Postelectrospinning "click" modification of degradable amino acid-based poly(ester urea) nanofibers

Amino acid-based poly(ester urea)s (PEU) are emerging as a new class of degradable polymers that have shown promise in regenerative medicine applications. Herein, we report the synthesis of PEUs carrying pendent "clickable" groups on modified tyrosine amino acids. The pendent species include alkyne, azide, alkene, tyrosine-phenol, and ketone groups. PEUs with M_w exceeding to 100K Da were obtained via interfacial polycondensation methods, and the concentration of pendent groups was varied using a copolymerization strategy. The incorporation of derivatizable functionalities is demonstrated using ¹H NMR and UV-vis spectroscopy methods. Electrospinning was used to fabricate PEU nanofibers with a diameters ranging from 350 to 500 nm. The nanofiber matricies possess mechanical strengths suitable for tissue engineering (Young's modulus: 300 ± 45 MPa; tensile stress: 8.5 ± 1.2 MPa). A series of bioactive peptides and fluorescent molecules were conjugated to the surface of the nanofibers following electrospinning using bio-orthogonal reactions in aqueous media. The ability to derivatize PEUs with biological molecules using translationally relevant chemical methods will significantly expand their use in vitro and in vivo.