Electrochemically Triggered DNA Release from a Mixed‐brush Polymer‐modified Electrode

Single-stranded DNA molecules were loaded on the mixed poly(N, N-dimethylaminoethyl methacrylate) (PDMAEMA)/poly(methacrylic acid) (PMAA) brush covalently attached to an indium tin oxide (ITO) electrode on a flexible support. The DNA deposition was performed at pH 5.0 when the polymer brush is positively charged due to protonation of tertiary amino groups in PDMAEMA, thus resulting in electrostatic attraction of the negatively charged DNA. By applying electrolysis at -1.0V (vs. Ag/AgCl reference) electrochemical oxygen reduction resulted in the consumption of hydrogen ions and local pH increase in the vicinity of the electrode surface. The process resulted in the transition to negative charge of the mixed polymer-brush due to dissociation of carboxylic groups of PMAA. This resulted in the electrostatic repulsion and release of the loaded DNA. The developed approach allows cyclic load-release of the DNA with the significantly increased amount of the released DNA comparing with previously reported systems. Further options for the improvements of the system are discussed.