New β-carboline fluorophores with superior sensitivity and endoplasmic reticulum specificity for tracking ER changes

Fluorescent probes for targeting endoplasmic reticulum: design strategies and their applications

Advances in developing organic fluorescent probes and fluorescence imaging techniques have enhanced our understanding of cell biology. The endoplasmic reticulum (ER) is a dynamic structure that plays a crucial role in protein synthesis, post-translational modifications, and lipid metabolism. The malfunction of ER contributes to several physiological and pathological conditions. Therefore, the investigations on the imaging and role of ER have attracted a lot of attention. Due to their simplicity, synthetic tunability, photostability, high quantum yields, easier cellular uptake, and lower cytotoxicity, organic fluorophores offer invaluable tools for the precision targeting of various cellular organelles and probe ER dynamics. The precision staining is made possible by incorporating specific functional groups having preferential and local organelle biomolecular interactions. For instance, functional moieties such as methyl sulfonamide, sulfonylurea, and pentafluorophenyl assist in ER targeting and thus have become essential tools to probe a deeper understanding of their dynamics. Furthermore, dual-function fluorescent probes that simultaneously image ER and detect specific physiological parameters or biological analytes were achieved by introducing special recognition or chemically reactive sites. This article attempts to comprehensively capture various design strategies currently employed by researchers utilizing small organic molecules to target the ER and detect specific analytes.

Small Molecule Modifications Significantly Increase the Transfection Efficiency of Low-Molecular Polymer

Gene vectors with high biocompatibility and transfection efficiency are critical for successful gene therapy. PEI 25K (Polyethyleneimine 25K) is a common polymeric gene vector that has been employed as a positive control material in gene transfection studies due to its good performance in endosome escape. PEI 25K's indegradability and abundance of positive charges, on the other hand, cause toxicity in cells, limiting its use. In this study, we developed the PEI-ER non-viral vector by adding an endoplasmic reticulum (ER) targeting ligand to low molecular weight PEI 1.8K. These small molecule modifications dramatically improved PEI transfection efficiency while barely interfering with compatibility. PEI-ER/DNA complexes were discovered to enter the cell via caveolin-mediated endocytosis, avoiding destruction in the endosome. We believe that this little chemical alteration is a simple solution to enhance the efficacy of cationic polymer vectors in gene transport, and it has a lot of medicinal applications.

Design and Synthesis of Fluorescent 1,3-Diaryl-β-carbolines and 1,3-Diaryl-3,4-dihydro-β-carbolines

The 1,3-diaryl-β-carboline derivatives, including 3,4-dihydro variants, were synthesized via a multiple-step approach. These compounds possess rigid and twisted configurations, which are expected to exhibit unique optical properties. The absorption and fluorescence properties of the newly synthesized compounds were investigated. These synthetic 1,3-diaryl-β-carbolines displayed strong emission in the range of 387-409 nm and exhibited absolute photoluminescence quantum yields of up to 74%. Density functional theory calculations were performed to better elucidate the geometric, electronic, and optical properties of these novel 1,3-diaryl-β-carbolines.

Efficient β-Carboline Alkaloid-Based Probe for Highly Sensitive Imaging of Endogenous Glutathione in Wheat Germ Tissues

Discriminative detection of GSH is achieved by employing a highly sensitive and selective fluorescent probe (KL-DN) that bears β-carboline alkaloid as a potential fluorophore and an azide group as the recognition unit. A rapid fluorescence off-on change is caused by special redox reaction; KL-DN has the capability of monitoring endogenous GSH in wheat germ tissues, indicating that this probe holds great potential for biological applications in plant tissues.