Zhao Yong, Tang Yifan, Star Alexander
Department of Chemistry, University of Pittsburgh, USA.
J Vis Exp. 2013 May 13(75):e50383. doi: 10.3791/50383.
Nitrogen-doped carbon nanotubes consist of many cup-shaped graphitic compartments termed as nitrogen-doped carbon nanotube cups (NCNCs). These as-synthesized graphitic nanocups from chemical vapor deposition (CVD) method were stacked in a head-to-tail fashion held only through noncovalent interactions. Individual NCNCs can be isolated out of their stacking structure through a series of chemical and physical separation processes. First, as-synthesized NCNCs were oxidized in a mixture of strong acids to introduce oxygen-containing defects on the graphitic walls. The oxidized NCNCs were then processed using high-intensity probe-tip sonication which effectively separated the stacked NCNCs into individual graphitic nanocups. Owing to their abundant oxygen and nitrogen surface functionalities, the resulted individual NCNCs are highly hydrophilic and can be effectively functionalized with gold nanoparticles (GNPs), which preferentially fit in the opening of the cups as cork stoppers. These graphitic nanocups corked with GNPs may find promising applications as nanoscale containers and drug carriers.
氮掺杂碳纳米管由许多杯状石墨隔室组成，这些隔室被称为氮掺杂碳纳米管杯（NCNCs）。通过化学气相沉积（CVD）方法合成的这些石墨纳米杯以头对头、尾对尾的方式堆叠，仅通过非共价相互作用维系在一起。通过一系列化学和物理分离过程，可以从其堆叠结构中分离出单个的NCNCs。首先，将合成后的NCNCs在强酸混合物中氧化，以在石墨壁上引入含氧缺陷。然后，使用高强度探针超声处理氧化后的NCNCs，这有效地将堆叠的NCNCs分离成单个的石墨纳米杯。由于其丰富的氧和氮表面官能团，所得的单个NCNCs具有高度亲水性，并且可以用金纳米颗粒（GNPs）有效地进行功能化，这些金纳米颗粒优先作为软木塞嵌入杯口。这些用GNPs封闭的石墨纳米杯作为纳米级容器和药物载体可能具有广阔的应用前景。
