Liu Zhuang, Sun Xiaoming, Nakayama-Ratchford Nozomi, Dai Hongjie
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
ACS Nano. 2007 Aug;1(1):50-6. doi: 10.1021/nn700040t.
We show that large surface areas exist for supramolecular chemistry on single-walled carbon nanotubes (SWNTs) prefunctionalized noncovalently or covalently by common surfactant or acid-oxidation routes. Water-soluble SWNTs with poly(ethylene glycol) (PEG) functionalization via these routes allow for surprisingly high degrees of pi-stacking of aromatic molecules, including a cancer drug (doxorubicin) with ultrahigh loading capacity, a widely used fluorescence molecule (fluorescein), and combinations of molecules. Binding of molecules to nanotubes and their release can be controlled by varying the pH. The strength of pi-stacking of aromatic molecules is dependent on nanotube diameter, leading to a method for controlling the release rate of molecules from SWNTs by using nanotube materials with suitable diameter. This work introduces the concept of "functionalization partitioning" of SWNTs, i.e., imparting multiple chemical species, such as PEG, drugs, and fluorescent tags, with different functionalities onto the surface of the same nanotube. Such chemical partitioning should open up new opportunities in chemical, biological, and medical applications of novel nanomaterials.
我们表明，通过常见的表面活性剂或酸氧化途径进行非共价或共价预功能化的单壁碳纳米管（SWNTs）上存在用于超分子化学的大表面积。通过这些途径用聚乙二醇（PEG）功能化的水溶性SWNTs允许芳香族分子进行惊人高度的π堆积，包括具有超高负载能力的抗癌药物（阿霉素）、广泛使用的荧光分子（荧光素）以及分子组合。分子与纳米管的结合及其释放可以通过改变pH来控制。芳香族分子的π堆积强度取决于纳米管直径，从而产生了一种通过使用具有合适直径的纳米管材料来控制分子从SWNTs释放速率的方法。这项工作引入了SWNTs“功能化分区”的概念，即在同一纳米管表面赋予多种具有不同功能的化学物质，如PEG、药物和荧光标签。这种化学分区应该会为新型纳米材料在化学、生物和医学应用中带来新的机遇。
