Preparation of Au nanoparticles-coated polystyrene beads and its application in protein immobilization

Au-coated micro-sized polystyrene beads have potential application in suspend chips. A simple approach to prepare well-covered, high-density and stable Au particles-coated micro-sized polystyrene beads (Au@PS) is described in this paper. First, citrate-stabilized and negative charged 20 nm Au nanoparticles were synthesized in the experiments, then different charged PS were prepared by grafting, and then the deposition and assembly of Au nanoparticles on the charged PS core were studied. The scanning electron microscope (SEM) images indicate that the electric charge has important influence on the deposition and assembly of Au nanoparticles. The assembly process might be initialized by the aggregation of Au nanoparticles from solution. And the results also indicate that this coating process could be accelerated by the positive electric charge on the PS. This method can be used to prepare well-covered Au@PS composite entities. For the potential application, human IgG as a sample was tested for the ability of protein immobilization. And the Au positive charged Au-coated PS has the protein loading of 16.1 μg/g, which is about 6 times of the uncoated beads.