N n n n tetramethylethylenediamine temed

DL-lactide, 2-azidoethanol and 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU) were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). Cuprous bromide (CuBr) was provided by Macklin Biochemical Co., Ltd. (Shanghai, China). T4 DNA ligase, exonuclease I (Exo I), phi29 DNA polymerase, and 4S Red Plus solution were purchased from BBI Life Sciences Co., Ltd. (Shanghai, China). N,N,N',N'-tetramethylethylenediamine (TEMED) and deoxynucleotides (dNTPs) were obtained from Sangon Biotechnology Co., Ltd. (Shanghai, China). All oligonucleotides used in this study were synthesized and HPLC-purified by Sangon Biotechnology Co., Ltd. (Shanghai, China), and the sequences are listed in Table S1. The doxorubicin hydrochloride (Dox·HCl) was ordered from Aladdin (Shanghai, China). The healthy human serum was obtained from the affiliated hospital of Qingdao University (Qingdao, China), and diluted 100 times with ultrapure water for further use. Fetal bovine serum (FBS) and RPMI-1640 medium were purchased from Biological Industries (Israel) and HyClone (USA), respectively. The 1× TAE buffer (40 mM Tris, 1 M glacial acetic acid, 2 mM EDTA-2Na, 15 mM MgCl₂) with different pH values were used in the experiments. All regents were of analytical grade and used without further purification. Ultrapure water was used during all the experiments.

All oligonucleotides used in this work were synthesized and purified by Sangon Biotechnology Co., Ltd. (Shanghai, China), and their sequences are listed in Additional file 1: Table S1. Fetal bovine serum (FBS) and Dulbecco’s modified Eagle’s medium (DMEM) were obtained from Biological Industries (Israel) and HyClone (USA), respectively. Lipofectamine 3000 was ordered from ThermoFisher scientific (USA). Annexin V-FITC apoptosis detection kit was purchased from CoWin Biosciences (Beijing, China). Hoechst 33342 solution, 4 S Red Plus Nucleic Acid Stain and N,N,N′,N′-tetramethyl ethylenediamine (TEMED) were ordered from Sangon Biotechnology Co., Ltd. (Shanghai, China). All the reagents were of analytical grade and used without further purification.