In pH 4.0 succinic acid-sodium hydroxide buffer solution, laccase catalyzed the oxidization of guaiacol substrate to form red particles, which exhibited a strong resonance scattering (RS) peak at 590 nm. Under the chosen conditions, as the laccase increased, the RS intensity (ΔI) increased linearly. The ΔI was proportional to laccase activity in the range of 0.10-1.2 U/mL, with a regression equation of ΔI = 734.0 U(laccase) - 9.7, and a detection limit of 0.05 U/mL. This RS method was applied to the detection of laccase activity in real samples, and the results were agreement with those from spectrophotometry.

In pH 7.2 Na 2 HPO 4 -NaH 2 PO 4 buffer solution, polyphenoloxidase (PPO) could catalyze the oxidization of dopamine (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 (∆I 780 nm ) was linear to the PPO activity in the range of 0.10-6.0 U•mL PPO. The proposed method was applied to detecting PPO activity in potato sample with satisfactory results.