Inexpensive small molecules as promising fluorescent labels for biomolecules.

Abstract

Fluorescent labels are indispensable in various modern scientific applications, including direct and indirect immunochemistry, fluorescence microscopy, histochemistry, flow cytometry and fluorescence in situ hybridization (FISH) [1,2]. Small fluorescent labels offer significant practical benefits, enabling the optimization of fluorescence signals through the attachment of multiple fluorophores to a single biomolecule [3,4]. The commonly used fluorescent labels are prohibitively expensive for regular use in routine applications and most of them have small Stokes shifts. In this work we present three new small molecules (Figure 1), as promising fluorescent labels for biomolecules, obtained through an efficient, straightforward, and cost-effective synthetic strategy. Additionally, we evaluate the fluorescent three new small molecules labels as potentially effective fluorescent labels for biomolecules. Six new fluorescent oligonucleotide probes have been obtained, three directed to the rRNA region of eukaryotic cells (EUK516) and three to the rRNA region of prokaryotic cells (EUB338). The developed fluorescent probes were tested on microorganisms belonging to the culture collection of the Laboratory of Biodegradation and Biotechnology of the HERCULES Laboratory (University of Évora), showing effective performance as RNA-FISH probes. Density functional theory and time-dependent density functional theory calculations were carried out to gain insights into the observed photophysical properties. These findings evidenced the applicability of these new small molecules in labeling of biomolecules and bioimaging.