Agilent 110 hplc

PLEL triblock copolymer was synthesized by ring-opening copolymerization of D, L-lactide with PEG, and characterized by nuclear magnetic resonance spectroscopy (¹H NMR, Varian 400 spectrometer, USA), fourier infrared spectroscopy (Bruker, INVENIO R, Germany) and gel permeation chromatography (GPC, Agilent 110 HPLC, USA) as described previously [58 ]. Then PLEL copolymer was dissolved in the phosphate buffered saline (PBS, pH = 8.0) at room temperature and stirred to gain the PLEL micelle solution. Finally, GEM was dissolved directly in the PLEL solution and CpG in PBS (pH = 7.0) mixed with PLEL copolymer solution at room temperature (T = 25 °C) to obtain GEM/PLEL (20 wt%) and CpG/PLEL (10 wt%) hydrogel. All drug-loaded samples were filtered by the 0.22 μm membrane for sterilization.

Firstly, MPEG-PDLLA was synthesized from the D, L-lactide, and MPEG by ring opening polymerization (ROP) in an environment of nitrogen with 130 ^oC oil bath for 8 hrs, and purified by precipitation in petroleum ether 53 (link). By connecting MPEG-PDLLA and Boc-Phe-OH, the amino end-group of MPEG-PDLLA was obtained after removing the t-butoxycarbonyl end group from Boc-L-Phe end-capped MPEG-PDLLA. And then, the MPEG-PDLLA-PLL was synthesized by the ROP with Lys (Z)-NCA through amino terminated MPEG-PDLLA, which was stirred in chloroform for 72 hrs. Finally, to get the MPEG-PDLLA-PLL triblock copolymer, the deprotection reaction of the copolymer MPEG-PDLLA-PLL was carried out in HBr/HAc solution. Purified MPEG-PDLLA-PLL was obtained by dialysis and freeze drying 55 (link). The structure of the polymer was characterized by nuclear magnetic resonance spectroscopy (¹H-NMR) (Varian 400 spectrometer, Varian, USA) and FTIR, the molecular weight was characterized by Gel Permeation Chromatography (GPC) (THF, 0.6 ml/min, Agilent 110 HPLC, America).

5-FU and DDP loaded PLEL hydrogel (5-FU + DDP/PLEL hydrogel) was prepared in three steps. First, the PDLLA-PEG-PDLLA (PLEL) triblock copolymer was synthesized via ring-opening copolymerization of D,L-lactide initiated by PEG and characterized through nuclear magnetic resonance spectroscopy (1H NMR, Varian 400 spectrometer, USA) and gel permeation chromatography (GPC, Agilent 110 HPLC, USA), according to our previous work [38 ]. Secondly, the obtained PLEL copolymer was completely dissolved in the phosphate buffered saline (PBS, pH 8.0) at room temperature and stirred well to obtain the PLEL micelle solution. Finally, 5-FU + DDP/hydrogel was prepared by dissolving 5-FU and DDP with the PLEL micelles solution by stir (60 rpm, 25 °C) for about 2 h and ultrasound for about 30 min to form a homogeneous solution. The concentration of the PLEL in the mixed 5-FU + DDP/PLEL here was 10 wt %, 15 wt % and 20 wt %. All drug-loaded samples were filtered with the 0.22 μm membrane for sterilization. The concentration of the PLEL in the mixed 5-FU + DDP/PLEL here was 10 wt %, 15 wt %, 20 wt %, and 25 wt %. The concentration of 5-FU and DDP of 5-FU + DDP/PLEL after filtration was detected by high performance liquid chromatography (HPLC) and inductively coupled plasma (ICP), respectively.

The biodegradable PLA–10R5–PLA block copolymers were synthesized by ring-opening copolymerization method. In brief, calculated amount of _L-LA (30 g for sample S1 and 45 g for S2) and 10R5 (20 g for sample S1 and 5 g for S2) were added into a dry glass ampoule under nitrogen atmosphere, and catalyzed by 0.15 g of Sn(Oct)₂. The reaction system was kept at 130°C for 10 hours and rapidly heated to 140°C under vacuum for another 1 hour. After being cooled to room temperature under nitrogen atmosphere, the PLA–10R5–PLA copolymer was firstly dissolved in methylene chloride and then precipitated using excess cold petroleum ether. The mixture was filtered and dried at 40°C under vacuum for 48 hours. The purified copolymers were kept in a desiccator before use. ¹H nuclear magnetic resonance spectroscopy (¹H NMR; Bruker Avance III 400, Bruker Optik GmbH, Ettlingen, Germany), Fourier transform infrared spectroscopy (FTIR; Nicolet 200 SXV, Thermo Fisher Scientific) and gel permeation chromatography (GPC; Agilent 110 HPLC, Agilent Technologies, Santa Clara, CA, USA) were used to characterize the obtained copolymers.