A Tailored Multifunctional Anticancer Nanodelivery System for Ruthenium-Based Photosensitizers: Tumor Microenvironment Adaption and Remodeling.

Ruthenium complexes are promising photosensitizers (PSs), but their clinical applications have many limitations. Here, a multifunctional nano-platform PDA-Pt-CD@RuFc formed by platinum-decorated and cyclodextrin (CD)-modified polydopamine (PDA) nanoparticles (NPs) loaded with a ferrocene-appended ruthenium complex (RuFc) is reported. The NPs can successfully deliver RuFc to the tumor sites. The release of RuFc from the NPs can be triggered by low pH, photothermal heating, and H2O2. The combined photodynamic and photothermal therapy (PDT-PTT) mediated by PDA-Pt-CD@RuFc NPs can overcome the hypoxic environment of tumors from several aspects. First, the platinum NPs can catalyze H2O2 to produce O2. Second, vasodilation caused by photothermal heating can sustain the oxygen supplement. Third, PDT exerted by RuFc can also occur through the non-oxygen-dependent Fenton reaction. Due to the presence of PDA, platinum NPs, and RuFc, the nanosystem can be used in multimodal imaging including photothermal, photoacoustic, and computed tomography imaging. The NPs can be excited by the near-infrared two-photon light source. Moreover, the combined treatment can improve the tumor microenvironments to obtain an optimized combined therapeutic effect. In summary, this study presents a tumor-microenvironment-adaptive strategy to optimize the potential of ruthenium complexes as PSs from multiple aspects.

Mitochondria-Accumulating Rhenium(I) Tricarbonyl Complexes Induce Cell Death via Irreversible Oxidative Stress and Glutathione Metabolism Disturbance.

Mitochondria play a critical role in tumorigenesis. Targeting mitochondria and disturbing related events have been emerging as a promising way for chemotherapy. In this work, two binuclear rhenium(I) tricarbonyl complexes of the general formula [Re2(CO)6(dip)2L](PF6)2 (dip = 4,7-diphenyl-1,10-phenanthroline; L = 4,4'-azopyridine (ReN) or 4,4'-dithiodipyridine (ReS)) were synthesized and characterized. ReN and ReS can react with glutathione (GSH). They exhibit good in vitro anticancer activity against cancer cell lines screened. Besides, they can target mitochondria, cause oxidative stress, and disturb GSH metabolism. Both ReN and ReS can induce necroptosis and caspase-dependent apoptosis simultaneously. We also demonstrate that ReN and ReS can inhibit tumor growth in nude mice bearing carcinoma xenografts. Our study shows the potential of Re(I) complexes as chemotherapeutic agents to kill cancer cells via a mitochondria-to-cellular redox strategy.