Doxorubicin entrapped carbon dots (DOX-CDs) were prepared for bioimaging and enhanced intracellular drug delivery. The CDs were synthesized via the hydrothermal method using citrate and urea under 200 °C for 1 h. Then, DOX was successfully conjugated on the CDs via physicochemical interactions. The DOX-CDs exhibited good crystal structure, remarkable aqueous stability, excellent photoluminescence property, and a high quantum yield of 93%. The fluorescent images revealed that the DOX-CDs could be readily taken up by the cancer cells for cell labeling. Furthermore, endo-lysosomal pH-assisted DOX release behavior was observed from DOX-CDs, and the cytotoxicity of DOX-CDs was confirmed by the MTS assay against H0-8910 ovarian cancer cells. In addition, the CDs indicated bright fluorescent signal in the animal imaging test and demonstrated low toxicity after administration for 7 and 21 days. Therefore, the prepared CDs could be a promising imaging probe for biomedical imaging and intracellular drug delivery.

A novel magnetic-fluorescent manganese(II)–carbon dots hybrid nanoprobe conjugated with anti-HE4 antibody was successfully prepared for ovarian cancer cell targeting and bifunctional optical and MR imaging. In vitro and in vivo studies demonstrated the nanoprobe had high bio-compatibility, excellent tumor-targeting ability, superior MR and fluorescence imaging effects.

Anti-tumor M1-like and pro-tumor M2-like tumor-associated macrophages (TAMs) coexist in tumor microenvironments (TME). The adverse effects of these M1/M2 subsets on tumors directly affect the current strategies to improve anti-tumor immune response. Therefore, it has attracted great attention to change the tumor immunosuppressive microenvironment by reprogramming TAMs. In this paper, we constructed biomimetic nanoparticles (HMMDN-Met@PM) targeting M2-like TAMs for macrophage re-polarization. In detail, the core of the biomimetic nanoparticles is metformin-loaded hollow mesoporous manganese dioxide nanoparticles (HMMDN-Met). Benefited from the hollow and porous structure of HMMDN, metformin, the regulator of M1/M2 adopted in this work, can be easily and widely loaded into HMMDN. Moreover, macrophage membranes were utilized for HMMDN-Met coating (HMMDN-Met@MM) to prevent the premature drug leakage and provide specific molecular recognition/TME targeting. In addition, M2 macrophage targeting peptide (M2pep) was modified on the surface of macrophage membrane to specifically deliver the drug to M2-like TAMs to promote the polarization of M2 to M1 macrophages. Through in vitro and in vivo studies, we found that the expression of surface markers and inflammatory factors CD206, Arg-1 and IL-10 of type M2 macrophages decreased, while the surface markers of type M1 macrophages and the expression of inflammatory factors CD80, TNF-α and iNOS increased, indicating the successful re-polarization of M2 macrophages and finally realizing the inhibition of tumor growth. At the same time, under the acidic and GSH conditions of tumor, HMMDN was decomposed into Mn²⁺, which is a contrast agent for magnetic resonance imaging, thus realizing the tracking of tumor. This work practices biomimetic nanosystem in targeted imaging and immunotherapy, paving the way for strategy designing for tumor inhibition.