980nm infrared neural stimulation of sciatic nerve enhanced by carbon nanoparticles
Infrared neural stimulation (INS) provides a contact free, high spatial resolution method to regulate neural activities. Due to photothermal effect, neurons which located in the beam path, could be depolarized by infrared light. How to keep the high efficiency of opto-thermal transduction in nerve tissue, and meanwhile increase the photon penetration depth in untargeted tissues is the key question in current INS. Here in our study, we tried to use 980nm laser light to increase photon penetration depth in tissues, and use carbon nanoparticles as photon absorber to enhance the photothermal effect of INS in sciatic nerve. The compound muscle action potentials are evoked and the radiant threshold reduces by about 2 times with carbon nanoparticles. In-vitro temperature measurements detect a significant temperature increment in target neurons with carbon particles during laser irradiation. These findings demonstrate that carbon nanoparticles can improve the efficiency and enhance infrared neural stimulation.