Highly sensitive biosensor based on bionanomultilayer with water-soluble multiwall carbon nanotubes for determination of phenolics

A highly sensitive biosensor was developed based on bionanomultilyer with water-soluble carbon nanotubes (CNTs). The water-soluble poly(allylamine hydrochloride)-wrapped multiwall carbon nanotubes (PAH-MWNTs) can be obtained for the first time relying on the function of barbiturates, which provides a useful avenue for CNT application in material science and biosensor technology. Based on this, the PAH-MWNTs/horseradish peroxidase (HRP) bionanomultilayer was prepared via layer-by-layer (LBL) assembly. Electrochemical impedance spectroscopy, atomic force microscopy and UV–vis spectra were adopted to monitor the uniform LBL assembly of the homogeneous bionanomultilayer. The bionanomultilayer was used to construct a phenolic biosensor. Under the optimal conditions, the biosensor presented a linear response for catechol from 0.1 to 20.4 μM, with a detection limit of 0.06 μM. A series of phenolics were detected by the bionanomultilayer biosensor. The introduced MWNTs in the biosensor provided a suitable microenvironment to retain the HRP activity and acted as a transducer for amplifying the electrochemical signal of the product of the enzymatic reaction. So the developed bionanomultilayer biosensor exhibited a fast, sensitive and stable detection.