Ferric chloride

Ammonium polyphosphate (APP, form II) and melamine (MEL) were supplied by Hangzhou JLS Flame Retardants Chemical Co., Ltd. (Hangzhou, China). The phosphorus content of ammonium polyphosphate is 31~32%, the water solubility at 25 °C is less than 0.5, and the particle size is 18 μm. Pyrrole (PY) and ferric chloride were purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). The epoxy resin (E-44) was obtained from Zhenjiang Danbao Resin Co., Ltd. (Zhenjiang, China). The epoxy value of the epoxy resin is 0.41~0.47 per 100 g, and the production standard is GB13657-1992. 4,4′-diaminodiphenylmethane (DDM) was purchased from Changzhou Runxiang Chemical Co., Ltd. (Changzhou, China). The molecular weight of DDM is 198.26 g/mol and its melting point is 89~91 °C. Ethanol was supplied by Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd. (Tianjin, China). All the reagents were used as received.

NaOH, AlCl₃, NaNO₂, 2,2′-Diphenyl-1-picrylhydrazyl (DPPH), gallic acid, Na₂CO₃, 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), potassium persulfate, potassium ferricyanide, ferric chloride, and trichloroacetic acid were obtained from Shanghai Macklin Biochemical Technology Co., Ltd. (Shanghai, China) Rutin, methyl thiazolyl tetrazolium (MTT) and Vitamin C (Vc) were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China), while foline-phenol, β-sitosterol, and vanillin were purchased from Sigma-Aldrich Corporation (St. Louis, MI, USA). Assay kits for LDH, MDA, SOD, and GSH-PX were bought from Nanjing Jiancheng Bioengineering Institute (Nanjing, China). RPMI-1640 culture medium, phosphate buffer solution (0.01 M, pH 7.2), dimethyl sulfoxide (DMSO), and 0.05%Trypsin-EDTA were purchased from Gibco (Grand Island, NY, USA), while fetal bovine serum (FBS) was purchased from Zhejiang Tianhang Biotechnology Co., Ltd. (Huzhou, China). ROS assay kit and 30% H₂O₂ solution were gained from Beijing Solarbio Technology Co., Ltd. (Beijing, China). All organic reagents used in the experiments, including petroleum ether (bp. 60–90 °C), ethyl acetate, n-butanol, and 95% ethanol, were of analytical grade.

Frozen silver carp surimi was purchased from Fujian Anjing Foods Co., Ltd. (Xiamen, China), and kept at −20 °C until used. Black tea powder (caffeine removed) was purchased from Damin Foodstuff (Zhangzhou) Co., Ltd. (Zhangzhou, China). Tapioca starch, phosphate, salt and glutamine transaminase (TG enzyme) were commercially available.
1,1-diphenyl-2-picrylhydrazyl (DPPH) was purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China); 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was purchased from Beijing Solarbio Technology Co., Ltd. (Beijing, China); sodium dihydrogen phosphate, dibasic sodium phosphate, trichloroacetic acid, hydrogen peroxide, ferrous sulfate and potassium persulfate were of analytical grade and purchased from Xilong Chemical Co., Ltd. (Guangzhou, China). Absolute ethanol was purchased from Sinopharm Group Chemical Reagent Co., Ltd. (Shanghai, China); ferric chloride, potassium ferricyanide, and 3,5-Dinitrosalicylic acid were purchased from Shanghai Macklin Biochemical Technology Co., Ltd. (Shanghai, China).

Ferric chloride (FeCl₃·6H₂O), nickel nitrate (Ni(NO₃)₂·6H₂O), and sodium hydroxide (NaOH) are analytical reagent grade, which were purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China), Tianjin Bodi Chemical Co., Ltd. (Tianjin, China), and Tianjin Kaitong Chemical Reagent Co., Ltd. (Tianjin, China), respectively. The natural plant fibers were purchased from Jiangxi Zhonggan Medical Instrument Co., Ltd. (Nanchang, China). High purity N₂ (Taiyuan Taineng Gas Co., Ltd., Taiyuan, China) was used as protective gas.