In the field of inherently conducting polymers, polyaniline (Pani) has elicited tremendous interest due to its promising electrical properties and unique redox tunability. Synthetic routes involving the use of polyelectrolytes have significantly improved the processability of polyaniline. Recently, a template guided synthesis catalyzed by an enzyme, horseradish peroxidase (HRP), has provided a means of polymerizing aniline under milder pH conditions (pH 4.3) and subsequently widened the choice of templates to more delicate biological macromolecules. Here we report a strategy that exploits the inherent molecular order as well as the polyelectrolyte behavior of DNA to enzymatically synthesize and biologically assemble conducting polyaniline. This "wrapping" of polyaniline on DNA has been found to induce reversible changes in the secondary structure of DNA, leading to the formation of an over-wound polymorph. The polyaniline synthesized on the DNA also exhibited a template-induced macroasymmetry. This unique polyaniline/DNA intertwined complex has been used to "probe" and control the conformation of the DNA double helix.

A new biomimetic route for the synthesis of a conducting molecular complex of polyaniline (Pani) and a natural polyelectrolyte, lignosulfonate (LGS) is presented. A poly(ethylene glycol) modified hematin (PEG-hematin) was used to catalyze the polymerization of aniline in the presence of LGS to form a Pani/LGS complex. UV-vis, FTIR, conductivity and TGA studies for the LGS-polyaniline complex indicate the presence of a thermally stable and electrically conductive form of polyaniline. Also the presence of LGS in this complex, an inexpensive byproduct from pulp processing, provides a unique combination of properties such as electronic conductivity, processability and biodegradability. The use of this conductive complex for corrosion protection is also proposed.

We report the fabrication of novel metal oxide-coated polymeric nanofibers using the electrospinning technique. Polyacrylonitrile fibers were electrospun into a nonwoven fiber membrane. The membranes were subsequently immersed in an aqueous solution of metal halide salts and halogen scavengers at room temperature to apply the metal oxide coating. Tin dioxide and titanium dioxide were both successfully coated by this method. Coated fibers were characterized by scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Glass slides were coated with metal oxides by the same technique and were analyzed by X-ray photoelectron spectroscopy to determine the metal oxide surface composition. Fiber diameters were on the order of 100 nm, and the observed coating thickness ranged from about 20 to 80 nm.

Over the past decade, poly(3,4-ethylenedioxythiophene) (PEDOT) has been one of the widely investigated conjugated polymers due to its excellent electro-optical properties. The conventional synthesis of PEDOT/PSS involves oxidation of EDOT using strong oxidants in aqueous polystyrenesulfonate (SPS) solution. The low pH conditions and strong oxidants render this synthetic protocol unsuitable for use of PEDOT in applications such as biosensing. For the purpose of expanding the utility of PEDOT in these applications, it is important to develop a route that can provide the possibility of synthesizing PEDOT in the presence of the appropriate biological entities. Here we report the use of terthiophene as a radical mediator to synthesize PEDOT/PSS under milder pH conditions using soybean peroxidase (SBP). The oxidation potential of terthiophene is sufficiently low for initiation of the polymerization reaction catalyzed by SBP. The oxidized terthiophene helps the subsequent oxidation of EDOT, thus mediating the polymerization reaction. This novel approach involving the use of conjugated oligomers as redox mediators is generic and vastly expands the types of substrates (thiophenes, pyrroles) that can be polymerized using enzymatic methods and benign conditions.