Embodiments of the present invention provide methods for coating nanoparticles with polymeric coatings and nanoparticles that are coated with polymeric coatings. The polymeric coatings typically comprise two or more layers wherein the first layer has a charge that is opposite to that of the second layer. In further embodiments, the nanoparticles that can act as labels or reporters are coated with polymeric coatings. Optionally, these reporter or label nanoparticles may be Raman-active, such that they provide a distinctive Raman signature upon excitation with electromagnetic radiation.