Fibril-to-Fiber Structure: Hierarchically Fabricated Amyloid Fiber via Evaporation-induced Self-assembly

Prof. Yoon’s group at KAIST and Prof. Mezzenga’s group in ETH have presented a new platform on which to fabricate and control amyloid fibrils, which are linked to the development of various diseases. They combined liquid crystal (LC) characteristics and evaporation-induced self-assembly during the formation of fiber structures from amyloid fibrils. The finely controlled deposited amyloid fibers can provide a means by which to use nature-abundant nano-bio materials for practical applications such as the fabrication of conducting gold wire. The study was published in the December 2021 issue of ACS Nano (Hierarchically Fabricated Amyloid Fibers via Evaporation-Induced Self-Assembly, ACS Nano, 15, 12, 20261-20266 (2021)).

Amyloid fibrils are protein-based anisotropic colloids formed by the self-assembly of β-sheets, which aggregate into twisted and helical ribbons. They have been intensely investigated in biology and medicine due to their relationship with pathological conditions such as age-related dementia. Recently, new approaches are emerging to recognize amyloids as one class of promising building blocks for engineering bio- and nanotechnology purposes due to their molecular functionalities and sustainability. However, only a few studies have dealt with the structural properties of ordered amyloid fibrils aggregates on a macroscopic scale because there is a lack of understanding of the interplay between their self-assembling behaviors during the condensing process.

Yoon’s group collaborated with Prof. Raffaele Mezzenga of ETH Zurich, Switzerland, and attempted to combine the unique collective behavior of amyloid fibrils with an evaporation-induced self-assembly process. Their ordering and orientation could be finely controlled depending on the concentration of aqueous amyloid dispersions. The resultant anisotropic aggregation of amyloid fibers is rationalized using a capillary flow, known as the coffee ring effect, which increases the concentration gradient towards the air-liquid-solid interface, effectively fabricating a condensed thin film. The protocol presented here allows for the fabrication of conductive micro-wires from AuNP-coated amyloid fibrils by exploiting the unique functionality of amyloid fibrils to nucleate inorganic nanoparticles on their surfaces. This attractive platform will suggest a way to produce controlled amyloid-based micro-aggregates to open new opportunities for developing novel functional biomaterials.

This work was supported, in part, by the KAIST Institute for NanoCentury and by the National Research Foundation of Korea.