Enhanced Hydrolytic Resistance of Fluorinated Silicon-Containing Polyether Urethanes

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

Biodegradable shape memory polymers are promising biomaterials for stents used in minimally invasive surgical procedures such as intestinal stents. Herein, a series of biodegradable shape memory polyurethanes (SMPUs) containing a novel phenylalanine-derived chain extender PHP were synthesized. Inspired by the fact that the function of biomacromolecules such as proteins is rich and varied because of the multiple combinations of the amino acid in highly evolved biosystems, we found that the sequence distribution of PHP in SMPU would also have a great influence on the phase structure and degradation behavior, especially the difference of surface morphology caused by degradation. Considering that the transition temperature (T_trans ) of SMPU we obtained is higher than physiological temperature, oxidized carbon black (OCB) with the ability of photothermal conversion was introduced into SMPU, which can not only endow SMPU with near-infrared response shape recovery characteristics, but also enhance phase separation degree and mechanical properties of them. SMPU/OCB composites show excellent shape memory effect and rapid photothermal response, and they can be degraded by chymotrypsin with an adjustable degradation rate. These SMPU/OCB composites show broad potential for application as intestinal stents. This article is protected by copyright. All rights reserved.

Shape memory polyurethane potentially used for vascular stents with water-induced stiffening and improved hemocompatibility

We designed a shape memory polyurethane potentially used for vascular stents with water-induced stiffening in vivo and improved hemocompatibility.

Improved in vivo stability of silicon-containing polyurethane by fluorocarbon side chain modulation of the surface structure

As a class of widely used biomedical materials, polyurethanes suffer from their insufficient stability in vivo. Although the commercialized silicone-polyetherurethanes (SiPEUs) have demonstrated excellent biostability compared with polyetherurethanes (PEUs) for long-term implantation, the usage of polydimethylsiloxane (PDMS) inevitably decreased the mechanical properties and unexpected breaches were observed. In this study, we introduced a fluorinated diol (FDO) into SiPEU to modulate the molecular interactions and micro-separated morphology. The fluorinated silicon-containing polyurethane (FSiPEU) was achieved with desirable silicone- and fluorine-enriched surfaces and mechanical properties at a low silicon content. As evidenced by in vitro culture of macrophages and in vivo hematoxylin-eosin (H&E) staining, FSiPEU demonstrated a minimized inflammatory response. After implantation in mice for 6 months, the material was devoid of significant surface degradation and had the least chain cleavage of soft segments. The results indicate that FSiPEU could be promising candidates for long-term implantation considering the combination of biostability, biocompatibility and mechanical performances.

Physical and thermo-mechanical properties of shape memory polyurethane containing reversible chemical cross-links

Orthodontic chains are one of the main parts of orthodontic braces. In this study, in order to obtain a suitable polymer for this application as well as troubleshoot the main drawbacks such as stress relaxation and water absorption, thermoplastic polyurethane (TPU) elastomers with various compositions were synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses. Mechanical properties of samples were evaluated by tensile, elasticity, and stress relaxation tests. According to the required properties for orthodontic chain application, PU2000-311 which contains reversible crosslinks, was selected as the most favorable sample among other pure samples. Moreover, to reduce the water absorption content of PU2000-311, its nanocomposite containing 1 wt% of silica nanoparticles was prepared via solution casting method. As water content angle and field emission scanning electron microscopy (FESEM) images illustrate, incorporation of 1 wt% of modified silica nanoparticles has increased PU2000-311-1S hydrophobicity. In vitro oral environment study showed crystability of samples has recovered great portion of relaxed force. Stress relaxation study indicated samples are applicable in oral temperature range and temperature changes have assisted recovery of relaxed force and reduced treatment period. Finally, shape memory study showed that optimum samples could recover 100% of their original shape.

Bioactive 3D porous cobalt-doped alginate/waterborne polyurethane scaffolds with a coral reef-like rough surface for nerve tissue engineering application

Bioactive 3D porous cobalt-doped alginate/waterborne polyurethane scaffolds with a coral reef-like rough surface were prepared for nerve tissue engineering application.