Amperometric biosensor based on coupling aminated laccase to functionalized carbon nanotubes for phenolics detection

Abstract

A biosensor for phenolic compounds based on a chemically modified laccase from Coriolus hirsuta immobilized on functionalized screen-printed carbon electrodes (SPCEs) was achieved. Different enzyme modifications and immobilization strategies were analyzed. The electrochemical response of the immobilized laccase on SPCEs modified with carboxyl functionalized multi-walled carbon nanotubes (COOH-MWCNT) was the highest when laccase was aminated prior to the adsorption onto the working electrode. The developed laccase biosensor sensitivity toward different phenolic compounds was assessed to determine the biosensor response with several phenolic compounds. The highest response was obtained for ABTS with a saturation value of I_max = 27.94 μA. The electrocatalytic efficiency (I_max/K^app_m) was the highest for ABTS (5588 μA μM^-1) followed by syringaldazine (3014 μA.μM^-1). The sensors were considerably stable, whereby 99.5, 82 and 77% of the catalytic response using catechol as substrate was retained after 4, 8 and 10 successive cycles of reuse respectively, with response time average of 5 s for 12 cycles. No loss of activity was observed after 20 days of storage.

Keywords: Amination; Amperometry; Biosensor; Carbon nanotubes; Laccase; Phenols.