Nontoxic Enzymatically Degradable Poly(ester-urethane): Studies on Solvent-Induced Self-Assembly and Nonconventional Luminescence

In this work, luminescent vesicular self-assemblies via phase inversion route were generated by harnessing the intrinsic nonconventional luminosity of amphiphilic amino acid-based non-isocyanate poly(ester-urethane)s (NIPEUs). Structural variations in NIPEUs, from linear to branched units, were achieved by varying the monomer structure from diols to triols, which demonstrated a significant impact on their self-assembled morphologies. By tuning the polarity of the mix-solvent medium, polarity-dependent morphological alternations from vesicles to large compound micelles (LCPs) were attained, enabling the NIPEUs to undergo solvent-induced self-assembly. In terms of the biocompatibility, the cytotoxicity of the NIPEUs was evaluated against human embryonic kidney (HEK) 293 cell line, which demonstrated promising cytocompatibility over a large concentration range. Moreover, both enzymatic and hydrolytic degradation studies were conducted to analyze the degradability of the prepared NIPEUs. Esterase, targeting ester bonds, and α-chymotrypsin, targeting urethane bonds, were employed for enzymatic degradation studies, and hydrolytic degradation was subsequently carried out in a PBS buffer at 37 °C. In a nutshell, this report is an amalgamation of five distinct aspects: unconventional luminescence; polarity-dependent solvent-induced self-assembly; nontoxic, non-isocyanate approach; promising cytocompatibility; and in vitro enzymatic and hydrolytic degradability, making it distinct in its own right. Due to these combinations, the NIPEUs can emerge as an effective tool in various biomedical applications ranging from drug delivery to bioimaging.