Natural Melanin/Polyurethane Composites as Highly Efficient Near-Infrared-Photoresponsive Shape Memory Implants

Abstract

Natural melanin is recognized as a biocompatible photothermal agent because of its biologically derived nature and efficient photothermal conversion ability. Here, yak hair melanin (YM) is added to polyurethane (PU) for the fabrication of NIR-photoresponsive shape memory implants. The in vitro toxicity of the YM/PU composites is carried out by exposing them to human mesenchymal stem cells (hMSCs) and mouse fibroblast (L929) cells lines for 24 h, while the in vivo toxicity is investigated by implanting the YM/PU composites in the mouse for two months. No significant differences on cell viability, blood chemistry, hematology, and histological results are observed between YM/PU composites and control groups, suggesting their excellent biocompatibility. The biostability of the YM/PU composites is confirmed by monitoring their in vitro degradation for 12 weeks. The YM/PU column implanted in the back subcutis or vagina of the mouse rapidly recovered to its original state within 60 s under a very low NIR laser (808 nm, 0.5 W/cm2) intensity, which is much lower than the general laser intensity for photothermal cancer therapy (1–2 W/cm2). This work confirms the applicability of the YM/PU composites as long-term implant materials and expedites the use of YM/PU composites as cost-effective candidates for biomedical applications.

Polydopamine Nanoparticle-Reinforced Near-Infrared Light-Triggered Shape Memory Polycaprolactone–Polydopamine Polyurethane for Biomedical Implant Applications

“…2 The near-infrared (NIR) light in the range of 700−950 nm has been widely used in biomedical systems because of its high tissue penetration and safety to the human body. 3 An NIR-triggered thermal sensitive SMPs could be obtained by adding a photothermal agent into the SMPs because the photothermal agent can convert light energy into heat energy, which can cause an increase in temperature up to the transition temperature (T trans ) and trigger the shape recovery effect. Plenty of photothermal agents have been reported for NIR light-triggered SMPs, for example, metallic particles, 4,5 organic rare-earth complex, 6 carbon nanotubes (CNTs), 7 and so forth.…”

“…However, metallic nanoparticles and carbon-based nanomaterials are restricted for biomedical applications because of their biotoxicity. 3 Moreover, the dispersion of the photothermal agent in the SMP matrix is a crucial factor for the photothermal conversion efficiency, and the aggregation of additives usually leads to a dramatic decrease in mechanical properties. 8 Thus, it is necessary to find an appropriate photothermal agent, which can both satisfy the biocompatibility and maintain the mechanical performance of SMPs.…”

Recent Advances in Stimuli‐Responsive Commodity Polymers

“…[ 140 ] When melanin or dopamine are incorporated into a PUR matrix, efficient photo‐thermal conversion upon NIR irradiation can be achieved. [ 142,143 ]…”

Biomass Shape Memory Elastomers with Rapid Self-Healing Properties and High Recyclability

“…As smart materials, the application prospect can be further expanded by introducing shape memory function on the basis of self-healing materials. − The stimulus that triggers the shape memory effect can be temperature, current, magnetic field, and light. , Wen et al prepared a novel humidity-responsive self-healing material consisting of N , N -bis­(2-hydroxylethyl) isonicotinamide, hexamethylene diisocyanate, and 1,3-propanesultone . The maximum tensile strength of the material is up to 32.5 MPa, and the elongation at break is 12.5%.…”