Biophotonics is an area of research concerned with the development of novel optical techniques for applications in biology and medicine including the study of molecules, cells and tissue systems. It combines biology and physics (and sometimes chemistry!) to achieve this goal. Our work is focused on the development of a Terahertz imaging and temperature sensing technique that can be used for cancer diagnostics and hyperthermia therapeutic applications. The pillars of this research include the synthesis and photothermal characterization of gold nanoparticles, capable of heating following irradiation with light. It also focuses on heating processes in gold nanomaterials, particularly collective heating effects. In combination with Terahertz radiation, our aim is to develop an imaging technique that can also address a significant challenge in biological and medical applications, namely temperature measurements at the cellular level.