Biomaterials

This Defense Intelligence Reference Document, produced in fiscal year 2009 under the Defense Intelligence Agency's Advanced Aerospace Weapon System Applications (AAWSA) program, provides a comprehensive technical overview of biomaterials. Biomaterials are defined as nonliving substances—including metals, ceramics, polymers, glasses, and carbons—designed to interface with biological systems to treat, augment, or replace bodily tissues and functions. The document highlights that while biomaterials are primarily used for medical applications, they are also utilized in cell culture and biotechnology. A central theme of the report is the critical importance of biocompatibility, as the body's foreign-body reaction to implanted materials remains a major obstacle to the development of stable, long-term devices. The report details the phenomenon of biofouling, where sensors become coated with proteins and scar tissue, often rendering them ineffective. The document systematically reviews several classes of biomaterials. Silicones, specifically polydimethylsiloxanes, are noted for their flexibility, blood compatibility, and use in implants and biosensors. Teflon (polytetrafluoroethylene) is highlighted for its chemical inertness, hydrophobicity, and low friction, making it ideal for vascular grafts and patches. Biodegradable polymers, such as polylactic acid (PLA) and polyglycolic acid (PGA), are discussed for their ability to degrade into harmless byproducts, eliminating the need for surgical removal. Hydrogels are described as water-rich networks used in drug delivery and tissue engineering. The report also covers bioceramics, such as alumina and hydroxyapatite, which are used in bone repair and dental applications due to their hardness and ability to integrate with bone. Titanium is identified as a premier material for orthopedic implants, particularly for its strength and its unique ability to osseointegrate with living bone, a process first recognized by Per-Ingvar Brånemark. Finally, the document addresses the role of biomaterials in dialysis, specifically the use of semipermeable membranes like Cuprophane to cleanse blood. The report concludes that while the biomedical industry is often slow to adopt new materials due to stringent safety requirements, the field is expanding, with ongoing innovation focused on new applications and the refinement of existing materials to improve patient recovery.