Introduction to Science and Engineering Principles for the Development of Bioinspired Materials

Muhammad Wajid Ullah1,2, Zhijun Shi1,2, Sehrish Manan3, and Guang Yang1,2,*

1 College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China

2 National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan, China

3 College of Plant Sciences and Technology, Huazhong Agricultural University, Wuhan, China

I.1 Bioinspiration

Bioinspiration refers to the process of learning from nature and its biological principles. The science of bioinspired materials aims to develop novel functional materials with advanced and multi-functional properties by using the nano-, micro-, meso-, and macro-structures and features of natural materials with the aim to meet the requirements of human well-being. Natural mechanisms and biological materials can be exploited to design advanced materials to solve the problems encountered in human life. Indeed, the focus of materials science is being increasingly shifted toward the development of bioinspired materials, prompted by the shortage of resources, the low cost, and the superior characteristics of natural materials, and the environmental and climatic concerns. To this end, understanding the biological phenomenon, natural biological materials, and the processes involved in their natural production is essential, and hence, developing biofabrication or bioinspired fabrication approaches.

I.2 Bioinspired Materials

Bioinspired materials are synthetic products fabricated to mimic the structure and mechanical features of natural biological materials [1]. Biological materials are inherently multi-functional in nature but may have evolved to optimize a principal mechanical function such as the impact of fracture resistance, for armor and protection, for sharp and cutting components, for a light weight for flight, or special chemical and mechanical extremities for reversible adhesive purposes. These functions are regulated by the nano-, micro-, meso-, and macro-structures of the materials. Further, these structures determine the mechanism of the biological systems to adapt themselves to the external mechanical stimuli. These inherent functions and structural properties are inspiring scientists and engineers to design novel multi-functional synthetic materials with a wide range of structural features and a broad spectrum of potential applications. In the past few decades, several natural biological materials have been examined by researchers for various aspects to explore their potential in different fields. Studies reveal that the inherent multi-scale structures of natural biological materials possess several functions. Nature as a school for scientists and engineers has served as a great source of inspiration to fabricate new materials [2]. At present, biomimetic and bioinspired approaches have been adopted for the fabrication of several biological materials with multi-scale structures for function integration, as summarized in Table I.1. An interdisciplinary collaboration of materials science and engineering, chemistry, biology, physics, and bioinformatics, etc. may lead to the design and fabrication of novel multi-functional bioinspired materials.

Table I.1 Typical biological materials with function integration.

Source: Reproduced from [2] with permission from Elsevier.

To date, several biofabrication approaches have been developed by studying and exploiting unique and basic biological aspects, including evolution, growth, and structure (formation and performance) which are not found in engineering materials. Based on the "growth and functional adaptation" concepts, the strategies adopted mainly aim at creating hierarchical structures and self-assemblies (dynamic strategies) and those associated with the "damage repair and healing" principle designs, and self-repair or self-healing materials. To achieve these objectives, several models have been presented by the researchers to describe the design, fabrication, and optimization of properties of bioinspired materials. Modeling of biological materials helps in rational understanding of the design principles which can lead to subsequent designing of bioinspired complements. For example, mechanical modeling of biological materials based on natural materials has attracted immense attention owing to their diverse applications in medicine and engineering. This can be attributed to the structurally hierarchical biomaterials which possess a highly desirable structure-properties relationship and can serve as templates for the fabrication of bioinspired materials. Several approaches, such as single- and multi-scale, micro-structural and phenomenological, and continuum and discrete, etc. have been developed for the mechanical modeling of biological and bioinspired materials [37]. However, further extensive research is required to fabricate bioinspired materials due to their greater flexibility in design variables, such as the selection of material components, the varying degree of constraints among the different available components, the variable boundary conditions, and the novel architectural conformations.

I.3 Biofabrication

Biofabrication is the combination of two words: "bio" means living and "fabrication" means to synthesize or design using templates etc., thus biofabrication refers to the synthesis of living structures using some standard templates or models. Precisely, biofabrication refers to the application principle of engineering and information science to produce an automated robotic assembly of living cells, tissues, and organs, etc. [38]. Further narrowing down the concept, biofabrication refers to the biomedical applications of rapid prototyping or computer-aided additive technologies. It is closely related to tissue engineering and is considered an integral part of it and uses engineering approaches in the assembly of complex tissues and organs. Despite extensive developments in the field of tissue engineering, the transformation of this labor-intensive technology into an automated industry still requires further innovative and creative strategies.

I.3.1 Summary of Part I Biofabrication

In Part I, "Biofabrication," we discuss various biotemplating principles and recent advances in the one-dimensional and two-dimensional biotemplated formation of inorganic functional materials using natural templates. The chapters in Part I (Chapters 2-6) also discuss microbial-mediated material manufacturing techniques for the fabrication of a variety of functional materials. Recently developed tubular structures are discussed, which serve as templates for in vitro recapitulating of highly complex tissues such as blood vessels, etc. and microfluidics-based cell manipulation and development of tubular...