Recent progress in side-chain amino acid-based polymers: synthesis, self-assembly, and emerging biomedical...

Side-chain amino acid-based polymers (SCAAPs), as a class of functional polymeric materials constructed from natural amino acids or their derivatives, have garnered significant attention in recent years in the fields of materials science and biomedicine. Their unique structural designability, excellent biocompatibility, and "smart" responsive properties make them an ideal platform for biomedical applications. This review systematically summarizes the synthetic strategies of SCAAPs, covering the rational design of amino acid-based monomers and their controlled polymerization through typical techniques (including reversible addition-fragmentation chain transfer polymerization, photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer polymerization, atom transfer radical polymerization, ring-opening metathesis polymerization, and activated ester substitution). Additionally, this review delves into the self-assembly behavior and multi-responsiveness (temperature, pH, and ionic responsiveness) of these polymers, revealing the mechanisms by which they form nanostructures driven by noncovalent forces such as hydrophobic interactions and hydrogen bonding. Finally, this review highlights recent progress in biomedical applications of SCAAPs, encompassing anticancer therapy, antimicrobial treatment, biosensing, tissue engineering scaffolds, and antifouling coatings. By integrating perspectives from chemical synthesis, materials science, and biology, this review aims to provide a theoretical foundation and technical reference for further research and application of SCAAPs.