Hydrotropic hyaluronic acid conjugates: Synthesis, characterization, and implications as a carrier of paclitaxel

Amphiphilic hyaluronic acid conjugates were synthesized as a potential drug carrier by chemical conjugation of an amine-terminated hydrotropic oligomer, which has a unique ability to enhance the solubility of paclitaxel (PTX), to a hyaluronic acid (HA) backbone using carbodiimide chemistry. The physicochemical properties of the hydrotropic hyaluronic acid (HydroHA) conjugates were investigated using ¹H NMR, dynamic light scattering, transmission electron microscopy (TEM), and fluorescence spectroscopy. HydroHA conjugates could form self-assembled nanoparticles in an aqueous medium because of hydrophobic interactions among hydrotropic oligomers. Their particle sizes were in the range of 274-356nm, depending on the degree of substitution (DS) of the hydrotropic oligomer. TEM images showed that particle morphology was spherical in shape. Critical aggregation concentrations of HydroHA conjugates ranged from 0.034 to 0.125mg/mL, which decreased with an increase in the DS of the hydrotropic oligomer. The HydroHA conjugates were selectively taken up by the cancer cell line (SCC-7) over-expressing CD44, a hyaluronic receptor. The nanoparticles could encapsulate PTX up to 20.7wt.% by the dialysis method. The in vitro release pattern of PTX from nanoparticles was significantly dependent on drug loading content, in which the release rate was lower for the nanoparticles that contained larger amounts of the drug. From the cytotoxicity test, it was found that the drug-loaded HydroHA nanoparticles exhibited stronger cytotoxicity to SCC-7 than to normal fibroblast cell (CV-1). These results suggest that HydroHA nanoparticles have potential as the carrier of PTX for cancer therapy.