FUNDAMENTALS OF BIOMATERIALS AND BIOCOMPATIBILITY - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 14

or osteolysis is concerned. In addition, in vitro dissolution tests assess the weight
change or deposition of any mineralized phase (such as CaP-rich) on the surface
of biomaterial. In the absence of prescribed ISO guidelines, all the above
mentioned tests are carried out in simulated body fl uid solution, such as Ringer's
solution or Hank's balanced salt solution (HBSS). Depending on the intended
use of biomaterials, different proteins such as bovine serum albumin (BSA) or
other serum proteins are added to SBF. During corrosion/wear/ in vitro dissolu-
tion tests, the pH of 7.4 and temperature of 37 °C are closely maintained during
the entire test duration. In case of tests with dental restorative material, such as
glass - ceramics, in vitro dissolution tests are carried out in artifi cial saliva.
1.6 STEPS FOR CHARACTERIZATIONS OF BIOMATERIALS
In order to evaluate the cell/tissue interactions for biomaterials, certain specifi c
experiments have to be followed. These include:
a) The fi rst step is the material development and its characterization. Previ-
ous experience and literatures help in choosing the appropriate system to
evaluate a material for a specifi c application.
b) After evaluating the physical properties and some other necessary tests,
the material goes to microbiology section, where the material is steril-
ized by ethanol or gamma ray or some other techniques. Depending on
the desired biomedical application of the materials under investigation,
it goes to thrombosis lab and tissue culture lab, to evaluate the in vitro
properties of materials. In thrombosis lab, materials are tested in contact
with blood. The tests are platelet count, platelet adhesion, hematology,
coagulation test, and immunology. In tissue culture lab, the interaction
of cells as well as different tissues with materials is observed. The tests
are cell proliferation and cell adhesion and in vitro toxicity. Depending
on end use, a specifi c property of a material is evaluated. For orthopedic
implant applications, cell adhesion is mostly desirable, but cell adhesion
assessment is not desirable for heart valve materials. For the latter, the
desirable property is thromboresistance.
c) Subsequently, material goes to the in vivo toxicity lab. Here, materials
extract is injected into animal bodies or material is placed in the animal
body. After a long-term observation, the animal is sacrifi ced and the con-
tacting body parts of the animal are taken to the histopathology lab for
further experiments
d) In the histopathology lab, animal tissues are prepared for microscopic
analysis. Special techniques are adopted to make the sample for optical,
scanning and transmission electron microscopy.
e) There are some important aspects to choose the animal for in vivo
experiments. The animal welfare committee and ethical committee decide