Dual-Responsive Controlled Drug Delivery Based on Ionically Assembled Nanoparticles

Abstract

Ionically assembled nanoparticles (INPs) have been formed from poly­(ionic liquid-<i>co</i>-<i>N</i>-isopropylacrylamide) with deoxycholic acid through electrostatic interaction. The structure and properties of the INPs were investigated by using ¹H NMR, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), and so on. Due to pH-responsive deoxycholic acid (p<i>K</i>_a = 6.2) and thermo responsive <i>N</i>-isopropylacrylamide included in the ionic complex, the INPs exhibit highly pH and thermal dual-responsive properties. The potential practical applications as drug delivery carriers were demonstrated using doxorubicin (DOX) as a model drug. With a lower pH (pH 5.2) and higher temperature (above 37 °C), structural collapse of the INPs occurred as well as release of DOX owing to protonated DA departure from the INPs and a lower LCST (lower critical solution temperature) at the pathological conditions. The result shows that 80% of DOX molecules were released from INPs within 48 h at pH 5.2, 43 °C, but only 30% of the drug was released within 48 h at 37 °C and pH 7.4. Moreover, drug-loaded INPs exhibit an inhibitory effect on cell growth