Preparation of fluorescent polystyrene microspheres by gradual solvent evaporation method

Highly cross-linked polystyrene beads of 9.2 μm were synthesized by seed polymerization with styrene as monomer and divinylbenzene as cross linker. Other sized monodisperse PS microspheres were also prepared by varying seed particle diameter and proportion of swelling agents. Furthermore, the polystyrene beads were stained by gradual solvent evaporation method using dyes such as rhodamine 101 and acridine orange. Gradual solvent evaporation method facilitates a high concentration of fluorescent dyes on beads. This is the key to obtain fluorescent beads with high intensity. The results showed that the fabricated fluorescent microspheres could be excited to various wavelengths (such as yellow, green, red and scarlet). Our synthesized microspheres offer high fluorescence emission efficiency compared to commercial fluorescent microspheres in the mean time have other properties in common.