Synthesis， characterization and biological evaluation of functionalized polystyrene particles.

In this paper we synthesized a series of carboxylate and amino functionalized polystyrene nanoparticles with controllable size and surface properties by conventional and seed emulsion polymerization methods. They are characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). Additionally the content of carboxylate and amino groups on the surface of the particles are determined accurately by conductometric titration and fluorescamine technique respectively. Afterwards the toxicity of amino modified polystyrene particles was tested in 1321N1 astrocytoman cell line and the results showed the degree of the toxicity is proportional to the amino content of the particles， suggesting the amino group is responsible for the toxicity of the particles. Furthermore those particles were labeled by fluorescent dye and confocal fluorescent microscopy experiment showed that the particles can be well absorbed by cells.