In the present study, we used a large-scale integration (LSI)-based amperometric sensor array system, designated Bio-LSI, to image in-vivo light-induced oxygen release from Spinach Leaves. The Bio-LSI device consists of 400 sensor electrodes with a pitch of 250 μm for rapid electrochemical imaging of large areas. Fig.1 shows schematic diagram for detection of oxygen production from Spinach leaves during photosynthesis using Bio-LSI. The imaging of oxygen production from Spinach leaves using Bio-LSI was also measured at light intensities of 20 and 30 klx (Fig 2, A3; a and b) which was found to be considerably higher as compared to the dark control (Fig 2, A2). The real-time monitoring of oxygen reduction current in control and light illuminated samples has also been presented (Fig. 2B). The results shows almost no changes in oxygen reduction current in non-illuminated Spinach leaves while a considerable changes have been observed in leaves illuminated with intensities of either 20 klx and 30 klx which was found to drop immediately at the switching off of the light source.

Our results show that light induced oxygen release can be monitored using the device, suggesting that the Bio-LSI is a promising tool for real time imaging of oxygen release and the effects of stresses in whole Spinach leaf under in-vivo conditions. To the best of our knowledge, this report is the first to describe real time electrochemical imaging of light induced oxygen release in Spinach leaves using LSI-based amperometric sensors.

References

(1) T. Yasukawa, et al., Chem. Lett., 28,975-976, 1999.

(2) K.Y.Inoue, et al. Lab Chip. 5, 848-856, 2015.