# New Fluorescent Chemodosimetric Mechanism for Selective Recognition of Selenocysteine by Dansyl-Appended Ruthenium Nitrosyl Complexes

## TL;DR

This paper introduces a new fluorescent method to detect selenocysteine, an important amino acid, using special ruthenium complexes that work quickly and effectively in both solutions and living yeast cells.

## Contribution

A novel fluorescent chemodosimetric method for selective and rapid detection of selenocysteine using dansyl-appended ruthenium nitrosyl complexes is introduced.

## Key findings

- The complexes detect selenocysteine with a limit of detection as low as 0.12 μM within 5 minutes.
- The method works effectively in living Saccharomyces cerevisiae cells.
- Multiple analytical techniques confirm the release of NO• upon reaction with selenocysteine.

## Abstract

Selenocysteine (Sec) is a biologically essential amino
acid that
serves as a crucial component in selenoproteins that play a key role
in various cellular functions. Thus, developing a reliable and rapid
method for detecting Sec in physiological media is of paramount importance.
This report introduces for the first time a novel fluorescent chemodosimetric
mechanism for the selective recognition of Sec using dansyl-appended
ruthenium nitrosyl complexes. These complexes consist of a tetradentate
ligand featuring a π-extended system (L = N,N′-bis(2-hydroxy-1-naphthylidene)-1,2-phenylenediamine)
and a monodentate ligand derived from the conjugated dansyl group,
which acts as a strong fluorescent signaling unit (ID = dansyl-imidazole, BD = dansyl-benzimidazole). The
reaction between Sec and the complexes {RuNO}6 = [RuL(NO)(ID)]Cl or [RuL(NO)(BD)]Cl in an aqueous
phase enhances fluorescence; as a result, it releases NO• that has been demonstrated through fluorimetric titrations, UV–vis
titrations, 77Se NMR, EPR, IR, MS, and electronic density
calculations. [RuL(NO)(ID)]Cl and [RuL(NO)(BD)]Cl quantitatively detect Sec within a micromolar concentration range,
achieving the limit of detection as low as 0.31 and 0.12 μM,
respectively, within just 5 min. Remarkably, these chemodosimeters
can also be conveniently employed to detect Sec in living Saccharomyces cerevisiae cells.

Selenocysteine (Sec) is a biologically essential amino acid
that serves as a crucial component in selenoproteins that play a key
role in various cellular functions.