Detect Alkaline Phosphatase Activity And Ascorbic Acid Content Based On Fluorescent Silicon Nanoparticle Analysis

In recent years,fluorescent sensing technology has been widely used in the field of testing substances,disease diagnosis and food safety due to its many advantages such as high sensitivity,easy operation,fast and low cost.Accordingly,the study of various novel fluorescent nanomaterials make great advances.Fluorescent silicon nanoparticles(SiNPs),gotten the researchers’ extensive concern,has promising future in the area of biological and chemical analysis on account of its superiority of abundant,low cost,good water solubility,low toxicity and high biocompatibility.Part one:IntroductionFirstly,the concept,principle,classification,characteristics and application of fluorescent nanomaterials were summarized.Secondly,the synthesis methods of fluorescent SiNPs and their applications were briefly introduced.Furthermore,the regular fluorescence analysis method and the fluorescence polarization method were summarized.Finally,the purpose and significance of this paper were presented.Part two:Fluorescence analysis method to detect alkaline phosphatase activityAlkaline phosphatase,widely exist in the tissues of living organisms,can catalyze the hydrolysis process of transphosphorylation of various phosphate compounds,and it is necessary in signal transduction and regulation of intracellular processes involved in cell growth and apoptosis.The abnormal level of alkaline phosphatase in serum is closely related to various diseases,such as bone disease,diabetes,breast cancer,prostate cancer and hepatitis.Therefore,it is significant to establish a sensitive and efficient method for the determination of alkaline phosphatase activity.In this study,we used the green,low toxicity and good water soluble fluorescent SiNPs as a fluorescent probe to detect alkaline phosphatase activity for the first time.p-Nitrophenylphosphate(PNPP)can be catalyzed by ALP and produced p-nitrophenol(PNP)which is able to functioning as a powerful absorber to influence the excitation of SiNPs based on IFE.Alkaline phosphatase activity was determined by monitoring the relationship between the fluorescence quenching rate of SiNPs and the content of PNP.The linear range of alkaline phosphase activity detection was 0-40 U·L-1(R2=0.9951),and the detection limit was 0.30 U·L-1(S/N=3),which was lower than the previous detection method.The IC50 value of the typical inhibitor(Na3VO4)is 86.62 μmol/L.The new method of detecting alkaline phosphatase activity has the advantages of simplicity,high sensitivity and selectivity,and has been used for the determination of alkaline phosphatase in human serum samples.Moreover,it is expected to be used for alkaline phosphatase inhibitor screening.Part three:Fluorescence polarization method to detect ascorbic acid content.L-ascorbic acid,commonly known as vitamin C,is a necessary vitamin for human and rich in many fruits and vegetables.Lack of ascorbic acid in humans can cause many diseases,including influenza,scurvy,mental illness and cancer.However,ascorbic acid is a kind of exogenous chemicals that the body cannot synthesis and only obtained from food intake.Therefore,it is of great significance to establish an efficient and sensitive method for the determination of ascorbic acid content in daily life.This study made use of the absorption effect of manganese dioxide nanosheerts on SiNPs and the redox reaction between MnO2 and ascorbic acid to build a general,fast,low-cost fluorescence polarization detection method of ascorbic acid content.MnO2 nanosheets with a larger molar extinction coefficient and wide absorption spectrum usually be used as fluorescence quenching agent and fluorescence polarization signal amplifier in biological sensing,SiNPs could absorb on MnO2 nanosheets to enhance the fluorescence polarization signal of SiNPs.Reductive ascorbic acid reduced manganese dioxide to Mn2+ or Mn3+,which destroyed the structure of MnO2 nanosheets and decrease the fluorescence polarization signal of SiNPs,the relatonship could be used to detect ascorbic acid.The linear range of ascorbic acid content detection was 0.03-0.1 μmol/L(R2=0.9930),and the detection limit was 0.004 μmol/L(S/N=3).The experimental results show that the method has the advantages of simple operation,high sensitivity,good selectivity and small sample quantity.Furthermore,the method was successfully used to determine ascorbic acid content in some commercial fruit juice.