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 Km 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.