Reversible Condensation of DNA Using a Redox-Active Surfactant

Abstract

We report characterization of aqueous solutions of dilute Lambda phage DNA containing the redox-active surfactant (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) as a function of the oxidation state of the FTMA. FTMA undergoes a reversible one-electron oxidation from a reduced state that forms micelles in aqueous solution to an oxidized state (containing the ferrocenium cation) that does not self-associate in solution. This investigation sought to test the hypothesis that FTMA can be used to achieve reversible control over the conformation of DNA-surfactant complexes in solution. Whereas DNA adopts extended coil conformations in aqueous solutions, our measurements revealed that addition of reduced FTMA (2-5 microM) to aqueous solutions of DNA (5 microM in nucleotide units) resulted in coexistence of extended coils and compact globules in solution. At higher concentrations of reduced FTMA (up to 30 microM), the DNA was present as compact globules only. In contrast, oxidized FTMA had no measurable effect on the conformation of DNA, allowing DNA to maintain an extended coil state up to a concentration of 75 microM oxidized FTMA. We further demonstrate that it is possible to chemically or electrochemically transform the oxidation state of FTMA in preformed complexes of FTMA and DNA, thus achieving in situ control over the conformations of the DNA in solution. These results provide guidance for the design of surfactant systems that permit active control of DNA-surfactant interactions.

Spatial and temporal control of surfactant systems

“…57, 58 These studies have been driven by the opportunity presented by ferrocenyl surfactants to provide fundamental insights into the interactions between surfactants and macromolecules species, as well as the technological promise of surfactant-macromolecular complexes that are placed under active control. Below, we provide highlights of some recent studies of electrochemical control of complexes formed by electro-active amphiphiles with either semi-synthetic polymers or DNA.…”

“…A recent study has explored the extent to which this physical situation can be manipulated through changes in the oxidation state of FTMA in solutions containing DNA. 57 …”

Light and host–guest inclusion mediated salmon sperm DNA/surfactant interactions

“…Smith demonstrated that using a chemically degradable dendron framework allows multivalent binding to be switched off, with subsequent loss of affinity for DNA [38]. Lynn and Abbott reported the reversible condensation of DNA using a redox-active surfactant [39]. Compared with the other external stimuli to trigger DNA decompaction and release, light input is considered to be advantageous benefitting from its capability of remote control [40][41][42].…”

Micellar Aggregation Behavior and Electrochemically Reversible Solubilization of a Redox-Active Nonionic Surfactant

“…For the purpose of solving these problems, Tian et al [11] has proposed a novel principle of reversible surfactantenhanced remediation (RSER) based on switchable surfactants. Nowadays, there is a growing attention on switchable surfactants, and it has been found that the aggregation and disruption of the micelles can be reversibly controlled by means of CO 2 /air, electrochemical, photochemical and acid-base changes [12][13][14][15][16][17][18].…”