Shape Memory Properties and Enzymatic Degradability of Poly(ε‐caprolactone)‐Based Polyurethane Urea Containing Phenylalanine‐Derived Chain Extender

Abstract

Biodegradable shape memory polymers are promising biomaterials for minimally invasive surgical procedures. Herein, a series of linear biodegradable shape memory poly(ε-caprolactone) (PCL)-based polyurethane ureas (PUUs) containing a novel phenylalanine-derived chain extender is synthesized. The phenylalanine-derived chain extender, phenylalanine-hexamethylenediamine-phenylalanine (PHP), contains two chymotrypsin cleaving sites to enhance the enzymatic degradation of PUUs. The degradation rate, the crystallinity, and mechanical properties of PUUs are tailored by the content of PHP. Meanwhile, semicrystalline PCL is not only hydrolytically degradable but also vital for shape memory. Good shape memory ability under body temperature is achieved for PUUs due to the strong interactions in hard segments for permanent crosslinking and the crystallization-melt transition of PCL to switch temporary shape. The PUUs would have a great potential in application as implanting stent.

Biostable Segmented Thermoplastic Polyurethane Shape Memory Polymers for Smart Biomedical Applications

“…Introducing peptides and amino acids that are naturally present in the body into these STPUs provides an opportunity to design biocompatible materials that respond to specific wound healing conditions . Peptide sequences can be designed to have high selectivity at mild conditions (37 °C and pH: 5–8) for their enzymatic breakdown. , For instance, matrix metalloproteinase (MMP)-responsive peptides could enable shape change as wound healing progresses to release drugs; phenylalanine enables a response to chymotrypsin, which could be used in intestinal applications; and Ala-Ala-Lys peptides could be used as chain extenders that respond to elastase . Another wound healing process stimulus that could be exploited with this STPU system is secretion of ROS. , Introducing ROS-labile moieties into this stable platform could trigger shape change only in response to ROS production by immune cells in the wound.…”

“…49 Peptide sequences can be designed to have high selectivity at mild conditions (37 °C and pH: 5−8) for their enzymatic breakdown. 48,50 For instance, matrix metalloproteinase (MMP)-responsive peptides could enable shape change as wound healing progresses to release drugs; 51 phenylalanine enables a response to chymotrypsin, which could be used in intestinal applications; 52 and Ala-Ala-Lys peptides could be used as chain extenders that respond to elastase. 20 Another wound healing process stimulus that could be exploited with this STPU system is secretion of ROS.…”

Rational design of biodegradable thermoplastic polyurethanes for tissue repair

“…Incorporation of peptides into a PU backbone can endow the PU with improved biocompatibility and biodegradability, and create a specific biological function, such as enzyme liability or enhanced cell attachment [ 67 , [139] , [140] , [141] , [142] , [143] , [144] ]. A YIGSR peptide as a chain extender was introduced into a PU backbone to enhance the endothelialization of the PU as a small-diameter vascular graft [ 139 ].…”

NIR Photothermal‐Responsive Shape Memory Polyurethane with Protein‐Inspired Aggregated Chymotrypsin‐Sensitive Degradable Domains

“…[29] In our previous work, we synthesized SMPU using PCL as soft segments and a phenylalanine derivative with two chymotrypsin cleavage sites (PHP) as chain extenders, exhibiting potential application as intestinal stents. [19,30] Inspired by the fact that the function of biomacromolecules such as proteins is varied because of the multiple combinations of amino acids in highly evolved biosystems, [31] we speculate that the sequence distributions of PHP in SMPU would also have a great influence on SMPU, especially the enzymatic degradation performance.…”