Research interests
Our lab's research is focused on understanding the mechanics of deformation and failure of biological materials. By utilizing a computational materials science approach, our goal is to understand the mechanical properties of biological materials from a fundamental level.
Catastrophic phenomena that afflict millions of lives, ranging from the failure of the Earth’s crust in earthquakes, to the collapse of buildings, to the failure of bones due to injuries, all have one common underlying theme: the breakdown of the basic constituents of any material ultimately leads to the failure of its overall structure and intended function.
The failure and deformation of engineering materials has been studied extensively and has impacted our world by enabling the design of complex structures and advanced devices. However, the mechanisms of failure in biological systems are not well understood, and represents an opportunity to generate novel concepts to initiate a new paradigm of materials science.
|
|
Fracture mechanics of protein materials
The properties of protein networks arise from their hierarchical structure and the deformation and fracture mechanisms that occur at each scale from the nano to macro level. Modeling studies are revealing a great deal about the interplay of these mechanisms (link...). |
We apply an atomistic multi-scale simulation approach that explicitly considers the architecture of proteins from the atomistic level up to the overall structure, supporting the structure-process-property paradigm of materials science. In addition to contributing to a fundamental understanding of the role of materials in biology, the long-term goal of our research is to develop a new engineering paradigm that encompasses the design of structures and materials starting from the molecular level, to creating new materials that mimic and exceed the properties of biological analogs. We envision that our work can lead to the development of a new set of tools that can be applied, together with synthetic biological techniques, to select, design, and manufacture a new class of materials, similar to what is done today in computer aided design of engineering buildings, cars and machines.
Civil engineering is a broad subfield of engineering that focuses on strategies to develop and maintain the infrastructures to enable and evolve modern civilization. Environmental engineering is concerned with the complex interaction of synthetic structures with natural environments, and with development of environmentally friendly engineering concepts. In both fields, materials and their properties play an essential role for many applications. Its fundamental, theoretical and scientific understanding is the primary goal of the research carried out in our Lab. For example, a better understanding of the failure mechanisms of materials has high impact in preventing failure of existing structures. Development of new materials may lead to better designs and could replace classical designs, as for example by using enviromentally friendly coatings. Our research program will extend our ability to carry out structural engineering, as used for buildings or bridges today, to the ultimate scale, the nanoscale. Methods developed and utilized in nanoscience and nanotechnology will enable to make structures at such small scales.
 |
Merger of structure and material
Biological protein materials provide the foundation for the integration of structure and material, thereby enabling the inclusion of molecular and multi-scale features in the material design process.
We are particular interested in the combination of disparate properties in biological materials, such as strength, robustness, great elasticity, adaptability, changeability, or evolvability. We use an interdisciplinary approach for the analysis that combines supercomputer atomistic and multi-scale modeling with theoretical model development.
(Figure from: M. Buehler, T. Ackbarow, Materials Today, 2007) |
Materials science of biological materials: Materiomics
The mechanical properties of biological materials have been the focal point of extensive studies over the past decades, leading to formation of a new research field that intimately connects biology, chemistry and materials science. Significant advances have been made throughout many disciplines and research areas, ranging throughout a variety of material scales, from atomistic, molecular up to continuum scales. Experimental studies are now carried out with molecular precision, including investigations of how molecular defects such as protein mutations or protein knockout influence larger length- and time-scales. Simulation studies of biological materials now range from electronic structure calculations of DNA, molecular simulations of proteins and biomolecules like actin and tubulin to continuum theories of bone and collagenous tissues. The integration of predictive numerical studies with experimental methods represents a new frontier in materials research. The field is at a turning point when major breakthroughs in the understanding, synthesis, control and analysis of complex biological systems emerge.
Materiomics is defined as the study of the material properties of biological materials (e.g. hierarchical protein structures and materials, mineralized biological tissues, etc.) and their effect on the macroscopic function and failure in their biological context, linking processes, structure and properties at multiple scales through a materials science approach.This term has been coined in analogy to genomics, the study of an organism's entire genome. Similarly, materiomics refers to the study of the processes, structures and properties of materials in an a biological organism or biological system, its materiome.
Examples of current research projects
|
Nanomechanics of collagen fibrils
Atomistic based hierarchical multiscale modeling of a complex biological composite material. Our hierarchical multi-scale simulation scheme enables us to develop a fundamental, atomistic based description of collagen.
Our molecular model of collagen is used to investigate several aspects related to collagen based tissues, including source of elasticity, fracture behavior, molecular origin of diseases, synthesis of synthetic collagen and the mechanics of mineralized tissue such as bone.
(Proc . Nat'l Academy of Sciences USA, link to paper..., MIT News Release...).
|
This multi-scale viewpoint of materials deformation and failure provides novel insight into structure-property link of biological materials. Our laboratory focuses on several materials, including bone and spider silk. A particular focus for studies in bone is the analysis of disease mechanisms.
|
 |
Fracture mechanics and plasticity of bone
Molecular modeling is used to study the elementary deformation mechanisms of fracture of bone materials. This provides insight into the origin of bone's great toughness, high strength and light weight.
Molecular nanomechanics of bone:
fibrillar toughening by mineralization (link to paper ... )
MIT probes secret of bone's strength
(link to news release...) |
| Advances in experimental, computational and theoretical methods now enable the integration of a variety of tools, providing synergies with significant impact on advancing our knowledge base. |
Multi-scale simularion and analysis paradigm: Integration of computational and theoretical methods with experimental analysis and characterization methods.
|
Geometric Confinement Governs the Rupture Strength of H-bond Assemblies at a Critical Length Scale
The ultrastructure of protein materials such as spider silk, muscle tissue or amyloid fibers consists primarily of beta-sheets structures, composed of hierarchical assemblies of H-bonds. Despite the weakness of H-bond interactions – intermolecular bonds 100 to 1,000 times weaker than those in ceramics or metals – these materials combine exceptional strength, robustness and resilience. We discover that the rupture strength of H-bond assemblies is governed by geometric confinement effects, suggesting that clusters of at most 3-4 H-bonds break concurrently, even under uniform shear loading of a much larger number of H-bonds. This universally valid result leads to an intrinsic strength limitation that suggests that shorter strands with less H-bonds achieve the highest shear strength. Our finding explains how the intrinsic strength limitation of H-bonds is overcome by the formation of a nanocomposite structure of H-bond clusters, enabling the formation larger, much stronger beta-sheet structures. Our results explain proteomics data, suggesting a correlation between shear strength and prevalence of beta-strand lengths in biology.
|
S. Keten and M.J. Buehler, Nano Letters, Vol. 8(2), 2008 (link to paper...)
|
|
