All-polysaccharide hydrogels for drug delivery applications: Tunable chitosan beads surfaces via physical or chemical interactions, using oxidized pullulan.

The present work reports a versatile approach to the manufacture of chitosan beads with tunable pore size and targeted properties. To achieve this, the as prepared chitosan beads were allowed to interact with aqueous solutions of two types of oxidized pullulan derivatives. Depending on the functional groups present on the pullulan structure after oxidation, i.e., carboxyl or aldehyde, covalent or physical hybrid hydrogels could be prepared. The attachment of oxidized pullulan onto chitosan structure was checked by FTIR, RMN, XPS and thermal analysis. The morphology of the hybrid structures was evaluated by using Scanning Electron Microscopy (SEM). After structural evaluations, all the prepared hydrogels were characterized by means of dynamic vapor sorption and swelling degree studies, exhibiting a Case-II swelling mechanism. Drug model compounds, such as ibuprofen, bacitracin and neomycin were used for drug loading and release assays, proving high drug loading capacity and tunable release behavior. Drug loaded beads exhibited antibacterial activity and hemocompatibility experiments indicated no coagulation phenomena.