Fabrication of ultrasmall single‐component omnipotent nanotheranostic agents integrated with multimodal imaging and multiple therapeutic functions becomes more and more practically relevant but challenging. In this article, sub 10 nm Bi 2 S 3 biocompatible particles are prepared through a bovine serum albumin (BSA)‐mediated biomineralization process under ambient aqueous conditions. Owing to the ultrasmall size and colloidal stability, the resulting nanoparticles (NPs) present outstanding blood circulation behavior and excellent tumor targeting ability. Toward theranostic applications, the biosafety profile is carefully investigated. In addition, photothermal conversion is characterized for both photoacoustic imaging and photothermal treatment of cancers. Upon radiolabeling, the performance of the resulting particles for SPECT/CT imaging in vivo is also carried out. Additionally, different combinations of treatments are applied for evaluating the performance of the as‐prepared Bi 2 S 3 NPs in photothermal‐ and radiotherapy of tumors. Due to the remarkable photothermal conversion efficiency and large X‐ray attenuation coefficient, the implanted tumors are completely eradicated through combined therapies, which highlights the potential of BSA‐capped Bi 2 S 3 NPs as a novel multifunctional nanotheranostic agent.
Cationic amphiphilic drugs (CADs) are small molecules that can induce phospholipidosis (PLD), causing the intracellular accumulation of phospholipid in the lamellar bodies. Nanotechnology based drug delivery systems have been used widely, while it is unknown if drug-induced PLD (DIP) can be potentiated through drug retention by indigestible nanocarriers. Due to the high drug loading capacity of graphene, we investigated if PEGylated graphene oxide (PEG-GO) loaded with CAD could potentiate DIP. Tamoxifen induced the accumulation of NBD-PE, a fluorescence labeled phospholipid in human hepatoma HepG2 cells, while PEG-GO loaded with tamoxifen (PEG-GO/tamoxifen) further potentiated PLD. PEG-GO/tamoxifen induced more gene expression of PLD marker than tamoxifen alone. PEG-GO enhanced DIP was also observed for other CAD, indicating that nanocarrier potentiated DIP could be universal. More lamellar bodies were observed in PEG-GO/tamoxifen treated cells than tamoxifen alone by transmission electron microscopy. When compared with tamoxifen alone, PEG-GO/tamoxifen showed a delayed but potent PLD. In addition, the retarded PLD recovery by PEG-GO/tamoxifen indicated that the reversibility of DIP was interfered. Confocal microscopy revealed the increased number of lysosomes, greater expression of lysosomal associated membrane protein 2 (LAMP2) (a PLD marker), and an increase in the co-localization between lysosome/LAMP2 and NBD-PE by PEG-GO/tamoxifen rather than tamoxifen alone. Finally, we found that PEG-GO or/and tamoxifen-induced PLD seemed to have no correlation with autophagy. This research suggests pharmaceutical companies and regulatory agencies that if nanoparticles are used as the vectors for drug delivery, the adverse drug effects may be further potentiated probably through the long-term accumulation of nanocarriers.
Mitochondria-targeted therapy is an alternative strategy for cancer therapy and may overcome the problems of metastasis and drug resistance that usually occur in conventional treatment. In this work, we demonstrate the mitochondria-targeted delivery of a cationic cyclometalated platinum(ii) complex, PIP-platin, in cancer cells. PIP-platin showed selective delivery and accumulation in the mitochondria and exhibited toxicity against a variety of tumor cell lines. The mitochondria were disrupted by PIP-platin, along with the generation of reactive oxygen species, depolarization of mitochondrial membrane potential, release of cytochrome c and necrosis. Interestingly, PIP-platin can promote cell adhesion within several hours and the cells became hard to dislodge from the culture plate. A wound healing assay, transwell migration/invasion assay and 3D spheroid migration assay all demonstrated that PIP-platin can inhibit cell migration/invasion. To illustrate the associated mechanisms, we investigated the intracellular trafficking of β-catenin, a central protein in the regulation of cell adhesion, and gene transcription for cell proliferation. Upon treatment with PIP-platin, this protein can translocate onto the plasma membrane for increased cell adhesion. In addition, PIP-platin was demonstrated to efficiently inhibit Wnt signaling by blocking the translocation of β-catenin into the nuclei, thereby preventing cell proliferation. We demonstrate that, accordingly, PIP-platin has remarkable potential for intracellular delivery in mitochondria and has inhibitory effects on cancer cell proliferation and migration/invasion through β-catenin, and may therefore be exploited as a dual-functional antitumor drug candidate in cancer treatment.
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