In this paper, we investigated the presence of gold nanoparticles in the pbs environment, which is a fundamental buffer in biological processes, in order to make it suitable for photo thermal therapy environment. For this purpose, a plasmonic structure consisting of gold onto a one-dimensional nano grating  is prepared by a thermal deposition method and after that, the effect of NPs in pbs media with and without NPs has been investigated. The spectroscopy  of the samples has been done under different polarizations and a given angle in the various environmental conditions and ploted reflection diagram in term of wavelength. Our results show that this media has a good a sensivity in multi wavelength to the presence of gold nanoparticles.