Effect of Surface Pretreatment on Electron Transfer of Methylene Blue Covalently Labeled Double-Stranded DNA Self- Assembled Monolayers on Gold

Lingling Zhang
2017 International Journal of Electrochemical Science  
In this article we investigated the effect of surface pretreatment procedures on electron transfer of methylene blue (MB) covalently labeled double-stranded DNA (ds-DNA)/mercaptohexanol (MCH) mixed self-assembled monolayers (SAMs) on gold by cyclic voltammetry (CV) and chronocoulometry (CC). The pretreatment procedures included M+E, M + C (piranha), M + C (dilute aqua regia), M + C + E (piranha), M + C + E (dilute aqua regia) and RM + C + E (piranha). The M was mechanical polishing, C was
more » ... a or dilute aqua regia dipping, E was electrochemical polishing and RM was roughly mechanical polishing. Results indicated electron transfer reaction of MB was mainly adsorption controlled. The electron transfer rate (k s ) values of MB labeled ds-DNA/MCH mixed SAMs on gold pretreated by M+C(piranha) and M+C(dilute aqua regia) were 0.84 ± 0.15 and 0.82 ± 0.17 s −1 , smaller than those (2.76 ± 0.28, 4.76 ± 2.68, 3.89 ± 2.06, 2.26 ~ 7.79 s −1 ) by M+E, M+C+E(piranha), M+C+E(dilute aqua regia) and RM+C+E(piranha) respectively. Thus, electrochemical polishing was an important pretreatment step, which might influence the k s of MB. Furthermore, the k s values of MB did not change monotonically with increasing gold surface roughness R f , indicating that R f was not the key factor to make the difference of k s . We considered that the difference of elemental composition on gold surface possibly led to different k s of MB. These conclusions provided the important reference for electrochemically studying DNA electron transfer mechanism.
doi:10.20964/2017.07.40 fatcat:zxtlz6bew5afnda3tpmvitk5lm