Design, Spectral Characteristics, Photostability, and Possibilities for Practical Application of BODIPY FL-Labeled Thioterpenoid

A novel terpene-BODIPY conjugates based fluorescent probes: Synthesis, spectral properties, stability, penetration efficiency into bacterial, fungal and mammalian cells

The design of fluorescent probes based on biocompatible luminophores for medical diagnostics is one of the rapidly developing areas worldwide. Here, we report the synthesis of a novel BODIPYs containing a propanoic acid residue at the α-position of one of the pyrrole rings conjugated to (+)-myrtenol or thiotherpenoid. Both conjugates are quite photostable (t1/2 ∼ 40 h) and exhibit high fluorescence efficiency (φfl ∼ 77-90 %). The advantage of the newly synthesized terpene-BODIPY conjugates lies in their stability and absence of fluorescence quenching over a wide pH range (1.65-9.18). Moreover, the affinity of the conjugates for lipid biostructures was significantly improved compared to the original α-BODIPY carboxylic acid. As opposed to unconjugated BODIPY, which shows negligible activity against any cell type used in the study, the luminophores with either (+)-myrtenol or thioterpenoid effectively stained the membranes of Gram-positive bacteria, while Gram-negative bacteria were not stained. In eukaryotic cells, both conjugates readily stained organelles, but not the cell and nuclear membranes, suggesting these compounds as tools for differential staining of microbes or cell structures. Taken together, our data demonstrates that conjugation of BODIPY to terpenoids significantly improves the fluorescence abilities and modulates the selectivity of the conjugates against various cells.

Molecular Diagnostics in the Postgenomic Era

Since the end of the 20th century, when the first eukaryotic organism was sequenced, genome sequencing as a technique has made incredible progress, and today new methods allow sequencing different genomes and genes at relatively low prices and in a short time [...].

Ammonia and temperature sensing applications using fluorometric and colorimetric microparticles and polymeric films doped with BODIPY-emitters

Four functionalized BODIPY derivatives (BDP1 to BDP4) were synthesized and their optical properties investigated both in solution and when incorporated into a solid matrix. Recognizing the versatility of BODIPY derivatives and the increasing interest in developing new luminescent organic dyes embedded in polymers, the BODIPY derivatives were dispersed into two types of polymeric matrices: Poly(methyl methacrylate) (PMMA) and Thermoplastic Polyurethane (TPU), both as films and microparticles. This resulted in eight new BODIPY-doped polymer films and eight types of BODIPY-doped polymeric microparticles for use in aqueous solutions. The integration of the BODIPY dyes into the polymeric matrices combines the unique properties of the polymer films, such as porosity, flexibility, and elasticity, with the excellent photophysical characteristics of the BODIPYs. Importantly, the dispersion minimized issues such as aggregation-caused quenching commonly observed in solid-state luminescent materials. The thermometric responses of all polymer films were evaluated by studying their solid-state emission spectra in the 25-200 °C temperature range. The reversibility of these temperature-induced changes was also assessed, revealing excellent recovery of luminescence. These promising results suggest these materials could have applications as fluorescent thermometric sensors. Furthermore, we explored the potential of the brominated (BDP3) and chalcogenated (BDP4) BODIPY derivatives as ammonia sensors. The two derivatives produced yellow fluorescent products upon interaction with the analyte. Kinetic studies using solid-state emission spectra of BDP4@TPU and BDP4@PMMA showed significant differences in reaction rates (minutes for BDP4@TPU and hours in the case of BDP4@PMMA) attributable to the higher permeability of TPU when compared with PMMA. Detection and quantification of ammonia concentration were conducted by means of simple photographic analysis, measuring the "R" (red) and "G" (green) components of RGB color parameters. The results from the photographic method correlated well with the results from fluorimetric spectroscopy studies. The photographic analysis is straightforward, portable, and does not require expensive equipment. Finally, we successfully applied polymeric microparticles doped with BODIPYs to detect ammonia in water, demonstrating their effectiveness without the need for organic solvents. This highlights their potential for environmental monitoring and other applications requiring sensitive and selective detection methods.

Terpenes and Terpenoids Conjugated with BODIPYs: An Overview of Biological and Chemical Properties

Advancements in small-molecule research have created the need for sensitive techniques to accurately study biological processes in living systems. Fluorescent-labeled probes have become indispensable tools, particularly those that use boron-dipyrromethene (BODIPY) dyes. Terpenes and terpenoids are organic compounds found in nature that offer diverse biological activities, and BODIPY-based probes play a crucial role in studying these compounds. Monoterpene-BODIPY conjugates have exhibited potential for staining bacterial and fungal cells. Sesquiterpene-BODIPY derivatives have been used to study sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA), indicating their potential for drug development. Owing to their unique properties, diterpenes have been investigated using BODIPY conjugates to evaluate their mechanisms of action. Triterpene-BODIPY conjugates have been synthesized for biological studies, with different spacers affecting their cytotoxicity. Fluorescent probes, inspired by terpenoid-containing vitamins, have also been developed. Derivatives of tocopherol, coenzyme Q10, and vitamin K1 can provide insights into their oxidation-reduction abilities. All these probes have diverse applications, including the study of cell membranes to investigate immune responses and antioxidant properties. Further research in this field can help better understand and use terpenes and terpenoids in various biological contexts.

Effect of meso-substituents and medium properties on the photo- and pH-stability, penetration efficiency into bacterial and microscopic fungi cells of terpene-BODIPY conjugates

In order to expand the arsenal of tools and areas for practical use of BODIPY dyes as bifunctional fluorescent theranostics, we studied the effect of the meso-substituents nature and medium properties on photo- and pH-stability, efficiency of singlet oxygen generation, and affinity to biostructures of terpene-BODIPY conjugates. The BODIPYs fused with myrtenol or thiotherpenoid via carboxylic acid residues exhibit high stability over a wide pH range and the presence of a bulky substituent at the meso-position of BODIPY conjugates increases their photostability two-fold compared to structurally related meso-unsubstituted analogues. Furthermore, the photodegradation rate of the conjugates directly depends on their ability to generate singlet oxygen and the course probability of the corresponding red-ox reactions involving reactive oxygen species. The conjugate of BODIPY with a thiotherpenoid demonstrated high ability to penetrate the membranes of filamentous and yeast-like fungi and bind to membrane of organelles in the fungal cell. At the same time, this compound also had a high ability to penetrate into biofilms of Staphylococcus aureus and Klebsiella pneumoniae and into bacterial cells within the matrix, which makes this compound promising for staining intracellular structures of eukaryotic cells and bacteria embedded into biofilms.