Clermont-Paquette Adryanne, Fuoco Gianluca, Brancheriau Cécilia R, Piekny Alisa, Naccache Rafik
Department of Chemistry and Biochemistry and Center for NanoScience Research, Concordia University Montreal QC H4B 1R6 Canada
Quebec Centre for Advanced Materials, Department of Chemistry and Biochemistry, Concordia University Montreal QC H4B 1R6 Canada.
RSC Adv. 2025 Aug 13;15(35):28770-28782. doi: 10.1039/d5ra03738g. eCollection 2025 Aug 11.
The surface charge of carbon dots (CDs) governs cellular uptake; however, studies seldom compare CDs with similar physico-chemical properties thereby introducing confounding variables. Here, we investigate how the surface charge of amine-passivated carbon dots with similar optical and chemical properties influences their uptake in human cells. We synthesized CDs using citric acid diethylenetriamine (DT3) or pentaethylenehexamine (PH6) using microwave-assisted synthesis. Extensive characterization confirmed their physico-chemical and optical properties. Ion exchange column chromatography was used to separate CDs into fractions with surface charges ranging from -35 mV to +7 mV, which were then added to HeLa cells. FT-IR analysis shows a visible increase of the amide stretch at 1646 cm as charge decreases for the separated fractions revealing changes to surface functionalities. Fluorescence microscopy revealed a correlation between surface charge and cellular uptake. Our study shows a greater uptake of DT3-CDs by 1.17-fold with a surface charge of -14 mV, which were also enriched in the cytosol by 4.12-fold, compared to those with a charge of -35 mV, which localized at the lysosomes which is in accordance with our previous study. In contrast, PH6-CDs remained consistent regardless of their charge (+7 mV -6 mV), with a preference for lysosomes. This study reveals how surface charge and chemical composition of CDs impacts cellular uptake and localization. These findings show how CDs could be tailored for specific applications in bioimaging and nanomedicine.
碳点（CDs）的表面电荷决定细胞摄取；然而，研究很少将具有相似物理化学性质的碳点进行比较，从而引入了混杂变量。在此，我们研究具有相似光学和化学性质的胺基钝化碳点的表面电荷如何影响其在人细胞中的摄取。我们使用微波辅助合成法，以柠檬酸二乙烯三胺（DT3）或五乙烯六胺（PH6）合成了碳点。广泛的表征证实了它们的物理化学和光学性质。离子交换柱色谱法用于将碳点分离成表面电荷范围从-35 mV到+7 mV的级分，然后将这些级分添加到HeLa细胞中。傅里叶变换红外光谱（FT-IR）分析表明，随着分离级分电荷的降低，1646 cm处酰胺伸缩振动明显增加，这揭示了表面官能团的变化。荧光显微镜显示表面电荷与细胞摄取之间存在相关性。我们的研究表明，表面电荷为-14 mV的DT3碳点的摄取量比电荷为-35 mV的碳点高1.17倍，且在胞质溶胶中的富集量高4.12倍，电荷为-35 mV的碳点定位于溶酶体，这与我们之前的研究一致。相比之下，PH6碳点无论电荷如何（+7 mV至-6 mV），摄取情况都保持一致，且优先定位于溶酶体。这项研究揭示了碳点的表面电荷和化学组成如何影响细胞摄取和定位。这些发现表明如何针对生物成像和纳米医学中的特定应用对碳点进行定制。
