Fig. 4

PC2 scores and loadings from a DNA spot on an NHS functionalized slide. a PC2 scores image. b PC2 loadings. Bright areas correspond with a series of silicon containing peaks, presumably from the silane linker used to tether the NHS groups to the surface and some other sulfur or phosphate containing peaks that could be from the buffer solutions used to deposit the DNA. The dark spots correspond with peaks of the form C_xH_yO_z, which likely originate from PEG