Label-free bioanalytical methods for investigating bimolecular interactions: A review

Abstract

Interactions between biological molecules such as DNA, RNA, protein, lipids, and carbohydrates are critical to the understanding of all biological, physical, and chemical processes such as protein function, disease diagnosis, and drug discovery.1 Most of the techniques currently used to detect and quantify biomolecular interactions are assisted by foreign molecules that are either permanently or temporarily attached to the molecule of interest; such labels most often fluorescence, luminescence, are radioactive, or are large enough to be easily detected (nanoparticles).2 Fluorescent labeling detection methods, the most common and convenient, are attractive due to their stability, easy manipulation, and high sensitivity and dynamic range.2 However, label-free and real-time detection methods are of high demand due to a number of potential disadvantages of the labels or the methods used to attach them: 1) altering the structure, conformation, or functional properties of the biomolecule of interest, 2) occupying the active site(s) of biomolecules thereby changing their binding affinity, 3) producing false-positive results by interacting with unanticipated components, 4) loss of sample during the labeling and purification process, 5) high sensitivity to changes in environmental conditions, and 6) potential to be tedious and expensive.