Target/Probe Interactions

This chapter is about interactions between molecules. The main aim here is to show how biological macromolecules interact with each other or with specific organic molecules. Of course, the final aim of learning such interactions to the aim of this book is the possibility of using one of the two interacting molecules as a probe in Bio/CMOS interfaces to then succeed in detecting the other molecule when present in a biological sample. The thermodynamics of such molecular interactions are learned through different cases, from DNA hybridization to antigen uptake or enzyme catalysis. The Gibbs free energy, enthalpy, and entropy of the different cases are deeply discussed by introducing different forces, which play a key role in such interactions: hydrophobic forces, van der Waals forces, conformational changes in the macromolecules, and the role of the solvent as a further contribution to the molecular interaction. The concept of denaturation is introduced, and the related melting temperature is defined. Different kinds of antibodies are discussed as well as different kinds of enzymes and related kinetics. The nearest neighbor model is also learned as related to the case of interactions between nucleic acids.