All solutions used in a high-performance liquid crystal (HPLC, Waters Associates, Milford, MA, USA) analysis were filtered and degassed using a 0.22-μm membrane filter with a filtration system. Preparation of the PTX-MPEG-PLA NPs The PTX-MPEG-PLA NPs were prepared by a facile dialysis method. In brief, 100 mg of MPEG-PLA and 10 mg of PTX were codissolved in 10 mL of organic solvent (acetone, selleck chemical unless specified) accompanied by vigorous stirring; then the resulting organic phase was introduced into a dialysis bag. Subsequently, the dialysis bag was placed with

gentle agitation (100 rpm) into 1,000 mL of water as the aqueous phase. The organic phase was dialyzed against the aqueous phase for 6 h. Following this, the aqueous phase was subjected to repeated cycles of replacing with fresh water this website at designed time points (1, 2, 3, 4, 5, and 6 h) to remove the diffused organic phase by dialysis. The as-prepared PTX-MPEG-PLA NPs were lyophilized for 24 h using a freeze drier (Labconco Plus 12, Labconco, Kansas City, MO, USA) and stored at 4°C for future use. The PTX-PLA NPs were prepared in a similar way by using 100 mg of PLA. The drug loading content and drug encapsulation efficiency of PTX-MPEG-PLA NPs and PTX-PLA NPs were

determined by a HPLC system consisting of a Waters 2695 Separation Module and a Waters 2996 Photodiode Array Detector with the following conditions: stationary phase: Thermo C18 column (150 mm × 4 mm, 5 μm), temperature 26 ± 1°C; mobile phase: methanol/ultrapure water (65/35, v/v), freshly prepared, filtered through a 0.22-μm Millipore (Billerica, MA, USA)membrane filter buy Trichostatin A before use, and degassed utilizing a sonication method; elution flow rate, 0.8 mL/min; and detection

wavelength, 227 nm. The concentration of PTX was determined based on the peak area at the retention time of 7.5 min by reference to a calibration curve. XRD analysis The Cyclin-dependent kinase 3 physical state of PTX in the MPEG-PLA NPs or PLA NPs was analyzed using a Philips X’Pert Pro Super X-ray diffractometer (Philips, Amsterdam, Netherlands) equipped with CuKα radiation generated at 30 mA and 40 kV. The diffraction angle was increased from 5° to 60°, with a step size of 0.05. As control, the characteristic of PTX and MPEG-PLA NPs/PLA NPs, and the physical mixture of PTX and MPEG-PLA NPs/PLA NPs with the same ratio were investigated as well. FTIR analysis FTIR spectra were obtained using a NicoletAVTAR36 FTIR spectrometer (Thermo Scientific, Logan, UT, USA) with a resolution of 4 cm−1 from 4,000 to 400 cm−1. The PTX-MPEG-PLA NPs or PTX-PLA NPs were lyophilized to obtain the FTIR sample. Two milligrams of dried powder was added to 200 mg of KBr. The powder was pressed into a pellet for analysis. Besides, the FTIR spectra of MPEG-PLA NPs/PLA NPs and pure drug were obtained as control.