Ascorbic acid

Ethanol, n-hexane, and ethyl acetate were purchased from Guangdong Guanghua Sci-Tech Co., Ltd. (Shantou, China). Potassium dihydrogen phosphate, dipotassium hydrogenphosphate, ascorbic acid (≥99.0%), trichloroacetic acid, Iron(III) chloride (FeCl₃), starch, and sodium hydroxide were purchased from Damao Chemical Reagent Factory (Tianjin, China). Phloroglucinol (≥99.0%), sodium carbonate, diammonium salt (ABTS), α-glucosidase, α-amylase, 3,5-dinitro salicylic acid, and potassium sodium tartrate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). 4-nitrophenyl-α-D-glucopyranoside (PNPG), acarbose, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), and Folin-Ciocalteu reagent were purchased from Beijing Solarbio Technology Co., Ltd. (Beijing China). Potassium ferricyanide and potassium persulfate were purchased from Xilong Science Co., Ltd. (Shantou, China). Methanol was chromatographic grade and purchased from Concord Technology (Tianjin, China).

Commercial Chlorella Pyrenoidosa powder and Antarctic krill oil were obtained from Dalian Jianyang Biological Company (Dalian, China) and Liaoyu Group Co., Ltd. (Dalian, China), respectively. The neutral proteases (EINECS:253-457-5) and alkaline proteases (EINECS:232-752-2) were obtained from Yuanye Biotechnology Co., Ltd. (Shanghai, China). Ferrous chloride and ascorbic acid were obtained from Damao Chemical Reagent Factory (Tianjin, China). Sodium dodecyl sulfate (SDS), linoleic acid (stored at −20 °C), 1,1,3,3-tetraethoxypropane, trichloroacetic acid, Thiobarbituric acid (TBA), Nile Red, and Nile Blue were bought from Aladdin Industrial Co., Ltd. (Shanghai, China). Ammonium thiocyanate was bought from Sinopharm Group Reagent (Shanghai, China). Trypsin-EDTA, fetal bovine serum (FBS), and DMEM cell culture medium were bought from Invitrogen (Carlsbad, CA, USA). A superoxide dismutase (SOD) assay kit and reactive oxygen species (ROS) assay kit were bought from Nanjing Jiancheng Bioengineering Research Institute (Nanking, China).

Multi-wall carbon nanotubes (30–50 nm diameter and 0.5–1 μm length, with >95% purity, and carboxylic acid groups 0.73 wt%) were obtained from Institute of Organic Chemistry, Chinese Academy of Sciences (ChengDu, China). Hydrogen peroxide (30%, v/v aqueous solution) was obtained from Tianjin Eastern Chemical Reagent Co. Potassium chloroplatinate (K₂PtCl₆) was obtained from Tianjin KRS Fine Chemcal Co. Ltd. (Tianjin, China). Uric acid, ascorbic acid and acetaminophen were obtained from Tianjin Damao Chemical Reagent Co. (Tianjin, China). All other reagents were of analytical grade and used without further purification. All aqueous solutions were prepared with Milli-Q deionized water. Phosphate-buffered saline (PBS) was prepared by mixing 25 mL 0.2 M KH₂PO₄ aqueous solution with 29.54 mL 0.1 M NaOH and diluted to 100 mL with deionized water. All experiments were performed in PBS at room temperature, approximately 25 °C.