Nakano Yuriko, Ochiai Asumi, Kawamoto Keisuke, Takeda Ayaka, Ichiyoshi Kenta, Ohnuki Toshihiko, Hochella Michael F, Utsunomiya Satoshi
Department of Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi, 819-0395, Japan.
Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Tecnology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.
Sci Rep. 2018 Feb 26;8(1):3648. doi: 10.1038/s41598-018-21976-9.
To understand the competing effects of the components in extracellular substances (ES), polymeric substances (PS) and low-molecular-weight small substances (SS) <1 kDa derived from microorganisms, on the colloidal stability of cerium dioxide nanoparticles (CeNPs), we investigated their adsorption to sparingly soluble CeNPs at room temperature at pH 6.0. The ES was extracted from the fungus S. cerevisiae. The polypeptides and phosphates in all components preferentially adsorbed onto the CeNPs. The zeta potentials of ES + CeNPs, PS + CeNPs, and SS + CeNPs overlapped on the plot of PS itself, indicating the surface charge of the polymeric substances controls the zeta potentials. The sizes of the CeNP aggregates, 100-1300 nm, were constrained by the zeta potentials. The steric barrier derived from the polymers, even in SS, enhanced the CeNP dispersibility at pH 1.5-10. Consequently, the PS and SS had similar effects on modifying the CeNP surfaces. The adsorption of ES, which contains PS + SS, can suppress the aggregation of CeNPs over a wider pH range than that for PS only. The present study addresses the non-negligible effects of small-sized molecules derived from microbial activity on the migration of CeNP in aquatic environments, especially where bacterial consortia prevail.
为了解源自微生物的细胞外物质（ES）、聚合物质（PS）和分子量小于1 kDa的低分子量小分子物质（SS）中各成分对二氧化铈纳米颗粒（CeNPs）胶体稳定性的竞争影响，我们在室温及pH 6.0条件下研究了它们在难溶性CeNPs上的吸附情况。ES是从酿酒酵母中提取的。所有成分中的多肽和磷酸盐优先吸附到CeNPs上。ES + CeNPs、PS + CeNPs和SS + CeNPs的zeta电位在PS自身的图上重叠，表明聚合物质的表面电荷控制着zeta电位。CeNP聚集体的尺寸为100 - 1300 nm，受zeta电位限制。即使在SS中，聚合物产生的空间位垒在pH 1.5 - 10范围内增强了CeNP的分散性。因此，PS和SS对修饰CeNP表面具有相似的作用。含有PS + SS的ES的吸附在比仅PS更宽的pH范围内可抑制CeNPs的聚集。本研究探讨了微生物活动产生的小分子对CeNP在水生环境中迁移的不可忽视的影响，特别是在细菌群落占主导的地方。
