In vitro degradation and erosion of degradable, segmented polyurethanes containing an amino acid-based chain extender

Abstract

In vitro degradation and erosion of novel, degradable segmented polyurethanes containing a phenylalanine diester chain extender were investigated by exposing the polymers to buffer. chymotrypsin, and trypsin solutions for up to 28 days. Polyurethane degradation and erosion were monitored by gravimetry, scanning electron microscopy (SEM), and gel permeation chromatography (GPC) and compared to a control polyurethane. Polyurethanes were synthesized using two different soft segments (polycaprolactone diol and polyethylene oxide) of variable molecular weight. Inclusion of the phenylalanine-based chain extender resulted in an increased susceptibility to enzyme-mediated, but not buffer-mediated, erosion in comparison to the control polyurethane. SEM analysis indicated that enzyme-mediated erosion proceeded via a surface-limited mechanism resulting in a progressive removal of material from the surface inwards with time. The magnitude of degradation and erosion was highly variable and was dependent on soft segment type and molecular weight. The range of degradation rates, as well as physicochemical properties, makes these polyurethanes potentially useful for a wide range of biomedical applications.

Elastase-Sensitive Elastomeric Scaffolds with Variable Anisotropy for Soft Tissue Engineering

“…Placement of a cell-laden scaffold, or scaffold alone into these tissue beds could provide for better mechanical coupling, without stress shielding, to these active tissues using this polymer and processing approach. Earlier work by Woodhouse and colleagues has similarly developed enzymatically sensitive polyurethanes by utilizing a phenylalanine diester chain extender and a polyester soft segment (44,45). This chain extender was shown to introduce chymotrypsin and, to a lesser extent, trypsin, sensitivity.…”

Biomimetic materials for tissue engineering

“…A major limitation of PU for biomedical applications is the involvement of toxic precursors (such as toluene diisocyanates) in the synthesis. Progress has been made in the development of biodegradable PU or urethanebased polymers using less toxic diisocyanates [26]. These polymers have been explored for vascular and other tissue engineering applications [27][28][29].…”

DNA gel particles: An overview

“…In many applications, it is important to control their degradation rates, which is usually achieved by incorporating hydrolytically or enzymatically cleavable groups into the polymer structure [16][17][18][19][20][21][22][23]. Biodegradable polymer constructs can also be prepared via reversible physical cross-linking, where the degradation rates depend on the strength of electrostatic, hydrophobic, or hydrogen bonding interactions [24][25][26][27].…”