A biosensor having enhanced sensitivity to physical or chemical parameters comprises a waveguide and a coating disposed on the waveguide. The coating has a refractive index that enhances the sensitivity of the biosensor to physical or chemical parameters. In a preferred embodiment, the coating comprises at least one dendrimer disposed on the waveguide, wherein the coating has a refractive index ranging from about 1.0 to about 1.5. A method for fabrication of the biosensor is also provided.