Silica-based Magnetic Nanobiosensor For The Detection And Evaluation Of Pb(?)

The half-period of Pb(?)in the human body can be as long as 5 years,and it can accumulate in the body,mainly manifested as symptoms of chronic poisoning,which has toxic effects on the human nervous system,blood and blood vessels.Therefore,it is very important to develop an ultra-sensitive and highly selective method for Pb(?)ion detection.With the deepening of research,new methods have been developed for the detection of Pb(?)ion based on peroxidase mimetic enzyme,such as electrochemical method,fluorescence,enzyme-linked immunosorbent assay(ELISA),chemiluminescence method.In this paper,two methods,colorimetry and chemiluminescence,are designed for rapid detection of Pb(?)ion.Regarding on the shortcomings of existing technology,this work proposes new ideas for the detection of Pb(?)ion.The method has the characteristics of high efficiency,rapidity,sensitivity and low detection limit,and is easy to operate with low detection cost,which is beneficial to practical promotion and application.The main idea of the study is summarized as follows:1.Construction of magnetic colorimetry for Pb(?)ion based on G4Specifically,first,Fe3O4 magnetic nanoparticles(magnetic nanoparticles,MNPs)with uniform size,good dispersibility and stability are prepared in a reactor by a thermal solvent method,in which ethylene glycol is used as a solvent and a reducing agent Ferric chloride provides an iron source and sodium citrate as a stabilizer.Then,in order to make better use of MNPs in sensor construction,they were then modified and functionalized.Simply put,a layer of silicon shell is wrapped on the surface of TEOS,and then the amino functionalization is performed with APTES.In this process,Fourier transform infrared spectroscopy(FT-IR),dynamic light scattering instrument(DLS),and transmission electron microscopy(TEM)were used to characterize their property and morphology.Next,p DNA is coupled to the surface of MNPs with abundant amino groups.When p DNA and its complementary strand t DNA are paired to form a double strand,the target Pb(?)is added to induce the double strand to unwind and fold to form a G-quadruplex(G4).Under the action of Hemin,the constructed sensor exhibits peroxidase-like activity,enabling TMB to develop color quickly within 5 minutes.After the 2% sulfuric acid solution is terminated,the UV absorption value is measured,and the calculated absorption value is calculated.It is linearly related to the concentration.The linear equation can be put as Y=0.062X+0.355,R=0.994,and the limit of detection(LOD)is 4.3 n M.The high R value and low LOD indicate that the method has high reliability and sensitivity.2.Fabrication of luminol-QDs dual-signal sensor for the detection of Pb(?)In this chapter,based on the above study,the luminol(chemiluminescence,CL) signal is added to further synthesize the luminol-QDs complex to enhance the CL signal.First,the luminol and QDs are combined under the action of EDC/NHS activated reaction,and the luminol-QDs conjugate activated is modified on one end of t DNA.Due to its complementary pairing with MNPs@Au NPs-p DNA,it can be separated together with MNPs to build a chemiluminescent switch under the action of a magnetic field.In the absence of Pb(?)ion,the luminol-QDs conjugate can realize magnetical separation with under an external magnetic field,and no chemical signal was detected in the supernatant.After Pb(?)ion was added,luminol-QDs-t DNA fell off from the complex,the chemiluminescence switch was turned on,and CL signal was detected in the supernatant.