LAUSR

Electrodynamic systems for bioanalytical applications constantly encounter biofouling issues due to electrical-field-induced nonspecific bio-adsorption occurring on electrode surfaces. To minimize this issue, surface modification using anti-biofouling and conductive materials is necessary to not only protect the electrode surface from nonspecific bio-adsorption, but also maintain desired electrodynamic properties for electrode operation. The homogeneity and stability of the coating plays a critical role in providing effective passivation, and the anti-biofouling ability of the layer can be determined by the coating lifetime and zwitterionic degree. In this study, we designed and prepared a conductive, zwitterionic, and self-doped sulfonated polyaniline (SPANI) coating on Au electrode surfaces to fulfill the aforementioned three criteria, including anti-biofouling, conductive, and long life-time. The zwitterionic coating was functionalized with cysteamine (HS-CH2CH2-NH2) by electrochemical polymerization of aniline and a post-polymerization treatment with fuming sulfuric acid. We also found that the SPANI-coated electrodes exhibited an excellent anti-biofouling ability in dielectrophoresis (DEP) capturing-and-releasing processes, with a residual mass below 1.44%, whereas electrodes modified with poly(ethylene glycol) (PEG) depicted a residual mass of 14.3%. A three-cycle DEP test showed that the standard deviation (SD) of surface contamination on the electrode coated with SPANI and PEG was 22.47 and 208.99 counts, respectively. Even under more than 1hour continuous operation, the SPANI-5s electrode still provides stable anti-biofouling ability as low average residual mass (1.62%). Besides, the capturing rate of the SPANI-modified electrodes was five times higher than that observed for the PEG-coated electrodes, indicating a better conductance of the SPANI films as compared to the PEG films for electrodynamic operation. This study demonstrates that electrodynamic systems with zwitterionic SPANI coated on open electrode surfaces show decent conductivity and excellent anti-biofouling properties.