Upconversion Luminescence Nanoprobe Based On Luminescence Resonance Energy Transfer For Biomolecular Detection

In recent years,luminescence resonance energy transfer(LRET)has been widely used as a powerful tool,which could be applied in detection,biosensing,bioimaging and immunoassay.In this paper,we not only designed,but also synthesized two types of LRET nanoprobes composed of UCNPs and Ag NPs,in which UCNPs and Ag NPs were respectively as the energy donors and acceptors.And the two nanoprobes were also used for the detection of biomolecular.The morphology features and other properties of obtained samples were carefully characterized by upconversion fluorescence spectrum,SEM,XRD,TEM,PL,UV-vis,FT-IR and other characterization methods.This paper consists of following three chapters:Chapter 1:The background,basic principles and development prospect of the study were introduced firstly.And then the application of the luminescent nanoprobe based on the principle of LRET were discussed in detail.Chapter 2:A new fluorescent nanoprobe based on LRET was explored for the first time.The positively charged NaYF4:Yb,Tm UCNPs were used as the energy donors and the negatively charged Ag nanodisks as the energy acceptors,thus they bound together through electrostatic interaction.The blue emission peak of UCNPs located at the 478 nm was the strongest among all peaks,which was good overlapped with the absorption spectrum of Ag NPs.As a result,luminescence quenching was observed due to the LRET from UCNPs to Ag nanodisks.With the addition of cysteine,LRET process was inhibited and then the luminescence intensities of UCNPs recovered.Moreover,the luminescence recovery was found to show a good linear to its concentration and could be used to detect cysteine.Chapter 3:In the one hand,a simple hydrothermal method was used to prepare the NaYF4:Yb,Tm UCNPs,and a layer of SiO2 was coated with uniform thickness through the Stober method.Then,the surface of UCNPs was connected to the thiol groups by a mild method.In the other hand,because of the reduction of dopamine,Ag nanoparticles with different UV characteristic peaks were prepared by using different concentrations of dopamine solution as reducing agent.As a result,the qualitative detection of dopamine was realized by the colorimetric method of noble metal.Next,we use the Ag-S bond to shorten the distance between SH-NaYF4:Yb,Tm@SiO2 UCNPs and Ag nanoparticles,so that the LRET system had been successfully constructed.At the same time,we established a linear relationship between the concentration of dopamine and the fluorescence intensity of LRET nanopro'be,which realized the quantitative detection of dopamine.