The innards of the cell: studies of water dipolar relaxation using the ACDAN fluorescent probe

OTAIZA-GONZÁLEZ, SANTIAGO; CABADAS, MANUEL; ROBERT, GERMAN; STOCK, ROBERTO P; MALACRIDA, LEONEL; LASCANO, RAMIRO; BAGATOLLI, LUIS A

Methods and Applications in Fluorescence

IOP PUBLISHING

Año: 2022 vol. 10

This article reviews the use of the 6-acetyl-2-(dimethylamino)naphthalene (ACDAN) fluorophore tostudy dipolar relaxation in cells, tissues, and biomimetic systems. As the most hydrophilic memberof the 6-acyl-2-(dimethylamino)naphthalene series, ACDAN markedly partitions to aqueousenvironments. In contrast to 6-lauroyl-2-(dimethylamino)naphthalene (LAURDAN), thehydrophobic and best-known member of the series used to explore relaxation phenomena inbiological (or biomimetic) membranes, ACDAN allows mapping of spatial and temporal waterdipolar relaxation in cytosolic and intra-organelle environments of the cell. This is also true for the6-propionyl-2-(dimethylamino)naphthalene (PRODAN) derivative which, unlike LAURDAN,partitions to both hydrophobic and aqueous environments. We will i) summarize the mechanismwhich underlies the solvatochromic properties of the DAN probes, ii) expound on the importance ofwater relaxation to understand the intracellular environment, iii) discuss technical aspects of the use of ACDAN in eukaryotic cells and some specialized structures, including liquid condensates arising from processes leading to liquid immiscibility and, iv) present some novel studies in plant cells and tissues which demonstrate the kinds of information that can be uncovered using this approach to study dipolar relaxation in living systems