Synthesis Of NaYF₄ Rare Earth Upconversion Nanoparticles And Application Of Bio-probe

Sandwich enzyme-linked immune(ELISA)has high specificity and sensitivity,has been widely applied in the biomarker and antibody detection,but the main drawback of this method is low sensitivity and long time consuming,low antibody detection sensitivity,break the existing medical detect bottleneck solution is to improve luminescence materials or targeted biological antibody protein.The new luminescent materials are used to replace the traditional luminescent materials,so as to avoid the shortcomings of the traditional luminescent materials,such as short life span,easy photodegradation and photobleaching,high biological toxicity,and easy to produce background fluorescence.The upconversion of rare earth nanoparticles has good infrared luminescence and up-conversion properties and has a good biological application prospect.In this paper,uniform and dispersed up-conversion rare earth up-conversion nanoparticles were prepared to form up-conversion biometric probes instead of traditional luminescent materials,and a sandwich ELISA method for antigen detection was developed.The improved rare earth upconversion nanoparticles(UCNP)have great application prospects in in vitro biological detection,and their infrared excitation properties provide certain advantages for the development of in vivo imaging technology.The main conclusions are as follows:(1)In this paper,the effects of preparation conditions on the synthesis of UCNP under different conditions were discussed.The reaction speed did not affect the synthesis of UCNP,and the optimal reaction time and temperature were 1.5 h and 300?.The reaction temperature plays a decisive role in the nucleation and growth of UCNP.Uniform UCNP with good morphology and monodispersity can be prepared when the reaction temperature reaches 300?.The increase of temperature and the lengthening of time have no significant effect on the morphology and phase,but improve the crystallinity of nanoparticles and enhance their fluorescence intensity.(2)3,4-dihydroxy phenylpropionic acid was used to replace the oleic acid ligands on the original surface of the prepared hexagonal UCNP,so that it had better dispersion,better binding force and better stability in water.Due to the replacement of surface ligands,a variety of biological problems in subsequent reactions are reduced,which provides a good stable environment for further exploration of the application of up-conversion nanoparticles,as well as the binding sites.(3)The modified UCNP was conjugated with different types of specific targeting antibodies through EDC to prepare macromolecular biological probes and shark nano antibody probes.In terms of detection limit,sensitivity and stability,different antigen concentration tests were carried out to compare with traditional ELISA.The intensity gradient of the macromolecular antibody probe was up to 1×10~5,and the gradient was obvious.The minimum detection limit was1E-6?g/m L,far lower than the detection limit of 1/1000?g/m L for traditional ELISA.The strength gradient of the shark nano antibody probe was 2×10~5,which was about twice that of the macromolecular antibody probe.The detection sensitivity was greatly improved and the minimum detection limit was still 1E-6?g/m L.Conclusion Shark nano antibody probe is superior to macromolecular biological probe and superior to traditional ELISA.