Polyvinylpyrrolidone

Prunus mume Sieb. et Zucc. were purchased at commercial maturity in Dazhou, Sichuan province in June. The pulps were cut from the fruits at 4 °C and frozen at −78 °C until used. Polyvinylpyrrolidone (PVPP, USP), catechol, polyethylene glycol (PEG 15000), and cellulose membranes (76 × 49 mm) were purchased from Yuanye (Shanghai, China). l-Cysteine (Biological reagent, BR) was purchased from Sigma-Aldrich (USA). Tris–HCl was purchased from Amresco (USA). 4-Hexylresorcinol (BR) was purchased from Aladdin (USA). SDS-PAGE Gel Kit and Tris were purchased from Solarbio (Beijing, China). Glycine (BR) was purchased from Biofroxx (Germany). Markers were purchased from Tiangen (China). Bovine albumin serum (BSA, BR) was purchased from Regal (Shanghai, China). All other reagents were purchased from KESHI (Chengdu, China), including the brilliant blue G250 (BR). All reagents and chemicals used in this study were of analytical grade, except where indicated otherwise.

Tetrahydrofuran (THF), anhydrous sodium sulfate (Na₂SO₄), N,N-Dimethylformamide (DMF), copper nitrate trihydrate (Cu(NO₃)₂·3H₂O), and p-phthalic acid (H₂BDC) were procured from Aladdin (Shanghai, China). Tetrabutylammonium fluoride (TBAF) was purchased from Beijing InnoChem Science and Technology Co., Ltd. Polyvinylpyrrolidone (PVP) and doxorubicin hydrochloride (DOX) were procured from Shanghai Yuanye Biotechnology Co., Ltd. Roswell Park Memorial Institute (RPMI) 1640 medium, fetal bovine serum (FBS), penicillin-streptomycin and phosphate-buffered saline (PBS) were purchased from Gibco (USA). The cell counting Kit-8 (CCK-8) was obtained from Meilunbio (Dalian, China). The ROS assay kit was procured from Beyotime Biotechnology (Shanghai, China). Unless otherwise stated, all the solvents and chemicals were purchased commercially and used without further purification.