Synthesis Of W₁₈O₄₉@Carbon Nanomaterials And In Vitro Synergistic Antitumor Study By Photothermal-Chemotherapy

The high incidence of malignant tumors has attracted worldwide attention.Currently,the mainstream clinical anti-tumor means include surgery,chemotherapy and laser therapy,while the limitations of single therapy force us to seek more effective treatment means.Combined therapy can produce a superposition effect and has great application potential.The advantage of the combination of photothermal therapy（PTT）and chemotherapy is that it can kill cancer cells by thermal ablation while using fewer drugs to clear deep diseased cells,thus fighting multidrug resistance（MDR）and reducing toxic side effects.Photothermal therapy（PTT）,as a non-invasive tumor treatment method,has attracted much attention because of its significant efficacy and small side effects.The key of photothermal therapy is to seek nanomaterials with good biocompatibility,stable photothermal properties and effective control.There are still some problems to be solved in the synergistic treatment of PTT and chemotherapy:preparation of nanomaterials with excellent photothermal properties and high drug load;How to accurately control the release of nano drug delivery system;The photothermal material and the improvement of the biological safety of the material.It’s a problem that needs to be solved.In this paper,experiments will be conducted to explore the above problems,and an efficient nano-controlled release drug delivery system will be constructed for the study of tumor ablation mechanism.Previous studies have found that W₁₈O₄₉with plasma resonance effect（LSPR）is cheaper than precious metal photothermal nanomaterials and has the advantages of high photostability compared with organic nanomaterials.Therefore,W₁₈O₄₉ is selected as a photothermal agent in this paper to compound it with carbon nanospheres with good biocompatibility.Enhance the photothermal properties and improve the drug load;W₁₈O₄₉ was coated with polyaniline（PANI）to slow down oxidation,stabilize oxygen vacancy and enhance drug adsorption.And the active targeting of the synergistic antitumor of photothermal and chemotherapy was improved by adding magnetic targeting.The main research is as follows:（1）W₁₈O₄₉@C Study on the synergistic antitumor effect of photothermal-chemotherapyThe best reaction conditions（200℃,24 h,3:1）W₁₈O₄₉@C were obtained by orthogonal experiment.Scanning electron microscopy（SEM）showed that the surface of carbon nanospheres was coated with loose needle-like monoclinic crystalline phase W₁₈O₄₉,and the W₁₈O₄₉@C nanoparticles showed a flake-like spherical structure with a particle size of 200-300 nm.When the temperature of W₁₈O₄₉@C dispersion increases from 25.6℃to 73.9℃,the photothermal conversion efficiency reaches 69.30%by using an 808nm exciter for continuous illumination for 5min.The drug adsorption amount of W₁₈O₄₉@C can be up to 139.55 mg/g,and the drug release can reach 81.65%under the simulated tumor microenvironment and near infrared（NIR）light irradiation.In vitro cell experiments using He La cells as a biological model using W₁₈O₄₉@C+DOX·HCl showed that the survival rate of cancer cells was 19.47%after chemotherapy and photothermal ablation.（2）Study on the antitumor effect of photothermal-chemotherapy on surface modified composite nanomaterialsBased on the study of W₁₈O₄₉,this paper further improved it,C spheres were reflux to get hollow carbon nanospheres,then it was modified.The surface modification of polyethylene glycol 2000（PEG）and polyvinyl pyrrolidone（PVP）was used to obtain PEG-W₁₈O₄₉@R-C and PVP-W₁₈O₄₉@R-C,respectively.Scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray powder diffraction（XRD）were used to determine the morphology and crystal phase structure of the samples.After continuous illumination with an808nm exciter for 5min,the temperature of PEG-W₁₈O₄₉@R-C and PVP-W₁₈O₄₉@R-C dispersions can reach 64.7℃（△=36.5℃）and 57.3℃（△=27.4℃）,respectively,and the photothermal conversion efficiency is 59.51%and 42.88%.The maximum drug loads of PEG-W₁₈O₄₉@R-C and PVP-W₁₈O₄₉@R-C reached 162.49 mg/g和154.68 mg/g,respectively,and the drug release rates reached 84.35%and 70.21%in the simulated treatment of tumor,respectively.After chemotherapy and combined photothermal ablation,83.40%and 78.53%of He La cells were destroyed by PEG-W₁₈O₄₉@R-C and PVP-W₁₈O₄₉@R-C,respectively.The results of combined index（CI）analysis showed that the CI values of PEG-W₁₈O₄₉@R-C+DOX·HCl and PVP-W₁₈O₄₉@R-C+DOX·HCl were less than 1.The results of live staining experiment also confirmed that the two nanocomposites had the superposition effect in chemotherapy and photothermal coordination of anti-tumor.（3）PANI@W₁₈O₄₉ and the anti-tumor study of photothermal-chemotherapy synergistic effect of magnetized nanomaterialsThe photosensitizer polyaniline（PANI）and W₁₈O₄₉ were combined to improve the photothermal efficiency and stability.At the same time,magnetic targeting of Fe₃O₄ was added to obtain the nanocomposite PANI@W₁₈O₄₉@Fe₃O₄.The composite material has strong absorption in the near infrared region of 800-1200 nm,which can realize the absorption of the first and second biological windows.The material is in loose state and has a large pore structure,which is conducive to drug adsorption in the later stage,and the gap is relatively large to a certain extent of aggregation.The saturation magnetization is 0.429 emu·g^-1,showing controllable magnetic targeting by superparamagnetism.The experimental results show that the photothermal properties of PNAI and W₁₈O₄₉ are improved obviously.After continuous illumination with 808nm exciter for 5min,the temperature of PANI@W₁₈O₄₉@Fe₃O₄dispersion can reach 67.1℃（△=37.8℃）,and the photothermal conversion efficiency is as high as 62.65%.The maximum drug loads of PANI@W₁₈O₄₉ and PANI@W₁₈O₄₉@Fe₃O₄ were149.75 mg/g和157.82 mg/g,respectively.Under the simulated tumor microenvironment and NIR irradiation,the drug release amount could reach 65.96%and 51.40%,respectively.The survival rates of cancer cell after chemotherapy and photothermal ablation were 79.95%and77.67%,respectively.The IC₅₀ of PNAI@W₁₈O₄₉@Fe₃O₄+DOX·HCl decreased from 0.08mg/m L to 0.011 mg/m L and the CI value was 0.42,compared with the non-near-infrared light（NIR）group,indicating that both inorganic/inorganic(PEG-W₁₈O₄₉@R-C,etc.)and organic/inorganic(PANI@W₁₈O₄₉)composite nanomaterials prepared on the W₁₈O₄₉ substrate show synergistic anti-tumor potential.