Stimuli-Responsive PEGylated Nanogels for Smart Nanomedicine

Abstract

PEGylated nanogels are composed of cross-linked polyamine gels core with tethered PEG chains. The stimuli-responsive PEGylated nanogels have significant volume phase transitions in response to the extracellular pH (7–6.5) of a tumor environment as well as endosomal/lysosomal pH (6.5–5.5). The pH-responsive PEGylated nanogels containing 19F compounds in the polyamine gels core have remarkable on–off 19FMR signals (T 2 values of 19F) and signal-to-noise (S/N) ratio in response to the extracellular of tumor environment, making these nanogels effective as tumor-specific smart 19F MRI (magnetic resonance imaging) nanoprobes. The doxorubicin (DOX)-loaded pH-responsive PEGylated nanogels release DOX intracellular in response to endosomal/lysosomal pH, thereby conferring more antitumor activity than free DOX against naturally drug-resistant human hepatoma cells. The PEGylated nanogel with gold nanoparticles as the fluorescence quencher in the core and fluorescence dye-labeled DEVD (Asp-Glu-Val-Asp) peptide at the tethered PEG chain end provide pronounced fluorescence signals in response to apoptotic cells. Thus, stimuli-responsive PEGylated nanogels can be utilized as smart nanomedicines for cancer diagnosis and therapy.