Inspired by Biology From Molecules to Materials to Machines (2008) / Chapter Skim
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2 Understanding Biomolecular Processes: Toward Principles That Govern Biomaterial Design
2 Understanding Biomolecular Processes: Toward Principles That Govern Biomaterial Design
Pages 10-30
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From page 10... ...
New knowledge of gene regulation and cell signaling is resulting in an ever more detailed understanding of these complex phenomena. With this increasing amount of data comes increased understanding of the mechanisms that underlie many of these processes.
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From page 11... ...
• Create new biomolecular materials with highly adaptable and controllable properties based on the mechanical design principles of cells, where bio molecular motors can actively control the stiffness of the networks that give the cell its rigidity. • Assemble new materials with the incredibly detailed precision made pos sible by interactions that result from the sequence of oligonucleotides.
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From page 12... ...
Research at the crossroads of statistical mechanics, materials science and engineering, and molecular and cell biology should pay dividends for both fundamental biological research and the understanding of these essential highly cooperative processes and interactions. Some examples of research focused on understanding the specificity of detection and the precision of response in biological systems follow in the next subsections.
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From page 13... ...
Further work along these lines will result in an understanding of the biomolecular processes that could then be harnessed to design synthetic materials that can mimic the specificity of the cells that comprise the immune system.
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From page 14... ...
These will probably be based on synthetic vesicles that contain the key biochemical elements of the signaling machinery and secretory apparatus identified by studies of the biomolecular pro cesses inherent in T cells. One specific class of candidate materials that may suit this purpose are polymersomes, capsules formed from bilayers of complex amphiphiles (for example, short peptide amphiphiles or co-assembled cationic-anionic amphi philes)
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From page 15... ...
This is mainly because the molecular motors and other molecules that are present convert chemical energy, usually in the form of adenosine triphosphate (ATP) , into mechanical energy, increasing the level of mechanical activity in the cell.
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From page 16... ...
For example, can the understanding of ion transport be generalized to nonbiological systems, where control of charge can be a mechanism to control the structure or function of biomolecular materials? While motor activity within the cell drives nonequilibrium fluctuations, the cell is, nevertheless, always near room temperature, and many biochemical pro cesses can be described by traditional equilibrium statistical mechanics.
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From page 17... ...
Internal tension is provided by activity of biomolecular motors within the cell. The elasticity is highly sensitive to the degree of internal prestress, providing a sensitive control mechanism through regulation of motor activity.
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As a result, the cell typically relies on molecular motors to actively trans port materials. Mimicking such active transport could qualitatively change the way transport is accomplished in biomolecular materials.
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From page 19... ...
Such bioinspired materials can be designed to mimic the behavior and dynamics of the cell and to recreate its remarkably adaptive and highly controllable mechanical properties. Any material fabricated with these design principles would, ideally, be scalable: The same principles could apply, for example, to the construction of macroscopic networks, which could have similar strength-to-weight ratios and which would have similar controllable mechanics.
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From page 20... ...
Processes carried out in living cells, for example, depend on the spatial organization of many different chemical components. These assembly processes are often hierarchical: Self-assembly of elementary building blocks results in secondary building units, which assemble into tertiary building units, and so on.
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From page 21... ...
These DNA structures and nanoarrays can further serve as templates for nonbiological materials and as scaffolds for nanoelectronic components and nanomechanical devices; examples include a bipedal walker and a translation device. The field of structural DNA nanotechnology is an emerging area of biomolecular materials research at the intersection of the physical and biological sciences.
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From page 22... ...
Many theoretical models exist, most involving the complex interplay of specific and directional noncovalent interactions among protein building blocks. Control of these interactions and the subsequent assembly process would allow the design of antiviral drugs to interrupt virus replication or the fabrication of empty viral capsids containing disease-fighting
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From page 23... ...
In addition, it could open the way to the exploitation of similar principles to create hierarchically arranged structures with nonbiological materials. Complex Spatiotemporal Assembly In many biological systems, different spatial patterns form over time.
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From page 24... ...
Movies that make these observations of the spatiotemporal evolution of protein patterns and cell shape vivid can be seen online. Similar spatiotemporal patterns were first observed at the junctions between a T cell and an APC. These spatial patterns are thought to form by a guided self-assembly processes.
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From page 25... ...
The exploitation of anisotropic, noncovalent interactions at nano and colloidal scales is an important biological approach that could be applied to the assembly of nonbiological materials. Breakthroughs in understanding biological assembly processes, and in mimicking it to create new materials and devices, will revolutionize materials fabrication and development.
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From page 26... ...
For example, might not some of the complex calculations performed by living organisms be designed into synthetic biology sys tems, and might not such a capability be harnessed to perform computations?
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From page 27... ...
Understanding the way living systems adapt will help us to design biomolecular materials with the same traits. Living organisms also adapt over time, through the process of evolution.
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From page 28... ...
The committee discussed the essential nonlinearity in biological processes, illustrating this in particular through the behavior of cells, and considered its implications for new materials, with the creation of materials with cell-mimetic capabilities a prime example. The committee discussed the conversion of chemical energy to mechanical energy by molecular motors, with the consequence that most biological materials cannot be described by equilibrium processes.
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From page 29... ...
-- Opportunity: Exploit specificity of DNA interactions to fabricate bio molecular materials -- Opportunity: Use viruses as building blocks for the assembly of more complex materials -- Opportunity: Mimic viral function in synthetic materials • Biological systems are the ultimate example of the construction of highly complex structures and systems from simple and common building blocks. This is accomplished by very fine control of the spatiotemporal assembly.
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From page 30... ...
-- Opportunity: Materials that can self-replicate -- Opportunity: Materials that can adapt by changing the stored information -- Opportunity: Modification of materials properties with analogues of RNAi Suggested Reading Arnold, F.H. "Design by directed evolution," Accounts of Chemical Research 31:125 (1998)
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