In pH 7.2 Na2HPO4-NaH2PO4 buffer solution, polyphenoloxidase （PPO） could catalyze the oxidization of do- pamine （DA） to form polymer particles in dark-red color, which exhibited a strong resonance scattering （RS） peak at 780 nm. In the chosen conditions, as the PPO activity increased, the RS intensity at 780 nm increased linearly. The increased RS intensity （△I780nm） was linear to the PPO activity in the range of 0.10--6.0 U·mL^- 1, with a regression equation of △I780 nm = 96.6C＋ 15.1, a relative coefficient of 0.9987 and a detection limit of 0.06 U·mL^-1 PPO. The proposed method was applied to detecting PPO activity in potato sample with satisfactory results.
In pH 3.8 acetic acid-sodium acetate （HAC-NaAC） buffer solution, laccase exhibited a strong catalytic effect on the H2O2 oxidation of I- to form I2, and I2 combined with excess I- to form I3- that reacted with cationic surfactants of tetradecyl dimethylbenzyl ammonium chloride （TDMAC） to produce the （TDMAC-I3）n association complex particles, which exhibited a strong resonance scattering （RS） peak at 468 nm. Under the chosen conditions, as the concentration of laccase activity increased, the RS intensity at 468 nm （1468 nm） increased linearly. The increased RS intensity A1468 nm was linear to laccase activity in the range of 0.08-0.96 U/mL, with a regression equation of △1468 nm =88.8 U-1.9, and a detection limit of 0.02 U/mL laccase. This proposed method was applied to detect laccase activity in waste water, with satisfactory results.
