Sustainable Recovery of Keratin from Chicken Feather Waste and Its Processing for Biomedical Applications

ConspectusThe global poultry industry has grown significantly in recent decades and is currently producing vast amounts of chicken feather waste, corresponding to around 7 wt % of the total weight of an adult chicken. This waste, which is typically incinerated or landfilled, poses both environmental and economic challenges, while being inconsistent with the principles of the circular economy. Chicken feathers are composed primarily of keratin (approximately 90 wt % on a dry weight basis), a natural protein with valuable properties, namely, anti-inflammatory and antioxidant activities, superior cytocompatibility, and ability to promote cellular migration. These characteristics make keratin an ideal candidate for various biomedical applications. However, traditional methods of recovering keratin from natural biomass are inefficient and costly and involve the use of toxic chemicals, limiting the broader use of this waste. In this Account, we discuss a sustainable and efficient process for keratin recovery and processing using ionic liquids. By employing acetate-based ionic liquids (80 wt % in water), we have developed a method that not only dissolves chicken feathers but also allows for high-yield keratin recovery. The developed process significantly reduces the need for harmful chemicals and energy-intensive steps traditionally associated with keratin recovery. Furthermore, the ionic liquids can be recovered and reused, which are important elements highlighted by our technoeconomic assessment. According to the process simulation, the minimum selling price for keratin is 22 $ per kg, based on a productivity of 350 tons of keratin per year, which is suitable for biomedical applications. The recovered keratin has been used to develop biocompatible films and hydrogels for wound healing, incorporated into biocomposites with melanin, cellulose, and chitin to enable tunable material properties, and integrated into advanced 3D printing technologies for tissue engineering applications. The produced keratin films exhibit remarkable properties, including strong antioxidant and anti-inflammatory effects and the potential to promote cell proliferation, thereby accelerating wound closure. Furthermore, the hydrogels produced with keratin and melanin presented outstanding UV-blocking capabilities (up to 99.9%), while the 3D printed scaffolds exhibited a dynamic shape-change over time, mediated by cellular traction forces, highlighting their potential for 4D printing toward innovative bioapplications. The work developed demonstrates the feasibility of transforming a largely untapped waste stream into high-value materials, contributing to both environmental sustainability and advancements in biomedical technologies. By offering a scalable and cost-effective method for keratin recovery, we aim to inspire future research in the development of keratin-based materials and the exploration of other waste-to-resource opportunities.