Se@OMVs Synthesized Directely By Bacteria For Tumor Chemodynamic Therapy

In recent years,the incidence and mortality of malignant tumors have gradually increased,which has seriously threatened the health of people all over the world.Selenium,as the anti-cancer king among trace elements,has always received widespread attention.A large number of studies have shown that selenium nanoparticles have a variety of biomedical effects,whether as an antioxidant to reduce oxidative stress in the body or as a drug carrier,they can play a significant role in the treatment of cancer.In addition,selenium nanoparticles can be used as chemotherapy drugs to directly kill tumor cells.However,traditional chemical-based synthesis of Se nanoparticles has disadvantages such as high cost,poor biocompatibility,and insufficient tumor targeting ability.Therefore,it is urgent to develop a green and large-scale preparation strategy for selenium nanoparticles with better tumor tissue targeting ability.Using living cells as a reactor and using the biochemical reaction of the biological system itself can precisely control the synthesis of inorganic nanoparticles,providing a new idea for the preparation of nanomaterials.At the same time,the nanoparticle encapsulation technology based on cell membrane will further improve the biocompatibility and tumor targeting of nanomedicine.Based on this,this paper uses wild-type E.coli(Nissle 1917)as a bioreactor,and synthesizes selenium nanoparticles(Se@OMVs)encapsulated with bacterial outer membrane vesicles by adding Na₂SeO₃ to the medium.Through transmission electron microscopy,it is found that the prepared Se nanoparticles have a size of about 50 nm,exhibit good uniformity and monodispersity,and have a clear biofilm structure on the surface.Elemental analysis and infrared absorption spectroscopy confirmed the composition of the cell membrane on the surface of the nanoparticles.In the presence of H₂O₂,Se@OMVs can react to produce a large amount of hydroxyl radicals(·OH).Cell experiments confirmed that Se@OMVs has better tumor cell uptake ability than unmembrated Se nanoparticles,and the intracellular reactive oxygen species(ROS)is significantly increased,showing excellent tumor cell motility(Chemodynamic).therapy,CDT)killing effect.After the tumor-bearing mice were injected through the tail vein,Se@OMVs could be enriched in a large amount at the tumor site and showed a certain anti-tumor effect.In this paper,aiming at the limitations of the current preparation of anti-tumor Se nanoparticles,a green method capable of large-scale production of Se nanoparticles is designed.Bacterial outer membrane vesicles coated on the surface of selenium nanoparticles can not only enhance targeting,but also have the potential of combining chemokinetic therapy and immunotherapy due to the presence of lipopolysaccharide(LPS)on the surface.