Single Particle Fluorescence Enumeration Detection For Biomolecules Based On Upconversion Nanoparticles

The light-sensitive upconversion luminescent nanomaterials(lanthanide-doped nanomaterials)have attracted more and more attention in optical microimaging studies in complex biological environments.It is rather important to prepare up-converting nanoparticles(UCNPs)with uniform size and good biocompatibility.In this work,UCNPs with good monodispersity by thermal decomposition were prepared and applied to the detection of cancer markers and mycotoxins.The main research works are as follows:(1)Firstly,several common optical nanomaterials are introduced.Secondly,the preparation of upconversion luminescent nanomaterials,surface modification methods and their applications in different research fields are mainly focused on.(2)The green flurescent UCNPs prepared by thermal decomposition method were transformed into UCNPs with uniform size,morphology and good dispersity by optimizing its reaction temperature and time.Polyacrylic acid(PAA)with good biocompatibility was modified to the surface of UCNPs by ligand exchange method.The structure and photochemical properties of UCNPs were characterized by dynamic light scattering(DLS),transmission electron microscope(TEM),fluorescence spectrophotometer,improved positive microscope and Fourier transform infrared spectrometer(FTIR).The results showed that it has good optical properties and is beneficial to subsequent biological detection experiments.(3)Gold nanoparticles(GNPs)with uniform size were prepared by seed growth method and the structure properties of GNPs were characterized by dynamic light scattering(DLS),transmission electron microscope(TEM),UV spectrophotometer,dark field microscope.Sandwich-type immunosensors were constructed based on luminescence resonance energy transfer(LRET)between UCNPs and GNPs.The experimental results show that the UCNPs-GNPs nanoprobe does well in detecting the PSA in the buffer solution and serum with the detection limit of 1.0 pM.This method detects the recovery rate of PSA in actual blood samples as high as 97.4%,which shows a good application prospect for selectively detecting the cancer markers in the field of clinical diagnosis.(4)A nano-aptamer sensor was constructed based on LRET between UCNPs and GNPs.Quantitative detection of aflatoxin(AFB1)was performed according to the method of single particle counting method with the detection limit of 0.53 nM.This method detects the recovery rate of AFB1 in actual samples(fresh peanuts)as high as 101.9%,which reveals a good application prospect in biological sensing detection.