Lecithin

All reagents were used without further purification, and deionized distilled water was used throughout the experiments. A stock solution of Na₃Au(SO₃)₂ was purchased from Changzhou Institute of Chemical Research (Changzhou, China). L012 was bought from Wako Chemical USA Inc. (Richmond, VA, USA). PLD and COD were purchased from Sigma-Aldrich Co., Ltd. (Shanghai, China), lecithin was obtained from Tokyo Chemical Industry Co., Ltd., and hydrogen peroxide was purchased from Shanghai Ling Feng Chemical Reagent Co., Ltd. (Shanghai, China). A 0.01 M stock solution of luminol was kept at 4 °C in a dark bottle when not in use. hydrogen peroxide solutions were prepared by making appropriate dilutions from a 30% hydrogen peroxide solution. lecithin was dissolved in trichloromethane, and the solvent was evaporated in nitrogen. PLD and COD were dissolved in 10 mM phosphate buffered solution (PBS, pH 7.4) and diluted to 10 U/mL and 4 U/mL, respectively.