(187a) Advances in Biosensing Methods

A fractal analysis is presented for the binding and dissociation (if applicable) kinetics of analyte-receptor reactions occurring on biosensor surfaces. The applications of the biosensors have appeared in the recent literature. The examples presented together provide the reader with a perspective of the advances in biosensors that are being used to detect analytes of interest. This should stimulate interest in applying biosensors to other areas of application. The fractal analysis limits the evaluation of the rate constants for binding and dissociation (if applicable) for the analyte-receptor reactions occurring on biosensor surfaces. The fractal dimension provides a quantitative measure of the degree of heterogeneity on the biosensor surface. Predictive relations are presented that relate the binding rate coefficient with the degree of heterogeneity or the fractal dimension on the biosensor surface. The biosensor systems analyzed include (a) the binding of different concentrations of mouse monoclonal anti-rabbit IgG in solution to rabbit patterned cells using a diffraction-based sandwich immunoassay (Goh et al., 2003), (b) the binding and hybridization of DNAs using a double-wavelength technique for surface plasmon resonance measurements (Zybin et al., 2005), binding and dissociation of GSH (Glutathione-MPC (monlayer protected clusters) in solution to polyclonal antibody plus protein A immobilized on a quartz crystal microbalance (QCM) (Gerdon et al., 2005), and the (d) binding and dissociation of substance P (neuropeptide) (SP) in solution to quencher-labeled MAb (monoclonal antibody) SP31 using SPIT-FRI (solid-phase immobilized tripod for fluorescent renewable immunoassay) procedure ( Volland et al., 2005).