Binding of the Same Analyte (Glucose) to Different Biosensor Surfaces: A Fractal Analysis of the Kinetics - Biosensors and Biosensor Kinetics - page 184

Figure 7.7c and Tables 7.4 and 7.5 show the increase in the binding rate coefficient, k 2 , with
an increase in the fractal dimension, D f2 , for a dual-fractal analysis. For the data shown in
Figure 7.7c , the binding rate coefficient, k 2 , is given by:

D 0 : 685 0 : 108

k 2 ¼ð 0 : 03884 þ 0 : 00170 Þ ð 7 : 6c Þ

f2

The fit is reasonable. Only three data points are available. The availability of more data
points would lead to a more reliable fit. The binding rate coefficient, k 2 , is only mildly sen-
sitive to the degree of heterogeneity on the biosensor surface or the fractal dimension since it
exhibits an order of dependence between one-half and one (equal to 0.685) on the fractal
dimension on the biosensor surface.

Hu (2009) has recently reviewed commercialized glucose sensors in China. According to a
report issued by the Chinese CDC (Center of Disease Control, 2006), Ministry of Health,
there were 40 million diabetics in China. Williams et al. (1970) first demonstrated the amper-
ometric blood glucose determination using a redox couple-mediated, glucose oxidase (GO x )-
catalyzed reaction. However, Hu (2009) points out that this research did not lead to the self-
monitoring blood glucose levels at home. He points out that many studies on blood glucose
determination have been conducted since the 1980s. These include the studies by Cass et al.
(1984), Neuman et al. (1970) , Wang et al. (1995), Cui et al. (2000), Gao et al. (2005),
Neuman and Turner (2005), and Heller and Feldman (2008) .

Figure 7.8 shows the binding and dissociation of whole blood glucose with a glucose con-
centration of 400 mg/dl to a FAD-GDH that was screen-printed on the working side of the
biosensor strip. The operating potential is 300 mV. The hematocrit was adjusted to 40%

7

6

5

4

3

2

1

0

0 0.5 1 1.5

Time (s)

2 2.5 3

Figure 7.8
Binding of 400 mg/dl glucose in solution (hematocrit adjusted to 40%) to FADGDH (flavin adenine
dinucleotide-dependent glucose dehydrogenase)/ferricyanide that was screen-printed on a
biosensor strip ( Hu, 2009 ).