Electrochemically Stimulated DNA Release from a Polymer‐Brush Modified Electrode

Abstract

Single‐stranded DNA molecules were loaded on the mixed poly(2‐vinylpyridine) (P2VP)/polyacrylic acid (PAA) brush covalently attached to an indium tin oxide (ITO) electrode. The DNA deposition was performed at pH 3.0 when the polymer brush is positively charged due to protonation of pyridine groups in P2VP, thus resulting in electrostatic binding of the negatively charged DNA. By applying electrolysis at −1.0 V (vs. Ag/AgCl reference) 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 local pH ca. 7.5 which yielded the negative state of the mixed polymer‐brush due to dissociation of carboxylic groups of PAA. 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.

Electrochemically‐controlled DNA Release under Physiological Conditions from a Monolayer‐modified Electrode

“…Therefore, the potentials applied on the electrode surface for the DNA deposition and release should be determined specifically for each application in different biological environments. Another approach to the DNA release based on the electrostatically‐controlled load/release of DNA using polyelectrolytes with the charge dependent on pH value has been developed recently . In these systems the electrode surfaces were modified with grafted polyelectrolyte brushes containing base and acid groups (e.g, pyridine and carboxylic functions) .…”

“…Another approach to the DNA release based on the electrostatically‐controlled load/release of DNA using polyelectrolytes with the charge dependent on pH value has been developed recently . In these systems the electrode surfaces were modified with grafted polyelectrolyte brushes containing base and acid groups (e.g, pyridine and carboxylic functions) . While the base groups being protonated at acidic pH values produced the positive charge for the adsorption of the negatively charged DNA, the acid groups were dissociated at basic (sometimes almost neutral) pH values, thus stimulating the electrostatic repulsion and release of the DNA from the modified surface.…”

“…While the base groups being protonated at acidic pH values produced the positive charge for the adsorption of the negatively charged DNA, the acid groups were dissociated at basic (sometimes almost neutral) pH values, thus stimulating the electrostatic repulsion and release of the DNA from the modified surface. The pH changes produced locally near the electrode surface were generated electrochemically upon reduction of O 2 (note that the bulk pH value was not affected by the electrochemical process due to the buffer present in the solution) . The protonation‐deprotonation processes in the polymer‐brush systems proceeding upon the electrochemically stimulated local pH change resulted in the conformational changes of the polymer chains, reversibly restructuring the modified layer and resulting in the DNA adsorption‐desorption (loading‐release) processes.…”

DNA Release from a Bioelectronic Interface Stimulated by a DNA Signal – Amplification of DNA Signals

“…Among different methods of the DNA controlled release, electrochemically stimulated release of DNA pre‐loaded on an electrode surface is particularly convenient and interesting due to its simplicity and versatility of the method. Electrochemical systems releasing DNA from electrode interfaces in response to electrical signals represent particular interest due to possibility of their connection to biosensing systems triggering the DNA release. The electrical signals triggering DNA release can be generated in situ by bioelectrocatalytic electrodes in the presence of electron‐donating species, e.g., NADH .…”

Diffusion of Oligonucleotides from within Iron‐Cross‐Linked, Polyelectrolyte‐Modified Alginate Beads: A Model System for Drug Release

“…DNA release triggered by various external signals (e.g. electrochemical, photochemical, thermal) is of interest for many applications including gene‐delivery therapy and biomolecular computing . Polyelectrolyte micro‐ or nanocapsules loaded with encapsulated substances (including DNA) that are freed on application of a triggering signal are particularly promising systems for controlled molecular release …”