Yildiz Ibrahim, McCaughan Bridgeen, Cruickshank Stuart F, Callan John F, Raymo Françisco M
Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146-0431, USA.
Langmuir. 2009 Jun 16;25(12):7090-6. doi: 10.1021/la900148m.
We designed four polymeric ligands for semiconductor quantum dots and synthesized these macromolecular constructs in four steps, starting from commercial precursors. These ligands have a poly(methacrylate) backbone with pendant thiol groups and poly(ethylene glycol) chains. The thiol groups anchor these ligands on the surface of preformed CdSe-ZnS core-shell quantum dots, and the poly(ethylene glycol) chains impose hydrophilic character on the resulting assemblies. Indeed, three of the four sets of quantum dots are soluble in aqueous environments and are stable under these conditions for days over a wide pH range (5.0-9.0). Furthermore, the polymeric coatings wrapped around the inorganic nanoparticles preserve the photophysical properties of the CdSe core and ensure relatively compact dimensions. Specifically, the luminescence quantum yield is ca. 0.4 and the hydrodynamic diameter ranges from 15 to 29 nm with the nature of the polymeric ligand. Model studies with human umbilical vein endothelial cells demonstrated that these hydrophilic quantum dots cross the cell membrane and localize either in the cytosol or in the nucleus. The length of the poly(ethylene glycol) chains appears to guide the intracellular localization of these luminescent probes. In addition, these studies indicated that these particular nanoparticles are not cytotoxic. In fact, their cellular internalization has essentially no influence on cell growth. In summary, we developed novel polymeric ligands able to impose hydrophilic character and biocompatibility on CdSe-ZnS core-shell nanoparticles. Thus, our results can lead to a new family of valuable luminescent probes for cellular imaging, based on the unique photophysical properties of semiconductor quantum dots.
我们设计了四种用于半导体量子点的聚合物配体，并从市售前体开始，通过四个步骤合成了这些大分子构建体。这些配体具有带有侧链硫醇基团和聚乙二醇链的聚（甲基丙烯酸酯）主链。硫醇基团将这些配体锚定在预先形成的CdSe-ZnS核壳量子点的表面上，而聚乙二醇链赋予所得组装体亲水性。实际上，四组量子点中的三组可溶于水性环境，并且在这些条件下在很宽的pH范围（5.0 - 9.0）内稳定数天。此外，包裹在无机纳米颗粒周围的聚合物涂层保留了CdSe核的光物理性质，并确保了相对紧凑的尺寸。具体而言，发光量子产率约为0.4，流体动力学直径随着聚合物配体的性质在15至29nm范围内变化。用人脐静脉内皮细胞进行的模型研究表明，这些亲水性量子点穿过细胞膜并定位在细胞质或细胞核中。聚乙二醇链的长度似乎引导这些发光探针的细胞内定位。此外，这些研究表明这些特定的纳米颗粒没有细胞毒性。事实上，它们的细胞内化对细胞生长基本上没有影响。总之，我们开发了能够赋予CdSe-ZnS核壳纳米颗粒亲水性和生物相容性的新型聚合物配体。因此，基于半导体量子点独特的光物理性质，我们的结果可以导致一类用于细胞成像的有价值的新型发光探针。
