Nanomaterials Inspired from the Bacterial Adhesome and Mechanome
Abstract
This project aims to establish design concepts for stronger and tougher nanocomposites based on strategies used by bacteria to achieve greater adhesion and cohesion when they are in biofilm matrices. Those strategies include: (1) the adhesive capability granted by the molecular designs of fimbrial adhesins on the surface of bacterial cells, and (2) the cohesive strength of bacterial biofilms arising from extracellular polysaccharides produced by the bacteria, notably the nanocellulose fibrils that have strength and stiffness comparable to Kevlar. It is known that the performance of nanocomposites depends not just on the constituents of the nanocomposites , but also on how those constituents interact at internal interfaces, which is similar to biofilms and how the individual bacterial cells interact within the biofilm matricies. The Principal Investigator~s hypothesis is that the processes that allow bacteria to effectively adhere to surfaces and form biofilms are similar to those that confer toughness to nanocomposites. His research objective is to combine bacterial adhesive strategies with cellulose nanoparticles to create nanocellulose particles with adhesion-mimetic ~hairs~ attached to their surfaces, and then assemble those ~hairy nanoparticles~ into nanoparticle networks. First, he will conduct studies aimed at understanding bacterial adhesives (the adhesome), and then he will incorporate those elements into composites. The chaperone/usher fimbriae found in Escherichia coli and other bacteria demonstrate three notable mechanical properties that make them promising for the interface. First, they have a tip protein which binds through catch bonds (i.e. bonds whose lifetimes intriguingly increase with applied tension). Second, their long helical shafts exhibit tremendous extensibility at a preset activation force, giving rise to a force plateau that provides plasticity, distributes forces equally among bonds, and facilitates robust attachment. Third, as in the case of Type 1 and F1C fimbriae in uropathogenic E. coli (UPEC), seemingly redundant homology structures exhibit vastly different unfolding times, which leads to the Principal Investigator~s novel hypothesis that incorporating multiplexed relaxation times may be a biological strategy for robust bacterial interfaces. A major effort in the proposed project will be to determine how best to incorporate the the hallmark features of chaperon/usher adhesins with the properties of bacterial nanocellulose in composites. A multipronged approach will be pursued that combines molecular simulation, theory, and force spectroscopy to establish strategies for designing tough assembled hairy nanoparticle systems outfitted with catch bonds, force plateaus, and multiplexed relaxation times. There are three specific project aims: (1) Discover strong interface designs by studying fimbrial adhesins; (2) Investigate the interfacial properties of hairy nanocellulose particles; and (3) Design nanocellulose composites with adhesion-inspired interfaces. Fundamental biophysical investigations on the chemistry and structure of adhesion will enable better adhesives, hydrogels, and nanocomposites, which all rely on strong, dissipative interfaces for achieving high performance. Additionally, a deeper understanding of the mechanical strategies common to the bacterial adhesome will yield insights into the origins of biofouling. The secondary aim of transferring the properties of bacterial nanocellulose, a main constituent of the extracellular polymeric substances in many bacteria, to engineering materials will help develop sustainable high performance materials. Assemblies of bacterial cellulose functionalized with hairs will lead to materials that can be used in applications such as tissue engineering, drug delivery, or materials with dynamic properties. With the incorporation of bacterial adhesion inspired interfaces, the composites will have improved performance in str
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 23, 2016
- Source ID
- N000141613175
Entities
People
- Sinan Keten
Organizations
- Northwestern University
- Office of Naval Research
- United States Navy