The multipurpose application of resazurin in micro-analytical techniques: Trends from the microbial, catalysis and single molecule detection assays

Resazurin (RZ) is a low-toxic redox-sensitive indicator that is weakly fluorescent but becomes strongly fluorescent after reducing to resorufin (RS). The focal point attracting the attention of researchers to this indicator is connected to its excellent sensitivity to a wide range of physical and chemical reaction properties. The sensitive reduction of RZ causing the colour/fluorescence change could be readily triggered by i) biochemical agents or enzymes found in the mitochondria of both the prokaryotic and eukaryotic cells ii) chemical agents like the electrochemical redox species or reductants, single molecule catalytic species, and iii) some physical properties like UV radiation, pH, etc. Interestingly, these redox reaction activators are a segment of most biochemical, electrochemical, photochemical, and microbial reaction processes. Hence, they have been exploited to develop quite several analytical assays for analyzing photo-catalysts, food, drugs, nanoparticles catalyzed reactions, single-molecule detection, and the metabolic activity of a wide range of micro-organisms.