Quantitative evaluation of brightness of fluorescent nanoparticles usingDNAorigami standards

Abstract

AbstractFluorescent nanoparticles (FNPs) are widely used in various applications owing to their brightness, stability, and biocompatibility. When FNPs are used as probes, the quantities of the targets are estimated from the fluorescence generated by the probes. Information on the brightness of FNPs is thus essential for the reliable analysis of targets; however, accurate methods to measure it have not been established yet. Here, we present a novel method that quantitatively evaluates the brightness of FNPs, using DNA origami as a standard. DNA origami particles labeled with different numbers of fluorophores are imaged, and their brightness is analyzed at the single‐particle level. By comparing with the origami data, the brightness of two commercially available FNPs was determined in terms of the equivalent number of fluorophores (ENF). This method is easy to implement because DNA origami standards with various fluorophores and stoichiometry can be readily prepared.