Effective immobilization of tyrosinase via enzyme catalytic polymerization of l-DOPA for highly sensitive phenol and atrazine sensing.

The facile preparation of poly(l-DOPA)-tyrosinase (PDM-Tyr) composite and its application both in substrate (phenol) and inhibitor (atrazine) sensing is reported here for the first time. Effective immobilization of enzyme is realized via in-situ entrapping Tyr in poly(l-DOPA) (PDM), which is formed by Tyr catalytic polymerization of l-DOPA. The Tyr modified electrode is simply prepared by dipping the PDM-Tyr composite on an Au electrode and then covered by Nafion. The thus-prepared Tyr-immobilized electrode exhibits excellent performance superior to most Tyr-based electrochemical biosensors, the sensitivity to phenol is as high as 5122 μA mM(-1) in the linear range of 10nM~1.25 μM, the apparent Michaelis-Menten constant (KM(app)) determined as low as 3.13μM indicates strong substrate binding and high catalytic activity of the immobilized Tyr. The biosensor also works well in atrazine biosensing, with a linear detection range of 50ppb~30ppm and a low detection limit of 10ppb obtained. In addition, the biosensor shows excellent stability, precision, high sensitivity and fabrication simplicity.