Electroactivity and stability of polylactide/polypyrrole composites.

Electrically conductive biodegradable composites are useful in biomedical engineering to mediate electrical interactions between cells and electrical components. Because conductive polymers are often subjected to progressive oxidative deterioration and dedoping, their electrical stability in aqueous environment is, therefore, critical. We used cyclic voltammetry (CV) to investigate the electroactivity and stability of conductive membranes made of only 5% conductive polypyrrole (PPy) particles blended with 95% insulating polylactide (PLLA). During 1000 CV scans, the electroactivity of the composite membranes revealed a period of initial activation, followed by a relatively stable period and subsequent slow deterioration process. PPy membranes doped with heparin, a cell-adhesive polysaccharide and polyanion, displayed electrical stability superior to that of PPy membranes doped with chlorine anions. The latter, however, recorded a higher initial electroactivity during the first ca. 150 scans. XPS analysis s...