Ti(3)C(2)T(x) MXene Flakes for Optical Control of Neuronal Electrical Activity

[Image: see text] Understanding cellular electrical communications in both health and disease necessitates precise subcellular electrophysiological modulation. Nanomaterial-assisted photothermal stimulation was demonstrated to modulate cellular activity with high spatiotemporal resolution. Ideal candidates for such an application are expected to have high absorbance at the near-infrared window, high photothermal conversion efficiency, and straightforward scale-up of production to allow future translation. Here, we demonstrate two-dimensional Ti(3)C(2)T(x) (MXene) as an outstanding candidate for remote, nongenetic, optical modulation of neuronal electrical activity with high spatiotemporal resolution. Ti(3)C(2)T(x)’s photothermal response measured at the single-flake level resulted in local temperature rises of 2.31 ± 0.03 and 3.30 ± 0.02 K for 635 and 808 nm laser pulses (1 ms, 10 mW), respectively. Dorsal root ganglion (DRG) neurons incubated with Ti(3)C(2)T(x) film (25 μg/cm(2)) or Ti(3)C(2)T(x) flake dispersion (100 μg/mL) for 6 days did not show a detectable influence on cellular viability, indicating that Ti(3)C(2)T(x) is noncytotoxic. DRG neurons were photothermally stimulated using Ti(3)C(2)T(x) films and flakes with as low as tens of microjoules per pulse incident energy (635 nm, 2 μJ for film, 18 μJ for flake) with subcellular targeting resolution. Ti(3)C(2)T(x)’s straightforward and large-scale synthesis allows translation of the reported photothermal stimulation approach in multiple scales, thus presenting a powerful tool for modulating electrophysiology from single-cell to additive manufacturing of engineered tissues.