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. Author manuscript; available in PMC: 2008 Sep 15.
Published in final edited form as: Langmuir. 2006 Dec 5;22(25):10816–10820. doi: 10.1021/la061212y

Figure 2.

Figure 2

Characterization of the immobilization and electrochemical release of RGD ligands using MALDI-ToF MS. (A) A monolayer presenting QE groups gave two molecular ion peaks corresponding to disulfides as shown above the peaks (top). After treatment with a CGRGDS solution, the original peaks were absent and gave rise to new peaks corresponding to the peptide-conjugated products (middle). The identical monolayer was treated with an electrical potential of −650 mV for 4 min and analyzed by mass, which gave two peaks corresponding to electrochemical reaction products. (B) The mass spectrum of the monolayer presenting SHQ groups displayed peaks at m/z 1236.2 and m/z 1752.6 corresponding to the SHQ containing disulfides (top). Treatment of the monolayer with the CGRGDS peptide gave new peaks at m/z 1457.9 and m/z 1806.9 corresponding to the peptide-conjugated products (middle). After application of an electrical potential of 650 mV for 4 min and −550 mV for 30 seconds, the original peaks disappeared and gave rise to a new peak corresponding to the hydroquinone-terminated disulfide at m/z 899.9 (bottom).