Center of Excellence for Nanostructured Materials (CENMAT), Dipartimento di Scienze Farmaceutiche and INSTM UdR Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
ACS Nano. 2010 Apr 27;4(4):2051-8. doi: 10.1021/nn100257h.
Functionalized carbon nanotube (CNT) derivatives are currently under thorough investigation in different biomedical investigations. In this field of research, the composition of sample either in terms of covalently attached or physisorbed moieties can greatly affect the observed results and hamper the comparison between different studies. Therefore, the availability of a fast and reliable analytical technique to assess both the type of interaction (covalent vs noncovalent) and the composition of CNT conjugates is of great importance. Here we describe that the two-dimensional diffusion-ordered (DOSY) NMR spectroscopy is extremely useful to discriminate between conjugated and unconjugated polyethylene glycol groups in samples obtained by condensation with oxidized single-walled carbon nanotubes (SWNTs). This fast and nondestructive technique allows us to follow the removal of unconjugated polyethylene glycol chains during the purification. In particular, DOSY analysis reveal that about 1/3 (wt %) of the polyethylene glycol used for the condensation remained physisorbed to functionalized SWNTs after dialysis. Complete elimination of physisorbed polyethylene glycol was achieved using diafiltration.
功能化碳纳米管（CNT）衍生物目前正在不同的生物医学研究中进行深入研究。在这个研究领域中，样品的组成（无论是通过共价键连接还是物理吸附的基团）都会极大地影响观察到的结果，并阻碍不同研究之间的比较。因此，需要一种快速可靠的分析技术来评估 CNT 缀合物的相互作用类型（共价与非共价）和组成。在这里，我们描述了二维扩散排序（DOSY）NMR 光谱技术在区分经氧化单壁碳纳米管（SWNTs）缩合得到的样品中结合和未结合的聚乙二醇基团方面非常有用。这种快速且无损的技术可以在纯化过程中跟踪未结合的聚乙二醇链的去除。特别是，DOSY 分析表明，在用透析法纯化时，用于缩合的聚乙二醇中有大约 1/3（wt%）仍物理吸附在功能化的 SWNTs 上。通过渗滤可以完全去除物理吸附的聚乙二醇。
