Vatansever Fatma, Hamblin Michael R
Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA. Department of Dermatology, Harvard Medical School, Boston, MA 02115, USA.
Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA. Department of Dermatology, Harvard Medical School, Boston, MA 02115, USA. Harvard-MIT Division of Health Sciences and Technology, Boston, MA 02139, USA.
J Nanopart Res. 2016 Oct;18(10). doi: 10.1007/s11051-016-3328-y. Epub 2016 Oct 10.
Core-shell CdSe/ZnS quantum dots (QDs) are useful as tunable photostable fluorophores for multiple applications in industry, biology, and medicine. However, to achieve the optimum optical properties, the surface of the QDs must be passivated to remove charged sites that might bind extraneous substances and allow aggregation. Here we describe a method of growing an organic polymer corona onto the QD surface using the bottom-up approach of surface-initiated ring-opening metathesis polymerization (SI-ROMP) with Grubbs catalyst. CdSe/ZnS QDs were first coated with mercaptopropionic acid by displacing the original trioctylphosphine oxide layer, and then reacted with 7-octenyl dimethyl chlorosilane. The resulting octenyl double bonds allowed the attachment of ruthenium alkylidene groups as a catalyst. A subsequent metathesis reaction with strained bicyclic monomers (norbornene-dicarbonyl chloride (NDC), and a mixture of NDC and norbornenylethylisobutyl-polyhedral oligomeric silsesquioxane (norbornoPOSS)) allowed the construction of tethered organic homo-polymer or co-polymer layers onto the QD. Compounds were characterized by FT-IR, 1H-NMR, X-ray photoelectron spectroscopy, differential scanning calorimetry, and transmission electron microscopy. Atomic force microscopy showed that the coated QDs were separate and non-aggregated with a range of diameter of 48-53 nm.
核壳结构的CdSe/ZnS量子点（QDs）作为可调节的光稳定荧光团，在工业、生物学和医学等多个领域具有广泛应用。然而，为了实现最佳光学性能，量子点的表面必须进行钝化处理，以去除可能结合外来物质并导致聚集的带电位点。在此，我们描述了一种使用格拉布催化剂通过表面引发的开环易位聚合（SI-ROMP）的自下而上方法在量子点表面生长有机聚合物冠层的方法。首先通过取代原始的三辛基氧化膦层，用巯基丙酸包覆CdSe/ZnS量子点，然后使其与7-辛烯基二甲基氯硅烷反应。生成的辛烯基双键允许作为催化剂的钌亚烷基基团附着。随后与张力双环单体（降冰片烯二羰基氯（NDC）以及NDC和降冰片烯基乙基异丁基多面体低聚倍半硅氧烷（降冰片烯POSS）的混合物）进行复分解反应，从而在量子点上构建连接的有机均聚物或共聚物层。通过傅里叶变换红外光谱（FT-IR）、核磁共振氢谱（1H-NMR）、X射线光电子能谱、差示扫描量热法和透射电子显微镜对化合物进行了表征。原子力显微镜显示，包覆后的量子点相互分离且未聚集，直径范围为48-53nm。
