Figure 2
Near-infrared (NIR) up-conversion activation of C1V1.
(A) Experimental setup. The NIR laser light (975 nm) was irradiated from a fiber (diameter, 50 μm) in the patch electrode at a distance of 5.0 mm from the tip. (B) Two methods to apply LNPs to the specimens. Method 1: cells were cultured on a mixture of collagen and LNP on a coverslip. Method 2: the LNP-coated coverslip was put underneath the specimens upside down in the recording chamber. (C) A sample photocurrent of C1V1 evoked by filtered Hg lamp (530–550 nm, 14 mW/mm2) at a holding potential of −60 mV (ND7/23 cells). (D) In the same cell, photocurrents were also evoked by the NIR laser light (975 nm, 58 and 94 W/mm2). (E) Rate of rise of C1V1 photocurrent as a function of irradiance at 549 nm. Each symbol is a mean ± SEM (n = 5). The red line is drawn by the least squares fitting to the experimental responses to light less than 1 mW/mm2: y = 420x + 8.8 or x = 0.0024y − 0.021. (F) The relationship between the estimated power of green light emission and the NIR laser power in the case of Method 1. Each symbol represents individual ND7/23 cell. The slope of linear approximation gives the energy efficiency. (G) Similar to F, but in the case of Method 2. Note that the scale of ordinate is different.
