Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.
Nanotechnology. 2009 Oct 28;20(43):434005. doi: 10.1088/0957-4484/20/43/434005. Epub 2009 Oct 2.
The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740,000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.
强 CTAB（十六烷基三甲基溴化铵）表面活性剂是金纳米棒溶液合成和稳定的原因，这使其在生物医学中的应用变得复杂。维持纳米棒稳定性的关键参数是 CTAB 与纳米棒浓度的比值。通过从纳米棒溶液中用氯仿萃取 CTAB，确定该比值约为 740,000。通过比较巯基末端 PEG 和阴离子聚合物对纳米棒的稳定作用，发现 PEG 化可在去除 CTAB 时产生更高的产率和更少的聚集。杂双功能 PEG 可得到具有暴露羧基的纳米棒，用于通过零长度碳二亚胺连接物 EDC 与抗体进行共价偶联。根据荧光法和 ELISA 测定，该偶联策略导致每个纳米棒上有约两个功能性抗体。纳米棒在体外特异性靶向细胞，并且可以通过双光子和共聚焦反射显微镜观察到。这种共价策略应该适用于金纳米棒以及用 CTAB 合成的其他金纳米粒子的其他生物医学应用。
