Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, 563-8577, Japan; School of Materials Science and Engineering, Tianjin University of Technology, Xiqing, Tianjin, 300384, People's Republic of China.
J Colloid Interface Sci. 2013 Dec 1;411:82-91. doi: 10.1016/j.jcis.2013.08.053. Epub 2013 Sep 8.
A synthesis process was reconsidered for encapsulating hydrophobic quantum dots (QDs) into silica capsules with high photoluminescent (PL) efficiency. The process comprises three steps: silanization of QD surfaces, seed formation by assembly of the QDs, and coating of the QD seeds with a silica shell. Analysis of the encapsulation mechanism enabled this process to be adapted for application to CdSe-based core-shell QDs with various organic ligands such as oleic acid and with various emission wavelengths. Formation of the seeds is the key step in synthesizing the silica capsules, so that they have high PL efficiency. Due to the differences in QD size and in the affinity of the ligands on their surfaces, the concentration of QDs used in the synthesis must be optimized to maximize emission efficiency. Contrary to an initial assumption, several ligands remained on the QD surfaces even after the QDs were transferred from organic solution to water. This greatly affected the size and PL efficiency of the seeds. Judicious selection of the conditions for seed and silica capsule synthesis resulted in seeds with PL efficiency greater than 70% and in silica capsules encapsulating multiple CdSe/CdZnS QDs with PL efficiency as high as 41%. Silica capsules incorporating QDs with various emission peak wavelengths from green to red were also prepared. The process presented serves as a guideline for encapsulating various types of hydrophobic QDs into silica capsules for biological tagging applications.
一种将疏水性量子点 (QD) 封装到具有高光致发光 (PL) 效率的硅胶囊中的合成方法被重新考虑。该过程包括三个步骤：QD 表面的硅烷化、QD 组装形成种子，以及用硅壳涂覆 QD 种子。对封装机制的分析使该过程能够适应各种有机配体（如油酸）和各种发射波长的基于 CdSe 的核壳 QD 的应用。种子的形成是合成硅胶囊的关键步骤，因此它们具有高光 PL 效率。由于 QD 尺寸和表面配体的亲和力的差异，合成中必须优化 QD 的浓度以最大化发射效率。与最初的假设相反，即使将 QD 从有机溶剂转移到水中，几种配体仍留在 QD 表面。这极大地影响了种子的尺寸和 PL 效率。明智地选择种子和硅胶囊合成的条件，得到了 PL 效率大于 70%的种子，以及封装多个 PL 效率高达 41%的 CdSe/CdZnS QD 的硅胶囊。还制备了具有从绿色到红色各种发射峰波长的掺入 QD 的硅胶囊。所提出的方法为将各种类型的疏水性 QD 封装到硅胶囊中用于生物标记应用提供了指导。
