Fehling s solution

The chemicals used in this study—2,2-diphenyl-1-picryl-hydrezyl (DPPH), 2 N Folin-Ciocalteu reagent, polyvinyl polypyrolidone (PVPP), tannic acid, gallic acid, quercetin hydrate, rutin, Tocopherol standard solution, and Fehling’s solution—were obtained from Sigma Aldrich. All the chemicals were analytical grade, and no further purification of the chemicals was conducted.

Sodium alginate (SA) (99%) was purchased from J&K Chemicals (Beijing, China). Carboxymethyl chitosan (CMCS) and chitosan (CM) were purchased from Aladdin Industrial Corporation (Shanghai, China). Polyacrylic acid (PAA), Fehling’s solution, and sodium periodate (NaIO₄) were purchased from Sigma‑Aldrich (St. Louis, MO, USA). Epidermal growth factor (EGF) was purchased from Beijing Biosynthesis Biotechnology Co. Ltd. (Beijing, China). Fetal bovine serum (FBS), phosphate buffer solution (PBS, pH 7.4), Dulbecco’s modified Eagle’s medium (DMEM), and 1% penicillin‑streptomycin solution were purchased from Corning (Corning, NY, USA). All other reagents and solutions were of reagent grade and used as received.