Optical neural stimulation using the thermoplasmonic effect of gold nano-hexagon

Abstract

The use of nanoparticle photothermal effect as adjuvants in neuromodulation has recently received much attention, with many open questions about new nanostructures’ effect on the action potential. The photothermal properties of hexagonal gold nanoparticles are investigated in this work, including the absorption peak wavelength and light-heat conversion rate, using both experimental and simulation methods. Furthermore, the ability to use these nanostructures in axonal neural stimulation and cardiac stimulation by measuring temperature changes of gold nano-hexagons under 532 nm laser irradiation is studied. In addition, their thermal effect on neural responses is investigated by modeling small-diameter unmyelinated axons and heart pacemaker cells. The results show that the increase in temperature caused by these nano-hexagons can successfully stimulate the small diameter axon and produce an action potential. Experiments have also demonstrated that the heat created by gold nano-hexagons affects toad cardiac rhythm and increases T wave amplitude. An increase in T wave amplitude on toad heart rhythm shows the thermal effect of nano hexagons heat on heart pacemaker cells and intracellular ion flows. This work demonstrates the feasibility of utilizing these nanostructures to create portable and compact medical devices, such as optical pacemakers or cardiac stimulation.

Optical neuromodulation at all scales: from nanomaterials to wireless optoelectronics and integrated systems

“…In addition to the direct pulsed laser light, optoelectronic devices based on different materials, such as graphene, gold nanoparticles, and PEDOT:PSS, have been used for the stimulation of cardiomyocyte cells. [180][181][182] Due to the biocompatibility, biodegradability, and ubiquity of silicon in optoelectronics, Si-based devices have shown promise for optical cardiac pacemaker applications. For example, a Si NW-polymer mesh structure containing randomly oriented high-density Si NWs can stimulate primary cardiomyocytes in vitro when implanted in a rat heart, and can control the beating frequency under pulsed green laser excitation.…”