ABSTRACT
Correction for 'A self-assessed photosensitizer: inducing and dual-modal phosphorescence imaging of mitochondria oxidative stress' by Jing Yang et al., Chem. Commun., 2018, DOI: .
ABSTRACT
Two novel Ir(iii)-nitroxide conjugates have been synthesized as mitochondria-targeted multi-functional theranostic photosensitizers, capable of simultaneously inducing and dual-modal phosphorescence imaging of mitochondrial oxidative stress under two-photon excitation, thus realizing the photodynamic therapy of cancer and self-assessment of their PDT efficacies.
Subject(s)
Antineoplastic Agents/pharmacology , Coordination Complexes/pharmacology , Cyclic N-Oxides/pharmacology , Iridium/chemistry , Luminescent Agents/pharmacology , Mitochondria/metabolism , Oxidative Stress , Photosensitizing Agents/pharmacology , Animals , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Cell Line, Tumor , Coordination Complexes/chemistry , Cyclic N-Oxides/chemistry , Humans , Hydrogen Peroxide/pharmacology , Light , Luminescent Agents/chemistry , Mitochondria/ultrastructure , Photosensitizing Agents/chemistry , Tetradecanoylphorbol Acetate/pharmacology , Theranostic Nanomedicine , ZebrafishABSTRACT
New TEMPO-functionalized Ru(ii) polypyridyl complexes were synthesized as efficient theranostic photosensitizers for cancer treatment. Interestingly, due to the presence of a redox sensitive TEMPO moiety, an enhancement in the intracellular fluorescence of TEMPO-functionalized Ru(ii) complexes was observed during photodynamic treatment in both confocal microscopy and flow cytometry. This can be explained by the conversion of the TEMPO radical moiety to diamagnetic non-radical species in cells upon PDT-induced oxidative stress. To the best of our knowledge this is the first ruthenium complex capable of simultaneously inducing and monitoring the oxidative stress. The tethered TEMPO moiety decreased the inherent dark-cytotoxicity and increased the photo-toxicity simultaneously, both of which contributed to the greatly improved photodynamic therapy (PDT) efficacy, ultimately resulting in cancer cell apoptosis. The phototoxicity index value for TEMPO-functionalized Ru(ii) complexes was selective towards cancer cell lines (280.5 for HeLa cells vs. 30.2 for LO2 cells) and ca. 40-fold higher than that for TEMPO-free Ru(ii) analogues (6.7 for HeLa cells). The main contributor for such a greatly enhanced PDT efficacy was the effect of the TEMPO moiety on the cellular uptake and intracellular ROS levels. We therefore demonstrate that the combination of TEMPO with the photosensitizers may be an emerging strategy to develop novel photosensitizer-based theranostic platforms, which can induce and monitor the PDT response simultaneously.
ABSTRACT
Polyvinylpyrrolidone-stabilized iridium nanoparticles (PVP-IrNPs), synthesized by the facile alcoholic reduction method using abundantly available PVP as protecting agents, were first reported as enzyme mimics showing intrinsic catalase- and peroxidase-like activities. The preparation procedure was much easier and more importantly, kinetic studies found that the catalytic activity of PVP-IrNPs was comparable to previously reported platinum nanoparticles. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterization indicated that PVP-IrNPs had the average size of approximately 1.5 nm and mainly consisted of Ir(0) chemical state. The mechanism of PVP-IrNPs' dual-enzyme activities was investigated using XPS, Electron spin resonance (ESR) and cytochrome C-based electron transfer methods. The catalase-like activity was related to the formation of oxidized species Ir(0)@IrO2 upon reaction with H2O2. The peroxidase-like activity originated from their ability acting as electron transfer mediators during the catalysis cycle, without the production of hydroxyl radicals. Interestingly, the protective effect of PVP-IrNPs against H2O2-induced cellular oxidative damage was investigated in an A549 lung cancer cell model and PVP-IrNPs displayed excellent biocompatibility and antioxidant activity. Upon pretreatment of cells with PVP-IrNPs, the intracellular reactive oxygen species (ROS) level in response to H2O2 was decreased and the cell viability increased. This work will facilitate studies on the mechanism and biomedical application of nanomaterials-based enzyme mimic.
