Fabrication Of Chalcogenide Semiconductor Nanomaterials Based On Vacancy Engineering And Their Applications In Tumor Theranostic

Inorganic semiconductor nanomaterials have attracted extensive attention in the fields of photocatalysis,electrocatalysis and biology due to their special physicochemical properties and excellent photoelectric properties.However,most inorganic semiconductor nanomaterials have few exposed active sites and poor electrical conductivity,which severely limit their further application.Especially in the field of biological diagnosis and treatment,the absorption of most semiconductor nanomaterials is located in the visible region,whose penetration depth is far less than that of near-infrared light,thus greatly limiting the practical application of semiconductor nanomaterials in tumor therapy.In order to solve these problems,inorganic semiconductor nanomaterials based on vacancy engineering have attracted extensive attention.Vacancy is a typical form of crystal defect,which can effectively change the morphology,elemental composition,lattice structure and electron distribution of semiconductor nanomaterials,thus improving their electrocatalytic and photocatalytic properties.Semiconductor nanomaterials can be endowed with many special properties by introducing vacancy in nanomaterials.If oxygen vacancy is introduced into metal oxides,then the phenomenon of local surface iso-in-vivo resonance（LSPR）will appear,and the absorption of metal oxides will change significantly in the near infrared region,and it can even have strong absorption in the second region of the near infrared region,Second,vacancies in nanomaterials can act as additional intermediate energy levels,facilitating the separation of photo-induced electron and holes,thus enhancing their photochemical reactions.At the same time,the vacancy can cause the change of the valence state of metal ions inside the material,so that the semiconductor nanomaterials show more active sites,which greatly improves the catalytic ability.According to the charge polarity of the existing ions,the vacancies are mainly divided into anionic vacancies,cationic vacancies and mixed vacancies.In this paper,two types of vacancies are designed and regulated based on chalcogenide semiconductor,and the following studies are carried out:First,polyvinylpyrrolidone（PVP）modified copper vacancy sulfide nanoparticles(Cu_2-xS)were prepared by one-step solvothermal method.Compared with common copper sulfide（Cu S）,the absorption peak of Cu_2-xS was redshifted by about 71 nm in the second region of near infrared due to the LSPR effect induced by copper vacancy,and showed stronger light absorption capacity in this region.The copper vacancy also greatly enhanced the electron transfer ability of Cu_2-xS,which made it have higher peroxidase activity.The intermediate energy level brought by the copper vacancy also makes Cu_2-xS exhibit stronger photodynamic effect under the irradiation of the NIR-II laser.After the irradiation of the NIR-II laser,a large number of ROS can be produced for tumor treatment.At the same time,the copper vacancy endowed the nanomaterial with higher NIR-II photothermal conversion ability,which can effectively realize the NIR-II photothermal imaging function.Finally,the prepared Cu_2-xS could achieve the combined therapeutic effect of photodynamic therapy（PDT）,photodynamic therapy（PTT）and chemical dynamic therapy（CDT）under the irradiation of NIR-II.Secondly,polyethylene glycol（PEG）modified molybdenum sulfide nanoparticles(Mo S_2-x)have been prepared by hydrothermal method.Compared with common Mo S₂,the sulfur vacancy improves the light absorption ability in the NIR second region,which makes it have higher photothermal conversion ability in the NIR second region,and can realize the photothermal imaging function in the NIR second region.The sulfur vacancy concentration of Mo S_2-x prepared by hydrothermal method is also relatively higher,which effectively speeds up the separation rate of photogenerated electrons and holes,and greatly improves the photodynamic effect of Mo S_2-x under the irradiation of NIR-II.After NIR-II photostimulation,Mo S_2-x will continue to generate more ROS in the tumor microenvironment and release heat at the same time,so as to achieve thermal ablation of tumor cells while promoting CDT therapy,and finally achieve the synergistic therapy of PDT,PTT and CDT mediated by MoS_2-xunder the irradiation of NIR-Ⅱ.