Layer-by-Layer Combination of MWCNTs and Poly(ferulic acid) as Electrochemical Platform for Hesperidin Quantification

The electrochemical polymerization of suitable monomers is a powerful way to create voltammetric sensors with improved responses to a target analyte. Nonconductive polymers based on phenolic acids were successfully combined with carbon nanomaterials to obtain sufficient conductivity and high surface area of the electrode. Glassy carbon electrodes (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and electropolymerized ferulic acid (FA) were developed for the sensitive quantification of hesperidin. The optimized conditions of FA electropolymerization in basic medium (15 cycles from -0.2 to 1.0 V at 100 mV s(-1) in 250 mu mol L-1 monomer solution in 0.1 mol L-1 NaOH) were found using the voltammetric response of hesperidin. The polymer-modified electrode exhibited a high electroactive surface area (1.14 +/- 0.05 cm(2) vs. 0.75 +/- 0.03 and 0.089 +/- 0.003 cm(2) for MWCNTs/GCE and bare GCE, respectively) and decreased in the charge transfer resistance (21.4 +/- 0.9 k Omega vs. 72 +/- 3 k Omega for bare GCE). Under optimized conditions, hesperidin linear dynamic ranges of 0.025-1.0 and 1.0-10 mu mol L-1 with a detection limit of 7.0 nmol L-1 were achieved, which were the best ones among those reported to date. The developed electrode was tested on orange juice and compared with chromatography.

Automated summary

Electrochemical polymerization of phenolic acids with carbon nanotubes was used to create highly conductive and high surface area electrodes for sensitive quantification of hesperidin. The optimized electropolymerization conditions and modified electrode showed improved electroactive surface area and reduced charge transfer resistance. The developed electrode achieved the best linear dynamic ranges and detection limit for hesperidin quantification. It was successfully tested on orange juice and compared with chromatography.