N n dimethylformamide dmf

Sodium citrate (Na₃Ct, 99.5%) and ascorbic acid (AA) was purchased from Aladdin Pte Ltd. Gold chloride trihydrate (HAuCl₄·3H₂O) was purchased from Shanghai Macklin Biochemical Co., Ltd. Cobalt (II) acetate tetrahydrate (C₄H₆CoO₄·4H₂O) and 5,10,15,20-tetrapyridylporphyrine (TPyP) were purchased from J&K Scientific Ltd. N,N-dimethylformamide (DMF, ≥ 99.5%) and methanol (CH₃OH, AR) were purchased from China National Pharmaceutical Group (Shanghai, China). All chemicals were used without further purification, and ultrapure water (18.2 MΩ·cm at 25 °C, MZY-U10V, Miaozhiyi) was used in all experiments.

The seaweed was sourced from South American brown algae, while sodium dihydrogen phosphate (NaH₂PO₄) and disodium hydrogen phosphate (Na₂HPO₄) were purchased from Sigma-Aldrich. DA was obtained from Merck. Fe(NO₃)₃, N,N-dimethylformamide (DMF), Nafion reagent, anhydrous ethanol, acetic acid, chitosan, and potassium nitrate (KNO₃) were provided by China National Pharmaceutical Group Corporation. Potassium chloride, potassium ferricyanide, potassium ferrocyanide, glucose (GLU), uric acid (UA), and ascorbic acid (AA) were supplied by Shanghai Sango Biotech Co., Ltd., Shanghai, China. Collected urine samples were immediately sealed and were stored in a refrigerator. A phosphate-buffered saline (PBS) solution, of 0.1 M and pH = 7.0, was prepared by mixing NaH₂PO₄ and Na₂HPO₄ stock solutions. Deionized water with a resistivity of 18 M/cm was obtained from a Millipore Milli-Q water system (Millipore Inc., Burlington, MA, USA) and used throughout the experiment. All chemicals were of analytical grade and, unless otherwise stated, the chemicals or solvents used in this study did not require further purification.