Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University , Beijing 100084, People's Republic of China.
ACS Appl Mater Interfaces. 2017 Jun 28;9(25):21413-21421. doi: 10.1021/acsami.7b05951. Epub 2017 Jun 19.
Graphene oxide (GO) is an important two-dimensional material since it is water-soluble and can be functionalized to adapt to different applications. However, the current covalent functionalization methods usually require hash conditions, long duration, and sometimes even multiple steps, while noncovalent functionalization is inevitably unstable, especially under a physiological environment where competing species exist. Diselenide bond is a dynamic covalent bond and can respond to both redox conditions and visible light irradiation in a sensitive manner. Thus, in this work by combining the stimuli response of diselenide bond and the oxidative/radical attackable nature of GO, we achieved the in situ covalent functionalization of GO simply by stirring GO with diselenide-containing molecules in aqueous solution. The covalent functionalization was proved by Fourier transform infrared, time-of-flight secondary ion mass spectrometry, atomic force microscopy, thermogravimetric analysis, and so forth, and the functionalization mechanism was deduced to involve both redox reaction and radical addition reaction according to the X-ray photoelectron spectrscopy, atomic emission spectroscopy, and Raman spectroscopy. Moreover, we modified GO with a biocompatible diselenide-containing polymer (mPEGSe) and found selenium-functionalized GO could modulate the balance of reactive oxygen species (ROS). GOSe could decrease ROS level by accelerating the reduction of peroxides when the ROS concentration is high while boosting the ROS level by in situ generating ROS when its concentration is relatively low.
氧化石墨烯（GO）是一种重要的二维材料，因为它具有水溶性并且可以进行功能化以适应不同的应用。然而，目前的共价功能化方法通常需要苛刻的条件、较长的时间，有时甚至需要多个步骤，而非共价功能化不可避免地不稳定，尤其是在存在竞争物种的生理环境中。二硒键是一种动态共价键，可以对氧化还原条件和可见光照射做出敏感响应。因此，在这项工作中，我们通过结合二硒键的刺激响应和 GO 的氧化/自由基攻击性质，仅通过将含有二硒键的分子在水溶液中搅拌 GO 就实现了 GO 的原位共价功能化。通过傅里叶变换红外光谱、飞行时间二次离子质谱、原子力显微镜、热重分析等手段证明了共价功能化，并且根据 X 射线光电子能谱、原子发射光谱和拉曼光谱推断功能化机制涉及氧化还原反应和自由基加成反应。此外，我们用生物相容性的含二硒键聚合物（mPEGSe）对 GO 进行了修饰，发现硒功能化的 GO 可以调节活性氧物种（ROS）的平衡。当 ROS 浓度较高时，GOSe 通过加速过氧化物的还原来降低 ROS 水平，而当 ROS 浓度较低时，通过原位生成 ROS 来提高 ROS 水平。
