2.1. Materials

DTX was purchased from Biocompounds Pharmaceutical Inc. (Shanghai, China). PLGA (Mw = 15 kDa) was purchased from Jinan Daigang Biological Tech Co., Ltd. Borneol was purchased from Lei Yunshang Drug Store. PEI (Mw = 1.8kDa), Folic acid (USP grade), 1-ethyl-3-(3-dimethylamino propyl) carbodiimide hydrochloride (EDC.HCl, purity > 98%), N-hydroxysuccinimide (NHS, purity > 98%), succinic anhydride (SA, purity > 98%), 4-(dimethylamino) pyridine (DMAP) were provided by Aladdin Chemistry (Shanghai, China). Coumarin-6 was obtained from Sigma-Aldrich (St. Louis, MO, USA). Rhodamine123 (R123) (purity ≥ 95%) was obtained from Wako Pure Chemical Industries, Ltd. Dichloromethane was obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Dimethyl sulfoxide (DMSO), triethylamine (TEA), N,N-Dimethylformamide (DMF) and other solvents were analytical grade reagents and obtained from Shanghai Lingfeng Chemical Reagent Co., Ltd. Fetal bovine serum (FBS), Dulbecco’s phosphate buffer saline (PBS), Trypsin 0.25%-EDTA and culture medium DMEM were purchased from Biosera (Biosun Science & Technology Co., Ltd., Shanghai, China). Caco-2 cell lines (Caco-2) were provided by Cell Bank of Chinese Academy of Sciences (Shanghai, China).