Use of gold nanoparticles (NPs) as a contrast agent for medical imaging is shown to improve the efficiency of optoacoustic signal generation; this signal enhancement allows differentiation between different tissue types. This aspect of medical imaging is important when concerned early cancer detection. The present paper presents the results on the interaction process between the laser light and gold NPs, providing valuable information necessary for improved and more efficient NP synthesis. The attenuation of laser is studied for NP solutions of different geometrical characteristics and concentrations where the study is based on both optical and optoacoustic characterization techniques. First results show that the absorption and scattering are correlated by increasing the size of the nanoparticles between 5nm and 60nm. The optoacoustic signals we have been obtained demonstrate similar behavior for gold NP diameters of 5nm to 12nm.