In Situ Synthesis Of Microparticles Containing Te Nanoparticles From Tumor Cells

In recent years,countries all over the world have devoted themselves to the study of tumor treatment and its mechanism.How to eliminate tumor cells effectively while activating and enhancing the body’s immune response is an important way to prevent and treat cancer.The treatment methods mainly include surgical resection,radiotherapy,chemotherapy,etc.,but a single treatment method is often difficult to cure.Nano drug delivery system（NDDS）can not only lighten the toxic and side effects of medicines with improving the bioavailability of drugs,but also make the combined application of multiple treatment methods come ture,which has a more significant therapeutic effect than a single tumor treatment method.Microparticles（MPs）derived from cells are a kind of nanodrug carrier with good biocompatibility and easy preparation.MPs secreted by tumor cells can obviously upgrade the concentration of anti-tumor drugs in the tumor area while improve the tumor microenvironment.However,Nano-drug loading systems based on microparticles often face limitations such as cumbersome drug loading processes and low drug loading levels.In this paper,tumor cells are used as reactors to synthesize Te nanoparticles in situ in the cell and induce the drug loading micro-particles with high expression of Hsp70,Te@MPs.The main research contents and results are as follows:（1）.Te@MPs were constructed in situ by tumor cells.After co-incubating H22 tumor cells with Na₂Te O₃,the synthesis of Te nanoparticles in situ is completed in the cell and the cell suspension is irradiated with a certain power of near-infrared laser to heat up,which induces tumor cells to overexpress Hsp70 and then induces cell apoptosis by UV and secretion package Te nanoparticles microparticles（Te@MPs）.Transmission electron microscopy（TEM）results show that as the co-incubation time increases,Te nanoparticles in the cell gradually increase,and the purified Te@MPs surface has a clear membrane structure,with a particle size of about 50 nm.Te@MPs have good water dispersibility,the hydrated particle size is about 270 nm,and the Zeta potential is-21 m V.XPS and XRD analysis confirmed that Te exists in the form of 0-valence,amorphous element.（2）.Study on the photo-thermal performance of Te@MPs.Te@MPs solutions with different concentrations are irradiated with different laser powers and the heating effect is obvious,indicating that Te@MPs have a good photothermal effect and the photothermal effect is concentration dependent and laser power dependent.The photothermal conversion efficiency of Te@MPs is 28.44%.Through repeated heating experiments,the heating and cooling time curve shows periodic changes,indicating that Te@MPs has good photothermal stability,but laser irradiation will cause the destruction of the surface membrane structure of Te@MPs,result in affecting its stability and dispersion.（3）.Study on the expression of Hsp70 on the surface and cytotoxicity of Te@MPs。When suffering from external stimuli（such as drugs,laser irradiation,temperature changes,etc.）,cells will produce corresponding protective mechanisms to prevent cell apoptosis or death（such as up-regulation of Hsp70 protein expression）.Studies have shown that Hsp70can also act as a molecular chaperone to promote the uptake and cross-presentation of related antigens by APC cells such as DCs,thereby causing corresponding immune responses.We give a certain dose of near infrared light before the tumor cells are induced to secrete micro-particles.The results of flow cytometry show that Hsp70 is highly expressed on the surface of cells and the collected Te@MPs,so that Te@MPs are expected to achieve enhanced immune regulation.In this paper,a nano-Te microparticle drug delivery system was prepared by in-situ synthesis of tumor cells.Te@MPs has obvious membrane structure and high expression of Hsp70 on the membrane surface.It has good biological safety and photothermal killing effect and can be used for Follow-up treatment of mouse solid tumor model.