A Co-doped Photosensitizer Mediated Nanosystems For Enhanced Photodynamic Therapy Against Metastatic Melanoma

In recent years,photodynamic therapy?PDT?has been an effective means of treating malignant skin cancers such as melanoma.However,PDT is currently facing two major challenges:hypoxia tumor tissue will greatly lower ROS content;the tumor cells produce an antioxidant defense system under the PDT-triggered oxidative stress.In order to solve the difficulties,an PDT enhancednanosystem?Au@MTM-HA?wasconstructed:co-doped photosensitizer composed of mesoporous titanium dioxide?TiO₂?doped with manganese dioxide?MnO₂?as a carrier?MTM?,then loaded with ROS scavenger Au₂₅Sv₉,then sodium hyaluronate?HA?as a tumor blocking agent and target,and we further investigated the properties of Au@MTM-HA nanosystem and applications of melanoma diagnosis and treatment.Firstly,Au@MTM-HA nanosysterm was constructed.MTM was synthesized by modified sol-gel method,and amino group was modified on the surface by electrostatic interaction.Au₂₅Sv₉ was loaded into the mesopores.HA was coated via amide bonds and acted as a blocking agent and tumor-homing agent.X-ray diffraction?XRD?verified that MTM was anatase titanium,Transmission electron microscopy and Fourier transform infrared spectroscopy confirmed that the MTM was wrapped with HA.MTM-HA could produce much of O₂ with H₂O₂ and weakly acidic conditions confirmed by a dissolved oxygen meter.The ROS production detection results showed that the ROS amount produced by Au@MTM-HA under 532 nm was approximately three times than control group.It certified that the ROS production efficiency of Au@MTM-HA is significantly improved.Secondly,we selected murine melanoma cells?B16-F10?as tumor cell model and study the anti-tumor activity of Au@MTM-HA nanosystem in vitro.The toxicity and ROS studies showed that Au@MTM-HA produced the strongest phototoxicity and significantly elevated ROS level in B16-F10 cells under a 532 nm laser.Fluorescence microscopy and flow cytometry study showed Au@MTM-HA could enter B16-F10 cells by active targeting ability.TrxR activity assay showed that Au@MTM-HA markedly suppressed the activity of antioxidant protease TrxR in a concentration dependent manner.The mitochondrial damage assay showed seriously mitochondrial damage in Au@MTM-HA group.Wound-healing assay and Transwell assay indicated that Au@MTM-HA effectively inhibited the migration of B16-F10 cells.Thirdly,we utilized female B16-F10 tumor-bearing C57/BL6 mice as animal model to research the in vivo anti-tumor activity of the Au@MTM-HA nanosystem.The results indicated that Au@MTM-HA has no obviously toxic side effects and could selectively target the tumor site and improved the anti-tumor effect.In addition,using a 3-T clinical MRI scanner to observed magnetic resonance?MR?imaging of Au@MTM-HA,the results showed that Au@MTM-HA exhibited good MR imaging capabilities in vivo/in vitro.Fluorescence imaging results showed that Au@MTM-HA accumulated significantly in the tumor site.All of the results indicated that Au@MTM-HA nanosysterm could greatly enhance PDT effect with high biosafety,which demonstrated the potential of Au@MTM-HA to achieve the diagnosis and treatment in melanoma.Finally,the Au@MTM-HA nanosystem could not only enhance the photocatalytic efficiency of photosensitizer,but also produced endogenous O₂ to provide sufficient O₂ source for PDT.Moreover,this system inhibited the ability of anti-oxidase TrxR to scavenge ROS in tumor cells.Heren,Au@MTM-HA nanosystems could significantly improve the level of ROS in tumor cells via these three approaches,inhibited the metastasis of tumor cells,and performed MR imaging at the tumor site,thus achieving the desired melanoma diagnosis and treatment effect.