Preparation method for gold magnetic particles

The invention provides a novel preparation method for gold magnetic particles. A series of gold magnetic particles with different colors and different sizes can be prepared by adjusting concentration of solution, and the obtained gold magnetic particles have good dispersity, stability and magnetic properties in water solution and can be applied to a plurality of fields such as catalyzing and magnetic quantitative detection. Fe3O4 nano particle crude products obtained in a coprecipitation synthesis method serve as reacting raw materials, first citric acid is adopted to modify magnetic nano particles, and after magnetic separation, the obtained Fe3O4 nano particles are dispersed in ultrapure water to be adjusted to be neutral; then chloroauric acid solution is adopted, polybasic carboxylic acid or salt containing polybasic carboxyl acid radical ions serves as a reducing agent to enable Au3+ to be reduced on the surfaces of the Fe3O4 nano particles to be Au0, and the gold magnetic particles are prepared. The novel preparation method has the advantages of being simple, easy to operate and controllable.