Carbon dots (CDs) as an emerging type of carbon nanomaterials exhibit great potential in bioimaging applications owing to their superior optical properties and excellent biocompatibility. However, it is still challenging to fabricate sole carbon dots with integrated functionalities of diagnostic and therapeutic modalities. Herein, we developed a facile strategy to prepare the ruthenium-containing carbon dots (Ru-CDs) via a hydrothermal method using the 5-amino-1,10-phenanthroline ruthenium­(II) complex (Ru-Aphen) and citric acid as starting materials. The structure and morphology of Ru-CDs were verified by transmission electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectra. The Ru-CDs exhibited good water solubility, intense red emission, and efficient reactive oxygen species (ROS) generation. The MTT assay against HeLa cells demonstrated favorable biocompatibility and distinct photodynamic effect of Ru-CDs. Owing to strong luminescence in water (QY = 20.79%) and efficient ROS generation, Ru-CDs were not only applied as bioimaging agents for tumor cells and zebrafish embryos, but also as photodynamic nanoagents for cancer therapy. Finally, the DNA photocleavage of Ru-CDs was verified through the experiment of gel electrophoresis. The results suggested that the plasmid DNA could only be damaged in the presence of Ru-CDs and light. Thus, the as-prepared Ru-CDs showed good prospects and a wide range of biological applications.

Light-activated phototherapy, including photothermal and photodynamic therapy, has become a new way for spatiotemporal control and noninvasive treatment of cancer. In this study, two new organic porphyrin molecules (NI-Por and NI-ZnPor) with donor (D)−acceptor (A) structure were designed and synthesized. The donor−acceptor pairs facilitated the intermolecular electron transfer, resulting in the enhancement of near-infrared (NIR) absorbance and nonradiative heat generation. After self-assembling, the nanoparticles were formed with the size around 60 nm. Relative to that of organic molecules, the absorption of NI-Por NPs and NI-ZnPor NPs broadened and red-shifted to the near-infrared region. Moreover, the porphyrin-containing nanoparticles can generate heat and reactive oxygen species (ROS) simultaneously induced by a single laser (635 nm). The intracellular reactive oxygen species production of NI-Por NPs and NI-ZnPor NPs was confirmed using DCFH-DA as an indicator. Furthermore, the localization of NI-Por NP and NI-ZnPor NP in HeLa cells was verified by fluorescence confocal laser microscopy. The photocytoxicity of two nanoparticles against HeLa cells was evaluated through the CCK-8 method. The IC 50 of NI-Por NPs and NI-ZnPor NPs upon 635 nm laser irradiation was calculated to be 6.92 μg/mL and 5.86 μg/mL, respectively. Furthermore, the PDT/PTT synergistic effect of NPs under a 635 nm laser was verified through different treatment groups in vitro. All these results demonstrated that the as-prepared porphyrin-based nanoparticles are promising nanoagents for PDT/PTT in clinic.

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The ROS generation ability and photocytotoxicity of the synthesized porphyrin compounds were enhanced with the number of porphyrin units in the photosensitizers.

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