【作者】 王莲；

【导师】 李全新；

【作者基本信息】 中国科学技术大学 ， 物理化学， 2007， 博士

【摘要】 本论文利用原子氧自由基阴离子（O^-）的强氧化性和反应性特点,结合我们研发的o^-储存发射材料（C12A7-O^-）以及高纯度O^-制备方法,首次开展了（1）原子氧自由基阴离子诱导的微生物失活和相互作用机理研究;（2）原子氧自由基阴离子诱导的聚合物表面改性及其机理研究;（3）原子氧自由基阴离子诱导的硅片表面氧化和二氧化硅薄膜形成研究。研究结果表明,O^-和O^-储存发射材料在微生物失活、聚合物材料改性和氧化硅薄膜制备等领域具有重要的潜在应用价值。本论文的主要研究内容与结果包括:1.原子氧自由基阴离子诱导的微生物失活和相互作用机理研究1)高纯原子氧自由基阴离子束的产生:C12A7-O^-材料是一种具有储存、发射原子氧自由基阴离子（O^-）的功能材料,我们利用等离子镀膜技术,将该材料镀在镶嵌有加热丝的陶瓷支撑体表面,制成O^-发生器。研究结果表明,由该O^-发生器产生的最大O^-束强度为220μA,发射的O^-束纯度大于90%。2)O^-水溶液的制备与表征:利用氩气为载气,将O^-发生器产生的O^-离子通入去离子水中制成O^-水溶液:形成的O^-水溶液一般呈酸性,利用电子顺磁共振（EPR）和紫外—可见分光光度计（UV-VIS）等表征方法,测量了O^-水溶液中O^-和H₂O₂等活性氧物种的浓度。3)气相原子氧自由基阴离子的微生物失活和机理研究:利用由O^-发生器产生的高纯O^-束,研究了气相原子氧自由基阴离子诱导的微生物失活和机理。主要考察了O^-束强度、处理温度、微生物初始浓度等对微生物失活效果的影响以及细胞结构的变化。结果表明,1.5μA/cm²O^-束在120 min内可以引起3个对数量级以上的微生物数目的减少,失活效率随O^-束强度、处理温度的增加而增加;微生物初始浓度对失活效率没有显著性影响;O^-束诱导的不同种类的微生物的失活效果不同,与微生物的结构有关。场发射扫描电镜（FESEM）、四极质谱（Q-MS）和时间飞行质谱（TOF-MS）结果显示大肠杆菌的细胞壁和细胞膜被O^-破坏,同时在失活过程中有CO和CO₂产物生成。4)O^-水溶液中微生物失活和机理研究:在不同条件下,考察了大肠杆菌在O^-水溶液中的失活过程,探讨了失活机理。结果表明,在60 min内,O^-水溶液[pH4.30±0.20,（2.5±0.8）×10^-2mmol/10 O^-;0.5±0.2 mmol/1 H₂O₂]可以使大肠杆菌的数目减少3个对数量级;在15—45℃的温度范围内,失活效率随温度的增加而增加;大肠杆菌的初始浓度升高,失活效率降低。O^-水溶液诱导的大肠杆菌失活过程中,存在大肠杆菌细胞的脂质过氧化反应,并出现核酸泄漏现象,FESEM观察发现细胞壁破损。因此,O^-诱导的细胞壁和细胞膜破损以及核酸泄漏可能是大肠杆菌死亡的潜在原因。2.原子氧自由基阴离子诱导的聚合物材料表面改性及其机理研究1)O^-水溶液对聚苯乙烯的表面改性研究:以O^-水溶液（0.03±0.01 mmol/1 O^-;0.5±0.1 mmol/1 H₂O₂）为反应液,研究了在常温下O^-水溶液对聚苯乙烯表面改性效果。利用接触角仪、原子力显微镜（AFM）、FESEM、X射线光电子能谱仪（XPS）、全反射傅立叶红外变换光谱仪（ATR-FTIR）等表征手段对改性后表面亲水性、粗糙度、表面形貌及表面物种进行了详细地分析。结果表明,O^-水溶液在48小时内使聚苯乙烯的接触角降低10°,引起表面能和亲水性提高:O^-水溶液改性后的表面变粗糙,引入了新的OH和C=O等亲水官能团。亲水官能团的引入是表面亲水性提高的原因。2)O^-水溶液对聚四氟乙烯的表面改性研究:O^-水溶液处理后的聚四氟乙烯表面有C—O,C—F和CF₃等新官能团生成,表明O^-引起了聚四氟乙烯表面化学键的断裂和氧化,同时未发现诸如C=O和OH等亲水官能团生成。常温下O^-水溶液处理48小时可使聚四氟乙烯表面的接触角提高14°,引起表面能和亲水性降低,疏水性提高。FESEM结果显示,O^-水溶液改性后的聚四氟乙烯表面变粗糙,这可能是表面疏水性提高的原因。3.原子氧自由基阴离子诱导的硅片表面氧化和二氧化硅薄膜形成研究利用O^-束对硅片表面氧化和二氧化硅薄膜形成过程进行了研究,并且由O^-氧化的硅片制备了金属-氧化物-半导体（MOS）电容器,测试了电容器的电学特性。更多还原

【Abstract】 This dissertation presents a novel approach to the inactivation of microorganisms and surface modification of materials by using atomic oxygen radical anion（O^-）which is prepared by C12A7-O^- material.In this work we mainly focus on the inactivation efficacy and inactivation mechanism of microorganisms induced by O^-,alterations of surface properties of polymers after surface modification via O^-, and oxidation of silicon and formation of SiO₂ on silicon surface by O^-.The major conclusions have been summarized as follows:1.Study of the microorganisms’ inactivation and inactivation mechanism induced by O^-1)The preparation of high pure O^- beam:O^- can be stored and emitted by C12A7-O^- material.An O^- generator was prepared through coating with C12A7-O^-material on the surface of ceramic in which was a heater.The maximum intensity of O^- beam emitted from O^- generator was 220μA and the purity of O^- beam was higher than 90%.2)The preparation and characteristics of O^- solution:The O^- solution was prepared by bubbling of the O^- beam into the deionized water for a duration time. The O^- solution was usually acid.The concentrations of active oxygen species such as O^- and H₂O₂ in the O^- solution were investigated by electron paramagnetic resonance（EPR）and ultraviolet-visible spectroscopy（UV-VIS）.3)Inactivation of microorganisms with gaseous O^- beam:The inactivation of microorganisms mainly depends on the intensity of O^- beam,treatment temperature, and kinds of microorganism.The results indicate that the O^- beam shows a good ability for microorganisms’ inactivation and the cell mortality is enhanced to more than 3-logarithm reduction with O^- beam of 1.5μA/cm² for 120 min.The inactivation efficacy increases with the increases of the intensity of O^- beam and treatment temperature,and independents on the concentration of microorganism.Different mortalities are obtained for different kind of microorganisms due to their different cytoarchitecture.Field emission scanning electron micrographs（FESEM）reveals that the cell structures are destroyed by the exposure to O^- beam.The observed anionic intermediates by a time-of-flight mass spectrometer（TOF-MS）and the neutral volatile products（CO,CO₂）by a Quadruple mass spectrometer（Q-MS）provide an evidence of the reactions between O^- and microorganism.4)Inactivation of microorganism with O^- solution:Effective inactivation of Escherichia coli through O^- solution has been obtained.Escherichia coli cells are reduced by more than 3 logarithm in the O^- solution[pH 4.30±0.20,（2.5±0.8）×10^-2mmol/l O^-;0.5±0.2 mmol/l H₂O₂]within 60 min at 30℃.Significant temperature dependent on the surviving populations is observed within our tested temperature range（15-45℃）.Lipid peroxidation reaction and nucleic acid release induced by O^- solution are identified.The treated cells by O^- solution also appear dramatically collapsed by FESEM observation.The release of nucleic acid and the disrepair of cell wall caused by O^- are responsible for the inactivation of Escherichia coli cells.2.Study of the surface modification of polymer materials with O^-1)Surface modification of polystyrene with O^- solution:The O^- solution（0.03±0.01 mmol/l O^-;0.5±0.1 mmol/l H₂O₂）treatment has caused an obvious increase of the surface hydrophilicity,surface energy,surface roughness and also caused an alteration of the surface chemical composition for polystyrene surfaces,which are indicated by the variety of contact angle and material characterization by atomic force microscope（AFM）imaging,FESEM,X-ray photoelectron spectroscopy（XPS）,and attenuated total-reflection Fourier transform infrared（ATR-FTIR）measurements. Particularly,it is found that some hydrophilic groups such as hydroxyl（OH）and carbonyl（C=O）groups are introduced onto the polystyrene surfaces via the O^-solution treatment,leading to the increases of surface hydrophilicity and surface energy.2)Surface modification of polytetrafluorethylene with O^- solution:C—O,C—F, and CF₃ chemical bonds have been formed after O^- solution（0.03±0.01 mmol/l O^-; 0.5±0.1 mmol/l H₂O₂）treatment,which indicate O^- solution leads to chain scission and oxidation.At the same time,no hydrophilic groups such as C=O,OH appeared. The contact angle on polytetrafluorethylene surface increases by 14°treated by O^-solution for 48 h at room temperature.The O^- solution treatments lead to the decreases of surface energy and hydrophilicity,the increase of hydrophobicity. FESEM results indicate the surface of polytetrafluorethylene become rougher after O^-solution treatment,which might be the reason for the increase of hydrophobicity.3.Study of the surface oxidation of silicon with O^-Surface oxidation of silicon（Si）wafers by O^- beam and production of metal-oxide-semiconductor（MOS）capacitors with the O^- -oxidized Si substrates were examined.The features of the MOS capacitor were investigated by measuring capacitance-voltage（C-V）and current-voltage（I-V）curves.更多还原