Biomedical Engineering Reference
In-Depth Information
3.3.1 Influent and total metal bound comparison
By taking the ratio of metal bound for the modified and native biomaterials at each position
in the sequence and averaging those ratios for both the influent metal bound and the total
metal bound, the average effect of the esterification procedure on metal binding can be
quantified. On average, the influent metal-ion bound decreased by 43% while the total metal
bound decreased by 54%. Figure 3 illustrates a further breakdown these comparisons by
metal-ion position within the sequence. For total metal bound to the biomaterial, metal ion
position had only a small effect in the percentage decrease in binding capacity observed in
the modified biomaterial. With the first metal ion capacity dropping 52%, the second
decreased to 54% and the third decreased to 55%. However, the influent metal ion capacity
seems to be more effected by its position in the sequence. The first metal ion exposed
demonstrated a decrease in its capacity of 52%, while the second and third ions exposed
decreased by only 42% and 40% respectively.
Figure 4 shows additional data regarding the influent metal bound by examining both
position and specific metal ion exposed in the sequence. For nickel and zinc there was a
steady decrease in the observed effect of the modification as their position in the sequence
moved from first to third. Nickel was most pronounced, as the effect of the modification
was decreased in capacity by 54% when nickel was the first ion exposed, 41% when it is
the second, and 35% when the third. Zinc was similar as it drops from a 51% decreased in
binding capacity when it was the first metal exposed, a 47% decrease when it was second,
to a 41% decrease when it was third. Cadmium did not follow this pattern of decreasing
effect based on position. When cadmium was the first metal exposed a decrease in
binding capacity of 49% is observed, a decrease in capacity of 38% was observed when it
was second, and a decrease of 44% when it metal on the column. The modified
biomaterial total metal bound decreased between 49 - 57% depending on influent metal
and position with no apparent pattern.
100
60
50
80
A
B
40
60
30
40
20
20
10
0
0
one two three
Total Number Metals Exposed
one two three
Total Number Metals Exposed
Fig. 3. Average total (A) and influent (B) metal-ion bound for native (shaded) and modified
biomaterial based on number of metals exposed in series. Metal bound given in percentage
metal bound.
Simultaneous exposure of the three metal-ions showed an overall decrease of 43.7% for total
metal bound for the modified biomaterial. Zinc showed the largest decrease showing a
50.2% decrease in binding capacity. The modified biomaterial exhibited a loss of 43.5% for
cadmium. Nickel showed the smallest effect from the modification losing 34.8% of its
capacity. It should be noted that zinc, which lost the most, had the largest capacity (28.5
mol g
-1
), while nickel, which demonstrated the smallest effect of modification, had the
smallest capacity on the native biomaterial (20.3 mol g
-1
).
