Preparation Of Novel Fluorescent Probes Based On Silicon Nanoparticles And Its Application In Biochemistry Analysis

Silicon nanoparticles are a new type of fluorescent semiconductor nanoparticles with special optical,electrical and chemical properties.It has been widely used in many fields,such as electronics,energy,biosensing,and drug delivery due to its remarkable advantages including non-toxicity,good biocompatibility,good stability and easy modification.Currently,various types of silicon nanostructures were been reported.Among them,zero-dimensional silicon nanoparticles have received more and more attention and expected to replace traditional organic dyes and semiconductor quantum dots used in bioimaging or biomedical research.In recent years,researchers have made significant progress in the synthesis methods,optical properties and potential applications of silicon nanoparticles,but there are still many problems that to been further studied such as the cumbersome synthesis process,the harsh synthesis conditions,and the need for surface functionalization to enhance water solubility.Based on this,the functionalized fluorescent silicon nanoparticle was prepaered in one-step by simple equipment,and the application of silicon nanoparticles in biosensing and cell imaging are studied.The details are as follows:Part one.:The water-soluble and carboxyl functionalized silicon nanoparticles（C-Si NPs）were synthesized in one step by using N-[（3-Trimethoxysilyl）propyl]ethylenediamine triaceticacid trisodium salt and L-Ascorbic Acid Sodium Salt as raw materials.The synthesis process is simple and low in cost.No need to use extreme conditions such as strong acid and alkali,high temperature.The fluorescence of C-Si NPs can enhance by adding Hg²⁺without surface modification.The C-Si NPs can use as a signal-enhanced novel fluorescent nanoprobe to measure Hg²⁺.The fluorescence intensity of C-Si NPs showed a good linear relationship with the concentration of Hg²⁺in the range of 0.05 to 180μmol/L.The detection limit was 50 nmol/L（S/N=3）.The fluorescent probe showed good selectivity,the metal ions do not interfere with the determination of Hg²⁺.Proposed probe has been applied for the detection of Hg²⁺in environmental water samples,and satisfactory results have been obtained.Part two:Using 3-aminopropyltriethoxysilane as the silicon source and ascorbic acid as the reducing agent,the amino-functionalized silicon nanoparticles（A-Si NPs）were synthesized at room temperature.And the p H of the solution was adjusted by HCl to prepare A-Si NPs with different emission wavelengths.A-Si NPs with a maximum emission wavelength of 495 nm were selected as fluorescent probes.And a new method for label-free detection of cytochrome c was constructed by using the internal filtration effect.The UV-visible absorption spectrum of cytochrome c（maximum absorption wavelength is 410 nm）overlaps with the fluorescence excitation spectrum（maximum excitation wavelength of 410 nm）of synthetic A-Si NPs.Based on the internal filtration effect,the fluorescence of A-Si NPs can quenche effectively.Therefore,A-Si NPs can be used as a new fluorescent nanoprobe for the detection of cytochrome c.The cytochrome c concentration in the range of 1 to 25000 nmol/L showed a good linear relationship with the fluorescence intensity of A-Si NPs,and the detection limit was 0.053 nmol/L（S/N=3）.The fluorescent probe has good selectivity,and the metal ions,amino acids and proteins commonly found in biological samples do not interfere with the detection of cytochrome c.This probe has been applied to fluorescence imaging of endogenous cytochrome c in Hep G2 cells.At the time of detection,different concentrations of etoposide were added to induce apoptosis,and cytochrome c was released from mitochondria,resulting in a decreasing in the fluorescence intensity of A-Si NPs.The method has the advantages of rapidity,sensitivity and good selectivity,and has broad application prospects in clinical diagnosis and biomedical research.Part three:The carboxyl functionalized silicon nanoparticles（AN-Si NPs）were synthesized by using 3-aminopropyltriethoxysilane and L-Ascorbic Acid Sodium Salt as raw materials.Using this fluorescent probe,a fluorescence analysis method was constructed by using internal filter effect（IFE）,which is a simple and sensitive to detect alkaline phosphatase（ALP）In this sensing system,ALP catalyzes the hydrolysis of p-nitrophenyl phosphate（PNPP）to form p-nitrophenol（PNP）.The absorption spectrum of ultraviolet absorption of PNP（maximum absorption wavelength is 400 nm）overlaps with the fluorescence excitation spectrum of synthetic AN-Si NPs.With the increasing of ALP concentration,the fluorescence intensity of AN-Si NPs decreased gradually.The ALP concentration in the range of 0.05 to 10 U/L showed a good linear relationship with the fluorescence intensity of AN-Si NPs,and the detection limit was0.002 U/L（S/N=3）.The fluorescent probe has good selectivity,and the common metal ions,amino acids and proteins in the biological sample do not interfere with the detection of ALP.We utilize this probe to detect the detection of ALP content in human serum samples,and the results are satisfactory.