Researchers from Wyss Institute have revealed a scalable method for building biomaterials from protein structures known as "amyloids." Ongoing work in the lab will focus on fabricating a wide variety of materials, including hydrogels that can interface with the body.

A new vacuum filtration method allows free-standing protein structures, such as the film pictured on the left, to be produced in bacterial broth culture and then quickly separated from the broth. A scanning electron micrograph of the amyloid film (right) shows the imprint of pores left behind by the filtration membrane used to separate it from bacterial broth culture.
(Credit: Wyss Institute at Harvard University)

Amyloids, naturally occurring fibrous structures, have nanometer-size features. Originally thought to be indications of Alzheimer’s and Parkinson’s diseases, triggered by protein misfolding, “functional amyloids” are now known to protect organisms in their interaction with surfaces, including insects and bacteria.

Because of the amyloid's molecular self-assembly capabilities, materials scientists have been interested in amyloid fibers as a powerful platform for building biomaterials. Amyloid biomaterials have already been used in applications ranging from water purification to vaccines and tissue engineering.

Conventional approaches to amyloid-based materials fabrication, however, either rely on protein components isolated from natural sources, which are difficult to customize for particular applications, or they require time-consuming and costly purification after recombinant production in a microbial host like E. coli.

A team, led by Wyss Core Faculty member Neel Joshi, Ph.D., has designed a streamlined, vacuum filtration method that enables fast separation of amyloid fibers from E. coli broth cultures. The technique relies on the ability of a particular class of amyloid fibers to remain intact even in the presence of harsh detergents and enzymes that will break down cells, DNA, and other proteins.

The vacuum filtration method developed by Joshi and postdoctoral researchers Noémie-Manuelle Dorval Courchesne and Anna Duraj-Thatte allows for E. coli’s manufacturing system to be harnessed and modified to produce biomaterials with specified shapes and sizes and useful properties, including the ability act as an adhesive between two biological surfaces, or to provide signals to biological tissues.

“Our method makes highly customized materials built from recombinant proteins accessible to anybody who can culture bacteria and perform filtration,” said Joshi, who is also Associate Professor of Chemical and Biological Engineering at the Harvard John A. Paulson School of Engineering and Applies Sciences.