Delivery of doxorubicin in vitro and in vivo using bio-reductive cellulose nanogels†
A methacrylation strategy was used to functionalize carboxymethyl cellulose and prepare redox-sensitive cellulose nanogels which contained disulfide bonds. Dynamic light scattering, zeta potential and electron microscopy were utilized to characterize these nanogels. It was found that these nanogels had a spherical morphology with a diameter of about 192 nm, and negative surface potential. These redox-sensitive nanogels were stable against high salt concentration but de-integrated in the reducing environment containing glutathione. When doxorubicin (DOX) was loaded into the nanogels, a high drug loading content (36%) and a high encapsulation efficiency (83%) were achieved. Confocal laser scanning microscopy and co-localization images showed that DOX-loaded nanogels were internalized by the cancer cells through endocytosis and the DOX could be delivered into the nucleus. Near-infrared fluorescence imaging biodistribution examination indicated that the nanogels could passively target to the tumor area by the EPR effect and had a significantly prolonged circulation time. In vivo antitumor evaluation found that DOX-loaded nanogels exhibited a significantly superior antitumor effect than the free DOX by combining the tumor volume measurement and the examination of cell apoptosis and proliferation in tumor tissues.