Fluorescence techniques for drug delivery research: theory and practice

Advances in drug delivery require an understanding of drug design, drug stability and metabolism together with the complexities imposed by the biological system such as cell/tissue penetration, drug-target interaction, and the pharmacodynamic consequences. Fluorescence microscopy provides a comprehensive tool for investigating many of these aspects of drug delivery in single cells and whole tissue. This review presents the fundamental concepts of fluorescence-based methodologies. The core principles which underlie the fluorescence process and the interpretation of these events drives instrument design and the components required to illuminate and detect fluorescent probes. Many drugs are inherently auto-fluorescent and therefore can be tracked using microscopy techniques, while other more indirect approaches assay the consequences of drug perturbation. This review addresses the two principle aims in fluorescence microscopy; to generate and enhance fluorescence-derived contrast that may reveal a central process of drug delivery.