Material science has always been at the forefront of human innovation, driving advancements in various industries. With the emergence of synthetic biology, a new era of material development has begun. By harnessing the power of living organisms and their ability to engineer complex molecular structures, scientists are revolutionizing material science and pushing the boundaries of what’s possible. In this article, we will explore how synthetic biology is transforming the creation of biomaterials, particularly in the fields of body armor, self-healing, and fire resistance.
Biological materials are materials that are produced by living organisms, such as, blood, bone, proteins, muscle, and other organic material. Biomaterials, on the other hand, are materials that are created specifically to be used for biological applications. These applications can include bone replacement, skin replacement, membranes for dialysis, artificial limbs, etc. Examples of biomaterials include metals, ceramics, glass, and polymers. These biomaterials can be found in things such as contact lenses, pacemakers, heart valves, orthopedic devices, and much more.
Bio-based materials are materials that are derived from living organisms but are repurposed for other applications. One example of a bio-based material would be enzymes mass-produced by microbes to be used in the synthesis of drugs. Biomimetic materials are materials that are physically or chemically similar to materials produced by living organisms. Biologically derived materials have numerous applications in biomedical fields and beyond. Yet, the properties of these materials are difficult to alter because the natural biosynthetic mechanisms are difficult to elucidate, imitate, or adjust. Thus, many bio-derived materials are isolated from natural tissues, or substitutes are recombinantly produced and then modified ex vivo.
Structural biomaterials, as the name implies, have as their primary function physical support and structure. Structural biomaterials are sometimes referred to as inert biomaterials. An example of a structural biomaterial would be a titanium steel implant with a ball and socket being used as a hip replacement. Functional biomaterials (also known as active biomaterials) have a non-structural application as their primary function. An example of a functional biomaterial would be membranes used during dialysis to filter impurities from blood.
The structural materials that are currently used in our human-built environments wear out due to age and damage, and have limited ability to respond to changes in their immediate surroundings. In contrast, living biological materials like bone, skin, bark, and coral, have attributes that provide advantages over the non-living materials people build with – they can be grown where needed, self-repair when damaged, and respond to changes in their surroundings.
Biological systems in nature assemble living materials that are autonomously patterned, can self-repair and can sense and respond to their environment; however, engineering materials typically cannot (grown engineering materials are not entirely new, e.g. wood, but they are rendered inert during the manufacturing process, so they exhibit few of their components’ original biological advantages).
The inclusion of living materials in human-built environments could offer significant benefits. Unfortunately, scientists and engineers are unable to easily control the size and shape of living materials in ways that would make them useful for construction.
A major shift in this paradigm is being driven by the maturing field of synthetic biology, which is innovating a ‘tool box’ of methods to tune biomolecules and biosynthetic mechanisms in vivo. Thus, application of the synthetic biology ‘tool box’ to bio-derived materials heralds a new era where bio-derived materials are replicated, mimicked, and modified with engineered biosynthesis.
Biomedically relevant structural polymers produced by microbes can be improved or modified with synthetic biology. These biomaterials fall into two broad classes—ribosomally synthesized proteins and non-ribosomally synthesized polymers.
Ribosomal protein-based structural biomaterials largely consist of polypeptides that comprise or mimic the extracellular matrix (ECM). These include ECM proteins such as collagen, laminin, fibronectin, and elastin, which are currently sourced from tissue or in low-yield recombinant fermentations. For example, collagen has historically been low-yield, and has only recently been produced in tobacco plants in quantities sufficient for the production of collagen-based medical devices.
The limited availability of ECM proteins has led to sourcing of ECM protein mimics from non-mammals. These include recombinant bacterial collagen-like proteins, silk from arthropods, and the insect elastomer resilin. These ECM analogs can be produced in microbial fermentation systems with recombinant DNA. In particular, silk fibroin is a protein with remarkable mechanical properties, inspiring its extensive use as a structural biomaterial.
Non-ribosomally synthesized structural polymers are naturally produced in several microorganisms and have garnered interest for biomedical applications, and more broadly as bioplastics and biofuels. These include exopolysaccharides, polyesters, and other heteropolymers. Exopolysaccharides are structural biopolymers made from sugars which are either synthesized extracellularly or secreted by microorganisms. The assembly mechanisms allow for the formation of high-molecular weight polysaccharides with a variety of properties, including branched or linear structures and homomeric or heteromeric composition.
While many polysaccharides are used as structural materials, bacterial cellulose and hyaluronic acid in particular have drawn recent attention. Bacterial cellulose has broad applications in electronics, acoustics, and medicine due to its regular nanostructure and high purity. Each of non-ribosomal polymers has a unique biosynthetic mechanism and utility as structural biomaterials.
Synthetic Biology: Redefining Possibilities
Synthetic biology combines biology, engineering, and computer science to design and construct new biological functions and systems. This multidisciplinary approach enables researchers to manipulate living organisms at the genetic level, reprogramming them to produce desired materials with exceptional properties.
Application of synthetic biology to structural material production
Synthetic biology is an emerging field that aims to create new materials and organisms with specific properties and functions, one of the areas of application is the development of structural biomaterials.
Synthetic biology involves engineering microbes like bacteria to program them to behave in certain ways. For example, bacteria can be engineered to glow when they detect certain molecules and can be turned into tiny factories to produce chemicals. Innovations in the synthetic biology have produced tools that can design, predict, and control complex biological processes—removing the historical barriers to designing materials in vivo. Future advances might include the construction of new biological parts and brain-computer interfaces. Synthetic biology has potential to provide on-demand bio-production of novel drugs, new materials, food, fuels, sensors and coatings whatever suits the military’s needs, according to DARPA.
- Synthetic spider silk: Scientists have been working to genetically engineer bacteria to produce spider silk proteins. The resulting silk is extremely strong and lightweight, making it a promising material for structural applications such as body armor, but also in the production of ropes, cables, and other materials that require high strength and low weight.
- Synthetic cellulose: Researchers are working to engineer bacteria and plants to produce cellulose, a natural polymer that is abundant, biodegradable, and has excellent mechanical properties. Cellulose can be used in the production of bioplastics, fibers, and other materials for structural applications.
- Synthetic chitin: Chitin, a natural polymer found in the exoskeletons of insects and crustaceans, has been studied as a potential material for structural applications such as body armor, but also in construction, packaging, and other industries.
- Synthetic lignin: Lignin is a complex biopolymer found in wood and other plants that has a high strength-to-weight ratio, making it a promising material for structural applications such as construction, transportation, and packaging.
Synthetic biology techniques can be used to control the properties of these materials, such as their strength, flexibility, and biodegradability, and to optimize their production in large-scale industrial settings.
Synthetic biology methods can control the biosynthesis of each of the materials described above, including gene expression, protein function, metabolism, secretion, and extracellular assembly. The majority of these methods focus on engineering gene expression—transcription, translation, and posttranslational modifications. Additionally, metabolic engineering and protein engineering methods have been applied to alter metabolism, secretion, and extracellular assembly.
This has led to the emergence of a relatively new research field: Engineered Living Materials (ELMs). This is a novel class of materials that exploit the properties of living organisms. DARPA has even launched an Engineered Living Materials program seeking to “revolutionize military logistics and construction in remote, austere, high-risk, and/or post-disaster environments by developing living biomaterials that combine the structural properties of traditional building materials with attributes of living systems, including the ability to rapidly grow in situ, self-repair, and adapt to the environment.”
Ultimately, ELMs could lead to a future where diverse materials could be grown at home or in local production facilities, using biology rather than resource-intensive centralized manufacturing.
Synthetic biology allows synthesis of new materials that mimic natural tissues and materials with no natural analog. One of the first examples is the use of metabolic engineering to synthesize new cellulose-chitin heteropolysaccharides in bacteria
For in-depth understanding on Synthetic Biology in materials technology and applications please visit: BioCraft: Revolutionizing Material Science with Synthetic Biology
Body Armor: Lightweight and Robust
Traditionally, body armor has been constructed using rigid materials like metals and ceramics. While effective in providing protection, these materials are heavy and restrict movement. Synthetic biology offers an innovative solution by creating biomaterials that are both lightweight and robust.
Scientists have turned to genetically engineering bacteria to produce spider silk, one of nature’s strongest and most flexible materials. Spider silk possesses remarkable properties such as high tensile strength, elasticity, and toughness. By modifying the genetic code of bacteria, researchers can produce synthetic spider silk in large quantities. This biomaterial, when woven into fabrics, can offer superior protection while allowing for increased mobility due to its lightweight nature.
Self-Healing Materials: Regenerating the Unthinkable
Imagine a material that can repair itself when damaged, just like our skin heals a wound. This concept is becoming a reality through the integration of synthetic biology into material science. Self-healing materials have the potential to revolutionize numerous industries, from construction to aerospace.
By incorporating microorganisms or synthetic cells into materials, scientists can create materials capable of self-repair. These living systems respond to damage by releasing healing agents, triggering a chemical reaction that repairs the material’s structure. For instance, a material with embedded bacteria could release compounds that mend cracks or fractures, restoring its integrity.
Fire Resistance: Nature’s Blueprint
Fire safety is a critical aspect of material development, especially in applications where human lives are at stake. Traditional fire-resistant materials often rely on chemical additives, which can be harmful to the environment and may have limited effectiveness. However, synthetic biology offers a sustainable and efficient solution inspired by nature.
Researchers are studying the fire-resistant properties of organisms like plants, animals, and bacteria, seeking to understand their inherent defense mechanisms. By identifying and manipulating the genetic code responsible for these properties, scientists can engineer materials with exceptional fire resistance. These biomaterials can withstand high temperatures, self-extinguish flames, and release fire-retardant compounds to suppress combustion.
Radical route produces non-natural polymers inside cells
Researchers in the UK have achieved a significant milestone by producing non-natural polymers inside living cells using free radical chemistry. This breakthrough technique provides a unique avenue for integrating synthetic materials with biology to manipulate cell behavior, potentially leading to a wide range of applications, including novel therapies for diseases like cancer.
Traditionally, free radicals are associated with cellular damage and aging due to their involvement in oxidative stress. Cells produce specific molecules, such as antioxidants, to counteract the harmful effects of free radicals. It was previously believed that generating radicals inside cells to create polymers would be impossible due to cellular defenses.
However, the research team at the University of Edinburgh, led by Mark Bradley, challenged this belief based on their understanding of radical scavenging mechanisms within cells. They hypothesized that free radical scavengers like glutathione would not react quickly enough to neutralize the radicals necessary for polymerization, thus enabling a unique way to modify and control cells.
To prove their hypothesis, the researchers developed a polymerization technique by introducing a cell-friendly photoinitiator molecule into human cell cultures. When exposed to UV light, the photoinitiator produced free radicals inside the cells. The team also introduced biocompatible monomers into the cell cultures. By triggering the production of free radicals and facilitating their reaction with the monomers, different polymers were synthesized inside the cells. These polymers exhibited various characteristics, such as fluorescence, nanoparticle formation, and altered cellular behavior.
This achievement represents a significant advancement in merging abiotic materials with the biotic world inside cells. The implications of this approach are far-reaching, with potential applications ranging from disease treatment to bioelectronic systems incorporating conductive polymers. The researchers are particularly interested in investigating the impact of polymers on cell longevity and exploring the potential for generating specific polymers inside cells to target and kill tumor cells.
The groundbreaking nature of this research opens up new avenues in the field of chemical biology, expanding the possibilities of conducting novel chemistries within cells. The ability to produce non-natural polymers inside living cells provides exciting prospects for advancing our understanding of cellular processes and developing innovative therapeutic strategies.
Scientists Take Big Step Towards Producing Novel Polymers In Living Cells reported in Nov 2018
In a breakthrough reported in November 2018, a team of Yale chemists made significant progress in using the ribosome, the cell’s protein-making factory, to create designer polymers. The researchers found that the ribosome has the ability to insert novel building blocks of polymers at the beginning of a protein sequence. This discovery opens up possibilities for developing stronger and more flexible materials, as well as life-saving drugs.
The ribosome’s main function is to string together amino acids to form proteins. The sequence of amino acids is encoded genetically and decoded by the ribosome. Scientists have been studying how to introduce novel amino acids into proteins for years. However, in this study, the researchers discovered that the ribosome can create bonds between amino acids and completely unrelated chemicals, such as those found in Kevlar or the precursors to important antibiotics.
The findings represent an important step towards using the ribosome to synthesize chains of unnatural polymers. Since the ribosome follows genetically encoded instructions, these unnatural polymers can be programmed in the same way as protein synthesis. This opens up possibilities for creating novel fabrics with unique properties or developing new therapeutics.
The study was conducted by the Center for Genetically Encoded Materials (C-GEM) at Yale, led by Alanna Schepartz. C-GEM brings together scientists from various fields, including chemistry and synthetic biology, to pursue the mission of making chemical polymers with defined sequences and lengths from living cells. The interdisciplinary nature of the research and collaboration within C-GEM played a crucial role in achieving these breakthrough results.
The potential applications of this discovery are vast. It could lead to the development of fabrics with the sheerness of nylon and the strength of Kevlar. Additionally, the ribosome’s ability to incorporate precursor molecules for valuable natural products offers possibilities for new antibiotics and cholesterol-lowering drugs.
This research is considered high-risk yet high-reward, and its progress highlights the power of harnessing biological chemistries for designing novel synthetic pathways. The interdisciplinary approach and collaborative environment fostered by C-GEM and supported by the National Science Foundation (NSF) are driving innovation in the field of biomaterials and paving the way for the development of new molecules and polymers with remarkable properties.
US Army project makes key findings in ribosomal monomers research reported in Nov 2019
In November 2019, a research project funded by the US Army made significant findings in ribosomal monomers research, paving the way for the development of new high-performance materials and therapeutics for soldiers. Synthetic biologists at Northwestern University focused on expanding the range of monomers used by the ribosome, which is a crucial step towards achieving sequence-defined synthetic polymers.
The researchers developed design rules that guided how ribosomes can incorporate new types of monomers. By utilizing a process called flexizyme, the team linked the monomers to transfer RNAs (tRNAs). They successfully created 37 monomers from a diverse range of scaffolds, expanding the possibilities for developing new classes of synthetic polymers.
The implications of this breakthrough are significant. The new synthetic polymers have the potential to be used in various applications, including electronics, advanced solar cells, nanofabrication, and personal protective gear for soldiers. Achieving sequence-defined synthetic polymers has long been a grand challenge in the field of polymer chemistry, and this research project represents a step forward in overcoming that challenge.
The project was carried out under the US Department of Defense’s Multidisciplinary University Research Initiatives program, emphasizing the military’s interest in developing innovative materials and technologies to enhance soldier protection and performance.
By expanding the repertoire of monomers and developing design rules for ribosomal incorporation, this research project sets the stage for future advancements in the field of synthetic polymers. It highlights the potential of synthetic biology to create new materials with tailored properties and functionalities, with implications not only for military applications but also for various other industries and technological advancements.
Start-up uses CO2 to create bio-building blocks reported in Oct 2021
Cemvita Factory, an industrial biotechnology start-up based in Houston, is using synthetic biology and microbes to address greenhouse gas emissions and produce bio-polymers for plastics manufacturing. The company has developed a conversion platform that utilizes genetically engineered microbes to transform carbon dioxide into valuable organic molecules.
Instead of traditional feedstocks like corn or sugar, Cemvita’s approach involves using carbon dioxide as the primary feedstock. By incorporating the gene for the ethylene-forming enzyme from bananas into a host micro-organism, the company has created a system that converts carbon dioxide and water into bioethylene.
Cemvita Factory has identified more than 30 critical molecules that can be synthesized from carbon dioxide, with a particular focus on the building blocks of polymers and plastics. By sequestering carbon in these longer-lasting materials, the company aims to contribute to carbon dioxide reduction efforts. In fact, their economic assessment suggests that by utilizing 1.7 million tonnes of carbon dioxide from the flue gas of a co-generation power plant, they could produce 1 billion pounds of bio-ethylene annually.
The innovative use of synthetic biology and carbon dioxide as a feedstock represents a significant step forward in sustainable manufacturing. Cemvita Factory’s approach has the potential to reduce greenhouse gas emissions, decrease reliance on traditional feedstocks, and contribute to the development of bio-based and environmentally friendly materials.
Using living bacteria to design self-growing engineering materials reported in March 2021
Researchers at the University of Southern California have made progress in using living bacteria and 3D-printed materials to create bionic mineralized composites with ordered microstructures. This breakthrough opens up possibilities for engineering materials that can self-grow, resembling living organisms.
The team developed a strategy to manufacture bionic mineralized composites by utilizing bacteria-assisted mineralization within 3D-printed polymer scaffolds. This method allows for the production of mineralized composites with high mineral fractions and highly ordered mineral orientations, surpassing existing techniques.
The focus of the research was on mineralized composites, which are tough materials found in nature, such as teeth, pearls, and mantis shrimp clubs. To design mineralized composites with high fracture toughness, two requirements must be met: a high mineral volume fraction and ordered mineral fiber orientations. While existing engineering methods typically fulfill only one requirement, the team’s approach fulfills both.
By harnessing bacteria-assisted mineral growth within 3D-printed microporous lattice scaffolds, the researchers employed specific bacteria (S. pasteurii) known for secreting the enzyme urease. When urease reacts with urea and calcium ions, it produces calcium carbonate, a strong mineral compound found in bones and teeth. Guiding the bacteria to grow calcium carbonate minerals resulted in ordered microstructures similar to those found in natural mineralized composites.
The bionic materials created through this method exhibit exceptional mechanical properties, including high specific strength, fracture toughness comparable to natural composites, and superior energy absorption capability. These materials have potential applications in high-performance structures like aerospace panels and vehicle frames, as well as lightweight defense applications such as body or vehicle armors.
An intriguing aspect of these materials is their self-growing properties. For instance, if used in a bridge, any damage can be repaired by introducing bacteria to grow the affected structures back. This suggests exciting opportunities for self-repairing structures in various applications.
Overall, this research demonstrates the potential of using living bacteria and 3D-printed materials to design self-growing engineering materials with exceptional properties, opening up new possibilities in the field of material science and engineering.
Naval Research Office-led program to demonstrate biosynthetic materials in Dec 2021
The Naval Research Office (NRL) is currently in the process of selecting a contractor to develop and test biosynthetic materials that can withstand fire, lasers, and use on drones. The NRL is interested in using resveratrol, a compound produced by certain plants that has a wide range of biological properties, to create these materials.
The contractor selected for this project will need to produce a biosynthetic resin and a man-sized drone with composite wings. The drone will be used to conduct ground tests, including fire-resistance testing and a laser strike simulation. Comparative laser tests with both a commercial epoxy composite and the resveratrol-based composite material will also need to be completed.
The development of biosynthetic materials could have a number of potential benefits for the military. These materials could be used to create lighter, stronger, and more durable structures that are also resistant to fire and lasers. This could lead to improvements in the performance of military aircraft, ships, and other vehicles.
In addition, biosynthetic materials could be used to create new types of sensors and other electronic devices that are more resistant to damage. This could improve the survivability of these devices in combat and make them more effective in gathering intelligence.
Ground-Breaking New Shock-Absorbing Material Can Stop Supersonic Impacts, reported in Dec 2022
Researchers at the University of Kent have developed a groundbreaking shock-absorbing material named TSAM (Talin Shock Absorbing Materials) that has the ability to stop supersonic projectile impacts. This protein-based material, a product of synthetic biology, has potential applications in defense and planetary science, including the development of next-generation bulletproof armor and materials for studying hypervelocity impacts in space and the upper atmosphere.
The team demonstrated the effectiveness of TSAM by subjecting the material to supersonic impacts exceeding 1.5 km/s (3,400 mph), which is faster than the velocities at which particles in space impact natural and man-made objects. TSAM not only absorbed the impact of basalt particles and aluminum shrapnel but also preserved these projectiles post-impact.
Compared to existing body armor composed of heavy ceramic and fiber-reinforced composites, TSAM offers a lighter and longer-lasting alternative. Traditional armor blocks bullets and shrapnel but doesn’t address the kinetic energy that can cause blunt trauma. In contrast, TSAM provides enhanced protection against a wider range of injuries, including those caused by shock.
TSAM’s ability to capture and preserve projectiles post-impact makes it valuable in the aerospace sector. It can be used to collect and study space debris, space dust, and micrometeoroids, improving the safety of astronauts and the longevity of aerospace equipment. TSAM may replace industry-standard aerogels, which are susceptible to melting due to temperature elevation resulting from projectile impact.
The development of TSAM represents a significant advancement in the field of shock-absorbing materials, with the potential to revolutionize defense technologies, space exploration, and aerospace equipment design. The patented material offers enhanced protection, durability, and projectile capture capabilities, paving the way for safer and more efficient applications in various industries.
Reference: “Next generation protein-based materials capture and preserve projectiles from supersonic impacts” by Jack A. Doolan, Luke S. Alesbrook, Karen B. Baker, Ian R. Brown, George T. Williams, Jennifer R. Hiscock and Benjamin T. Goult, 29 November 2022, bioRxiv.
Challenges and Future Outlook
While the potential of synthetic biology in material science is vast, several challenges must be addressed. Safety and ethical considerations are of utmost importance, ensuring the responsible use of genetically modified organisms and the impact of these materials on ecosystems and human health.
Looking ahead, the future of biomaterials through synthetic biology is promising. Ongoing research aims to refine the production methods, optimize material properties, and explore new applications. As our understanding of genetic engineering and synthetic biology deepens, we can expect even more groundbreaking advancements in the field of biomaterials.
The integration of synthetic biology into material science is revolutionizing the development of biomaterials. By leveraging the power of living organisms, researchers are pushing the boundaries of what materials can achieve. The creation of lightweight and robust body armor, self-healing materials, and fire-resistant compounds are just afew examples of the remarkable advancements made possible through synthetic biology. These biomaterials have the potential to enhance safety, improve performance, and revolutionize various industries.
As we continue to explore the possibilities offered by synthetic biology, it is essential to strike a balance between innovation and responsibility. The ethical considerations surrounding the use of genetically modified organisms and the long-term impact on the environment and human health must be carefully addressed.
With continued research and collaboration between scientists, engineers, and policymakers, the potential for synthetic biology to revolutionize material science is immense. As we unlock the secrets of nature’s blueprint, we open the door to a future where biomaterials with extraordinary properties become the norm, transforming industries and enhancing the quality of human life.
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