The Design And Synthesis Of Novel Fluorescent Silicon Nanoparticles And Their Applications In Determination Of Trace Components And PH

As an important zero-dimensional nanomaterial,fluorescent silicon nanoparticles(SiNPs)have attracted extensive attention due to their unique optical,electrical and mechanical properties,especially for the photo-stability,low toxicity and good biocompatibility.At present,SiNPs have sho wn great potential applications in optoelectronic devices,bio-imaging,photocatalysts,light-emitting diodes(LEDs),solar cells and sensors.In the past few years,researchers have developed many methods for preparing fluorescent SiNPs,while most of the reported SiNPs are easily oxidized in the surrounding environment and are not easily dispersed in aqueous solvents.Therefore,surface modification is required to improve stability and solubility of SiNPs.Most of these methods are complex,cumbersome,and the synthesis conditions are harshed.The synthesized SiNPs are mostly short-wavelength emission and single-emission,which severely limits the application of fluorescent SiNPs in analytical chemistry.Therefore,it is important to explore a simple method for synthesizing fluorescent SiNPs with water-soluble,long-wavelength emission or dual-emission properties and to use synthetic SiNPs for analytical chemistry,especially bioanalytical chemistry.Based on the previous works,the following research contents were carried out around the design,synthesis and practical application of water-soluble,long-wavelength emissive or dual-emissive fluorescent SiNPs:(1)A new one-pot method for synthesizing water-soluble fluorescent SiNPs was developed and a new method for the determination of potassium ferrocyanide in salt and salt foods was established using the prepared SiNPs as probes.One-pot method for synthesizing water-soluble fluorescent SiNPs was developed by using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane(DAMO)as silicon source and sodium ascorbate(AS)as reductant.The morphology and properties of the synthesized SiNPs were characterized and studied.On this basis,a new fluorescent method for the rapid and highly selective determination of po tassium ferrocyanide in salt and salted foods was established using the fluorescent SiNPs.Under the optimal detection conditions,the linear range of the method is 0.05-8.0?g/mL and the detection limit is 30 ng/mL.This method has been successfully used for the determination of potassium ferrocyanide in actual salt and salted foods.In addition,the SiNPs were also used as a probe,a new method for the rapid,convenient and visual determination of potassium ferrocyanide was developed by means of UV lamps and mobile APP software.(2)Development of a new one-pot method for synthesizing yellow fluorescent SiNPs and examining the application of prepared SiNPs in pH detection and cell imagingUsing DAMO as silicon source and 4-aminophenol as reductant,a new one-pot method for synthesizing water-soluble fluorescent SiNPs with longer emission wavelength was developed and the morphology and properties of the synthesized SiNPs were characterized and studied.The results show that the SiNPs have excellent salt tolerance,temperature stability and photobleaching resistance and ha ve a sensitive response to pH.On this basis,a new method for determining the pH value is established.The linear range of the established method was pH 5-10 and the sensitivity was 0.5 pH units.This method has been successfully used to determine the pH values of the Yellow River water,tap water and ultrapure water,and the relative error of the measured pH is less than 3%compared with the measured value of the commercial pH meter.In addition,the cytotoxicity of SiNPs was also investigated.The results showed that it has low biotoxicity and good biocompatibility.According to this property,the SiNPs were successfully applied to intracellular fluorescence imaging.This result indicates that the SiNPs are expected to determination of pH in cells.(3)A new one-pot method for synthesizing europium-doped dual-emissive fluorescent silicon nanoparticles(Eu@SiNPs)was developed and a new method of ratio fluorescence and test strips were established by used the Eu@SiNPs as a probe to determine the pathogenic bacteria-bacillus anthrax spores in environmental samples.For the first time,a one-pot method for the synthesis of Eu-doped water-soluble fluorescent silicon nanoparticles(Eu@SiNPs)with dual-emission properties without post-modification was developed and the morphology and properties of the prepared Eu@SiNPs were characterized and studied.Based on the antenna effect of Eu in the Eu@SiNPs and the specific recognition ability of SiNPs,a new method for the rapid,convenient,sensitive and highly selective determination of pathogenic bacteria-bacillus anthrax spores in environmental samples was established.Under the optimal detection conditions,the detection limit of the method for spores was as low as 2.38×10~4 spore/mL.This method has been successfully applied to the determination of bacterial spores in the Yellow River water,tap water and soil with good recoveries.In addition,based on the excellent performance of the Eu@SiNPs,a test paper which is convenient,economical and capable of visually measuring bacterial spores has been developed.