Self-Assembled Hyaluronic Acid Nanoparticles for pH-Sensitive Release of Doxorubicin: Synthesis and In Vitro Characterization

The nanoparticulate drug delivery systems (NDDS) demonstrate a relatively ideal therapeutic efficacy during cancer therapy Regarding the high tumor-target capacity and efficient drug release at the tumor site. Thus, in the present study, a novel macromolecular prodrug conjugates was designed and developed, which can target CD44-overexpressed tumor cells in addition to releasing doxorubicin (Dox) that is passively triggered by the acidic microenvironment of tumor cells. Briefly, the best reaction route from three different alternatives was selected and then the synthetic reaction conditions to get grafted hyaluronic acid products were optimized. Through constructing a schiff base covalent bond conjugation between grafted hyaluronic acid and Dox, the macromolecular prodrug micelles were endowed with acid-sensitive character. This character resulted in a delayed release at pH 7.4 and expedited release at pH 5.0. This was proved by the release experiments in vitro. In the aspect of nanostructure, the polymer prodrug can self-assembly into the core–shell structure nanoparticles in aqueous solution with the hyaluronic acid as the hydrophilic shell and doxorubicin as the hydrophobic core. By optimizing the process of preparation, nanoparticles showed the mean size of around 200 nm and a narrow particle size distribution which were verified by dynamic light scattering (DLS) and transmission electron microscopy (TEM). CCK-8 assays and fluorescence microscope experiments showed that the polymer prodrug nanoparticles possessed an enhanced targeting ability and antitumor activity toward HeLa cells.