Poly(noradrenalin) based bi-enzyme biosensor for ultrasensitive multi-analyte determination

In order to realize the multi-analyte assays for physiological molecules and environmental contaminants, a bi-enzyme biosensor based on horseradish peroxidase (HRP)-catalyzed noradrenalin (NA) polymerization in the presence of H2O2 was fabricated for the first time and utilized in immobilizing HRP and glucose oxidase (GOx) simultaneously. The resultant bi-enzyme modified electrode was demonstrated to be efficient in monitoring multi-analyte (H2O2, Cr(III), glucose, and Cr(VI)). It was shown that the prepared PNA-HRP-GOx/Pt electrode exhibits a sensitivity (S) high up to 628.4 mu A mM(-1) cm(-2) in the linear range (LR) of 0.50 mu M similar to 0.42 mM and a S of 208.9 mu A mM(-1) cm(-2) in the LR of 0.42 mM similar to 3.5 mM in glucose sensing, with a limit of detection (LOD) of 0.08 mu M observed; in Cr(VI) sensing a LOD of 0.20 nM and a LR of 0.50 similar to 6.0 nM were obtained. With the addition of polyaniline (PANI), the resultant PNA-HRP-GOx/PANI/Pt electrode potentiostated at - 0.20 V responded linearly to H2O2 concentration in 0.05 similar to 30.2 mM range, with linearly responses to Cr(III) concentration in the LR of 0.01 similar to 3.8 mu M. Hence, amperometric biosensors with high S, low LOD and good anti interference ability for detection of glucose, H2O2 and heavy metal ions (Cr(III) and Cr(VI)) were developed.