Akiel R D, Stepanov V, Takahashi S
Department of Chemistry, University of Southern California, Los Angeles, CA, 90089, USA.
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA.
Cell Biochem Biophys. 2017 Jun;75(2):151-157. doi: 10.1007/s12013-016-0739-4. Epub 2016 Jun 21.
Nanodiamond (ND) is an attractive class of nanomaterial for fluorescent labeling, magnetic sensing of biological molecules, and targeted drug delivery. Many of those applications require tethering of target biological molecules on the ND surface. Even though many approaches have been developed to attach macromolecules to the ND surface, it remains challenging to characterize dynamics of tethered molecule. Here, we show high-frequency electron paramagnetic resonance (HF EPR) spectroscopy of nitroxide-functionalized NDs. Nitroxide radical is a commonly used spin label to investigate dynamics of biological molecules. In the investigation, we developed a sample holder to overcome water absorption of HF microwave. Then, we demonstrated HF EPR spectroscopy of nitroxide-functionalized NDs in aqueous solution and showed clear spectral distinction of ND and nitroxide EPR signals. Moreover, through EPR spectral analysis, we investigate dynamics of nitroxide radicals on the ND surface. The demonstration sheds light on the use of HF EPR spectroscopy to investigate biological molecule-functionalized nanoparticles.
纳米金刚石（ND）是一类极具吸引力的纳米材料，可用于荧光标记、生物分子的磁传感以及靶向药物递送。这些应用中的许多都需要将目标生物分子 tethering 在 ND 表面。尽管已经开发出许多方法将大分子连接到 ND 表面，但表征 tethered 分子的动力学仍然具有挑战性。在这里，我们展示了氮氧化物功能化 ND 的高频电子顺磁共振（HF EPR）光谱。氮氧化物自由基是一种常用的自旋标记物，用于研究生物分子的动力学。在研究中，我们开发了一种样品架以克服 HF 微波的水吸收。然后，我们展示了氮氧化物功能化 ND 在水溶液中的 HF EPR 光谱，并显示了 ND 和氮氧化物 EPR 信号的清晰光谱区分。此外，通过 EPR 光谱分析，我们研究了 ND 表面上氮氧化物自由基的动力学。这一演示为使用 HF EPR 光谱研究生物分子功能化纳米颗粒提供了启示。
