Preparation And Application Of Nanosized Hydroxyapatite Doped CdTe Quantum Dots

Hydroxyapatite（HAp）is the main inorganic component of mammalian bone and tooth tissue with good biocompatibility and high biological safety.HAp has been widely used in biomedicine materials,drug carrier materials and other fields.With the sustain development of biomedical materials,the preparation of functional HAp is the basis and guarantee for the realization of new hydroxyapatite applications.In this study,a new type of fluorescent material was created that hydroxyapatite（HAp）loaded with cadmium telluride quantum dots（CdTe QDs）.The hydroxyapatite composite particles（HAp/CdTe）exihibit good fluorescent properties and biosafety,and explore the feasibility of this fluorescent material used in heavy metal ions monitoring and biomarkers in the environment.Methods:1)The precursors of CdTe QDs were synthesized by the condensation-reflow method in the aqueous phase;then the CdTe QDs precursors containing solution were quickly added during the hydrothermal reaction when preparing hydroxyapatite（HAp）.The solution was finally centrifuged,washed and dried to prepare HAp/CdTe particles.The effects of hydrothermal reaction conditions on the HAp/CdTe particles shape,size,fluorescence intensity and other characteristics were detected.Through fluorescence spectrophotometer,thermal field emission scanning electron microscope（SE-FEM）,transmission electron microscope（TEM）,X-ray diffractometer（XRD）,Fourier transform infrared spectrometer（FT-IR）and dynamic light scattering（DLS）to characterize the physicochemical properties such as size,morphology,fluorescence properties,and surface potential of the synthesized particles.2)The fluorescence of HAp/CdTe particles can be quenched by copper ions.Based on this the feasibility of using HAp/CdTe particles as copper ion fluorescent probes to detect copper ion concentration has investigated.Firstly,this study explored the sensitivity of the fluorescence intensity of HAp/CdTe particles on copper ions at different pH.Then explored the change of fluorescence intensity with the concentration of HAp/CdTe particles before and after adding a specific amount of copper ions,to explore the optimal pH and particle concentration conditions to detect copper ions content,obtained a linear correlation curve,and detect the content of copper ions content in the aqueous phase.At last investigated the interference effects of other common ions on this method.3)The in vitro cytotoxicity of synthesized HAp/CdTe particles,pure CdTe QDs and pure HAp particles was detected by CCK-8 assay.The survival rates of cancer cells and normal cells after 24h and 48h of HAp/CdTe particles treatment with different concentrations were detected.The adherent growth HAp/CdTe treated cells were observed by SEM.4)After treated with HAp/CdTe particles,the cell labeling and labeling efficiency was investigated by compare the fluorescence image and bright field plots in same confocal laser scanning field.Results:1)In this project,nano-HAp/CdTe acicular particles with good water dispersibility were prepared.When the synthesis temperature was 50℃,the average size of HAp/CdTe is about 250 nm in length and 50 nm in width;When the synthesis temperature was 70℃,the average size of HAp/CdTe is about 350 nm in length and80 nm in width.2)At 50℃ synthesis temperature,incorporated CdTe QDs with different refluxing reaction time exihibit different excitation fluorescence of synthesized HAp/CdTe particles.At 70℃,incorporated CdTe QDs with different refluxing time exihibit red excitation fluorescence of synthesized HAp/CdTe particles.3)The study performs high sensitivity of the particles in the detection of Cu²⁺in the aqueous phase.In the Cu²⁺content range of 1.3-51.2 mg/L,the fluorescence intensity of HAp/CdTe particles show a good linear relationship with Cu²⁺concentration（R²=0.9986）,the detection limit was 0.4 mg/L.Other ions(Na⁺,Mg²⁺,Ca²⁺,Li⁺,NH⁴⁺,K⁺,Cd²⁺)did not interfere with this detection method.4)CCK-8 cell proliferation experiments demonstrated that the HAp/CdTe particles have good biocompatibility.The in vitro transfection results demonstrated the particles successfully entered the cells with obvious fluorescence excitation,indicating that the HAp/CdTe particles synthesized in this study can be used as cell markers.