Biological and Biomedical Materials Overview A Paradigm for the Integration of Biology in Materials Science and Engineering Ryan K. Roeder The integration of biology in materi- sa, have invariably encountered several als science and engineering can be com- How would you… challenges. These challenges may be plicated by the lack of a common frame- …describe the overall significance grouped into two aspects of “biocom- of this paper? work and common language between plexity.” The materials science and engineering otherwise disparate disciplines. History paradigm was modified to account First, biomaterials replace or inter- may offer a valuable lesson as modern for the adaptive and hierarchical face with biological substances, espe- materials science and engineering itself nature of biological materials. The cially tissues and cells. Biological tis- resulted from the integration of tradi- modified paradigm may be useful sues, or biological materials, are living, for the integration of biology and tionally disparate disciplines that were biomedicine in materials research and adapt to chemical and physical stimuli, delineated by classes of materials. The education, as well as in advocating perform multiple functions, and exhibit integration of metallurgy, ceramics, and the application of materials science hierarchical structure with precise or- polymers into materials science and en- and engineering principles in ganization over multiple length scales.5 biomedical research and education. gineering was facilitated, in large part, Therefore, biological materials exhibit by a unifying paradigm based upon pro- …describe this work to a materials complex processing-structure-property science and engineering professional cessing-structure-property relationships with no experience in your technical relationships, unmatched in engineering that is now well-accepted. Therefore, a specialty? materials, which are only beginning to common paradigm might also help unify Materials science and engineering is be established. the vast array of perspectives and chal- expected to play a highly significant In contrast, the vast majority of bio- lenges present in the interdisciplinary role in the foreseeable future of materials used in biomedical devices biomedicine. Conversely, noting that study of biomaterials, biological ma- materials science finds its roots in have historically included common en- terials, and biomimetic materials. The solid state physics and chemistry, gineering materials (e.g., stainless steel, traditional materials science and engi- biology is logically the next great titanium, alumina, porcelain, polyethyl- frontier for materials science and neering paradigm was modified to ac- engineering. Therefore, materials ene, polymethylmethacrylate, etc.) that count for the adaptive and hierarchical scientists and engineers who wish to exhibited desirable properties that were nature of biological materials. Various make an impact at the intersection of borrowed for biomedical applications.1,6 examples of application to research and materials and biology must become These biomaterials enhanced the quality increasingly knowledgeable, or at education are considered. least conversant, in biology and of life for countless individuals through biomedicine. passive interaction with biological sys- INTRODUCTION …describe this work to a tems (bioinert). In other words, “do no Most materials scientists and engi- layperson? harm.”7 Thus, metallurgical or materials neers recognize the tremendous op- The integration of traditionally engineers were well-positioned to con- portunities available at this time in his- disparate disciplines of study can tribute to the design and manufacturing tory for advances in biotechnology or be complicated by the lack of a of a conventional stainless steel implant, common framework for critical biomedicine and, closer to home, the thinking and common language for for example, through traditional educa- intersection of materials and biology. communication. The integration of tion in physical metallurgy or materials Materials science and engineering is ex- metallurgy, ceramics, and polymers structure-property relationships, with pected to play a highly significant role in into modern materials science and little consideration of biology. engineering was facilitated, in 1,2 the foreseeable future of biomedicine. large part, by a unifying paradigm A second generation of biomaterials Conversely, noting that materials sci- based upon processing-structure- began to introduce materials that are ence finds its roots in solid state physics property relationships that is favorably reactive to biology, includ- now well-accepted. Therefore, and chemistry, biology is logically the a common paradigm might ing bioactive ceramics and glasses (e.g., next great frontier for materials science also help unify the vast array of hydroxyapatite and bioglass, respective- and engineering.2–4 However, research- perspectives and challenges present ly) and biodegradable polymers (e.g., ers and educators working to integrate in the interdisciplinary study of polylactide and polyglycolide).6,7 In the biomaterials, biological materials, biology or biomedicine into materials and biomimetic materials. present age, so-called third generation science and engineering, and vice ver- biomaterials are intended for proactive Vol. 62 No. 7 • JOM www.tms.org/jom.html 49 interaction with biology.6,7 Examples may include individuals educated in lenge of integrating biology in materi- include: tissue engineering scaffolds engineering (chemical, materials, me- als science and engineering. Modern able to guide cell differentiation and chanical, etc.), science (cell biology, materials science and engineering tissue growth via signal transduction;7–9 biochemisty, etc.), basic medical sci- resulted from the integration of tradi- vehicles for controlled and/or targeted ences (anatomy, pathology, pharmacol- tionally disparate disciplines that were delivery of pharmaceuticals, proteins, ogy, etc.), and clinical medicine (car- delineated by classes of materials, viz., and nucleic acids;10,11 and multifunc- diology, orthopedics, radiology, etc.). metals, ceramics, and polymers. As tional diagnostics and sensors;11–13 The diversity of thought contributed early as the 1950s materials education among others. Materials scientists and by each field of expertise is recognized was nascent, but critics suggested that engineers who wish to contribute to as a great benefit in interdisciplinary the breadth of a materials curriculum these and other exciting applications of work. However, a significant challenge without traditional demarcations be- biomaterials must become increasingly facing bioengineering as a discipline, tween material classes would compro- knowledgeable, or at least conversant, as well as the integration of biology mise depth of study.18 Proponents of in biology and biomedicine.2,3 in traditional disciplines, including materials-generic education, such as Second, biomaterials research and materials science and engineering, is Gerald L. Liedl, recognized the oppor- development requires diversity among the lack of a common framework and tunities and challenges: contributors and collaborators. For rea- common language for synthesizing the “The diversity in the field is, on one hand, a sons discussed above, no single indi- diversity of thought and expertise.3 major asset in addressing problems, but on vidual or discipline of study can be ex- See the sidebar for a glossary of bio- the other hand, a major obstacle in unifying pected to possess sufficient depth in the logical materials terminology. an educational approach. This problem is full breadth of knowledge required for not new since we have faced it over time as LESSONS FROM OUR PAST 19 most biomaterials applications. Thus, information and knowledge expands.” product development teams in industry The history of materials science and Despite the pre-existing traditions and (increasingly) collaborators in use- engineering provides valuable lessons and human nature to resist change, inspired basic research in academia that can be applied to the present chal- materials science and engineering has evolved over the last fifty years into GLOSSARIES a unified discipline of study with an identifiable, common core curricu- Intersection of Materials and Biology lum.20–23 The integration of metallurgy, 14–16 Adapted from various sources. ceramics, and polymers into materials Biological Material: A natural material produced by a biological organism. Examples science and engineering was facilitat- include bone, skin, seashells, wood, silk, etc. Biological Materials Science: The application of materials science and engineering ed in large part by a unifying paradigm principles to the study of biological materials, including the design, synthesis, and based upon the underlying principles fabrication of biomaterials and biomimetic materials from biological lessons. of processing, structure, properties, Biomaterial (or Biomedical Material): A synthetic material or processed biological and performance, and their interrela- material engineered to evaluate, treat, augment, or replace any component or function tionships, that is now well-accepted of a biological organism, while in continuous or intermittent contact with biological (Figure 1). substances. Interestingly, the reservations once Biomimetic Material (or Bioinspired Material): A material engineered to be physically, chemically, or functionally similar to a biological material.