Carbon nanotubes as potential candidate for photoacoustic imaging contrast agent

Photoacoustic (PA) imaging can visualize the biological objects with high contrast and high spatial resolution. The biological objects in PA imaging are not always good light-absorber. Moreover, the biological objects sometimes only absorb light with a specific wavelength. Correspondingly, the contrast agents are relatively needed in PA imaging. We present the application of carbon nanotube (CNT) for PA imaging contrast agent. We also provide the mathematical model to describe the temperature profile at CNT during laser irradiation. Theoretically, we showed that the maximum temperature during laser irradiation is proportional to the diameter of CNT. Additionally, our experimental results showed that the CNT has broad optical absorption in the visible-infrared regions. Furthermore, CNT gives high PA signal in compared with red ink even in the low-intensity of laser irradiation. These results extend our understanding of CNT for PA imaging contrast agent and provide the foundation for future PA imaging technology.