The retention of CdS/ZnS QDs on the epidermis has been confirmed to be one of the core procedures during the root uptake process. However, the retention mechanisms of QDs on the epidermis of woody plant were poorly understood for lacking of an appropriate QD quantitative method. In this study, a novel method for in situ determination of CdS/ZnS QDs retained on the root epidermis was established using synchronous nanosecond time-resolved fluorescence spectroscopy. No correlations between K_f values of oleylamine-CdS/ZnS QDs retained on the epidermal tissues and the surface/bulk composition of mangrove root were observed (p > 0.05) due to the existence of endocytosis mechanisms during the QD uptake processes. Moreover, the difference of the CdS/ZnS QDs in water and further translocated to xylem/phloem of root rather than the combination with cell wall/membranes was the predominant reason that caused the K_f values to follow the sequence of PEG-COOH-CdS/ZnS QDs < PEG-NH₂-CdS/ZnS QDs ≪ oleylamine-CdS/ZnS QDs.

中文翻译：

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苯并[ a ] Do在木本植物根表皮上保留CdS / ZnS量子点（QDs）及其意义：来自原位同步纳秒时间分辨荧光光谱法的证据

CdS / ZnS QDs在表皮上的保留已被证实是根吸收过程中的核心程序之一。然而，由于缺乏适当的QD定量方法，人们对QD在木本植物表皮上的保留机制了解甚少。在这项研究中，建立了一种使用同步纳秒时间分辨荧光光谱技术原位测定保留在根表皮上的CdS / ZnS QD的新方法。在表皮组织上保留的油胺-CdS / ZnS QD的K _f值与红树林根的表面/大体组成之间没有相关性（p> 0.05），因为在QD摄取过程中存在内吞机制。此外，水中CdS / ZnS QDs的差异以及其进一步转移到根的木质部/韧皮部而不是与细胞壁/膜结合的原因是导致K _f值遵循PEG-COOH-CdS序列的主要原因/ ZnS QDs <PEG-NH ₂ -CdS / ZnS QDs≪油胺-CdS / ZnS QDs。