Preparation And Photothemal Applications Of Reducted State Molybdenum Oxide

Molybdenum oxide is a kind of important transition metal oxides,which have many potential applications,such as sensor,catalyst,electrochromism,photochromism,lithium-ion batteries,solar cells and so on.Non-stoichiometric molybdenum oxides are excellent photothemal materials because of tunable optical absorption in visible and near infrared regions.In this work,the oxygen-deficient molybdenum oxide quantum dots were synthesised by a hydrothermal method and theoretical modeling method was applied to study the origin of their uniqe optical property.Then,MoO_3-x quantum dots were used for interfacial water evaporation and photoacoustic imaging-guided photothermal/photodynamic combined cancer treatment.The detailed study included:In this study,molybdenum oxide nanomaterials of various morphologies have been prepared under solvothermal condition by varying the amount of chitosan,reaction temperature and concentration of Mo resource.On the basis of transmission electron microscopy,X-ray diffraction spectroscopy and ultraviolet-visible-near infrared absorption spectrum results,the MoO_3-x quantum dots sample that have strong absorption in visible and near infrared regions were selected as photothermal materials for further applications.In addition,we have proved the presence of oxygen defects in MoO_3-x quantum dots by X-ray photoelectron spectroscopy,electron spin resonance spectra and Raman spectra methods.Theoretical modeling suggested that strong absorption of MoO_3-x quantum dots in visible and near infrared regions resulted from oxygen defect level,instead of localized surface plasmon resonance.MoO_3-x quantum dots possess matchingabsorption-spectrum to the solar spectrum in both of visible and near infrared regions.The membrane containing MoO_3-x quantum dots has been fabricated by filtering method and applyed in interfacial water evaporation.The result revealed that membrane of MoO_3-x quantum dots exhibited excellent interfacial heating effect,realizing excellent interifacial vapor generation efficiency.This work realized photoacoustic imaging-guided photothermal/photodynamic combined cancer treatment just via a single matter of MoO_3-x quantum dots.Due to strong NIR harvesting ability,MoO_3-x quantum dots can convert NIR light into hyperthermia and generate singlet oxygen synchronously,hence,they can behave as photothermal agents and photosensitizer effectively.Resultantly,both in vitro and in vivo antitumor effect could be achieved.MTT experiments showed that MoO_3-x quantum dots have no obvious cytotoxicity.In addition,the desired photothemal effect also makes MoO_3-x quantum dots to be an exogenous PA contrast agent for in vivo live-imaging to depict tumors.In a further study,MoO_3-x quantum dots were used to eliminate solid tumors of the He La-tumor bearing mice.Histology analysis suggested that there were no obvious lesions to the major organs,and MoO_3-x quantum dots could be metabolized by the liver and spleen to a greater extent.In brief,MoO_3-x quantum dots in this thesis possess matching-absorptionspectrum to the solar spectrum and exhibit excellent interfacial heating effect.As a single matter multifunctional theranostic agent,it is exempt from unpredictable mutual interference between components and ease of leakage of virtual components from the composited system.