Post-Electrospinning "Triclick" Functionalization of Degradable Polymer Nanofibers

4-Dibenzocyclooctynol (DIBO) was used as an initiator for the ring-opening copolymerization of ε-caprolactone and 1,4,8-trioxaspiro[4.6]-9-undecanone (TOSUO) resulting in a series of DIBO end-functionalized copolymers. Following deprotection of the ketone group, the polymers were derivatized with aminooxyl-containing compounds by oxime ligation. Mixtures of keto- and alkyne-derivatized polymers were co-electrospun into well-defined nanofibers containing three separate chemical handles. Strain-promoted azide alkyne cycloaddition (SPAAC), oxime ligation, and copper-catalyzed azide alkyne cycloaddition (CuAAC) were used to sequentially functionalize the nanofibers first with fluorescent reporters and then separately with bioactive Gly-Arg-Gly-Asp-Ser (GRGDS), BMP-2 peptide, and dopamine. This translationally relevant approach facilitates the straightforward derivatization of diverse bioactive molecules that can be controllably tethered to the surface of nanofibers.