Structural characterization by confocal laser scanning microscopy and electrochemical study of multi-walled carbon nanotube tyrosinase matrix for phenol detection

Abstract

A novel visualization methodology based on the use of immunofluorescence and Confocal Laser Scanning Microscopy (CLSM) was used to quantify and visualize tyrosinase enzyme within a MWCNTs matrix immobilized onto carbon based screen-printed electrodes. CLSM was shown to be an extremely powerful technique which allowed a clear visualization of the distribution of the enzyme within both the MWCNTs and carbon based layers and provided additional and useful morphological data for a better understanding of the interaction between biomolecules and electrode materials. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were also employed to fully characterize the system components. The proposed MWCNT/Tyrosinase matrix was applied to the detection of phenol, as an alternative biosensor material. Electrochemical analytical performances of the biosensor were investigated in order to determine the optimal fabrication design along with the enzyme stability. The biosensor based on the developed biomaterial matrix proved promising results in terms of cost, simplicity and analytical performance. A detection limit of 1.35 μM and a sensitivity of 47.4 μA mM⁻¹ within a linear response range of 2.5 to 75 μM phenol were obtained. The biosensor performed well as a disposable device and could be stored in a refrigerator (−18 °C) without loss of activity for up to 2 months.