Unveiling the multifaceted potential of amyloid fibrils: from pathogenic myths to biotechnological marvels.

Amyloid fibrils, historically stigmatized due to their association with diseases like Alzheimer's and Parkinson's, are now recognized as a distinct class of functional proteins with extraordinary potential. These highly ordered, cross-β-sheet protein aggregates are found across all domains of life, playing crucial physiological roles. In bacteria, functional amyloids like curli fibers are essential for surface adhesion, biofilm formation, and viral DNA packaging. Fungal prions exploit amyloid conformations to regulate translation, metabolism, and virulence, while mammalian amyloids are integral to melanin synthesis, hormone storage, and antimicrobial defense. The stability and hydrophobic nature of amyloid scaffolds underpin these diverse biological functions. Beyond their natural roles, amyloid fibrils offer unique capabilities in biomedicine, nanotechnology, and materials science. Their exceptional mechanical strength and biocompatibility make them ideal for controlled drug delivery, tissue engineering scaffolds, and enzyme immobilization. The intrinsic fluorescence and optical properties of certain amyloids open up innovative applications in biosensors, molecular probes, and optoelectronic devices. Furthermore, amyloid fibrils can template metal nanowires, enhance conducting materials, and form nanocomposites by integrating with polymers. This newfound appreciation for the functional diversity of amyloids has ignited intense research efforts to elucidate their molecular mechanisms, stability, and tunable properties. By unraveling the structural intricacies of functional amyloids, researchers aim to harness their remarkable attributes for groundbreaking biomedical therapies, advanced nanomaterials, and sustainable biotechnological innovations. This review explores the transformative journey of amyloids from pathological entities to biotechnological marvels, highlighting their vast potential across agriculture, environmental remediation, and industrial processes.