Figure 2.

BHK cells that incorporated HPG in all newly synthesized proteins were labeled with BorEncode following strategy I. A) ¹¹B nanoSIMS image of a representative labeled cell (top row) and a non‐labeled cell (bottom row). The other images show ²³Na and ⁴⁰Ca. The overlay shows the co‐localization of ¹¹B (green), ²³Na (blue), and ⁴⁰Ca (red) in the cells. Scale bar=5 μm. B) Images of the labeled (top row) and non‐labeled cells (bottom row) obtained with an epifluorescence microscope before the nanoSIMS measurement. The fluorescence signal of the BorEncode is shown in magenta. The autofluorescence of the cells is shown in gray. The overlay image compares the signal of ⁴⁰Ca to the autofluorescence (gray) in cells, to indicate that indeed the same cell has been imaged. The fluorescence and ¹¹B nanoSIMS images show good correlation. Scale bar=5 μm. C) Plot of the normalized boron signal intensity. Significantly higher levels of ¹¹B are detected in labeled cells than in the negative control. The difference was highly significant (p<0.0001), as determined by Wilcoxon rank sum test. Analyzed number of circular cellular regions of interest (ROIs): 60. The middle line indicates the median, the box edges the 25th percentiles, the error bars the 75th percentiles, and the dots indicate the 90th percentile.