Polyurethane/doxorubicin nanoparticles based on electrostatic interactions as pH-sensitive drug delivery carriers

In order to obtain a pH-sensitive delivery carrier for doxorubicin (DOX), DOX-loaded polyurethane (PU·DOX) nanoparticles were readily prepared in water by electrostatic interactions between amphiphilic polyurethane with carboxyl pendent groups (PU-COOH) and doxorubicin hydrochloride (DOX·HCl). The structures of the products obtained were characterized by Fourier transform infrared spectroscopy, 1 H NMR spectroscopy, gel permeation chromatography, UV–visible spectroscopy, dynamic light scattering and transmission electron microscopy. The average hydrodynamic size of the PU·DOX nanoparticles was around 182 nm with negative surface charge (−1.1 mV) and a spherical or rodlike shape. PU·DOX nanoparticles had a higher drug-loading content of 14.1 wt%. The in vitro drug release properties of PU·DOX nanoparticles were investigated at pH 4.0, 5.0 and 7.4, respectively. PU·DOX nanoparticles exhibited a good pH-sensitive drug release property, but there was almost no release of DOX from PU·DOX nanoparticles at pH 7.4. The in vitro cellular uptake assay and the Cell Counting Kit-8 assay demonstrated that PU·DOX nanoparticles had a higher level of cellular internalization and higher inhibitory effects on the proliferation of human breast cancer (MCF-7) cells than pure DOX. The enhancement of the inhibition effects resulted from increasing apoptosis-inducing effects on MCF-7 cells, which was related to the enhancement of Bax expression and the reduction of Bcl-2 expression confirmed by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay, real-time polymerase chain reaction (PCR) assay and western blot assay. © 2018 Society of Chemical Industry