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

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Natural melanin is a biocompatible photothermal agent.
• Polyurethane (PU) is a versatile polymer for implants.
• Developing efficient photothermal agents is crucial for advanced biomedical devices.

Purpose of the Study:

• To fabricate near-infrared (NIR)-photoresponsive shape memory implants using yak hair melanin (YM) and polyurethane (PU).
• To evaluate the biocompatibility and biostability of YM/PU composites.
• To assess the NIR-induced shape recovery performance of the YM/PU implants.

Main Methods:

• YM/PU composites were fabricated.
• In vitro toxicity was assessed using human mesenchymal stem cells (hMSCs) and mouse fibroblast (L929) cell lines.
• In vivo toxicity was evaluated in mice over two months.
• In vitro degradation was monitored for 12 weeks.
• NIR laser (808 nm) was used to test shape recovery.

Main Results:

• YM/PU composites exhibited excellent biocompatibility with no significant toxicity observed in vitro or in vivo.
• Composites showed good biostability over 12 weeks of in vitro degradation.
• Rapid shape recovery (within 60 s) was achieved using a low-intensity NIR laser (0.5 W/cm²).

Conclusions:

• YM/PU composites are suitable for long-term implantation due to their biocompatibility and biostability.
• The low-power NIR responsiveness makes YM/PU composites promising for biomedical applications.
• Yak hair melanin offers a cost-effective and efficient photothermal agent for advanced implantable devices.