Polydopamine and Polydopamine-Glutaraldehyde Materials; Film and Particle Synthesis, Surface Modification, and Varying Behavior in an Optical Trap

Abstract

Materials derived from polydopamine are multifunctional and it is easily deposited on many surfaces because of highly reactive amine and indole chemistry. The structure of dopamine confers it both negative and positive moieties and materials derived from it are enabled by a great deal more available surface chemistries than other materials that only possess one. The ceramic surfaces from the trials in this thesis were found to not readily accept PDA deposition. By comparison, charged surfaces such as glass, metals, and plastics, easily interact with this flexible monomer. PDA is made from dopamine monomers and downstream oligomers. During synthesis, it conforms to surfaces and can completely envelop charged or metallic substrates. In this thesis, Y/Yb-doped ceramic crystals were uniformly coated using mole fraction excess concepts of Le Chȃtelier’s Principle. By adding an excess of monomer, the formation of nanospheres is made less favorable and films grow, instead. In response to downstream attempted enzyme conjugation, the uniform coating irreversibly aggregated. To improve chemical resistance, crosslinked versions of these coats were developed using glutaraldehyde and hydrothermal pressure to forcibly deposit a coating of polydopamine crosslinked by glutaraldehyde (PDAG). This polymer is stable in the presence of PBS and is therefore a good candidate for developing bioactive or corrosion-resistance applications for coated ceramics and possibly metals. PDA nanoparticles are able to be controllably aggregated/dispersed against a glass cover slip in a 1020nm optical trap are able whereas PDAG particles made via hydrothermal methods show differing interactions with the laser beam. These two particle types may be viable candidates for exploration in Brownian motion studies or possibly in the production of NV- diamond nanoparticles.