1200 series gpc system

¹H NMR analysis (AVANCE III 400, Bruker, Fällande, Switzerland) was performed on the polymer samples in deuterated chloroform (CDCl₃-d) with tetramethylsilane (TMS) as an internal standard operating at 400 MHz and 25°C.
Fourier transform infrared spectra measurements were executed on a Nicolet Nexus for Euro (America) spectrometer to confirm the structure of samples composed of KBr and freeze-dried polymer. The spectra were scanned from 400 to 4,000 cm⁻¹ with a resolution of 2 cm⁻¹.
The number average molecular weight (M_n) and the polydispersity index (M_w/M_n, PDI) were determined by the GPC method, and executed by the Agilent 1,200 series GPC system with THF as mobile phase (1.0 mL/min at 30°C) for 45 min.
The polymeric micelles self-assembled from synthesized polymers were prepared by dialysis for further study. The hydrodynamic diameter and zeta potential of micelles were measured by dynamic light scattering. The measurements were performed on a Malvern Zetasizer Nano S (Malvern Instruments, Malvern, UK) with a diode laser of 800 nm and a scattering angle 90° at room temperature.
The morphological shapes of the polymeric micelles treated at different pH values were confirmed using a transmission electron microscope (TEM, Hitachi H-7650, Tokyo, Japan) operating at 80 kV.

The purified and crude extract (5 mg) was dissolved in THF (2 mL) and filtered through a 0.45 μm nylon syringe filter (Millex-HN, Ireland) before GPC analysis, respectively. Twenty microliters were injected into a gel permeation chromatography (GPC) adopting an Agilent 1200 series GPC system equipped with a LC quant pump, PL gel 5 μm 500 Å, 100 000 Å column and RI detector. The column system was calibrated with a set of monodisperse polystyrene standards (molecular weight range of 162–5.0 × 10⁶ g mol⁻¹) using HPLC grade THF as mobile phase at a flow rate of 1.0 mL min⁻¹ at 30 °C.