Abstract：
The interfacial interaction between pollutants and organisms is a critical process in controlling the environmental fates of pollutants; however, in situ assay of the interaction is still a great challenge. Here, in situ determination of dissociation constants (Kd) for ZnO nanoparticles (ZnO NPs) from live algal cells disturbed by different-charged surfactants was established using microscale thermophoresis (MST). Moreover, in situ measurement of the adhesion force between the ZnO NPs probe and live single cell was performed using an atomic force microscope (AFM). Results showed that the cationic cetyltrimethylammonium chloride (CTAC) and anionic sodium dodecylbenzenesulfonate (SDBS) increased but nonionic Triton X-100 (TX-100) decreased the adhesion of ZnO NPs on cells. However, the force signature exhibited a smooth single retracted peak at short distances in the SDBS- and TX-100-treated groups, distinguished from the \"see-saw\" pattern peak in the CTAC-treated groups. The extended Derjaguin-Landau-Verway-Overbeek (XDLVO) calculation further confirmed that SDBS and TX-100 mainly disturbed the short-range hydration on the NP-cell interface, while CTAC reduced the long-range electrostatic repulsion. Furthermore, an excellent linear correlation between Zn bioaccumulation and two parameters (Kd and adhesion force) indicated that NP-cell interfacial interactions affected Zn bioaccumulation. Thus, in situ assay provides a quantitative basis for the pollutant-organism interfacial interaction to evaluate the environmental fate and ecological risk of pollutants.
摘要：
污染物与生物之间的界面相互作用是控制污染物环境命运的关键过程；然而，相互作用的原位测定仍然是一个很大的挑战。这里,使用微尺度热泳法（MST）原位测定了受不同电荷表面活性剂干扰的活藻细胞中ZnO纳米颗粒（ZnONP）的解离常数（Kd）。此外，使用原子力显微镜（AFM）对ZnONPs探针与活单细胞之间的粘附力进行了原位测量。结果表明，阳离子十六烷基三甲基氯化铵（CTAC）和阴离子十二烷基苯磺酸钠（SDBS）增加，而非离子TritonX-100（TX-100）降低了ZnONPs在细胞上的粘附力。然而,在SDBS和TX-100治疗组中，力信号在短距离表现出平滑的单个缩回峰，与CTAC治疗组的“see-saw”模式峰不同。扩展的Derjaguin-Landau-Verway-Overbeek（XDLVO）计算进一步证实，SDBS和TX-100主要干扰了NP-cell界面上的短程水合作用，而CTAC降低了远程静电斥力。此外，Zn生物积累与两个参数（Kd和粘附力）之间的良好线性相关性表明，NP-细胞界面相互作用会影响Zn的生物积累。因此，原位分析为污染物-生物界面相互作用评估污染物的环境归宿和生态风险提供了定量依据。
