Selective electrodissolution of inorganic ions/DNA multilayer film for tunable DNA release

In this contribution we illustrate a simple layer-by-layer assembly strategy to immobilize DNA on the surface of gold thin film and to trigger the selective release of DNA upon the exclusive control of external electric potential. The assembly of DNA-containing multilayer films is driven by coordination/electrostatic interactions between inorganic zirconium ion (Zr(4+)) and phosphate groups in the backbone of the DNA chain. The selective electrodissolution of the film is might attributable to the migration of ions in the multilayer film and the electrodeposition of ions on the gold surface, as demonstrated by X-Ray photoelectron spectroscopy (XPS) and atomic emission spectroscopy (AES). Further electrochemical surface plasmon resonance (EC-SPR) results demonstrate that the selective electrodissolution profiles of the film are depended on both of the applied potential and the ionic strength of electrolyte. The electrodissolution process can be switched off by removing the external electric potential and reactivated by reapplying the external electric potential under physiological pH condition. By incorporating plasmid DNA (pDNA) in to this system, the multilayer films can sustain the consecutive release of pDNA with its integrity and transcriptional activity retained. Given the non-specific nature of the electrostatic interactions the approach presented herein may, in principle, also be extended from polynucleotides to other negatively charged biomolecules, making this selective electrodissolution appealing model system for biomedical applications where spatiotemporal control of biological material is required.