Binding and Dissociation Kinetics During Hybridization on Biosensor Surfaces - Biosensors and Biosensor Kinetics - page 479

surface. A change in the degree of heterogeneity on the surface generally leads to a change in
the binding rate coefficient in the same direction.
It is suggested that the fractal surface (roughness) leads to turbulence, which enhances
mixing, decreases diffusional limitations, and leads to an increase in the binding rate coeffi-
cient ( Martin et al., 1991 ). For this to occur, the characteristic length of the turbulent bound-
ary layer may have to extend a few monolayers above the sensor chip or affect bulk diffusion
to and from the surface. However, given the extremely laminar flow regimes in most
biosensors this may not actually take place. The sensor chip surface is characterized by
grooves and ridges, and this surface morphology may lead to eddy diffusion. This eddy dif-
fusion can then help to enhance the mixing and extend the characteristic length of the bound-
ary layer to affect the bulk diffusion to and from the surface.
The analysis of the different hybridization examples especially of biomedical interest pres-
ented in this chapter (and in other chapters of the topic) should encourage experimentalists
to pay more attention to the nature of the surface, and how it may be manipulated to advan-
tage in desired directions. This is of particular value for biomedical cases (or the community)
wherein, with more sensitive and better hybridization biosensors, the earlier one may detect
and diagnose the probable onset of diseases, the earlier one can begin the medical protocols
necessary to help prevent, alleviate, or correct the onset of especially debilitating and intrac-
table diseases. The importance of a better understanding of hybridization reactions with
regard to disease prevention and management cannot be over-emphasized.
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