Biomedical Engineering Reference
In-Depth Information
activity using a molecular beacon (MB;
Ma et al., 2007
), and (f) binding and dissociation of
different rabbit IgG concentrations (in
m
M) in solution to A10B single-chain fragment vari-
able (ScFv;
Tang et al., 2006
).
Some of the other analyte-receptor binding (and dissociation, if applicable) kinetics on bio-
sensor surfaces that have appeared recently in the literature include (i) effects of geometry
on transmission and sensing potential of tapered fiber sensors (
Leung et al., 2006
),
(ii) screening antibody-antigen interactions in parallel using a Biacore A100 biosensor
(
Safsten et al., 2006
), (iii)
in vivo
biosensors for organic pollutants (
Tizzard and Lloyd-Jones,
2007
), (iv) immunoassays based on microelectrodes arranged on a silicon chip for high-
throughput screening of liver fibrosis markers in human serum (
Shi et al., 2006
), (v) detection
of
Eschericihia coli
0157:H7 with pure shear horizontal surface acoustic wave sensors
(
Berkenpas et al., 2006
), (vi) nanoscale sensors for multi-modal detection of genotoxic agents
(
Heller et al., 2008
), (vii) controlled assembly of biotinylated Au nanoparticles on metallic
nanowires for nanobiosensing (
Kizil, 2008
), (viii) preparation of bioanalytical sensors by
incorporating fluorophore in patternable poly(ethylene glycol) diacrylate-based membranes
(
Gao et al., 2008
), and (ix) impedance biosensor for peanut protein allergens (
Suni and
Huang, 2008
).
A fractal analysis method will be used to model the
kinetics of analyte-receptor binding and
dissociation (if applicable) on biosensor surfaces. As mentioned in previous chapters, this is
one method of analyzing the binding and dissociation kinetics, with the added advantage
that it permits a quantitative measure of the degree of heterogeneity on the biosensor
surface. This quantitative measure of heterogeneity on the biosensor surface may then be
used to enhance biosensor performance parameters such as selectivity, sensitivity, stability,
detection time, etc.
13.2 Theory
13.2.1 Single-Fractal Analysis
Binding Rate Coefficient
Havlin (1989)
notes that the diffusion of a particle (analyte [Ag]) from a homogeneous solu-
tion to a solid surface (e.g., receptor [Ab]-coated surface) on which it reacts to form a product
(analyte-receptor complex; Ab
Ag) is given by:
t
ð
3
D
f
,
bind
Þ=
2
t
p
,
¼
t
<
t
c
ð
Ab
Ag
Þ
ð
13
:
1
Þ
t
1
=
2
,
t
>
t
c
Here
D
f,bind
or
D
f
is the fractal dimension of the surface during the binding step.
t
c
is the
cross-over value.
Havlin (1989)
points out that the cross-over value may be determined by
