Surface functionalization of graphene quantum dots with small organic molecules from photoluminescence modulation to bioimaging applications: an experimental and theoretical investigation
Surface functionalization of graphene quantum dots with small organic molecules from photoluminescence modulation to bioimaging applications: an experimental and theoretical investigation
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石墨烯量子点与小有机分子的表面功能化从光致发光调制到生物成像应用：实验和理论研究
DOI：
10.1039/c3ra42066c
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发表时间：
2013-01-01
期刊：
影响因子：
3.9
通讯作者：
Feng, Hui
中科院分区：
文献类型：
--
作者：
Qian, Zhaosheng;Ma, Juanjuan;Feng, Hui
表面化学提供了一种替代方法来调节石墨烯量子点的发射颜色和效率。我们系统地研究了石墨烯量子点的表面化学功能化与一系列的有机小分子结合的实验和理论方法。实验结果表明，采用醇、胺、巯基等官能团对石墨烯量子点进行表面功能化可以有效地调控石墨烯量子点的荧光，并证明了氨基的引入可以显著提高石墨烯量子点的量子产率。1，2-乙二胺功能化的石墨烯量子点的发光效率高达17.6%，这是由于质子化形成的铵向共轭荧光团状结构的特定质子转移。提出了石墨烯量子点内部的多芳香结构来解释二胺功能化石墨烯量子点的荧光增强机制。计算结果表明，不仅石墨烯量子点中的聚芳结构的大小可以改变它们的发光，而且表面功能化也可以通过调节它们的带隙来调节它们的光致发光。毒性实验表明，二胺官能化的石墨烯量子点显示出与原始石墨烯量子点类似的低细胞毒性。此外，生物成像实验表明，官能化的石墨烯量子点由于其更高的量子产率而具有与原始石墨烯量子点相同的以更低浓度标记细胞的能力。
Surface chemistry provides an alternative approach to modulate the emission colour and efficiency of graphene quantum dots. We systematically investigated the surface chemistry of graphene quantum dots functionalized with a series of small organic molecules combining experimental and theoretical approaches. Experimental results indicated that surface functionalization with functional groups such as alcohol, amine and thiol can effectively tune the fluorescence of graphene quantum dots, and proved that amino groups can highly elevate the quantum yields of modified graphene quantum dots. The emission efficiency of 1,2-ethylenediamine functionalized graphene quantum dots reached up to 17.6% due to specific proton transfer to the conjugated fluorophore-like structure from ammonium formed by protonation. The polyaromatic structure within the graphene quantum dots was proposed to explain the fluorescence enhancement mechanism of graphene quantum dots functionalized by diamines. The computational results suggested that not only the size of the polyaromatic structures within graphene quantum dots can change their emissions, but surface functionalization can also tune their photoluminescence through modulating their band gaps. Toxicity experiments indicated that diamine-functionalized graphene quantum dots showed low cell toxicity similar to that of pristine graphene quantum dots. Moreover, the bioimaging experiments suggested that functionalized graphene quantum dots had identical abilities to label cells at a lower concentration than pristine graphene quantum dots owing to their higher quantum yields.