Chemistry Department, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
Chemistry Department, Johannes Gutenberg-Universität, Fritz-Strassmann-Weg 2, D-55128 Mainz, Germany.
Nanoscale. 2020 Oct 29;12(41):21344-21358. doi: 10.1039/d0nr06165d.
Preventing bacterial adhesion on materials surfaces is an important problem in marine, industrial, medical and environmental fields and a topic of major medical and societal importance. A defense strategy of marine organisms against bacterial colonization relies on the biohalogenation of signaling compounds that interfere with bacterial communication. These reactions are catalyzed by haloperoxidases, a class of metal-dependent enzymes, whose activity can be emulated by ceria nanoparticles. The enzyme-like activity of ceria was enhanced by a factor of 3 through bismuth substitution (Ce1-xBixO2-δ). The solubility of Bi3+ in CeO2 is confined to the range 0 < x < 0.25 under quasi-hydrothermal conditions. The Bi3+ cations are located close to the nanoparticle surface because their ionic radii are larger than those of the tetravalent Ce4+ ions. The synthesis of Ce1-xBixO2-δ (0 < x < 0.25) nanoparticles was upscaled to yields of ∼50 g. The halogenation activity of Ce1-xBixO2-δ was demonstrated with phenol red assays. The maximum activity for x ≈ 0.2 is related to the interplay of the ζ-potential of surface-engineered Ce1-xBixO2-δ nanoparticles and their BET surface area. Ce0.80Bi0.20O1.9 nanoparticles with optimized activity were incorporated in polyethersulfone beads, which are typical constituents of water filter membrane supports. Although Ce1-xBixO2-δ nanoparticles are not bactericidal on their own, naked Ce1-xBixO2-δ nanoparticles and polyethersulfone/Ce1-xBixO2-δ nanocomposites showed a strongly reduced bacterial coverage. We attribute the decreased adhesion of the Gram-negative soil bacterium Pseudomonas aeruginosa and of Phaeobacter gallaeciensis, a primary bacterial colonizer in marine biofilms, to the formation of halogenated signaling compounds. No biocides are needed, H2O2 (formed in daylight) and halide are the only substrates required. The haloperoxidase-like activity of Ce1-xBixO2-δ may be a promising starting point for the development of environmentally friendly, "green" nanocomposites, when the use of conventional biocides is prohibited.
防止材料表面细菌黏附是海洋、工业、医学和环境领域的一个重要问题，也是一个具有重大医学和社会意义的话题。海洋生物抵御细菌定植的防御策略依赖于对干扰细菌通讯的信号化合物的生物卤化。这些反应由卤过氧化物酶催化，卤过氧化物酶是一类依赖金属的酶，其活性可以通过氧化铈纳米颗粒模拟。通过铋取代（Ce1-xBixO2-δ），氧化铈的酶样活性提高了 3 倍。在准水热条件下，Bi3+在 CeO2 中的溶解度限于 0 < x < 0.25 的范围。由于其离子半径大于四价 Ce4+离子，因此 Bi3+阳离子位于纳米颗粒表面附近。Ce1-xBixO2-δ（0 < x < 0.25）纳米颗粒的合成产量提高到约 50 g。通过苯酚红测定法证明了 Ce1-xBixO2-δ 的卤化活性。对于 x ≈ 0.2，最大活性与表面工程化 Ce1-xBixO2-δ纳米颗粒的 ζ-电位及其 BET 表面积相互作用有关。具有优化活性的 Ce0.80Bi0.20O1.9 纳米颗粒被掺入聚醚砜珠中，聚醚砜珠是水过滤膜支撑物的典型成分。尽管 Ce1-xBixO2-δ 纳米颗粒本身没有杀菌作用，但裸露的 Ce1-xBixO2-δ 纳米颗粒和聚醚砜/Ce1-xBixO2-δ 纳米复合材料显示出明显降低的细菌覆盖率。我们将革兰氏阴性土壤细菌铜绿假单胞菌和海洋生物膜中主要的细菌定植物 Phaeobacter gallaeciensis 的粘附减少归因于卤化信号化合物的形成。不需要使用杀生物剂，H2O2（在日光下形成）和卤化物是所需的唯一底物。当禁止使用传统杀生物剂时，Ce1-xBixO2-δ 的过氧化物酶样活性可能是开发环保“绿色”纳米复合材料的一个有前途的起点。
