Abstract
Optical stimulation technologies are gaining great consideration in cardiology, neuroscience studies, and drug discovery pathways by providing control over cell activity with high spatio‐temporal resolution. However, this high precision requires manipulation of biological processes at genetic level concealing its development from broad scale application. Therefore, translating these technologies into tools for medical or pharmacological applications remains a challenge. Here, an all‐optical nongenetic method for the modulation of electrogenic cells is introduced. It is demonstrated that plasmonic metamaterials can be used to elicit action potentials by converting near infrared laser pulses into stimulatory currents. The suggested approach allows for the stimulation of cardiomyocytes and neurons directly on commercial complementary metal‐oxide semiconductor microelectrode arrays coupled with ultrafast pulsed laser, providing both stimulation and network‐level recordings on the same device.
Highlights
Optical stimulation technologies are gaining great consideration in cardiology, high spatial resolution
We have shown that plasmonic nanostructures and porous metamaterials can efficiently emit “hot” electrons under light excitation with ultrafast pulsed lasers[27,28] in the near infrared (NIR) range of the spectrum
Whereas stimulating photo-generated currents are typically obtained by hole–electron pairs in silicon nanomaterials,[18] the plasmonic capacitive–faradaic currents can be induced by ultrafast pulsed laser radiation of plasmonic nanostructures[27,34] and metamaterials.[29]
Summary
We exploit the well-established photo-electrochemical mechanism based on the combination of capacitive–faradaic currents at the cell/material interface.[10,17,18,32,33] In this approach, the local reduction of the extracellular potential and the local production of redox reactions are responsible for stimulating action potentials.[18]. In case of nanoporous metamaterials, the key factor enabling cell stimulation is that the energy collected from the incident light is efficiently confined into the nanopores of the metamaterial, generating plasmonic hot spots of intense electric field that results in charge photo-emission at the interface (Figure 1C). This intrinsic characteristic leads to an extremely localized process that does not affect the surrounding regions. We remark that the term hot spot does not refer to heating, but to increased field intensity To support this hypothesis, we first characterize and quantify the capacitive–faradaic currents at the interface between nanoporous metamaterials and electrolytes under ultrafast pulsed laser excitation
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