Conductive and enzyme-like silk fibers for soft sensing application

A combination of supercritical carbon dioxide (scCO₂) impregnation of pyrrole and sonochemical transformation of permanganate (KMnO₄) was used to impart conductive and catalytic properties to silk fibers. The results indicated that the conductivity (from polypyrrole -PPy) and catalytic activities (from manganese dioxide -MnO₂) were independent and complementary within the processing parameters used. The enhanced conductivity was attributed to scCO₂ preferentially distributing the pyrrole monomers along with the silk internal fibrillar structure and hence, yielding a more linear PPy. The oxidative properties of the PPy-MnO₂-silk hybrid showed an enzyme-like behavior for the degradation of hydrogen peroxide (H₂O₂) with a K_m of about 13 mM and specific activity of 1470 ± 75 μmol/min/g. Finally, we demonstrated that the PPy-MnO₂-silk hybrid could be used as soft working electrodes for the simultaneous degradation and detection of H₂O₂.