The Chemical Synthesis Of Upconversion Nanocrystals And Copper Sulphide Core-shell Nanostructures For Multi-model Therapies Of Cancer Cells

In recent years,cancer had been the most intractable deadly diseases for human.It’s of scientific and technological importance for the synthesis of core-shell nanoparticles combined upconversion nanoparticles（UCNPs）and semiconductors for multimodal treatment of cancers including photodynamic therapy,chemotherapy and photothermal therapy.Among the semiconductors,CuS nanoparticle has been widely used for photothermal therapy of cancer cells because of the better biocompatibility,lower fabricating cost and excellent photothermal conversion.However,it’s a challenging task for fabrication of core-shell nanoparticles of UCNPs and semiconductors because of the large lattice mismatching between the two components.Up to date,the synthesis of UCNPs@CuS core-shell nanoparticle involves the introduction of the intermediated layer,including silica,mesoporous silica or other amorphous layers to diminish the large lattice mismatch between CuS and UCNPs.However,the existed intermediated layers between UCNPs and CuS will decrease the energy transfer efficiency,which is disadvantage for production of singlet oxygen and effective thermal conversion.In this work,a gas vulcanization strategy has been adopted to fabricate core-shell nanoparticles UCNPs@ZnS for futher developing of upconversion nanoparticles（UCNPs）and CuS composite.Amorphous layer of AA-Zn[（OH）₄]^2-was coated on the UCNPS,which can be easily transferred to ZnS in H₂S gas atmosphere.The energy transfer mechanism of UCNPs@ZnS and the reactive oxygen species production were studied in detail.The core-shell nanoparticles UCNPs@ZnS was used as a template,and the shell ZnS can be easily transferred to Zn_xCd_1-xS by hydrothermal approach.The UCNPs@CuS（abbreviated as UCS）yolk-shell nanoparticles can be obtained via an ions exchanging process.It’s the first time to achieve the UCNPs and CuS composite without intermediated layer.Then,the optical properties of UCS have been extensive investigated.The UCS’s synergistic photodynamic and photothermal therapy effect of cancer cells was further investigated after surface modification.The result show the UCNPs in the as-prepared yolk-shell nanoparticles activate the shell layer（CuS）via fluorescence resonance energy transfer or non-irradiation energy transfer process to produce a large amount of reative oxide species and improve the photothermal efficiency of CuS to kill the cancer cells.The multimodality therapy for cancer cells has been achieved.