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仿生复合纳米酶的层状前体法可控制备及其杀菌机制研究
陈超
Subtype博士
Thesis Advisor张盾
2020-05-08
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士学位
Keyword海洋防污 层状前体 复合金属氧化物 纳米酶 杀菌机制
Abstract海洋生物污损是人类开发利用海洋资源亟需解决的重要问题之一。因此,开发高效绿色防污材料具有重要意义,同时也面临巨大挑战。环境友好型纳米材料模拟酶(纳米酶)在海洋防污方面有极大的应用前景。本文针对现有纳米酶的价格高、易于团聚失活、制备工艺复杂和应用环境苛刻等应用瓶颈,主要基于层状前体(LDHs)法制备复合金属氧化物(MMOs)的技术优势,通过调控层状前体活性过渡金属组成和比例可控制备出具有特定组成和结构的层状前体,经焙烧拓扑衍生构筑系列不同化学组成、微观结构和表面性质的具有氧化酶(OXD)和过氧化物酶(POD)样活性的双功能MMOs仿生复合纳米酶,明晰了影响其模拟酶催化调控活性氧(ROS)水平的核心控制要素,建立了MMOs与模拟酶催化杀菌性能的构效关系,阐明了不同MMOs介导的ROS水平对污损微生物的影响作用和分子机制,为新型、高效、绿色防污材料开发提供理论支持和指导。具体研究内容如下: 1. 采用尿素均匀沉淀法可控合成出不同[Ni2+]/[V3+]摩尔比的Ni-V LDHs层状前体,经过焙烧处理衍生制备出不同[Ni2+]/[V3+]摩尔比的Ni-V MMOs材料,系统研究了前体组成和焙烧温度对于MMOs材料晶体结构、微观形貌、比表面积等的调控机理,发现400 oC焙烧样品具有较大的比表面积和二维超薄纳米片结构,微观结构为粒径小于5 nm的Ni3V2O8纳米颗粒均匀镶嵌在NiO超薄纳米片基体中。首次发现Ni-V MMOs材料具有优异的POD模拟酶催化性能,前体组成和焙烧温度对POD模拟酶催化性能有调控作用,催化机理为·OH机理,可增强ROS水平。 2. 采用更具活性的Co替代Ni通过制备新型Co6(CO3)2(OH)8·H2O@Co3V2O8一维纳米线前驱体及焙烧处理两步控制合成法,经Co6(CO3)2(OH)8·H2O向Co3O4的拓扑化转变首次成功制备出由Co3V2O8和Co3O4组成的Co-V MMOs纳米线,并首次发现其具有OXD和POD双功能模拟酶活性,催化活性受[Co2+]/[V3+]摩尔比和焙烧温度控制。400 oC煅烧所得[Co2+]/[V3+]摩尔比为3的Co-V MMOs纳米线催化活性最优,可催化产生·O2杀菌,将H2O2的有效作用浓度降至50 μM,在中性介质中也具有广谱杀菌活性,杀菌机理为ROS增强机理。 3. 通过精确控制六亚甲基四胺(HMT)用量调控共沉淀体系的pH首次制备出单一相Co-V LDHs层状前体。焙烧后可制备化学组成为Co3V2O8和Co3O4的Co-V MMOs。LDHs层状前体的制备是得到高活性MMOs的关键控制要素,所得MMOs继承了LDHs的片状结构,为连续的二维超薄纳米片状形貌,且比非单一相层状前体制备MMOs材料具有更大的比表面积、更丰富的表面活性位点和分散更加均匀的复合结构。这些更优的表面性质赋予二维超薄Co-V MMOs纳米片比一维Co-V MMOs纳米线更优的OXD和POD双功能模拟酶催化杀菌活性。在生物安全范围内(不高于10 μg/mL)和1 μM H2O2(一维Co-V MMOs纳米线的1/50)的条件下具有优异的杀菌性能,在防污领域有良好应用前景。 4. 采用尿素均匀沉淀法合成了不同Ce掺杂量的三元Co-Al-Ce LDHs层状前体,发现在Ce掺杂量小于5%时可以得到单一相LDHs层状前体,焙烧后可转化为化学组成为CeO2、Co3O4和CoAl2O4的三元Co-Al-Ce MMOs。首次发现Co-Al-Ce MMOs为OXD和POD双功能模拟酶,Ce掺杂量和焙烧温度是调控MMOs模拟酶催化活性的控制要素,当Ce掺杂量为2.5%和焙烧温度为200 oC时所得MMOs具有最优活性,在无H2O2存在条件下即可杀灭细菌,杀菌机理为·O2机理。由于CeO2活性相的引入,Co-Al-Ce MMOs在近中性条件下在H2O2的协同作用下可通过提高胞内ROS水平杀灭Escherichia. coli,显示了在海洋环境中作为防污剂应用的潜力。 5. 前述层状前体法制备MMOs均由氧化物组成,为拓展层状前体法制备复合纳米酶的工艺途径,水热合成了粒径在300 nm单分散的VS4亚微球,发现在H2O2存在下,VS4具有模拟POD催化活性,对底物TMB和H2O2的亲和力优于天然辣根过氧化物酶,催化机理为·OH机理。相较于·O2,·OH具有更强的氧化性,在水溶液体系中可稳定存在,具有潜在的防污活性。建立了过渡金属硫化物与氧化物的有机联系,后续基于层状前体的可控硫化和氧化将有望得到性能更优的模拟酶防污材料体系。 总之,本论文主要基于层状前体衍生制备MMOs来获取具有良好模拟酶催化杀菌活性的仿生复合纳米酶材料。通过控制焙烧条件,MMOs可继承前体的特殊形貌,具有大的比表面积、丰富的表面活性位点和活性相分散均匀的复合结构,可有效克服纳米酶的团聚失活瓶颈问题。利用层状前体组成结构可调的特点,通过可控硫化和氧化工艺处理可实现ROS调控功能的调变,有望实现在海洋防污领域的实践应用。
Other AbstractMarine biofouling is one of the most important problems needing to solve in the development and utilization of marine resources. Therefore, it is of great significance to develop highly efficient and green non-toxic antifouling materials, and it also faces great challenges. Environment-friendly nanomaterials mimic enzymes (nanozymes) have great application prospects in antifouling field. In order to overcome the bottlenecks of materials in the application such as high cost, easy agglomerating deactivation, complex preparation process and harsh application environment, layered double hydroxide (LDHs) as precursor are performed to prepare mixed metal oxides (MMOs). By adjusting the composition and proportion of active transition metal in the LDHs and the baking temperature of the topotactic transition, MMOs with specific composition and structure can be prepared. A series of bifunctional MMOs with oxidase (OXD) and peroxidase (POD) like activities with different chemical composition, microstructure and surface properties were constructed. The key factors affecting the activity of ROS level were clarified. The relationship between structure of MMOs and the activity of mimic enzyme was established. The effects of ROS level mediated by different MMOs on fouling microorganisms were clarified, which provide theoretical support and guidance for the development of new, efficient and green antifouling materials. The specific research contents are as follows: 1. Ni-V LDHs precursors with different [Ni2+]/[V3+] mole ratios were synthesized by urea coprecipitation. After calcination, Ni-V MMOs with different [Ni2+]/[V3+] mole ratios were obtained. The controlling mechanism of the crystal structure, morphology and specific surface area of MMOs by composition ratio and calcination temperature of the precursor was studied systematically. Ni-V MMOs calcined at 400 oC had large specific surface area and ultrathin nano sheet structure. Ni3V2O8 nanoparticles with particle size of sub-5 nm were well dispersed on the NiO nanosheet matrix. For the first time, it was found that Ni-V MMOs exhibits excellent POD mimic activity. The composition and calcination temperature of precursor can be used to regulate the POD mimic activity. The ·OH radical was the intermediate in enhancing the level of ROS. 2. Co6(CO3)2(OH)8·H2O@Co3V2O8 nanowire precursor were synthesized by urea coprecipitation when Co was used to instead of Ni. The Co-V MMOs nanowires composed of Co3V2O8 uniform dispersing among Co3O4 by calcining Co6(CO3)2(OH)8·H2O@Co3V2O8 nanowires. Co-V MMO nanowires possessed intrinsic OXD and POD catalytic activity. When the [Co2+]/[V3+] molar ratio was 3 and the calcination temperature was 400 oC, Co-V MMOs showed the best activity. The activity originated from their ability to catalyze the generation of ·O2, which hydrolyze to ·HO2. Utilizing this unique bifunctional activity, Co-V MMOs exhibited a good antibacterial effect combining with a low level of H2O2 (50 μM). 3. The single phase of Co-V LDHs were first prepared by controlling the amount of HMT accurately and controlling the pH of the coprecipitation system. After calcination, Co-V MMOs composed of Co3V2O8 and Co3O4 could be prepared. The preparation of LDHs was the key factor to obtain highly active MMOs. MMOs inherited the layer structure of LDHs, which had larger specific surface area, richer surficial active sites and more evenly distributed composite structure. These superior surface properties enhanced the OXD and POD activity of 2D ultrathin Co-V MMOs nanosheets superior than 1D Co-V MMOs nanowires. It had excellent bactericidal properties under the condition of biological safety (not more than 10 μg/mL) and 1 μM H2O2 (1/50 of 1D Co-V MMOs nanowires), which showed a good application prospect in the field of antifouling. 4. The single-phase ternary Co-Al-Ce LDH was synthesized using a urea hydrolysis method with the ratio of Ce less than 5%. After calcination, Co-Al-Ce MMOs composed of CeO2 compounding with Co3O4 and CoAl2O4 had been successfully synthesized. It’s the first time found Co-Al-Ce MMOs with dual enzyme-like activities. The molar ratio of Ce and the calcination temperature were the control factors for the catalytic activity of MMOs mimetic enzyme. When the molar ratio of Ce was 2.5% and calcination temperature was 200 oC, the obtained 2.5CoAlCe-200 sample exhibited the best POD-like activity. 2.5CoAlCe-200 possessed dual enzyme-like activities similar to those of OXD and POD, which can catalyze H2O2 and O2 to generate ROS, mainly ·O2. Owing to the excellent antibacterial capacity of ·O2, Co-Al-Ce MMOs exhibited antibacterial activity even in near-neutral pH solution. This provided strong evidence that Ce-containing MMO could be utilized as the potential green marine antifouling nanozyme material. 5. We had hydrothermally synthesized VS4 submicrospheres, which were discovered to act as POD catalyst to oxidize the POD substrates in the aid of H2O2. The preparation of MMOs by LDHs was composed of oxides. In order to expand the preparation process of composite nano enzyme by layered precursor method, VS4 submicrospheres with a particle size of 300 nm were synthesized by hydrothermal method. The ·OH radical was the intermediate in POD mimic catalyzed colorimetric in the presence of H2O2, which had potential antifouling activity. The relationship between transition metal sulfides and oxides was established. It was hoped that a better simulated enzyme antifouling material system would be obtained by controlled sulfidation and oxidation based on layered precursors. In a word, biomimetic composite nanozyme materials with good activity of simulated enzyme catalysis and bactericidal activity were obtained by derivatization of LDHs in this paper. By controlling the calcination conditions, MMOs could inherit the special morphology of the precursor, such as having a large specific surface area, rich surface active sites and a well distributed composite structure of the active phase. LDHs derived MMOs could effectively overcome the bottleneck of agglomeration and deactivation of nanozyme. According to the adjustable characteristics of layered precursor, ROS could be adjusted by controlled sulfuration and oxidation process, which was expected to be applied in the field.
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/164758
Collection海洋环境腐蚀与与生物污损重点实验室
Recommended Citation
GB/T 7714
陈超. 仿生复合纳米酶的层状前体法可控制备及其杀菌机制研究[D]. 中国科学院海洋研究所. 中国科学院大学,2020.
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