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 (PD M -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) (PD M ), which is formed by Tyr catalytic polymerization of l -DOPA. The Tyr modified electrode is simply prepared by dipping the PD M -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 10   nM~1.25 μM, the apparent Michaelis-Menten constant ( K M app ) determined as low as 3.13   μM 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 50   ppb~30   ppm and a low detection limit of 10   ppb obtained. In addition, the biosensor shows excellent stability, precision, high sensitivity and fabrication simplicity.