A review on keratin-based sensor platforms: Structural properties of keratin, their role in analytical sensing applications, and future perspectives.

Keratin, a fibrous structural protein abundant in biological materials, has recently garnered attention as a novel and environmentally friendly material for sensor platforms due to its diverse properties and biocompatibility. This review provides a comprehensive and up-to-date overview of keratin-based sensor platforms, emphasizing the structural features, such as its complex disulfide (-S-S) bonding network and ability to form nanofibrous matrices, that make keratin particularly suitable for analytical sensing applications. The sensing performance of keratin-based materials is critically evaluated, with a focus on their sensitivity and selectivity toward various analytes, including pharmaceutical compounds, proteins, and heavy metals. Particular attention is given to the mechanisms by which keratin interacts with analytes to produce measurable electrical, optical, or mechanical signals. Furthermore, the review discusses current limitations, including the need for improved mechanical stability and long-term durability, and outlines strategies for functional modification. The review also addresses fabrication techniques such as electrospinning and layer-by-layer assembly used to integrate keratin into sensor platforms. Additionally, the potential for incorporating keratin-based sensors into wearable and implantable devices is explored, with a focus on their applications in medical diagnostics, environmental monitoring, and food safety. Unlike previous reviews that primarily address keratin's general biomaterial applications, this review presents a focused and in-depth analysis of keratin's role specifically in sensor technology, showcasing the most recent advances, fabrication strategies, and practical implementations. The review uniquely bridges the gap between fundamental keratin chemistry and real-world sensor development, offering novel insights into how keratin's molecular versatility can be harnessed to design next-generation, eco-friendly, and biocompatible sensing platforms.