Reduction-sensitive CD44 receptor-targeted hyaluronic acid derivative micelles for doxorubicin delivery

A reduction-sensitive CD44-positive tumor-targetable drug delivery system for doxorubicin (DOX) delivery was developed based on hyaluronic acid (HA)-grafted polymers. HA was conjugated with folic acid (FA) via a reduction-sensitive disulfide linkage to form an amphiphilic polymer (HA-ss-FA). The chemical structure of HA-ss-FA was analyzed by ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and H nuclear magnetic resonance (NMR) spectroscopy. The molecular weight of HA-ss-FA was determined by high-performance gel permeation chromatography. Blank HA-ss-FA micelles and DOX-loaded micelles were prepared and characterized. The reduction responsibility, cellular uptake, and in vivo biodistribution of HA-ss-FA micelles were investigated. DOX-loaded micelles were of high encapsulation efficiency (88.09%), high drug-loading content (22.70%), appropriate mean diameter (100-120 nm), narrow size distribution, and negative zeta potential (-6.7 to -31.5 mV). The DOX release from the micelles was significantly enhanced in reduction environment compared to normal environment. The result of in vitro cytotoxicity assay indicated that the blank micelles were of low toxicity and good biocompatibility and the cell viabilities were >100% with the concentration of HA-ss-FA from 18.75 to 600.00 μg/mL. Cellular uptake and in vivo biodistribution studies showed that DOX-loaded micelles were tumor-targetable and could significantly enhance cellular uptake by CD44 receptor-mediated endocytosis, and the cellular uptake of DOX in CD44-positve A549 cells was 1.6-fold more than that in CD44-negative L02 cells. In vivo biodistribution of HA-ss-FA micelles showed that micelles were of good in vivo tumor targetability and the fluorescence of indocyanine green (ICG)-loaded micelles was 4- to 6.6-fold stronger than free ICG within 6 h in HCCLM3 tumor-bearing nude mice. HA-ss-FA is a promising nanocarrier with excellent biocompatibility, tumor targetability, and controlled drug release capability for delivery of chemotherapy drugs in cancer therapy.