Biomedical Engineering Reference
In-Depth Information
CHAPTER 2
Modeling and Theory
Chapter Outline
2.1 Introduction
15
2.2 Theory
19
2.2.1 Variable Rate Coefficient
19
2.2.2 Single-Fractal Analysis
21
Binding Rate Coefficient
21
Dissociation Rate Coefficient
23
26
2.2.4 Triple-Fractal Analysis
26
2.2.5 Pfeifer's Fractal Binding Rate Theory
26
2.2.6 The Mautner Model
28
2.2.7 Kinetics of Analyte Capture on Nanoscale Sensors (
Solomon and Paul, 2006
)
29
2.2.8 Probing the Functional Heterogeneity of Surface Binding Sites Along with the Effect of Mass
Transport Limitation and its Influence on Binding and Dissociation of Analytes on Biosensor
Surfaces (
Svitel et al., 2007
)
30
2.1 Introduction
In a biosensor based assay the molecule to be detected (analyte) is present in solution and
the appropriate receptor is immobilized on a solid surface. The interaction between the ana-
lyte and the receptor on the solid biosensor surface is detected either by a change in the
refractive index (in SPR (surface plasmon resonance) instruments) or by changes in the fluo-
rometric intensity, ultraviolet light intensity, etc. The SPR biosensor protocol analyzes the
binding (and dissociation where applicable) kinetic curves using classical saturation models
involving analyte-receptor binding using 1:1, 1:2, etc. ratios, generally under diffusion-free
conditions and assuming that the receptors are homogeneously distributed over the sensor
surface. Computer programs and software that come with the equipment provide values of
the binding (and the dissociation) rate coefficients. Though a careful analysis and experimen-
tal protocol may eliminate or minimize the influence of diffusional limitations; realistically
speaking, it is more appropriate to include a heterogeneous distribution on the sensing
surface. Heterogeneity on the sensing surface and in the biosensor systems itself may be
