Study Of Biological Application Based On Chemical Properties And Fluorescence Of Silicon Quantum Dots

In recent years,silicon quantum dots(SiQDs)have gradually become a promising fluorescent nanomaterial with broad development prospects.Due to their unique physicochemical properties,low biological toxicity,especially the dimension-dependent fluorescence caused by quantum confinement effect,SiQDs have been widely developed and applied in fluorescent probes,chemical catalysis,cell imaging,photoelectric devices and so many other fields.Through decades of research,researchers have developed a variety of methods to prepare SiQDs,and the preparation technology became much more mature.However,SiQDs precursors are almost hydrophobic terminal groups with poor water solubility.Therefore,surface modification of SiQDs has become an urgent problem to be solved.On the other hand,SiQDs have mild reductive properties on account of the active Si-H on the surface of them.In this thesis,we mainly discuss the surface modification of hydrogen-terminated SiQDs obtained by electrochemical etching and the application of their properties.The main research contents are as follows:(1)The hydrogen-terminated SiQDs were firstly obtained by electrochemical etching.After modifying with glutamic acid and polyvinylpyrrolidone,SiQDs with high fluorescence stability and water solubility were finally obtained.Cytotoxicity studies have shown that the two-component modified SiQDs have good biocompatibility,and cell imaging experiment has further confirmed their potential in the field of bioimaging.(2)With the reduction properties of hydrogen-terminated SiQDs,we fabricate silicon-palladium composite nanomaterials for photoacoustic imaging and photothermal treatment of tumors.Due to the excellent near infrared absorption,the silicon-palladium nanomaterials can efficiently convert near infrared light energy into thermal energy,then furtherly realizing photoacoustic diagnosis and photothermal treatment of tumors.The systematic study on cytotoxicity has proved that the composite nanomaterials modified by polyvinylpyrrolidone have low toxicity.With their dramatic efficacy in photothermal therapy of tumors,silicon-palladium composite nanomaterials show great promise for application for cancer therapy.(3)The hydrogen-terminal SiQDs obtained via electrochemical etching were used as a reducing agent to reduce chloroauric acid to get silicon-gold composite nanomaterials,and then the composite nanomaterials were further modified with polyvinylpyrrolidone.Finally,the composite nanomaterials were applied to photothermal therapy of tumors.