Poly ethylene glycol monomethyl ether

Epsilon-caprolactone (ε-CL, 99%) was purchased from Alfa Aesar Chemical Company, Inc., and used after CaH₂ treatment and distillation. Carboxyl group modified poly(ε-caprolactone) (PCL-COOH) with 5700 average molecular weights was synthesized using aluminum isopropoxide as the initiator according to reported method (Dzienia et al., 2017 (link)). Poly(ethylene glycol) monomethylether (PEG, Mw = 5000) and 11-bromoundecanol were obtained from Sigma-Aldrich. The block copolymers of Poly(ethylene glycol) monomethylether and poly(ε-caprolactone) (PEG-b-PCL) was synthesized as previously reported and the average molecular weights of PCL was 5930 (Han et al., 2015 (link)). FA-PEG-b-PCL (PEG Mw = 5000, PCL Mw = 5240) were obtained from Xi'an Ruixi Biological Technology Co., Ltd. Disodium telluride and di(1-hydroxylundecyl) ditelluride were prepared according to the previous reports (Wang et al., 2016 (link)). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) was purchased from Energy Chemical Co., Ltd. (Shanghai, China). Doxorubicin hydrochloride (DOX·HCl) was obtained from Beijing HVSF United Chemical Materials Co., Ltd. All other reagents were purchased from Shanghai Aladdin Bio-Chem Technology Co., LTD. and used as received.

Ferrous chloride tetrahydrate (FeCl₂ · 4H₂O), ferric chloride hexahydrate (FeCl₃.6H₂O), ammonium hydroxide, acetic acid, dextran (M_w ≈ 13–23 kDa), poly vinylalcohol (M_w ≈ 13–23 kDa) and dichloromethane all were purchased from Merck (Germany). Chitosan of molecular weight in the range of 10⁵–3 × 10⁵ g/mol and degree of deacetylation ≥ 75 %, poly (ethylene glycol) monomethyl ether (mPEG, 5000 g/mol), ε-caprolactone and stannous octoate were purchased from Sigma. Ethanol (96 %) and oleic acid were provided by Kimia alcohol (Iran) and Fluka (Switzerland), respectively. All chemicals used as received without further purification. mPEG-PCL copolymer with the average molecular weight of 13 kDa was synthesized and characterized. The detailed procedures of the synthesis of mPEG-PCL copolymer and its corresponding characterization have been described in our previous paper [11 (link)].

Materials used in this study were graphene oxide (GO) solution (Xianfeng Biological Technology Co., Ltd., Jiangsu, China); 1-ethyl-3-[3-(dimethylamino)propyl] carbodi-imide hydrochloride (EDC), N-hydroxysuccinimide (NHS), triethylamine (TEA) and 80% hydrazine monohydrate (Yuanye Biological technology Co., Ltd., Shanghai, China); polyethylene glycol monomethyl ether (methoxy PEG, Mw: 3 kDa) and branched polyethylenimine (BPEI, Mw: 1.8 kDa) (Sigma-Aldrich, St. Louis, MO); Dulbecco’s modified Eagle’s medium (DMEM), trypsin, fetal bovine serum (FBS), violet crystal and Cell Counting kit-8 (CCK-8) (KeyGEN Bio TECH, Jiangsu, China); and doxorubicin (DOX, 99%) (Aladdin Co., Ltd., Shanghai, China). The other chemicals and reagents were of analytical grade.
Male Balb/c mice aged 6 weeks were purchased from Second Military Medical University Animal Care Center (Shanghai, China) and kept under SPF condition with free access to standard food and water. All the experiments were carried out according to the principles of care and use of Laboratory animals set by the Laboratory Animal Center of The Second Military Medical University of China.