Preparation Of SiNPs With Excellent Optical Properties And High Yield And Its Application In Biological Imaging And Fluorimetric Determination Of Acid Phosphatase

Fluorescent silicon nanoparticles（SiNPs）was a new type of semiconductor fluorescent nanomaterials.Because of its cheap and easily available raw materials,non-toxic and harmless,good biocompatibility and other advantages,silicon nanoparticles had a wide range of applications in the fields of analysis and detection,biomedicine,fluorescence imaging and so on.In this paper,a kind of SiNPs with high quantum yield and high synthesis yield was prepared.The low toxicity of SiNPs was verified,and it was confirmed that SiNPs was suitable for both in vitro and in vivo biological imaging,especially for long-range biological imaging.Taking SiNPs fluorescence as the signal,making use of the enzyme activity of SiNPs-ACP and using DA as the substrate for enzymatic catalysis,a new fluorescence sensing strategy was established,and the high sensitivity detection of acid phosphatase（ACP）was successfully realized.The main research content of this paper was divided into the following two chapters:Chapter 1:Preparation and characterization of SiNPs with excellent optical properties and high preparation yield.In this chapter,a kind of SiNPs with quantum yield up to 80%was prepared by one-step hydrothermal method using DAMO as raw material and trans-aconitum acid as reducing agent.Moreover,1.3195 g SiNPs could be obtained after a total mass of only 2.2341 g raw material was reacted and purified.And the synthesis rate was as high as 59.1%,which was higher than that of most SiNPs synthesis methods reported so far.The prepared SiNPs was characterized by UV-vis,FTIR,TEM,XPS and so on.The SiNPs had bright blue fluorescence,good water solubility and excellent long-time stability.The preparation method had the advantages of simple operation,easy availability of raw materials,low cost,high yield,few impurities and excellent optical properties,which was beneficial to the popularization and application of fluorescent silicon nanoparticles.Based on the low toxicity and good biocompatibility of SiNPs,it could be used as a satisfactory probe for fluorescence imaging of human non-small cell lung cancer cells（A549）and zebrafish,especially for long-range biological imaging.Chapter 2:The fluorescence analysis method of enzyme-catalyzed oxidation of dopamine based on silicon quantum dots as fluorescence probe for the detection of acid phosphatase.In this chapter,dopamine was used as the substrate for the enzymatic catalysis of acid phosphatase（ACP）.Under acidic conditions,SiNPs could interact with ACP to produce ROS,which further oxidized dopamine to produce polydopamine.The polydopamine could quench the fluorescence emission behavior of SiNPs by IFE.Based on this principle,we used SiNPs as a signal indicator to develop a novel fluorescence sensing strategy for ACP activity detection.By optimizing the reaction conditions such as temperature,time,pH and substrate concentration,25℃,100 min and pH 4.0 PBS were selected as the optimal reaction conditions for ACP detection,and the DA concentration of 300μM was selected as the optimal substrate concentration for ACP detection.There was a good linear relationship between（F₀-F）/F₀and C_ACPwhen the concentration of ACP was in the range of 0.1-60 U/L,the linear equation was y=0.0083C_ACP+0.0130（R²=0.9975）,and the detection limit was 0.1 U/L.The IC50 of its representative inhibitor NaF was 5.38 mM.Compared with previous detection methods,the ACP detection method had the advantages of low detection limit and wide linear range,and had been successfully applied to the detection of ACP in human serum samples,which indicated that this method had potential clinical application value and was expected to be used in the screening of ACP inhibitors.