Grafting of colloidal stable gold nanoparticles with lissamine rhodamine B: an original procedure for counting the number of dye molecules attached to the particles

It is shown that chromophores can be efficiently grafted on nanometer sized gold particles dispersible in an aqueous solution. The grafting is carried out in two steps: first, a primary grafting of thiols consisting both of stabilisers (2-mercaptoethane sulfonate and thiomaleic acid) and of linker molecules (4-mercaptophenol) and secondly the grafting of lissamine rhodamine B on these previously attached linkers. The efficiency of the grafting has been evaluated by dosing the remaining dye molecules in solution after forcing the precipitation of particles by salt addition. It is found that all the linkers participate in the efficient grafting of lissamine rhodamine B.