Ferrous ion content assay kit

The Urine protein test kit (C035-2-1), Urea Assay kit (C013-2-1), Creatinin Assay kit (C011-2-1), Malondialdehyde (MDA) assay kit (A003-1-2), Reduced glutathione (GSH) assay kit (A006-2-1), tissue iron assay kit (A039-2-1) were all obtained from Jiancheng Bioengineering Institute (Nanjing, China). The Dihydroethidium (S0063) was obtained from Beyotime (Jiangsu, China). Streptozotocin (STZ) (S0130-1g) was acquired from Sigma-Aldrich (St. Louis, Missouri, USA). Ferrous Ion Content Assay Kit (BC5415) was acquired from Solarbio (Beijing, China). qPCR SYBR Green Master Mix (11198ES08) was purchased from Yeasen Biotechnology (Shanghai, China). GPX4 antibody(67763-1-Ig), GAPDH antibody (60004-1-Ig) and α-SMA antibody (67735-1-Ig) were purchased from Proteintech (Wuhan, China). HIF-1α antibody (340462), HO-1 antibody (R24541) and Fibronectin antibody (250073) were purchased from ZEN-BIOSCIENCE (Chengdu, China). Vimentin antibody (AF7013) and β-actin antibody (AF7018) were purchased from Affinity Biosciences (Jiangsu, China). HRP AffiniPure Goat Anti-Mouse IgG (H+L) (FDM007) and HRP AffiniPure Goat Anti-Rabbit IgG (H+L) (FDR007) were obtained from Fude Biological Technology (Hangzhou, China).

The Fe²⁺‐chelating capacity of PDA NPs was investigated by the ferrous ion content assay kit (Solarbio Life Sciences). In brief, FeSO₄ solution (100 µm) was incubated with PDA NPs (25, 50, 100, 200, and 500 µg mL⁻¹) for 1 h at room temperature, respectively. The mixture was filtrated by a micropore filter membrane (0.22 µm), and the concentrations of Fe²⁺ in the filtrate were measured by monitoring the absorbance of blue tripyridyltriazine‐Fe²⁺ complex at 600 nm via UV–vis spectroscopy (n = 3 for each group). The Fe²⁺‐chelating capacity of PDA NPs was calculated according to the standard curve of FeSO₄ solution. Then, to determine the Fe³⁺‐chelating capacity of PDA NPs, the PDA NPs (25, 50, 100, 200, and 500 µg mL⁻¹) were mixed with Fe³⁺ standard solution (125 µm) for 4 h at room temperature. The mixture was filtrated by a micropore filter membrane (0.22 µm), and the concentrations of Fe³⁺ in the filtrate were measured and calculated by monitoring the absorbance of 2,2'‐ bipyridine‐Fe³⁺ complex at 520 nm via UV–vis spectroscopy (n = 3 for each group).