Free standing PEDOT films prepared by vapour phase polymerisation as electrically tuneable barriers to drug permeability

Abstract

We report the fabrication of PEDOT films using vapour phase polymerisation with Fe(III)tosylate as the oxidant and to provide the doping ion. Multiple polymerisation steps resulted in the formation of free-standing PEDOT films. The PEDOT films were highly conductive, a single layer was 1840±50S/cm with a small decrease in conductivity for the five layered films to 1550±60S/cm. The five-layered films were flexible and freestanding in air with a thickness of 1.66±0.06μm. The ability of the freestanding PEDOT films to act as electrically tuneable rate controlling membranes was determined for nicotine (MW 162.2Da), dexamethasone phosphate (MW 516.4Da) and bovine lactoferrin (MW 80kDa), using a customised Franz cell. The membranes were highly permeable to nicotine and dexamethasone phosphate, however, the large lactoferrin molecules could not diffuse through the PEDOT membranes. The permeability of dexamethasone phosphate could be controlled electrically with an increase in flux observed when the membranes were maintained in the oxidised state compared to the reduce state. This is the first report where free standing PEDOT films were prepared by vapour phase polymerisation; these films were capable of electrically modifiable permeation of small drug molecules. The free standing and highly conductive PEDOT membranes are exciting materials to explore for molecular separation and drug delivery applications.