Protein transport and separation using polypyrrole coated, platinised polyvinylidene fluoride membranes

Resolving sub-molecular binding and electrical switching mechanisms of single proteins at electroactive conducting polymers

Polymer-based electrodes for interfacing biological tissues are becoming increasingly sophisticated. Their many functions place them at the cross-roads of electromaterials, biomaterials, and drug-delivery systems. For conducting polymers, the mechanism of conductivity requires doping with anionic molecules such as extracellular matrix molecules, a process that distinguishes them as biomaterials and provides a means to control interactions at the cellular-electrode interface. However, due to their complex structure, directly observing the selective binding of target molecules or proteins has so far eluded researchers. This situation is compounded by the polymer's ability to adopt different electronic states that alter the polymer-dopant interactions. Here, the ability to resolve sub-molecular binding specificity between sulfate and carboxyl groups of dopants and heparin binding domains of human plasma fibronectin is demonstrated. The interaction exploits a form of biological 'charge complementarity' to enable specificity. When an electrical signal is applied to the polymer, the specific interaction is switched to a non-specific, high-affinity binding state that can be reversibly controlled using electrochemical processes. Both the specific and non-specific interactions are integral for controlling protein conformation and dynamics. These details, which represent the first direct measurement of biomolecular recognition between a single protein and any type of organic conductor, give new molecular insight into controlling cellular interactions on these polymer surfaces.

Deposition of Polypyrrole Onto Bucky Gel for Use in a Biomimetic Artificial Excitable Cell Membrane

A novel and inexpensive bucky gel electrode was investigated for use as the electrode substrate for polypyrrole deposition. Potentiostatic deposition of polypyrrole onto gold and bucky gel electrodes was carried out at +1.2 V versus saturated calomel electrode for 1 h in a standard three-electrode electrochemical cell. The electroactive polypyrrole membrane was successfully deposited onto bucky gel, and its surface morphology studied using scanning electron microscopy. Given the bucky gel’s dual ability to both conduct electricity and ions, this work establishes the first step toward a semisolid ion-gating system to be used in further applications.

Conducting polymers - bridging the bionic interface

Inherently conducting polymers (ICPs) such as polypyrroles, polythiophenes and polyanilines have become commonplace in today's materials research laboratories. However, the most intriguing aspect of these materials - the ability to electronically control a range of physical and chemical properties - remains an area of intense and intriguing research activity. As we understand more of this behaviour, we have turned our attention to a range of areas in which it can be utilised. Perhaps the most challenging of these areas is in bridging the bionic interface, providing a more effective conduit between electronics and biology.

The use of conducting polymers in membrane-based separations: a review and recent developments

As a material family, pi-conjugated polymers (also known as intrinsically conductive polymers) elicit the possibility of both exploiting the chemical and physical attributes of the polymer for membrane-based separations and incorporating its electronic and electrochemical properties to enhance the separation figures-of-merit. This review article, although by no means comprehensive, provides a current snapshot of the investigations from many research laboratories in the use of conducting polymers for membrane-based separations. The review focuses primarily on polyaniline, polypyrrole, and substituted-polythiophene and includes applications in gas separations, liquid (and/or vapor) separations, and ion separations. Additionally, we discuss the broad challenges and accomplishments in membrane formation from conducting polymers.