Surface engineering advances of semiconductor quantum dots (QDs) have enabled their application to molecular labeling, disease diagnostics and tumor imaging. For biological applications, hydrophobic core/shell QDs are transferred into aqueous solutions through the incorporation of water-solubility imparting moieties, typically achieved via direct exchange of the native surface passivating ligands or indirectly through the adsorption of polymers. Although polymeric encapsulation has gained wide acceptance, there are few reports addressing the characterization of the adsorbed polymers and existing theoretical analyses are typically based on simple geometric models. In this work, we experimentally characterize and quantify water-soluble QDs prepared by adsorption of amphiphilic poly(maleic anhydride-alt-1-tetradecene) (PMAT, MW~9000) onto commercially available CdSe/CdS/ZnS (CdSe/CdS/ZnS-PMAT). Using x-ray photoelectron spectroscopy (XPS) we determined that ~15 PMAT molecules are adsorbed onto each QD and sum frequency generation (SFG) vibrational spectra was utilized to investigate the mechanism of interaction between PMAT molecules and the QD surface. Importantly, when employed together, these techniques constitute a platform with which to investigate any polymer-nanoparticle complex in general.

中文翻译：

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聚合物封装 CdSe/CdS/ZnS 量子点的直接表征

半导体量子点 (QD) 表面工程的进步使其能够应用于分子标记、疾病诊断和肿瘤成像。对于生物应用，疏水性核/壳量子点通过掺入水溶性赋予部分转移到水溶液中，通常通过直接交换天然表面钝化配体或通过聚合物的吸附间接实现。尽管聚合物封装已获得广泛接受，但很少有报告讨论吸附聚合物的表征，并且现有的理论分析通常基于简单的几何模型。在这项工作中，我们通过实验表征和量化了通过将两亲性聚（马来酸酐-alt-1-十四碳烯）（PMAT，MW~9000）吸附到市售的CdSe/CdS/ZnS（CdSe/CdS/ZnS）上制备的水溶性量子点。 -PMAT）。使用 X 射线光电子能谱 (XPS)，我们确定每个 QD 上吸附了约 15 个 PMAT 分子，并利用和频生成 (SFG) 振动光谱来研究 PMAT 分子与 QD 表面之间的相互作用机制。重要的是，当一起使用时，这些技术构成了一个平台，可用于研究任何聚合物-纳米颗粒复合物。