Department of Chemistry, National Sun Yat-sen University , Kaohsiung, 804, Taiwan.
Department of Chemistry, National Taiwan University , Taipei City, 10617, Taiwan.
Anal Chem. 2017 Nov 7;89(21):11348-11356. doi: 10.1021/acs.analchem.7b02193. Epub 2017 Oct 11.
This study describes a bottom-up assembly route for monodisperse carbon dots (CDs) into different sizes of CD aggregates through the control of the concentration of fatty acids. The highly monodisperse CDs were prepared via solvent-thermal treatment of edible soybean oil, which generated glycerol-based polymer as a carbon source and fatty acid as a surface capping in the synthetic process. The as-synthesized CDs exhibited small particle size variation (2.7 ± 0.2 nm) and narrow emission bands (full width at half-maximum <20 nm). The monodisperse CDs can self-assemble into blue-, green-, yellow-, and red-emitting CD aggregates by tuning the concentration of fatty acids. Compared to commercially available organic dyes and semiconductor quantum dots, the CD aggregates provided a 10-7000-fold improvement in brightness. Additionally, their emission wavelength was tunable across the entire visible spectrum by tuning the excitation wavelength. Because of their high brightness, fluorescence imaging of a single carbon dot and CD aggregate was simply achieved using filter-free dark-field fluorescence microscopy (DFM). We also demonstrate the use of filter-free DFM to dynamically image cellular uptake of the monodisperse CDs in MCF-7 cells and Huh-7 liver cancer cells. Without the conjugation of the fluorophore to the CDs, the particle aggregation-induced red-shifted emission enables the development of the CD-based ratiometric sensor for Fe ions and pyrophosphate based on Fe-induced aggregation of the monodisperse CDs.
本研究描述了一种自下而上的组装途径，通过控制脂肪酸的浓度，将单分散的碳点（CDs）组装成不同大小的 CD 聚集体。高度单分散的 CDs 通过食用大豆油的溶剂热处理制备，在合成过程中，甘油基聚合物作为碳源，脂肪酸作为表面封端剂。所合成的 CDs 具有小的粒径变化（2.7±0.2nm）和窄的发射带（半峰全宽<20nm）。通过调节脂肪酸的浓度，单分散的 CDs 可以自组装成蓝色、绿色、黄色和红色发射的 CD 聚集体。与商业上可用的有机染料和半导体量子点相比，CD 聚集体的亮度提高了 10-7000 倍。此外，通过调节激发波长，其发射波长可以在整个可见光范围内进行调谐。由于其高亮度，使用无滤光片暗场荧光显微镜（DFM）可以简单地实现单个碳点和 CD 聚集体的荧光成像。我们还展示了使用无滤光片 DFM 动态成像 MCF-7 细胞和 Huh-7 肝癌细胞中单分散 CDs 的细胞摄取。由于没有将荧光团与 CDs 偶联，颗粒聚集诱导的红移发射使得基于 CD 的 Fe 离子和焦磷酸盐比率传感器得以开发，该传感器基于单分散 CDs 的 Fe 诱导聚集。
