Cerium oxide particles as functional haloperoxidase mimics to combat biofouling

水生生境中的表面通常会被微生物侵占。一个教科书上的例子是细菌、单细胞生物、藻类或贝壳在船舶或港口设施上的定居。目前减少这种所谓生物污垢的一种策略是在涂料中添加杀菌剂。微生物在生物膜的形成中进入协同群落，并通过信号分子(“群体感应”)信号来协调膜的形成。海洋生物的一种防御机制是基于通过酶促形成卤化的无效信号分子来扰乱表面生物体的细胞间通讯。拟议的项目使用CeO2-x纳米粒子(NP)酶(卤代过氧化物酶)模拟物，它类似于天然卤代过氧化物酶，催化过氧化氢(在白天产生)氧化无处不在的卤化物。生成的次卤酸(HOX)中间体后续与有机底物反应，形成卤化信号分子。金属氧化物颗粒可以作为涂料和树脂的组份固定在表面上，而不会失去它们的作用。一种卤化信号化合物的催化卤化已在实验室实验中得到证实。该项目旨在通过汇集两个项目合作伙伴的专门知识来实现以下目标：1.揭示卤化反应的顺序：反应是通过短暂的HOBr/HOCl中间体进行的，还是涉及其他活性中间体？哪些卤化信号化合物是在天然水域(即野外)中形成的？这些卤代初级中间体的稳定性如何？它们在什么浓度下形成？CeO2-x Np在卤化反应中的催化活性由缺陷决定。通过增加不同固溶体系列(如CeO2-M2O3，(M=La，Y，Bi等))中的缺陷浓度，可以在不同的固溶体系列(如：CeO2-M2O3，(M=La，Y，Bi.)主动性有待提高。替代卤化催化剂：除了CeO2-x及其替代变种的卤化性能外，还将测试Ce钙钛矿(BaCe-xO_3-y等)、Ce-取代二氧化硅化合物(Ce-TUD-1)、氟磷矿类化合物(CuCrO_2-CeO_2)或锰氧化物的卤化活性。在防污应用中使用CeO2-x NP(和可能的替代品)需要有足够数量的可用性。合成必须扩大到千克的规模。涂层电阻及其表面性能的分析检测和优化：应将颗粒整合到薄膜或涂层中，以便在面向应用的条件下使用。必须优化薄膜的表面性能，确定薄膜上的细菌和藻类生长情况，以及颗粒的浸出(环境兼容性)和释放的产品。

Surfaces in aqueous habitats are usually colonized by microorganisms. A textbook example is the settlement of bacteria, unicellular organisms, algae or shells on ships or port facilities. A current strategy to reduce this so-called biofouling is the addition biocides in paints. Microorganisms enter into synergistic communities in the formation of biofilms and co-ordinate film formation through signaling via signaling molecules ("quorum sensing"). A defense mechanism of marine organisms is based on disrupting cell-to-cell communication of epibionts by enzymatic formation of halogenated - and thus ineffective - signaling molecules. The proposed project uses CeO2-x nanoparticle (NP) enzyme (haloperoxidase) mimics, which - analogously to natural haloperoxidases - catalyze the oxidation of ubiquitous halides by hydrogen peroxide (generated in daylight). The resulting hypohalous acid (HOX) intermediates react with organic substrates in follow-up to form the halogenated signal molecules. The metal oxide particles can be immobilized on surfaces as a constituent of paints and resins without losing their effect. The catalytic halogenation of a halogenated signal compound has been demonstrated in laboratory experiments. The project aims to achieve the following objectives by pooling the expertise of both project partners:1. Unraveling the sequence of the halogenation reactions: Does the reaction proceed via short-lived HOBr/HOCl intermediates, or are other reactive intermediates involved? Which halogenated signaling compounds are formed in natural waters (i.e., in the field)? What is the stability of these halogenated primary intermediates and in what concentrations are they formed? Which other compounds are formed?2. The catalytic activity of CeO2-x NP in halogenation reactions is determined by defects. By increasing the defect concentration in different solid state solution series (e.g., CeO2-M2O3, (M = La, Y, Bi, etc.) the activity should be improved.3. Alternative halogenation catalysts: Besides the halogenation properties of CeO2-x and its substituted variants, the halogenation activity of Ce perovskites (BaCe1-xO3-y etc.), Ce-substituted silica compounds (Ce-TUD-1), delafossite-type composites (CuCrO2-CeO2), or Mn oxides will be tested.4. The use of CeO2-x NP (and possible alternatives) in antifouling applications requires the availability in sufficient amounts. The synthesis must be scaled up to the kg scale.5. Analytical examination and optimization of the resistance of the coatings and their surface properties: The particles should be integrated into films or coatings for use under application oriented conditions. The surface properties must be optimized, the bacterial and algae growth on the films and the leaching of the particles (environmental compatibility) and the released products will be determined.