Biomedical Engineering Reference
In-Depth Information
acrylamide/maleic acid (AAm/MA) hydrogels were investigated (Saraydin et al., 1995,
Karadağ et. al. 1996, Saraydin et al., 2001, 2004).
3.1 In vitro swelling of the hydrogels in the simulated body fluids
In
this stage of the study, the swelling of the hydrogels in the simulated physiological body
fluids was investigated (Saraydin et al., 1995, Karadağ et. al. 1996).
The phosphate buffer at pH 7.4 (pH of cell fluid, plasma, edema fluid, synovial fluid,
cerebrospinal fluid, aqueous humour, tears, gastric mucus, and jejunal fluid), glycine-HCl
buffer at pH 1.1 (pH of gastric juice), human sera, physiological saline and distilled water
intake of initially dry hydrogels were followed for a long time until equilibrium (Saraydin et
al., 2001, 2002).
The fluid absorbed by the gel network is quantitatively represented by the EFC (equilibrium
body fluids content), where: EFC% = [mass of fluid in the gel/mass of hydrogel] x 100. EFCs
of the hydrogels for all physiologically fluids were calculated. The values of EFC% of the
hydrogels are tabulated in Table 2.
Simulated body fluid
AAm
AAm /CA
AAm /MA
AAm /IA
Distilled Water
86.3
93.9
94,7
92.0
Isoosmotic phosphate buffer
87.5
93.8
89,7
92.2
Gastric fluid
87.7
93.6
92,4
88.7
physiological saline
87.8
92.9
89,7
88.7
Human Sera
88.6
92.5
89.8
86.4
In rat
89.0
93.1
91.9
91.7
Table 2. EFC values of the hydrogels
All EFC values of the hydrogels were greater than the percent water content values of the
body about 60%. Thus, the AAm and AAm/CA, AAm/MA and AAm/IA hydrogels were
exhibit similarity of the fluid contents with those of living tissues.
3.2 In vitro blood biocompatibility
In
the second stage of this study, the biocompatibility of the hydrogels was investigated
against some biochemical parameters of human sera at 25
O
C.
The mean and standard deviation values of control and test groups for biochemical
parameters of human sera are listed in Table 3
.
Table 3 shows that the values of means of control and test groups are in the range of normal
values and there is no significant difference in values before and after contacting these sera
with the hydrogels. On the other hand, Student's t-test is applied to control and test groups.
No significant difference in values of biochemical parameters was found.
3.3 In vivo tissue biocompatibility
In this part, hydrogels based on copolymer of AAm, AAm/MA, AAm/CA and AAm/IA
with capacity of absorbing a high water content in biocompatibility with subcutaneous
tissues of rats were examined. After one week implantation, no pathology such as necrosis,
tumorigenesis or infection were observed in the excised tissue surrounding the hydrogels
and in skin, superficial fascia and muscle tissues in distant sites. After 2-4 weeks, thin
fibrous capsules were thickened. A few macrophage and lymphocyte were observed in
