Bioinspiration and Biomimicry in Chemistry

Reverse-Engineering Nature

Gerhard Swiegers

• Publisher: Wiley
• Year: 2012
• Print ISBN: 9780470566671
• eBook ISBN: 9781118310076
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

Can we emulate nature's technology in chemistry?

Through billions of years of evolution, Nature has generated some remarkable systems and substances that have made life on earth what it is today. Increasingly, scientists are seeking to mimic Nature's systems and processes in the lab in order to harness the power of Nature for the benefit of society.

Bioinspiration and Biomimicry in Chemistry explores the chemistry of Nature and how we can replicate what Nature does in abiological settings. Specifically, the book focuses on wholly artificial, man-made systems that employ or are inspired by principles of Nature, but which do not use materials of biological origin.

Beginning with a general overview of the concept of bioinspiration and biomimicry in chemistry, the book tackles such topics as:

• Bioinspired molecular machines
• Bioinspired catalysis
• Biomimetic amphiphiles and vesicles
• Biomimetic principles in macromolecular science
• Biomimetic cavities and bioinspired receptors
• Biomimicry in organic synthesis

Written by a team of leading international experts, the contributed chapters collectively lay the groundwork for a new generation of environmentally friendly and sustainable materials, pharmaceuticals, and technologies. Readers will discover the latest advances in our ability to replicate natural systems and materials as well as the many impediments that remain, proving how much we still need to learn about how Nature works.

Bioinspiration and Biomimicry in Chemistry is recommended for students and researchers in all realms of chemistry. Addressing how scientists are working to reverse engineer Nature in all areas of chemical research, the book is designed to stimulate new discussion and research in this exciting and promising field.

Chapter 1: Introduction: The Concept of Biomimicry and Bioinspiration in Chemistry

Timothy W. Hanks

Gerhard F. Swiegers

1.1 What is Biomimicry and Bioinspiration?

The idea of looking to Nature to solve problems is undoubtedly as old as humanity itself. Observations of Nature, particularly of its biological face, have impacted the development of every facet of human society, from basic survival tactics to art, and from fashion to philosophy. Indeed, as a part of the biosphere ourselves, we cannot help but frame our conceptual understanding of ourselves and our environment in terms of biology. Bioinspiration and biomimicry, then, are ancient processes that take advantage of millions of years of evolutionary experimentation to help us address the many challenges that affect human well-being.

The term biomimetics was suggested by Schmitt in the early 1960s and was listed in Webster's dictionary as early as 1974. Webster's dictionary defined the concept as “The study of the formation, structure, or function of biologically produced substances and materials (as enzymes or silk) and biological mechanisms and processes (as protein synthesis or photosynthesis) especially for the purpose of synthesizing similar products by artificial mechanisms that mimic natural ones.”1

While there are many historical examples that fit this definition, the formalization of the concept occurred only in the late 20th century. This formalization was significant in that it arguably represented a key paradigm shift in which the chemistry community changed its focus from molecular composition to the morphology and function of molecular and supramolecular structures.

While biomimicry formally involves a direct replication of processes or techniques that are employed by Nature, bioinspiration involves a more indirect “drawing of ideas” from Nature. Here Nature serves as a rich and readily accessible source of new concepts and approaches. Of particular interest are approaches that have the potential to help solve intractable and challenging problems. Bioinspiration is mostly concerned with understanding the principles that underlie natural processes and then applying these principles in nonbiological settings. Benson, Share, and Flood describe the principle as follows in Chapter 4, “Bioinspired Molecular Machines”:

Bioinspiration is described as understanding the fundamental aspects of some biological activity and then recasting it in another form. Consider the Wright brothers' research program, where lift, control, and propulsion were all accepted elements of bird flight. The first two elements were recast in similar forms as wing shape and wing warp, whereas the latter was completely replaced with an engine-driven propeller. It is illustrative that propulsion was generated using very different means.

The distinction between biomimicry and bioinspiration is, however, not clear-cut. There are many shades of overlap between these two concepts. For example, a deliberate and systematic mimicry of techniques employed by Nature within systems that are far removed from Nature could be considered to be either biomimicry or bioinspiration. A good illustration of this is given by Hoffmann in his masterly exposition in Chapter 14, “Biomimicry in Organic Synthesis.” He says:

When the targets of natural product synthesis become even more complex in the 21st century, it is evident that the strategies and methods used in the last century reach their limits. Hence, organic chemistry is faced in the 21st century with the necessity to substantially increase the efficiency of syntheses by turning to new strategies. Combined with better synthesis methods, this should reduce the number of steps necessary to reach complex target structures. … Natural products are synthesized by Nature in the living cells from simple starting materials. … When new strategies for synthesis of such compounds are needed, it is obvious and advantageous to ask how Nature synthesizes such molecules in the process of biosynthesis. This raises the hope that Nature has found, through the process of evolution, an efficient route for the synthesis of a particular natural product, a route that could serve as a model for in vitro synthesis. Thus, knowledge of a biosynthetic pathway for a natural product of interest could serve as a guideline to develop a “biomimetic” synthesis. This line of thought could be expected to open reasonable approaches to the synthesis of a natural product, or at least provide a much better synthetic route than used before.

The formal distinctions between biomimicry and bioinspiration can therefore blur and become difficult to separate. For this reason, this book assigns the same weight and importance to both topics. It is left up to the reader to decide whether a particular experiment is best considered as biomimicry or bioinspiration.

1.2 Why Seek Inspiration from, or Replicate Biology?

1.2.1 Biomimicry and Bioinspiration as a Means of Learning from Nature and Reverse-Engineering from Nature

Perhaps the key reason for studying biomimicry and bioinspiration is to learn from Nature. Biological entities and processes have evolved over billions of years to achieve forms and functions that are often remarkable, both for their efficacy and their efficiency. Humanity has a lot to learn from Nature.

Zhu and Gu in Chapter 10, “Bioinspired Surfaces II: Bioinspired Photonic Materials,” put it very succinctly:

Nature provides inexhaustible wealth to humankind [and this is the reason to learn from it].

In Chapter 6, “Bioinspired Materials Chemistry II: Biomineralization as Inspiration for Materials Chemistry,” Nudelman and Sommerdijk state it thus:

Living organisms are well known to exploit the material properties of amorphous and crystalline minerals in building a wide range of organic–inorganic hybrid materials for a variety of purposes, such as navigation, mechanical support, protection of the soft parts of the body, and optical photonic effects. The high level of control over the composition, structure, size, and morphology of biominerals results in materials of amazing complexity and fascinating properties that strongly contrast with those of geological minerals and often surpass those of synthetic analogs. It is no surprise, then, that biominerals have intrigued scientists for many decades and served as a source of inspiration in the development of materials with highly controllable and specialized properties. Indeed, by looking at examples from the biological world, one can see how organisms are capable of manipulating mineral formation so as to produce materials that are tailor-made for their needs.

Finally, Benson and colleagues make the amusing note that we do not need an alien civilization to land on Earth in order to undertake technological development by reverse-engineering. We can reverse-engineer from Nature. That is, indeed, the very basis of biomimicry and bioinspiration. They state in Chapter 4, “Bioinspired Molecular Machines”:

A variation on this last notion of bioinspiration has a healthy life in our fertile cultural imagination—revisited in fiction and urban legend alike. The proposition has been made that the explosion in technological development over the past century or so came about when humanity reverse-engineered technology that was originally fabricated by advanced alien species. While absurd as an account of modern civilization, this sequence of events is somewhat analogous to chemistry's use of bioinspiration, which takes cues from Nature's mature “technology.”

1.2.2 Biomimicry and Bioinspiration as a Test of Our Understanding of Nature

It has often been said that one only truly understands a principle or a system if one is able to apply it in a functionally operational way, in a setting of one's own making. Much of the work described in this book is dedicated to this concept. It asks: Do we properly understand Nature's principles? If we do, then we should be able replicate, in at least some small measure, the feats of biology. If we cannot, then our understanding is necessarily and unambiguously incomplete. The experiment leaves little leeway for self-delusion. As noted by Benson, Share, and Flood in Chapter 4:

Here, the direct question to be answered once the machine has been made is: “Does it move?” Or, in the parlance of the Wright brothers, “Does it fly?”

Seen in this light, bioinspiration and biomimicry can also be considered to be a test of our understanding of Nature. Indeed, every experiment is, effectively, a measure of our understanding. Swiegers, Chen, and Wagner have stated it thus in Chapter 7, “Bioinspired Catalysis”:

Every winged aircraft and putative aircraft ever built comprises nothing less than a test of the builder's understanding of the underlying principle by which birds fly, namely, the law of the aerofoil.

1.2.3 Going Beyond Biomimicry and Bioinspiration

A question that arises is: what, in the fullness of time, is the ultimate purpose of biomimicry and bioinspiration? According to several commentators, this “ultimate purpose” is not merely to emulate Nature or achieve capacities similar to those enjoyed by Nature, but rather to go beyond Nature into a man-made realm that surpasses Nature. Nobel Laureate Jean-Marie Lehn is perhaps the foremost proponent of this approach. He describes it thus in his Foreword to this book:

Chemistry and in particular supramolecular chemistry entertain a double relationship with biology. Numerous studies are concerned with substances and processes of a biological or biomimetic nature. The scrutinization of biological processes by chemists has led to the development of models for understanding them on a molecular basis and of suitably designed effectors for acting on them. On the other hand, the challenge for chemistry lies in the development of abiotic, nonnatural systems, figments of the imagination of the chemist, displaying desired structural features and carrying out functions other than those present in biology with comparable efficiency and selectivity. Not limited by the constraints of living organisms, abiotic chemistry is free to invent new substances and processes. The field of chemistry is indeed broader than that of the systems actually realized in Nature.

1.3 Other Monikers: Bioutilization, Bioextraction, Bioderivation, and Bionics

Bioinspiration and biomimicry however, are arguably not the only descriptors of our interaction with Nature. There are several distinct approaches for making use of facts learned by observing the biosphere. The most obvious is to use natural materials directly; what we might call bioutilization. When the natural component of interest is too dilute for our purposes as harvested, such as natural products to be used in pharmaceuticals, they must be bioextracted. This technique has long been a major approach to exploiting the bounty of the biosphere and will continue to play a major role in society.

It is, moreover, often the case that a product of Nature does not meet our needs in the initially extracted form or that the extraction process may not be economically feasible. Bioderived materials are the result of modifying Nature's offerings to provide enhanced performance. The optimization and production of bioderived products has arguably been the key tool for the transformation of human society for centuries. For example, the development of organic chemistry from its origins in dye chemistry to its current key role in the pharmaceutical, plastics, and many other industries is largely a result of the modification of products found in Nature.

In addition to extracting and modifying natural materials for our own purposes, we have long strived to reproduce biological form and function. There are many examples of such efforts, including attempts by the Chinese to make artificial silk more than 3000 years ago, the invention of Velcro based on the hooked seeds of the burdock plant, and dry adhesive tape based on the surface morphology of gecko feet.2 The term bionics was introduced by Steele, in late 1958, to promote the study of biological systems for solving physical problems. Bionics was originally defined as “the science of systems which have some function copied from Nature,” but perhaps as a result of the TV series The Six Million Dollar Man, and recent interest in the brain/machine interface, the term has largely come to mean “biological electronics.” While specific interfaces between living systems and electronics may indeed have some of the features of the original definition, we will largely avoid the use of the term here to avoid confusion.

1.4 Biomimicry and Sustainability

In order to rationally exploit the products and processes of Nature for our own purposes, it is necessary to deconstruct very complex systems in order to decipher the underlying physical, chemical, and biological processes that result in the natural phenomena we wish to emulate. This process of deducing and exploiting the fundamental laws that govern the universe has proved to be a powerful strategy for technological development. Indeed, while modern science and technology has its origins in Nature, many of the products we surround ourselves with show little, or only superficial, resemblance to naturally occurring materials. The sheer number of humans on the planet and our ability to manipulate energy on a scale unlike anything found in the biosphere means that we have created (and continue to create) environments that are radically different from those produced by Nature. All biological systems impact their surroundings, but the unprecedented scale and rate of our activities has outstripped the capacity of the biosphere to adapt using its evolutionary approach. Our efforts to provide ourselves with comfort, security, and even amusement are often highly detrimental to the rest of the biosphere and ultimately to ourselves. Plastics are generally not degraded by the usual biological processes and their mass is not readily recycled. Sediment disruption from mining and concentration of particular elements in fabrication processes can lead to areas that are highly toxic to life forms, including our own. Pesticides, industrial waste, and pharmaceutical products can make their way into the environment, causing mutations or cellular disruptions in plants and animals. It has been clear now for some decades that the industrialization of society with scant regard for the larger biosphere has serious consequences.

The term biomimicry has been used since at least 1976 as a synonym...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Foreword
• Foreword
• Preface
• Contributors
• Chapter 1: Introduction: The Concept of Biomimicry and Bioinspiration in Chemistry
• Chapter 2: Bioinspired Self-Assembly I: Self-Assembled Structures
• Chapter 3: Bioinspired Self-Assembly II: Principles of Cooperativity in Bioinspired Self-Assembling Systems
• Chapter 4: Bioinspired Molecular Machines
• Chapter 5: Bioinspired Materials Chemistry I: Organic–Inorganic Nanocomposites
• Chapter 6: Bioinspired Materials Chemistry II: Biomineralization as Inspiration for Materials Chemistry
• Chapter 7: Bioinspired Catalysis
• Chapter 8: Biomimetic Amphiphiles and Vesicles
• Chapter 9: Bioinspired Surfaces I: Gecko-Foot Mimetic Adhesion
• Chapter 10: Bioinspired Surfaces II: Bioinspired Photonic Materials
• Chapter 11: Biomimetic Principles in Macromolecular Science
• Chapter 12: Biomimetic Cavities and Bioinspired Receptors
• Chapter 13: Bioinspired Dendritic Light-Harvesting Systems
• Chapter 14: Biomimicry in Organic Synthesis
• Chapter 15: Conclusion and Future Perspectives: Drawing Inspiration from the Complex System that Is Nature
• Index