AAWSAP DIRD, Biomaterials, January 2010

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laboratory, in processing biomolecules in biotechnology, for fertility regulation
implants in cattle, in diagnostic gene arrays, in the aquaculture of oysters, and
for investigational cell-silicon "biochips." The common thread in these
applications is the interaction between biological systems and synthetic or
modified natural materials.
Biomimetic materials, in contrast, are not made by living organisms but have
compositions and properties similar to materials made by living organisms.
For example, the calcium hydroxyapatite coating found on many artificial
hips-used as metal-bone interface cement to make it easier to attach
implants to bone-is similar to the coating found in mollusk shells.
IMPORTANCE OF BIOCOMPATIBILITY
Biocompatibility is an important issue in biomedical implants and sensors. A
material-tissue interaction that results from implanting a foreign object in the
body is a major obstacle to developing stable and long-term implantable
devices and sensors.
The processes that occur when sensors are placed in the complex living
environment of the human body are sometimes known as biofouling. In
biofouling, the physical or chemically sensitive portion of the sensor interface
becomes coated with proteins, blood-formed elements, adherent
immunological cells, and sometimes forms of scar tissue that tend to isolate
the sensor from the rest of the body environment. This response of tissue is a
foreign body reaction to any object introduced in tissue that does not express
surface characteristics that identify it as part of the host tissues.
Experiences of many investigators (more than 600 reported studies since 1996)
with the biocompatibility of biomaterials related to the function of implanted
biosensors have been poor such that many companies have abandoned
implantable sensor devices altogether. Rather, the recent trend in medical
biosensors is toward placing them outside the body. Newer sensors are often
based on optical principles in an effort to obviate the biocompatibility and
biomaterial issues of placing sensors inside the human body.
SCIENCE OF BIOMATERIALS
The study and use of biomaterials bring together researchers from diverse
academic backgrounds who must communicate clearly. Professions that
intersect in the development, study, and application of biomaterials include
bioengineer, chemist, chemical engineer, electrical engineer, mechanical
engineer, materials scientist, biologist, microbiologist, physician, veterinarian,
ethicist, nurse, lawyer, regulatory specialist, and venture capitalist.
The number of medical devices used each year in humans is very large. Figure
2 estimates usage for common devices, all of which employ biomaterials.
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