Hydrophilic Polymer-Brush Functional Fluorescent Nanoparticles to Suppress Nonspecific Interactions and Enhance Quantum Yield for Targeted Cell Imaging

Hydrophilic poly(glyceryl monomethacrylate) (PGMMA) brush-functional nanoparticles were prepared via macromolecular chain-transfer-agent-adjusted reversible addition-fragmentation chain-transfer precipitation polymerization (RAFTPP). Hydroxyethyl anthrancene-9-carboxylate methacrylate (AnHEMA) was used as the comonomer to label the nanoparticles with fluorescence. Then, small molecular phenylboronic acid tags were modified on the nanoparticles for highly specific and sensitive sensing of glycans on living cells. The introduction of hydrophilic PGMMA brushes into nanoparticles can strongly improve their surface hydrophilicity, reduce their nonspecific interactions with biomolecules in aqueous medium, and give them strong fluorescence properties. Compared with fluorescent nanoparticles without grafted PGMMA brushes, grafted fluorescent nanoparticles showed an obviously enhanced fluorescence quantum yield (similar to 7%), longer lifetime (similar to 2 ns), and higher fluorescence stability due to the shielding effect of PGMMA. Using PGMMA-functional fluorescence nanoparticles as probes could effectively visualize and discriminate cancer cells from normal cells in a highly selective and nonviral manner. Fluorescence imaging of human hepatoma carcinoma cells (HepG-2) over normal hepatic cells (L-02) and of human cervical cancer cells (HeLa cells) over normal human cervical epithelial cells (HCerEpiC) using these nanoparticles was also demonstrated. This strategy demonstrates a flexible molecular brush approach for a highly efficient probe in advanced bioimaging applications.