Hyaluronic acid nanogels with enzyme-sensitive cross-linking group for drug delivery.

A methacrylation strategy was employed to functionalize hyaluronic acid and prepare hyaluronic acid (HA) nanogels. Dynamic light scattering, zeta potential analyzer and electron microscopy were utilized to characterize the nanogels and their enzyme-degradability in vitro. It was found that these nanogels had a spherical morphology with the diameter of about 70nm, and negative surface potential. When doxorubicin (DOX) was loaded into the nanogels, the diameter decreased to approximately 50nm with a drug loading content of 16% and encapsulation efficiency of 62%. Cellular uptake examinations showed that HA nanogels could be preferentially internalized by two-dimensional (2D) cells and three-dimensional (3D) multicellular spheroids (MCs) which both overexpress CD44 receptor. Near-infrared fluorescence imaging, biodistribution and penetration examinations in tumor tissue indicated that the HA nanogels could efficiently accumulate and penetrate the tumor matrix. In vivo antitumor evaluation found that DOX-loaded HA nanogels exhibited a significantly superior antitumor effect.