Preparation And Characterization Of Polystyrene Microspheres With High Fluorescence Intensity

Fluorescent microspheres are widely applied in biomedicine field; one of themost important applications is Cytometric Bead Array, which could be used in basicand applied proteomic research as well as for clinical diagnosis. Two spheres are usedin this technology: quality-control beads for checking linearisy and sensitivity of theinstrument; encoded beads for high-throughput immunoassay. Both of them should bedyed precisely, monodisperse and can emit strong fluorescence.Many strategies have been proposed for the preparation of flurescent beads.Surface modification strategies such as adsorption method, chemical bonding methodand coating method are usually used in bead staining, but this approach is quite limitin stability. Encapulation and copolymerization method provide an alternative way tostain beads, but the dye added was interference to polymerization. Among all of thestaining methods, swelling method is the most popular approach because of its simpleand precisely staining progress and good stability. While traditional swelling methodused to disperse polystyrene seeds in organic solvent and take tulene, chloroform andso on as swelling agent, this method is contaminative and make the beads conglutinate,which will decrease fluorescence intensity.To address these problems, the preparation of monodisperse high intensityfluorescence microspheres was studied systematically in this paper.Firstly, improve the swelling method by dispersing polystyrene seeds in0.25%SDS and taking methylene dichloride as swelling agent to prepare microspheres withhigh fluorescence intensity. Monodisperse, photo stable and quantitative dyedfluorescence microspheres were prepared by this method. Encoded microspheres withtwo fluorescence signals were prepared by this method too.Secondly, studied the encapulation method、copolymerization method and twostep swelling method,then compare them with the improved swelling method,including stability, simpility, dispersity and so on.The results of comparation showthat fluorescent spheres prepared by these methods have good stability, among thesemethods, the improved swelling method is simplest.Thirdly, fluorescent beads prepared via swelling method were chatactraion byflow cytometry.In summary, we have developed a simple method to prepare fluorescent sphereswith high intensity and encoded spheres. Then compare it with traditional swelling method, encapulation method and copolymerization method, at last, the spheresprepared by this method were chatactraion by flow cytometry.