Optical Biosensors and Applications to Drug Discovery and Development in Cancer Research

Abstract

A biosensor is a device consisting of a biological part on the surface as the recognition element, and a physical transducer that converts the physical parameters of a specifi c biological interaction into a measurable analytical signal. Many optical biosensor instruments have been developed, most of them based on the surface plasmon resonance (SPR) technology. SPR has the potential to benefi t many important research fi elds, including pharmaceutical research, medical diagnostics, environmental monitoring, and food safety. SPR has a signifi cant role in biomolecular interaction analysis, and is bringing major benefi ts to drug discovery and development, where the characterization of protein/protein interactions and binding site studies are fundamental to understand the bio-recognition phenomena behind a biological process. SPR allows proteins to be studied in their native state and environment, preserving their native three-dimensional structure, and even associated to membranes: these targets can therefore be studied in conditions relatively close to those in vivo. The increasing interest in this analytical technique is due to the advantages of SPR, fi rst of all the lack of labelling requirements. Labelling imposes extra time and cost demands, and may eventually interfere with analysis by occluding a binding site, leading to false negatives. Furthermore, SPR allows real-time interaction studies between immobilized receptors and analytes, a fast collection of kinetic and thermodynamic data, and the detection of analytes over a wide range of molecular weights and binding affi nities. This technique allows the quantitation of a bound analyte at equilibrium in the presence of the unbound analyte, while the binding capacity and baseline stability give information about the stability of the immobilized ligand.