Direct synthesis of quaternized polymer brushes and their application for guiding neuronal growth.

We show that the poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) (PMETA) brush modified surfaces are excellent substrates for the directed growth of rat hippocampal neurons, which could prove useful for the coating of neural devices. Direct synthesis of quaternized poly(dimethylaminoethyl methacrylate) brushes was achieved by surface-initiated atom transfer radical polymerization (SI-ATRP) of META in protic media at room temperature. PMETA brushes were photolithographically patterned on silicon substrates in combination with patterned regions backfilled with short polyethylene glycol (PEG) SAMs.

In vivo multiphoton microscopy of deep brain tissue.

Although fluorescence microscopy has proven to be one of the most powerful tools in biology, its application to the intact animal has been limited to imaging several hundred micrometers below the surface. The rest of the animal has eluded investigation at the microscopic level without excising tissue or performing extensive surgery. However, the ability to image with subcellular resolution in the intact animal enables a contextual setting that may be critical for understanding proper function.