Fig. 2.

Scheme for the capture and detection of αKG. The composition of the monolayer and representative SAMDI-MS spectra upon self-assembly of maleimide- and tri(ethylene glycol)-functionalized alkanethiolates (left), after reaction of the hydrazide-thiol with the maleimide groups (center), and after immobilization of αKG by the hydrazide groups (right). The peak at m/z = 873 corresponds to the maleimide-terminated alkanethiolate (sodium adduct), the peak at m/z = 1007 corresponds to the hydrazide-presenting alkanethiolate (sodium adduct), the peak at m/z = 993 corresponds to the hydrolysis product of the hydrazide-presenting alkanethiolate that results from its exposure to aqueous solution (sodium adduct) and the peaks at m/z = 1091, 1135, 1157 and 1179 correspond to the alkanethiolate-αKG capture product (see Fig. 3 for individual peak assignments).