A biosensor based on microbial lipase immobilized on lamellar zinc hydroxide-decorated gold nanoparticles for carbendazim determination

Abstract

We report an enzymatic biosensor based on the microbial lipase Ceratobasidium sp.2 immobilized on lamellar zinc hydroxynitrate decorated gold nanoparticles and then incorporated into carbon paste with multi-walled carbon nanotubes (CNTs). The biosensor is useful for determination of the pesticide carbendazim (CBZ) by square-wave voltammetry (SWV). Specific lipase activities were determined for eight days using p-nitrophenyl palmitate (pNPP) as the substrate. The highest catalytic activity was found on the 8th day with 30.88 ± 0.18 U in a liquid medium containing olive oil. The practical applicability of the biosensor was demonstrated by analyses of CBZ in water samples by the lipase inhibition method. The biosensor response for the pesticide was linear in the range from 10 to 100 μg L⁻¹ (r = 0.9981) with the limits of detection and quantification at 3.13 and 9.50 μg L⁻¹, respectively. Recovery percentages of CBZ in fortified water samples ranged from 98.5 to 105.4%. The response biosensor showed good repeatability (n = 15) and reproducibility (n = 5) with the relative standard deviation lower than 4.4%. The results obtained using the proposed biosensor and those obtained by liquid chromatography-mass spectrometry (LC-MS) as the standard method were in agreement at the 95% confidence level, thus showing the applicability of this enzymatic biosensor for CBZ determination in water.