Innovative Chemicals and Materials.
Envision a future of materials that are renewable, repair themselves and can be shaped into any structural form with the desired functionality and performance. All this without complicated machinery and human intervention. Sounds like daydreaming but in fact describes the daily reality of natural processes. Look around in nature, all fauna and flora and even inorganic materials are shaped without human intervention. How is this possible, how does this work and what has this to do with bioeconomy?
When discussing sustainability, circularity, bioeconomy and associated topics, nature is often cited as the ultimate reference model. However, the workings of a fossil-fuel based society and nature cannot be more diverse. The key differences are the flow of energy, the cycle of matter and the time scale. Nature operates as a circular, solar powered system, whereas a fossil-fuel based society operates as a linear, extractive system. In nature all processes are continuously powered in real-time by solar energy, reuse or store constantly in a closed loop every atom and molecule so that there is no such thing as waste and efficiently built complex structures. Natural processes work from the bottom up through self-organization and self-assembly to shape structure and functionality. In a fossil-fuel based society stored solar energy that was captured and buried millions of years ago is used for brute-force processes to make goods and to release the once underground locked carbon into the atmosphere. These processes create structure rather inefficiently from the top down. Post-use, the goods are mostly wasted and disbanded in the biosphere for nature to take care off. All discarded goods are mostly incompatible with and often toxic for nature.
Slow and Fast Cycles
The most dramatic difference however is the distinctive time scale. Natural processes operate at two levels, the first are daily/seasonal “fast” biological cycles that grow carbon-based structures using atmospheric CO2. Plants capture and store CO2 to grow and upon decay eventually release the CO2 back into the atmosphere. Next to these fast cycles some of the carbon-based dead matter and released CO2 is sequestered into soils, rocks and ocean sediments in “slow” geological process cycles that take thousands to millions of years. Over the last 500 million years this process formed the fossil-fuels used today and brought atmospheric CO2 down to 180-280 ppm from 4’000-8’000 ppm about 2.5 million years ago. In the span of 200 years humanity raised it back to 430 ppm.
Taking carbon from the slow cycle and dumping it into the fast cycle causes disruption of the delicately created carbon cycle balance of the prevailing biosphere. The processes in nature do not operate at the timescale required to evolve or adapt to very fast releases of CO2 from burning fossil-fuels. The reduction of atmospheric CO2 over the last 500 million years is being undone at a rate 100 to 200 times faster than any natural historical increase.
If humanity wants to operate as a society in tune with the natural processes and create a bioeconomy with a net zero contribution a substantial paradigm shift will be necessary. Unfortunately, “no additional” GHG emissions will not be sufficient as a substantial removal of atmospheric CO2 is necessary to achieve the relatively balanced natural carbon cycles of the last 800’000 years.
The prevailing approaches to reduce emissions for energy production, materials processing, agricultural practices and all related societal operations need to be adapted much faster than the going rate of the last 40 years since the 1987 Brundtland report on sustainable development was published. On top it requires a change of mindset of individuals and organizations to accept a socio-economic paradigm shift.
Today, the focus in energy matters is on global electrification. Very possible although it requires a major overhaul of the distribution grid to accommodate for local electricity production alongside the existing centralized model. However, this transition places Europe in a new geopolitical dependence on critical raw materials such as lithium, copper, nickel, and rare earth metals. These are essential to make electrification a reality in view of the required cables, batteries, permanent magnets, and electronics.
If sufficient cheap renewable energy becomes available, the bioeconomy could become a major contributor, supplying essential chemicals and materials rather than serving only as a source of fuel or replacement chemicals. However, a bioeconomy limited to extracting or fermenting biomass to produce the same chemicals currently derived from fossil fuels falls short of its true potential. The current “bio-for-fossil” approach fits existing value chains and infrastructure, making it an attractive and straightforward option. Even so, uptake of the bioeconomy remains slow, mainly because production costs are still high relative to fossil-based alternatives, laboratory technologies are difficult to scale up commercially, and the regulatory landscape is fragmented, hindering market entry. Although the bioeconomy is widely seen as a key to sustainability, its transition is constrained by structural inertia, limited investment in infrastructure, and, in some cases, the absence of clear and consistent regional and cross-border policy support
Self-organisation and Self-assembly
The current approach also overlooks the ability of natural processes to build matter from the bottom up. Although self-organization and self-assembly have been extensively studied over the past 50 years, the development of practical applications remains limited, with only few exceptions in the pharmaceutical and medical fields.
Beyond the scientific and technological challenges, a similar explanation as for the current “replacement” approach may account for the slow adoption. This is somewhat surprising, given that self-organization and self-assembly are fundamental processes underlying all living and non-living matter on Earth. From the bottom up, these processes can spontaneously generate structures and functionalities that are difficult to achieve within the current fossil-fuel paradigm. The main challenge, therefore, is to identify and develop the chemicals and materials applications that become possible when moving beyond fossil-based systems.
Self-organization and self-assembly are often used interchangeably, but they differ in an important way related to the energy state of a system. A system can be understood as a collection of interacting components—such as atoms, molecules, birds, people, computers or machines—that function together as a single unit within defined boundary conditions to achieve an emergent outcome. This outcome arises from the interactions among the components under those specific conditions. In the present context, a system refers to a collection of atoms or molecules.
Self-assembly refers to the spontaneous association of interacting atoms or molecules that, under prevailing boundary conditions, move toward a lowest-energy state (equilibrium) and form a stable structure. This structure persists as long as the boundary conditions remain favorable, suggesting the possibility of reversible structures. A classic example is the formation of micelles from soap molecules in water. These spherical micellar structures can disassemble when conditions change—for instance, by altering pH, heating the system, or adding ethanol—and can re-form when the original conditions are restored.
By contrast, self-organization also involves the spontaneous emergence of stable structures from interacting atoms or molecules, but these structures are maintained only through a continuous influx of energy. Such dissipative systems are far from equilibrium. For example, a fluid vortex is a structure of molecules that can exist only when a sufficiently high flow rate is sustained by adequate energy input under the prevailing boundary conditions. If the energy input is reduced or stops, the vortex disappears and the fluid molecules return to a random state
All living systems are dissipative systems: they survive only when sufficient energy input—for example, sunlight, food, or feed—is available to keep self-organizing processes active in shaping and maintaining stable structures.
These two processes operate in nature primarily through peptides, nucleotides, saccharides, and lipids as basic building blocks. These molecules can organize and form structures on their own, in combination with other building blocks, or act as agents that guide and induce structure formation and biomineralization. In biological systems, spontaneously formed structures can be observed across multiple length scales. Bone, for instance, is a self-assembled construct organized hierarchically into 12 levels of structure spanning several orders of magnitude, from the atomic scale of the mineral unit cells to the macroscopic bones and the skeleton. Bone is produced by specialized cells that first generate a dense network of collagen and other protein fibers, followed by the release of calcium and phosphate, which crystallize into hydroxyapatite and fill the spaces between the fibers.
Application Spaces
The self-organization and self-assembly approaches are powerful strategies for producing materials by design. These processes go far beyond the current bioeconomy practices based mainly on extraction and fermentation. In recent years, some progress has been made in developing novel hybrid self-assembled materials as well as in functionalizing pre-existing materials with self-organizing conjugates. The most studied structures are micelles, vesicles, and gels, which can be produced in vitro or in vivo. However, foams, fibers, scaffolds, and composites and many other structures are also possible.
A key mechanism driving assembly is the use of so-called weak non-covalent interactions, including electrostatic interactions, hydrophilic and hydrophobic interactions, hydrogen bonding, and π–π interactions. A major challenge in smart material design is controlling the formation of the desired structure. This can be addressed through two main strategies: adjusting internal interactions and adjusting external stimuli. Internal interactions are determined by the detailed molecular composition and the three-dimensional structure of the building blocks, whereas external stimuli include temperature changes, variations in ionic strength, and pH adjustments through the addition of chemicals. By controlling internal interactions and applying external stimuli, self-assembled structures can be directed toward desired architectures.
Self-assembly is most advanced in medical and healthcare applications, where for example DNA, proteins, carbohydrates, and lipids naturally can be organized into “containers” that protect active compounds from degradation and release them at specific target sites. Beyond targeted drug delivery, other important applications include vaccine platforms, tissue engineering, and biosensors.
In the electronics and computer industry, self-assembly enables the nanoscale organization of molecular components, making it possible to fabricate structures that would be difficult or impossible to produce otherwise. This has relevance for molecular-scale diodes, transistors, and nanowires. DNA origami[i] can be programmed to store vast amounts of digital data or serve as a substrate for molecular computing.
Carbohydrates self-assemble by exploiting the structural diversity and biological recognition properties of sugars to build functional materials. For example, natural polysaccharides such as alginate, hyaluronic acid, and chitosan can form three-dimensional hydrogel networks that mimic the extracellular matrix and provide a structural framework for cell growth in bone and cartilage.
Likewise, cellulose nanocrystals can form helicoidal structures that generate vivid structural colors without the need for pigments or dyes.
Proteins and peptides are by far the most versatile in forming structures, directing assembly pathways, and defining functional properties. Self-assembled protein structures can increase the surface area of catalytic materials, thereby improving the speed and efficiency of chemical reactions. They also allow surface property modification through self-assembled monolayers, for example to create hydrophobic or hydrophilic surfaces, or to build layered organic-inorganic structures such as nacre and solar cells. Depending on peptide length and amino acid sequence, peptides and proteins can form secondary, tertiary, and quaternary structures, creating additional design opportunities in surfactants, antimicrobials, antifreezes, fibers, foams, adhesives, and construction materials.
It should be clear that the possibilities of self-assembly and self-organization are vast. So far, only a very small fraction of what is possible with nature’s building blocks has been explored. The bioeconomy is therefore more than biorefinery and biotechnology; it is also materials science at a scale that is hardly mainstream research, development, or exploitation. Moreover, using nature’s molecular building blocks opens the door to benefiting from nature’s “no-waste” infrastructure. Building a truly sustainable circular society will require moving beyond fragmented, short-term solutions and instead learning from and applying the principles embedded in natural processes.
[i] DNA origami is made from a long single strand of DNA (the paper) that acts as a scaffold to which are added hundreds of short nucleotide sequences designed to complement specific, distant sections of the scaffold. When mixed heated /cooled the short sequences seek out their matching sequence on the scaffold and force the long strand to fold in a predetermined shape (the origami structure).
