A novel electrically conductive and biodegradable composite made of polypyrrole nanoparticles and polylactide

A novel electrically conductive biodegradable composite material made of polypyrrole (PPy) nanoparticles and poly(d,l-lactide) (PDLLA) was prepared by emulsion polymerization of pyrrole in a PDLLA solution, followed by precipitation. The composite was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The electrical stability of the composite containing 5 wt% PPy was investigated in a cell culture environment for 1000 h with 100 mV DC applied voltage. Fibroblasts were cultured on the composite membranes and were stimulated with various DC currents. The PPy particles formed aggregations and constituted microdomains and networks embedded in the PDLLA. With the 1–17% increase in the PPy content, the conductivity of the composite increased by six orders of magnitude. The surface resistivity of the PPy/PDLLA membrane with 3% PPy was as low as 1×103 Ω/square. The electrical stability was significantly better in the PPy/PDLLA composite than in the PPy-coated polyester fabrics. For the composite with 5% PPy, the test membrane retained 80% and 42% of the initial conductivity in 100 and 400 h, respectively, following the addition of the MEM solution, compared to 5% and 0.1% for the PPy-coated polyester fabrics. Under 100 mV, a composite membrane 3.0×2.5×0.03 cm3 in size and containing 5% PPy sustained a biologically meaningful electrical conductivity in a typical cell culture environment for 1000 h. The growth of fibroblasts was up regulated under the stimulation of medium range intensity of DC current.