Study on Electron Transfer Across Nucleobases Terminated Surface Assembly

Abstract

3-Mercaptopropionic acid(MPA),Mg2+ and nucleotide monophosphate(NTMP)(including guanosine,adenosine,cytidine,uridine-5′-monophosphate,and abbreviations were GMP,AMP,CMP,UMP respectively) were adsorbed onto Au substrates stepwise to form nucleobases terminated surface.Electron transfer(ET) process across the NTMP/Mg2+/MPA/Au multilayer assembly was studied and the ET kinetics were determined using electrochemical methods including cyclic voltammetry(CV),chronoamperometry(CA) and electrochemical impedance spectroscopy(EIS).The experimental results obtained from electrochemistry showed that the rate of ET kinetics decreased in the order: GMP/Mg2+/MPA/AuAMP/Mg2+/MPA/AuUMP/Mg2+/MPA/AuCMP/Mg2+/MPA/Au.And the calculated energy gaps(ΔEgap=ELUMO-EHOMO) of their corresponding Mg-NTMP complexes motif increased in the order: ΔEMg-GMP(0.89 eV)ΔEMg-AMP(1.40 eV)ΔEMg-UMP(1.57 eV)ΔEMg-CMP(1.64 eV),which suggested that complexation of Mg with the NTMP,and their corresponding ΔEgap may play important role in their ET process across the nucleobases terminated multilayer assembly.