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Revolutionizing Light Intensity Measurement: Innovative Caged Fluorophores Unveiled by DREAM project

Person holding a small container with a fluorescent liquid inside.

In a recent study poised to redefine the parameters of light intensity measurement across multiple scientific domains, DREAM researchers have unveiled a series of hydrophobic and hydrophilic caged fluorophores. Published in the latest issue of Chemical Science, this research represents an important step in the quest for absolute precision in gauging light intensity—a crucial task in the fields of chemistry, biology, physics, and engineering.

Traditionally, the yardstick for measuring light intensity has been the actinometer, a tool scrutinizing the reaction extent over time under constant light. However, existing actinometers often fall short, relying on the less sensitive absorbance observable, making them unsuitable for state-of-the-art imaging systems and inadequate for measuring light intensity in small samples, such as those in microscope calibration.

This study, led by DREAM partners at the Chemistry Department of the Ecole Normale Supérieure, takes a new approach by introducing a suite of hydrophobic and hydrophilic caged fluorophores. Leveraging the robust pyranine backbone, these fluorophores boast an unprecedented ease of large-scale synthesis in one to a few steps. “What sets these fluorophores apart is their dynamic response to illumination. Unlike their predecessors, their brightness escalates in tandem with exposure to light, “ explains Ludovic Jullien, DREAM coordinator and Professor of Chemistry at Sorbonne Université and Ecole Normale Supérieure in Paris.

Furthermore, the synthesis of these compounds proposed by DREAM is distinguished by its large-scale scalability, bypassing the need for intricate separation procedures. The researchers have also meticulously characterized how the brightness changes over time when the caged fluorophores are exposed to light. This helps to thoroughly understand how efficiently these fluorophores are released across a wide spectrum of wavelengths and light intensities.

Thanks to this wealth of information, the caged pyranine derivatives emerge as a versatile tool for measuring light intensity, leveraging UV light in the 300–450 nm and 750 nm wavelength range through one and two-photon excitation, respectively.

The real-world applications of these fluorophores extend far beyond the confines of the laboratory. Through meticulous calibration, the research team demonstrated their efficacy in measuring light intensity in a diverse array of chemical and biological samples. Employing cutting-edge imaging systems, including epifluorescence and confocal technologies, the researchers showcased the versatility of their creation.

In a time where accuracy is crucial, these hydrophobic and hydrophilic caged fluorophores are poised to become a significant asset in the toolkit for precise light intensity measurement.

Image: “Cuvette with fluorophore” by MaximilianParadiz is licensed under CC BY 2.0.