Fig. 1: Calibration curves for O2-sensitive nanoparticles.

The calibration curves are obtained from plotting the ratio of the red and green channels obtained from luminescence images of O2-sensitive nanoparticles in HBSS (a) and DMEM (b). The colour-coded images at the bottom of the graph show the ratio images (red/green channel) in respective solutions. The mean ratio and standard deviation were obtained from the entire area of the coverslip. The dotted lines represent the curve fit of a quadratic polynomial function (r2 > 0.99).