Dual stimuli-responsive nanocarriers via a facile batch emulsion method for controlled release of Rose Bengal

Official URL: https://dx.doi.org/10.1016/j.jddst.2022.103547

Stimuli-responsive nanocarriers (SRN) hold great potential as drug delivery systems due to the ability to tune the release of the drugs by controlling the external stimuli. However, the synthesis of SRNs with layers of different functional polymers within their structure generally requires tedious processing steps involving surfactants. In this work, we report the synthesis of dual-responsive SRNs via a facile batch emulsion method without the use of any surfactants. The core-shell structure, which is composed of pH-responsive chitosan-polyacrylic acid complex shell and a temperature-responsive poly (n-vinyl caprolactam) core, is designed to tune the release of a model drug, Rose Bengal (RB), by controlling the pH and the temperature of the medium. At high pH values, fast release of the RB is observed within the first 24 h with release amounts in the range of 55–90%, depending on the temperature. At low pH values, on the other hand, sustained release of RB is observed with release amounts of approximately 10% within the first 24 h. Increasing the temperature from 25 °C to 40 °C increases the release rates and the total amount of RB released, confirming the temperature-dependent release kinetics of the SRNs. In vitro studies performed on human colorectal adenocarcinoma cells show that encapsulation of RB inside the SRNs promotes drug uptake by the cells, thus favoring a cytotoxic effect not observed in presence of the free drug.