Protein adsorption under electrical stimulation of neural probe coated with polyaniline.

Polyaniline (PANI) nanoparticles were successfully polymerized on the surface of Pt electrode to form nanostructured films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs showed that the just-synthesized films were compact with diameter of nanoparticles on films about 50 and 30nm for HClO(4) and citric acid doped PANI films, respectively. And the surface of the electrode was coated completely with PANI films. After electrical stimulation for 1 month in 0.9% sodium chloride solution, there were no fissures appearing on PANI films. The compact film would act as a protecting membrane of the Pt surface, and is suitable to be used as the electrode coating for long-time performance. The time frame of human plasma fibronectin (FN) and bovine serum albumin (BSA) adsorption illustrated that electrical stimulation enhanced the amount of protein adsorption on PANI films up to 1.7-fold increase as compared to that without electrical stimulation. The SEM images of BSA adsorption for 120min indicated that electrical stimulation might initiate the aggregation of BSA, and the nanostructure of the PANI films could inhibit the aggregation. We also found that the protein adsorption decreased conductivity of PANI films, which maybe due to the protein barriers formed on them. These results provided a good reference for the use of conducting polymers as neural probe coating.