2.1. Materials and reagent

DiR, Docetaxel and glutathione (GSH) were provided by Meilun Biotech (Dalian, China). Bromoacetic acid, selenium, 1-ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride (EDCI), 3-bromopropionic acid, sodium borohydride (NaBH₄), 4-dimethylaminopyrideine (DMAP), Hydrogen peroxide (H₂O₂), 4-bromobutyric acid and coumarin-6 were all supplied by Aladdin (Shanghai, China). 2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-methyl (polyethylene glycol)−2000 (DSPE-PEG_2k) were obtained from Shanghai Advanced Vehicle Technology Pharmaceutical Ltd. (Shanghai, China). Fetal bovine serum (FBS) was supplied by Hyclone (Beijing, China). Trypsin and 3-(4,5-dimethylthiazol-2-yl)−2,5-diphenyltetrazolium bromide (MTT) were obtained from Gibco (Beijing, China). The other reagents mentioned in this work were of analytical or HPLC grade.