acids and weak bases; SI-C bond formation by 40% NH4F solution corrosion, is first formed in the Si (111) surface perpendicular to the silicon plane of the Si-H bond, with one end with the functionality of a functional group, while the other end with the C = C bond of organic reactions, the formation of the monomolecular film of the terminally functionalized, can also be further chemically modified until meet certain requirements until the Si (111), the reaction process remain atomic level smoothness. These indicate the Si (111) wafers and other areas in biology, molecular devices will have broad application prospects. This article relates to the following aspects: First, under the conditions of microwave heating through the Si-H and 10 - en-1 - Acid direct reaction forming an end of the monomolecular film with a carboxyl group, a carboxyl group with N-hydroxy succinimide ( NHS) esterified later, with a primary amine group-containing aminobutyl nitrilotriacetic acid (ANTA) at pH = 8.0 aqueous solution of a nucleophilic reaction occurs, generating end formation the triacetic acid amine (NTA), using its strong coordination capability , so that Ni (Ⅱ) therewith ligands. Coordination bond, His-tagged protein (thioredoxin-urodilatin) fixed on the flat surface of the silicon. Likewise, with both FITC and Histidine labeled proteins also can be fixed on the flat surface of the silicon. To further enhance the density of reactive functional groups, we will be on the end of the step the obtained NTA acidified in 0.1M HCl, and then sequentially occur with the NHS esterified and ANTA occur to amidation reaction, to generate a second generation of NTA structure on the silicon surface. So that the density of the NTA groups will be significantly improved, so by such duplication means can be fixed more of Ni (II), and also can be fixed more protein molecules. Most of the reactions in the chemical modification process to take advantage of our group developed several transmission - reflection infrared (MTR-IR) attachment to characterize. Immobilized protein increase in the number of the silicon surface by MTR-IR, laser-assisted dissociation / ionization - time of flight mass spectrometry (MALDI-TOF-MS) and fluorescence scan characterized by X-ray, surface binding of Ni (II) amount Photoelectron spectroscopy (XPS) Characterization. MTR-IR and fluorescence scanning proved: second generation NTA/Ni2 of a fixed amount of protein is The first generation NTA/Ni2 of 1.63 times. In order to further enhance the number of the planar silicon surface functional groups of NTA, taking the application in the biological field, having anti-biological contamination in the planar silicon surface graft poly (polyethylene glycol mono methyl methacrylate) (PEGMA) polymer brush (Si-gP (PEGMA)), using the above method, the amount of protein that is bound. First through the Si-H and 10 - en-1 - ol reacted under microwave heating conditions, a hydroxyl group at the end of the assembly of the surface of the planar silicon substrate; then the atom transfer radical polymerization (ATRP) the necessary initiator 2 - bromo -2 - methylpropionyloxy the bromine (BMPB) introduced by the esterification reaction of the surface of the planar silicon; monomers PEGMA in the table to perform graft copolymerization, arising from the Si-gP (PEGMA) was activated with succinic anhydride to produce the terminal carboxyl group of the structure (Si-gP (PEGMA-COOH)). terminal carboxyl group with the NHS reaction NHS ester, then with ANTA reaction generated end of the NTA. Continue with the reaction with NHS, followed by reaction with ANTA generate a second generation of NTA structure; repeating the aforementioned method, generated until the third generation NTA structure. Used to bind Histidine modified structure with Ni2 coordination after three generations NTA Thioredoxin-urodilatin. MTR-IR tracking the gradual response. IR spectrum V (NH) integral area calculation, the ratio of the fixed amount of protein of the first generation of nitrilotriacetic acid to the third generation triacetate amine 1:1.7:2.3. Furthermore, we reported a brush on the silicon surface polymer (Si-gP (PEGMA-OH)) synthetic dendritic structure Polyamidoamine (PAMAM). Prepared by ATRP method first surface of the planar silicon Si-gP (PEGMA-OH). Reacted with SOCl2, and the end of the-OH is converted to-Cl, the terminal-Cl is ethylenediamine substituted, to give a terminal primary amine structure. Each one terminal primary amino group can theoretically occur with the two methacrylate Michael addition, in theory, to generate two terminal ester (- (C = O)-OCH3). These two terminal ester groups with ethylenediamine amidation reaction, to give the two terminal amino group. Repeat the above Michael addition and amidation reaction, having resistance to biological contamination of the Si-gP (PEGMA-OH) end of the dendritic structure PAMAM. The dense silicon surface amino group can be obtained through the (N-succinimidyl-6-maleimidylhexanoate, SMH) the crosslinking reaction with the amide group, -6 - maleic acid amide, N-succinimidyl group hexane ester activation. Biological molecules such as oxytocin can be bound plane in such a functionalized silicon surface. Further, this silicon surface can be used as a platform to dendritic structure PAMAM Synthesis of three amino acids in the small peptide H-Arg-Gly-OH (RGD). Every step of the reaction are MTR-IR monitoring tracking, assisted by XPS, UV-Vis and MALDI-TOF-MS for further proof. Finally, we polymer brushes on the silicon surface on the Si-gP (PEGMA) prepared by two different groups, to achieve Click Chemistry reaction. On one hand, Si-gP (PEGMA-OH) react with SOC12,-OH,-Cl substituted-Cl then is substituted NaN3-N3, obtained polymer brushes Si-gP (PEGMA-N3); other hand through the Si-gP (PEGMA-OH) is reacted with propargyl bromide to give (PEGMA-CH2C = CH) Si-gp. Propargyl amine of the end of the alkynyl group-containing model compound, propiolic acid and 10 - yn-1 - acid with terminal azido group polymer brush reaction, the terminal azido group-containing model compound benzyl azide The alkynyl group-containing polymer with the end brush reaction. These reactions under microwave conditions, Cu (Ⅱ) / L-sodium ascorbate system as a catalyst, and 30 ° C under the reaction is completed within 1h. Every step of the chemical reactions are used to interface sensitive technique: MTR-IR and XPS analyzed in detail. Attributable to the triazole ring v (HC =) 3139 cm-1 absorption peak and XPS N ls high resolution scanning as conclusive evidence that the Click chemistry reaction. By quantitative infrared analysis before and after the Click reaction, we found that microwave irradiation brings a high yield and efficiency. Therefore, the microwave radiation procure silicon surface Click reaction technology may be used for the fabrication of the device of the assembling of functional compounds, and organic / silicone.

Related Dissertations

CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Non-metallic elements and their compounds > Part Ⅳ family of non-metallic elements (carbon and silicon ) and its compounds > Si Si
© 2012 www.DissertationTopic.Net Mobile