(389d) Fractal Analysis of Binding Interactions of Environmental Contaminants on Biosensor Surfaces

A fractal analysis is used to analyze the binding and dissociation (if applicable) of analytes of environmental pollution interest on biosensor surfaces. The analytes analyzed include (a) the binding of anti-atrazine antibody (IgG) in solution to atrazine (rabbit IgG) coated on a 96-well plate (Cummins et al., 2006), (b) the binding of acetylcholine (ACh) in solution to acetylcholinesterase immobilized on an ion-selective field effect transistor (ISFET) biosensor (Hai et al., 2006), and (c) the binding of different concentrations (in nM) of catechol in solution to a 10-bilayer PAMAM polky(amidoamine) dendrimer/CCD (C1 catechol 1,2-deoxygenase) film on a nanostructured surface (Zucolotto et al., 2006). The binding kinetics is described by either a single- or a dual-fractal analysis. The dual-fractal analysis is used only when the a single-fractal analysis did not provide an adequate fit. This was done using Corel Quattro Pro (1997). The fractal dimension provides a quantitative measure of the degree of heterogeneity on, for example, the ISFET biosensor surface. An increase in the fractal dimension value or the degree of heterogeneity on the biosensor surface leads to an increase in the binding and in the dissociation rate coefficient. This is noted for the binding of acetylcholine (ACh) in solution to acetylcholinesterase immobilized on an ISFET biosensor surface (Hai et al., 2006). The binding rate coefficient, k for a single-fractal analysis is extremely sensitive to the degree of heterogeneity or the fractal dimension on the ISFET biosensor surface as noted by the greater than eighth (equal to 8.2) order of dependence exhibited. Similarly, the dissociation rate coefficient, kd is very sensitive to the degree of heterogeneity or the fractal dimension in the dissociation phase, Dfd on the ISFET biosensor surface as noted by the order of dependence between four and one-half and five (equal to 4.8) exhibited. The binding and dissociation (if applicable) kinetics of environmental pollutants present either in the gas phase or in soluton need to be analyzed. This is especially so since quite a few of these pollutants are resistant to chemical action and to biological degradation, and have been linked to the onset of intractable and insidious diseases, even if present in rather dilute solutions or concentrations. The identification of these environmental pollutants is the first step in their elimination from either water or air environments.