Preparation and Characterization of pH-sensitive Doxorubicin Grafted Hyaluronic Acid Nano-micelles

This study was done to achieve a new drug delivery system delivering two different chemotherapy molecules to the target tissue simultaneously.Significance: Co-delivery of chemotherapy medicines provides synergistic effects leading to lowering the dose of administered drugs and side effects.

Doxorubicin (DOX) was introduced to water-soluble hyaluronic acid (Hyal) using 1-amino-3,3-diethoxy-propane (ADEP), as a pH-sensitive linker, to develop a new hydrophobic structure, i.e. Hyal-ADEP-DOX. The conjugates were grafted in three ratios (7.5%, 12.5%, and 20%) to Hyal and characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1HNMR). Cannabidiol (CBD) was physically loaded in the core of nano-micelles.

Prepared nano-micelles were analyzed for critical micelle concentration (CMC) particle size stability and drug release before and after loading the CBD. Hyal-ADEP-DOX-12.5 was the optimized ratio and had a mean diameter of 50 nm before loading the CBD and 120 nm after loading (observed by transmission electron microscopy). The release results showed that DOX releases slowly in physiological pH, and CBD has a burst release at acidic pH from Hyal-ADEP-DOX-12.5. These properties altogether make Hyal-ADEP-DOX nano-micelles, as a stimuli-sensitive nano-carrier, a potential candidate for hydrophobic anticancer agents’ co-delivery.

The grafted DOX exhibited pH-sensitive release behavior, i.e. while 22.8% of the drug was released after 24 h at pH 5.5, and 5% was released after 24 h at pH 7.4. Hyal-ADEP-DOX due to its low CMC value, colloidal stability, slow drug release in physiological pH, and burst release in acidic pH Hyal-ADEP-DOX, is an excellent candidate as a carrier to co-deliver hydrophobic therapeutic agents to tumor tissues.