In this century, nanoparticles (NPs) have been given a great amount of attention by biomedical researchers. NPs can disperse hydrophobic drugs stably in aqueous conditions without aggregation. Importantly, their physicochemical properties, including size and surface charge, can easily be modified by adjusting the component molecules or fabrication method. NPs can delay the early release of drugs in order to allow enough time for therapeutic action. Along with NPs, hydrogel is also another representative material for biomedical applications. Hydrogels are three-dimensional network that contain large amount of water, and have used for drug delivery, cell therapy, and tissue engineering. In our recent studies, polymeric NPs and hydrogels have shown promising results in hearing loss and vocal cord paralysis, respectively.