Fe2O3 yolk-shell particle-based laccase biosensor for efficient detection of 2,6-dimethoxyphenol

The structural morphology and composition of a support play a key role in the performance of nanoparticle-based enzymatic biosensors. In the present study, the influence of different functional groups, including glutaraldehyde, 3-aminopropyltriethoxysilane, carbodiimide, cyano, and polyethyleneimine for the immobilization of laccase on synthesized Fe2O3 yolk-shell and commercially available Fe2O3, SrFe12O19, and Y3Fe5O12 particles was analyzed. Glutaraldehyde-activated particles showed higher laccase activity after immobilization and higher relative detection currents for 2,6-dimethoxyphenol (2,6-DMP). The multi-shelled structural morphology of Fe2O3 yolk-shell particles significantly improved the biosensing properties of immobilized laccase compared to that of spherical pure Fe2O3 and composite SrFe12O19 and Y3Fe5O12 particles. The prepared biosensors showed high selectivity towards 2,6-DMP, with a sensitivity of 452 μA/mM/cm2. Under optimum conditions, the linear ranges of detection were as follows: 2,6-DMP (0.025-750 μM), guaiacol (0.10-250 μM), pyrogallol (0.25-250 μM), and 3,4-dihydroxy-l-phenylalanine (1.0-125 μM), with limit of detection values of 0.010, 0.052, 0.093, and 0.273 μM, respectively. Laccase immobilized on bio-friendly multi-shelled Fe2O3 yolk-shell particles showed a broad linear range of detection, the lowest limit of detection, high sensitivity and stability, good reproducibility, anti-interference and recovery, and insignificant inhibition by laccase inhibitors.