Jiangsu Collaborative Innovation Center of Biomedical Functional Materials and Jiangsu Key Laboratory of Biofunctional Materials, School of Chemistry and Materials Science , Nanjing Normal University , Nanjing , 210023 , P. R. China.
Nanjing Normal University Center for Analysis and Testing , Nanjing , 210023 , P. R. China.
Anal Chem. 2019 Jul 16;91(14):8987-8993. doi: 10.1021/acs.analchem.9b01183. Epub 2019 Jul 2.
Although attractive for their low toxicity, CuInS/ZnS core/shell quantum dots (CIS/ZnS QDs) still suffer from poor luminescence efficiency and poor water solubility. Herein, two amino acids (AAs), i.e., cysteine (Cys) and threonine (Thr), are used to tune the properties of CIS/ZnS QDs by capping them in both core and shell. It is found that Thr can regulate the density of Cys on the surface of QDs, thus causing a synergistic effect on the enhancement of photoluminescence (PL) intensity. Capping in the shell mainly leads to the enhancement of PL intensity, and capping in the core results in a red-shift of PL wavelength. Accordingly, a new kind of near-infrared region CIS/ZnS QDs with improved optical properties has been prepared. In addition, the Cys- and Thr-capped CIS/ZnS QDs possess outstanding water solubility and biocompatibility. In this work, the QDs are further employed in Cd determination and multicolor imaging, indicating their potential applications. Relying on the enhancement of PL intensity via cation exchange, the Cys- and Thr-capped CIS/ZnS QDs can sense Cd sensitively. Notably, because ZnS shells of the QDs will not be affected by Zn, the analytical method can discriminate Cd from Zn depending on the inherent characteristics of QDs. Moreover, intercellular Cd can also be evaluated by the bright PL from the QDs, and the QDs can achieve multicolor imaging. Overall, this work demonstrates that various properties of QDs may be tuned by capping with AAs, and AA-capped QDs are of great value in advanced biosensing and bioimaging.
虽然铜铟硫/硫化锌（CIS/ZnS）核壳量子点（QDs）因其低毒性而具有吸引力，但它们仍存在发光效率低和水溶性差的问题。在此，使用两种氨基酸（AAs），即半胱氨酸（Cys）和苏氨酸（Thr），通过在核和壳中对其进行包覆来调节 CIS/ZnS QDs 的性质。研究发现，Thr 可以调节 QDs 表面上 Cys 的密度，从而对增强光致发光（PL）强度产生协同作用。壳中的包覆主要导致 PL 强度增强，而核中的包覆则导致 PL 波长红移。因此，制备了一种具有改进光学性质的新型近红外 CIS/ZnS QDs。此外，Cys 和 Thr 包覆的 CIS/ZnS QDs 具有出色的水溶性和生物相容性。在这项工作中，进一步将 QDs 用于 Cd 测定和多色成像，表明了它们的潜在应用。通过阳离子交换增强 PL 强度，Cys 和 Thr 包覆的 CIS/ZnS QDs 可以对 Cd 进行灵敏检测。值得注意的是，由于 QDs 的 ZnS 壳不会受到 Zn 的影响，因此该分析方法可以根据 QDs 的固有特性来区分 Cd 和 Zn。此外，还可以通过来自 QDs 的明亮 PL 来评估细胞内的 Cd，并且 QDs 可以实现多色成像。总体而言，这项工作表明，通过与 AAs 进行包覆可以调节 QDs 的各种性质，并且 AA 包覆的 QDs 在先进的生物传感和生物成像方面具有重要价值。
