An electrochemical enzymatic biosensor based on Xylaria sp. laccase isolated from cassava waste is applied to quantify dopamine

Abstract

Cassava waste (leaves and stems) was used to obtain endophytic fungi to assess laccase production. All the fungi (twenty-three) underwent an enzymatic extraction process to evaluate laccase production. The results revealed that six fungi from the stems and one from the leaves performed best. The fungus Xylaria sp. stood out for its greater productivity, and the growth parameters were optimized for this fungus (11 days, pH 6.70, and temperature 29°C). The enzyme extract enriched with laccase was then used to produce an electrochemical enzymatic biosensor immobilized in chitosan crosslinked with STMP. This biosensor was applied to quantify dopamine, with analysis conditions optimized for detecting low concentrations of the compound. The biosensor demonstrated its highest potential when operating at pH 5.60 and a temperature of 38.64°C, allowing the quantification of dopamine at concentrations from 0.17 to 492.83 µmol. L⁻¹ with a detection limit of 0.17 µmol. L⁻¹ . The biosensor demonstrated high reproducibility (0.4 % error) and stability after seven cycles.