Alex Paulsen

Hydrogels are hydrophilic 3D scaffold networks that have advantages of increased biocompatibility, tunable biodegradability, mechanical strength, and a porous structure. These physical properties can enhance the beneficial outcomes of drug delivery. However, due to their porous structure and high in-vivo degradation rate hydrogels are unable to encapsulate drugs for an extended period of time. In this proposal, alginate microbead design was manipulated to increase the length of drug retention. Prior research into electroless deposition layering of microspheres has demonstrated long term drug retention capabilities. Gold-plated alginate microbeads were developed by layering the external hydrogel matrix with polycation polymer polyethylenimine (PEI) or poly-l-lysine (PLL), absorbing platinum nanoparticles (Pt-NP) to the surface, and plating gold ions onto the Pt-NP catalyst via electroless deposition. The coating properties of the alginate microbeads coated with these materials were analyzed. Preparation parameters such as the length of electroless deposition, type of polycation, and size of platinum nanoparticles were investigated. The alginate microbeads layered with PEI were found to be more receptive to the Pt-NP allowing for a uniform distribution of nanoparticles. Furthermore, by increasing the length of electroless deposition the gold-plated layer increased in thickness. Microtomy and optical microscopy were used to analyze surface coating of the alginate microbeads. The results demonstrated that microbeads were concentrically gold-plated while maintaining their matrix scaffold.