Synthesis and Characterization of Dye-Labeled Poly(methacrylic acid) Grafted Silica Nanoparticles

The synthesis of dye-labeled poly(methacrylic acid) (PMAA) grafted silica nanoparticles was studied. Surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of tert -butylmethacrylate ( t BuMA) was conducted on dye-labeled CPDB coated silica nanoparticles followed by sequential removal of the thiocarbonylthio end groups and the tert -butyl moieties. Additionally, as a more straightforward strategy, direct polymerization of methacrylic acid on silica nanoparticles with a diameter size as small as 15 nm was conducted via the RAFT polymerization technique. A variety of PMAA brushes with different lengths and densities were prepared on nanoparticle surfaces via surface-initiated RAFT polymerization with excellent control and surface grafting densities as high as 0.65 chains/nm 2 . The grafted PMAA was methylated by trimethylsilyldiazomethane to conduct organic phase GPC characterization. The dye-labeled PMAA grafted nanoparticles provide a platform to bind biomolecules and to track the movement of the nanoparticles in biological systems.