Plasmonic properties of gold nanoparticles have been studied intensively in recent years for various applications including catalysis and imaging. [1,2] In the field of Photoacoustic Imaging (PAI), plasmonic gold is particularly interesting since localized resonance of gold plasmon could cause a red-shift in its absorption spectrum that is possible to fit the near-infrared range of commonly used excitation laser in PAI. [3] In this thesis, we report on using a controllable bottom-up method to develop clustered plasmonic gold nanoparticles localized on silica nanoparticle, that serves as an effective contrast agent in PAI. The results of photoacoustic imaging and spectroscopy show a significant higher contrast in these plasmonic gold nanoparticles compared to non-clustered gold nanoparticles.