Investigation On Nano Drug Delivery System For Tumor Phototherapy With Self-produced Oxygen Function

At present,the novel therapeutic modality-photodynamic therapy?PDT?with tumor high specificity and low toxicity has been a hotspot in the research of new anticancer therapies for its non-invasive and efficient advantages.Photosensitizer,light source and oxygen are the three main factors of photodynamic therapy.Besides,hypoxia is a prominent feature of tumor microenvironment,which greatly limits the efficiency of tumor photodynamic therapy.Therfore,how to improve the oxygen content of tumor tissues is the key to achieve the effective treatment of PDT.In this paper,mesoporous Prussian blue?HA-PB?nanoparticles with macrophage conversion function and self-produced oxygen were prepared according to the characteristics of tumor related macrophages?TAMs?concentrating in the tumor hypoxia regions.Low molecular weight hyaluronic acid with good biocompatibility and tumor targeting characteristics could skew M2 macrophages toward M1 macrophages,and it was grafted on the surface of mesoporous Prussian blue nanoparticles,resulting in that HA-PB were swallowed by macrophages into the hypoxic regions of the tumor and skewed M2 macrophages toward M1 macrophages.H₂O₂ produced by M1 macrophages reacted with PB with catalase activity and produced the higher release of O₂,to realize self-produced oxygen PDT system.After that,the tumor photothermal and photodynamic synergistic therapy was achieved by Indocyanine green?ICG?loaded in the HA-PB under the near infrared laser irradiation.In vitro studies have shown that HA-PB could efficiently load ICG,and the drug loading rate and encapsulation rate was 57.6%and 67.9%,respectively.In vitro release results showed that HA could be removed or degraded from PB surface by acidity and hyaluronidase,to achieve the release of drug with gate control.In vitro heat production and reactive oxygen species?ROS?tests proved that HA-PB/ICG could effectively convert light energy into local thermal energy under near infrared laser irradiation,and stimultaneously produce ROS.Cells experimental results showed that the HA-PB could be uptaked by 4T1 cells and M2 macrophages and skew pro-tumor M2-type macrophages toward anti-tumor M1-type macrophages,which produced a large amount of H₂O₂.After entering the 4T1 cell,a large amount of ROS was produced under the irradiation of the near infrared laser,which could induce DNA fragmentation and promote tumor cell injury and apoptosis.The results of cell inhibition rate showed that the cell inhibition rates of HA-PB/ICG in near-infrared laser were enhanced 2.85 times compared with free ICG.The cell inhibition rates of HA-PB/ICG cultured with M2-type macrophages further were improved to 4.03 times.The comet experiment results indicated that the DNA damage caused by HA-PB/ICG?37.9%?and HA-PB/ICG+M2?59.2%?was significantly higher than that in the ICG group?8.2%?.4T1 bearing mice were chosen as the model animals.The results indicated that the HA-PB/ICG could increase ICG accumulation and the residence time in the tumor site.Besides,HA-PB/ICG could increase the temperature of the tumor site up to 50.7?under the near infrared laser irradiation,which showed a good ability of solar-thermal conversion.At the same time,HA-PB/ICG could alleviate the hypoxic environment within tumor and reduce the microvascular density to inhibite tumor angiogenesis.Immunofluorescence and ROS detection results showed that the HA-PB/ICG system could skew M2 macrophages towards M1 macrophages and greatly increase ROS production rate in the process of PDT treatment,which significantly enhanced direct killing effect of ICG on tumor cells.Pharmacodynamics results showed that the oxygen self-produced HA-PB/ICG delivery system could significantly inhibit tumor proliferation under near infrared laser irradiation.The relative tumor volume V/V0 treated with HA-PB/ICG was only0.31,showing a good tumor inhibition effect.