Figure 6: (a) Whole-cell image data ranging from 3.5 to 90 minutes. Total nanosensor intensity per image is depicted with gray line, corresponding to primary axis. Total pixel count per image is shown with black line corresponding to secondary axis. Average intensity per pixel is displayed with dashed line and also corresponds to secondary axis. (b) Integrated SERS signal in the 1612 cm−1 range as a function of pH normalized to total pyridine signal and averaged overtime. Line is linear fit to the data, to guide the eye. (c) Percentage of pixels representing each pH grouping. (a and c) Reprinted with permission from Nowak-Lovato et al.  (copyright 2009 Society for Applied Spectroscopy), (b) Reprinted with permission from Nowak-Lovato and Rector  (copyright 2009 Thomson Corporation).