Cystamine dihydrochloride

ENR was obtained from the Agricultural Products Processing Research Institute, Chinese Academy of Tropical Agricultural Sciences, with an epoxy content of 25 mol%. Carbon dioxide (CO₂, 99.99%) was purchased from Hainan Jiateng Chemical Gas Co., Ltd. (Haikou, China). Tetrabutylammonium iodide (TBAI, 98%); cystamine dihydrochloride and deuterium chloroform were supplied by J&K Scientific Co., Ltd. (Beijing China). N-hydroxysuccinimide (NHS), 1-thioglycerol, 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide hydrochloride (EDC), and phosphate buffer solution (PBS) were supplied by Shanghai Macklin Biochemical Co., Ltd (Shanghai China). Deionized water was produced with an ultrapure water machine. Solvents such as toluene were analytical reagent grade without further treatment. All other reagents were purchased from Xilong Technology Co., Ltd (Shantou, China).

Cysteine, citric acid, PEG200, ε-caprolactone, pyrene, 1, 3-disphenylisobenzofuran (DPBF), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and benzylalcohol were all obtained from Aladdin (Shanghai, China). Enzyme 435, 4-nitrophenyl chloroformate (NPC), cystamine dihydrochloride, and glutathione were provided by J&K Scientific LTD (Beijing, China). Doxorubicin hydrochloride (DOX·HCl) was supplied by Dalian Meilun biotechnology Co., LTD (Dalian, China). Biotin-PEG2000-NH₂ (Mw = 2000 Da) was purchased from Shanghai Ponsure Biotechnology Co. Ltd (Shanghai, China). 2′, 7′-dichlorodihydrofluorescein diacetate (DCFH-DA), Annexin V-FITC, propidium iodide (PI), and Hochest 33342 were purchased from Beyotime biotechnology Co., LTD (Shanghai, China). Cypate was synthesized referring to previous work. All other chemicals were obtained from Beijing Chemical Works (Beijing, China) and were used without further purification.