Gold nanoparticles have great potential toward optical investigations in biological tissues which include imaging applications as well as therapeutic applications. However, introduction of gold nanoparticles such as nanospheres into the tissue may alter the inherent physical properties of the embedding medium. Of note, the thermal diffusivity of the medium will be significantly altered imposing serious limitations to the efficacy of several imaging and therapeutic modalities. In this context, we report experimental investigations based on open photoacoustic cell configuration to evaluate the thermal diffusivity changes in polyvinyl alcohol (PVA) phantom tissue doped with gold nanospheres. The investigations performed demonstrate a non-destructive methodology for the measurement of thermal diffusivity and the experimental results show that the thermal diffusivity of the tissue will be significantly reduced when they are administered with plasmonic nanoparticles.