Preparation And Protection Of Magnetic Polymer Microspheres With Fluorescence

Magnetic polymer microspheres composed of magnetic nanoparticles and polymer have been attracting much attention for their big surface area, Superparamagnetic and abundant biochemistry activity of functional group. Magnetic polymer microspheres can be easily prepared and be further processed to introduce various functional groups(such as-NH2,-OH,-CHO,-COOH)onto its surface area and be combined through covalent bond of enzyme further, enzyme, protein, cell and antibody, et al. It will quickly move or separate in external magnetic field, therefore magnetic polymer microspheres show important practical applications in fields of protein purification, cell separation, enzyme immobilization and microbe of environment/Food testing, et al. In addition, the magnetic polymer microspheres can also be carried out on the surface fluorescent microspheres. It carried out the combination of magnetic separation technology and fluorescent tags.However, until now the preparation and application of magnetic microspheres still are limited to laboratory and medical diagnostic scale.To develop this technology in large-scale application, there still exist lots of challenges, e.g., developing the technology suitable for the massive production of high quality magnetic microspheres with low price; improving the saturation magnetization and the magnetic microspheres stability. To meet these challenges, systematical study has been carried out on the preparation, protection and fluorescence in this paper. The main results are as follow:1. The Magnetic polymer Microspheres were synthesized by the electrostatic layer-by-layer self-assembly technology. The samples were characterized by SEM and FTIR. The results indicated that the content of magnetic materials in the microspheres enhanced with increasing enwrapped layers. Magnetic microspheres have a good stability. After 0.1mol/L HCl immersing 24h, magnetic materials of magnetic polymer microspheres were not lost. The carboxyl content of the microspheres surface is 0.34 mmol/g.2. The magnetic polymer microspheres were synthesized by the in-situ precipitation technology. The samples were characterized by SEM, FTIR and MPMS. The results indicated that the as-prepared microspheres were regular spherical. Magnetic property measurement showed that saturated magnetization of magnetic polymer microsphers was 20.9emu/g.3. In order to improve the stability of the magnetic polymer microspheres, it was protected via sol-gel approach. The samples were characterized by SEM. The results indicated that this operation did not affect the shape of the magnetic polymerspheres and did not bring impurities.Measurement of magnetic property showed that saturated magnetization of magnetic polymer microsphers was decreased with increasing SiO₂ layers. The saturated magnetization of enwrapped three layers SiO₂ microsphers is 10.0eum/g. This enwrapped three layers SiO₂ microsphers were stable.The fluorescent magnetic polymer microspheres were synthesized by covalent cross-linking method. The saturated magnetization was above 8. eum/g. The fluorescent microspheres had homogeneous fluorescence intensity.