The resulting conjugates were dried using a rotary evaporator and dissolved in dilute HCl

followed by precipitation with cold acetone. Finally, they were dissolved in deionized water, filtered, and freeze-dried. Analysis of the conjugates To assess their functional groups, drug-loaded and blank conjugates were characterized using a Fourier trans-form infrared (FTIR) spectrophotometer (Spectrum 100, PerkinElmer, Waltham, MA, USA) using the potassium bromide (KBr) disc method. For each sample, 16 scans were obtained at a resolution of 4 cm−1 in the range of 4,000 to 700 cm−1. Further characterization of the conjugates was also performed using nuclear magnetic resonance (NMR) spectroscopy (Bruker Avance BIBW2992 III, FT-NMR 600 MHz with cryoprobe, Germany). The CMCs of the micelles were determined using the dynamic light scattering method (Zetasizer Nano ZS, Malvern Instruments, Malvern, Worcestershire, UK) at

37°C with a scattering angle of 90°. The BMS202 mw alterations in light intensity were recorded, and a graph was plotted for the molar concentrations of the samples versus the mean intensity. A sharp learn more increase in the intensity signified the formation of micelles. Samples for morphological investigations were prepared by air-drying a drop of the micellar suspension on a carbon-coated formvar film on a 400-mesh copper grid. The morphology of the micelles was then visualized by transmission electron microscopy (TEM; Tecnai™ Spirit, FEI, Eindhoven, The Netherlands) at 220 kV and under various magnifications. The conjugates were observed under a light microscope (FluoView FV1000, Olympus, Tokyo, Japan). The X-ray diffraction (XRD) patterns of the CA-PEI conjugates were analyzed with an X-ray diffractometer (D8 ADVANCE, Cu Kα = 1.54184 Å, Bruker, WI, USA). The thermal behavior of the conjugates was investigated by differential scanning calo-rimetry (DSC) (Diamond DSC, PerkinElmer, Waltham, MA, USA). Preparation of the doxorubicin-loaded CA-PEI micelles Doxorubicin hydrochloride (2.5 mg) was dissolved in 2 mL chloroform and mixed with 2 μL of triethylamine. CA-PEI copolymers of different molar ratios (1:1,

1:2, 1:4, 3:1, and 4:1) were dissolved in 2 mL methanol. The doxorubicin and CA-PEI copolymer solutions were mixed in a glass vial and kept in the dark for 24 h. Lck The solution was then poured drop by drop into deionized water (20 mL) under ultrasonic agitation using a sonifier (Branson Ultrasonics Co., Danbury, CT, USA) at a power level of 3 for 10 min. The organic solvents namely chloroform and methanol were then completely removed by vacuum distillation using a rotary evaporator. The doxorubicin-loaded micelle solution was then dialyzed against 1 L of deionized water for 24 h at 20°C using a cellulose membrane bag (MWCO = 1,000) to remove unloaded doxorubicin. The deionized water was substituted every 2 h for the first 12 h and then every 6 h. Immediately after this, the product was freeze-dried.