30 Biomedical Applications of Aerogels Wei Yin and David A. Rubenstein Abstract This section highlights a few applications of aerogels in a biological context, as a biomaterial. Some aerogel formulations have been shown to have compatibility with the cardiovascular system and others have been able to induce apatite formation for potential bone growth. Others have provided proof that proteins can be embedded within aerogel samples maintaining their biological functionality, therefore aerogels may be used in a drug delivery system. At this point, more work is needed to determine how aerogels can be applied to the biological systems; however, with the improvements in aerogel processing along with a better understanding of biomaterials the use of aerogels in biological applica- tions will be significant in the future. 30.1. Introduction Synthetic materials have been used in biological environments for approximately 3,000 years. As new materials are developed and new material processing methods are designed, the biological effect of materials has been continually investigated to determine whether or not the material has any potential to be used in the human body. Over the past 100 years, our understanding of biological processes combined with our ability to precisely fabricate materi- als has led to the fast growing field of biomaterials. It was estimated that in the year 2000, about 20 million individuals had medical devices implanted, incurring an approximate annual cost of $300 billion (including hospitalization and surgical costs) [1]. The use of novel biomaterials in medical applications has significantly enhanced the longevity of patients. However, the failure of biomaterials can lead to symptoms, diseases, side effects, or sudden patient death, which leaves room for improvement in the current biomaterial properties and applications. Silica aerogel is a well-known lightweight solid. Even though it was invented in 1931, it only started to draw interest from materials scientists about 15 years ago, due to the improvements in the use of sol-gel processes to expedite the synthesis time (Chap. 1). However, traditional aerogels have never been used as a biomaterial. Along with the significant improvement in the mechanical strength, modern aerogels have demonstrated W. Yin (*) and D. A. Rubenstein l School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA e-mail: wei.yin@okstate.edu; david.rubenstein@okstate.edu M.A. Aegerter et al. (eds.), Aerogels Handbook, Advances in Sol-Gel Derived Materials and Technologies, DOI 10.1007/978-1-4419-7589-8_30, # Springer Science+Business Media, LLC 2011 683