Praparation Of Immunomagnefic Nanoparficles And Its Application In The Separation Of CD34~+ Cell

The use of nanoparticle materials offers many advantages due to their unique size,physical properties,large surface area/volume and so on. Among all these materials, the magnetic particles are paid more attention. As their special trait of magnetism, they have been widely applied in various fields of bioseparation and medicine such as protein and enzyme immobilization , immunoassay, RNA and DNA purification, cell isolation and recognition , target drug and the PCR reaction.Hematopoietic stem/progenitor cells are the primitive hematopoietic cells with high proliferative and differentiative capacity. Human umbilical cord blood transplanting has been applied in curing many malignancy hematonosis such as acute lymphocytic leukaemia, chronic granulocyte leukaemia, Hodgkin's disease and so on. Hematopoietic stem/progenitor cells have many surface symbols, but CD34 antigen is the most familiar antigen. This paper is focused on the research of synthesizing the complex of magnetic nanoparticles and antibody and applying them to isolate the CD34+ cells from umbilical cord blood.(1) The magnetic nanoparticles were synthesized by the chemical coprecipitation. And the magnetic nanoparticles were coated by the silica in the reverse microemulsion of TritonX-100, water, Nn-hexylalocohol and cyclohexane. The surface of the nanoparticles was modified with amine groups by alkoxysilanes. We can see from the picture of transmission electron microscope (TEM) that the coated particles are with uniform dispersity and the average diameter of the particles is about 60 nm. And the FT-IR spectrum shows the amine groups has been successfully modified to the surface of the magnetic nanoparticles.(2) Compared with other methods, 4-nitrobenzaldehyde colorimetric assay of the amine density has many advantages in many aspects, such as convenience, rapidity and safety. 4-nitrobenzaldehyde colorimetric assay can be used to quantitate the amount of amino groups on the surface of nanoparticles, which is very important to link biomaterial quantificationally. By variation of the experimental conditions, variants with different surface amine group densities have been obtained and characterized. And detailed study on magnetic nanoparticles'surface modification via silanization in terms of optimization has been performed.(3) Amine-modified particles were grafted with monoclonal antibody and used in the capture of targeted cells from sample. The complex of magnetic nanoparticles and antibody can capture targeted cells specifically in outer magnetic field. The results showed that the CD34+ cells from umbilical cord blood were isolated fast and effectively by the complex of magnetic nanoparticles and monoclonal antibody, moreover the isolated CD34+ cells still maintained the normal morphology , high proliferative and differentiative capacity. It is concluded that the complex of magnetic nanoparticles and monoclonal antibody has good effect on isolating CD34+ cells.