Fluorescence Intensity Of Molecules Research Articles

Design, synthesis, and applications of nucleic acid-specific benzoxazole-N,N-dialkylphenylamines derivatives for nucleolus imaging in the cells

Considered the brain of the nucleus, alterations in the structure and function of the nucleolus are linked to numerous cellular functions and, consequently, contribute to several diseases. The identification of nucleolar morphology and activity via novel biomarkers presents new avenues for the development of therapeutic approaches for a variety of human diseases, including cancer, neurodegeneration, and aging. Therefore, specific detection of the nucleolus with fluorescence probes is of critical importance for clinical applications. In the present study, a series of benzoxazole-N,N-dialkylphenylamines derivative compounds were designed and synthesized based on the benzothiazole-based fluorescence probe Thioflavin T (ThT). Among the compounds, BX-3 and BX-16, which carry electron-withdrawing substituents in the benzoxazole ring, were observed to have higher fluorescence emission at wavelengths of 470 and 465 nM, respectively. The general morphology and divisions of the cells were examined under inverted and light microscopes, respectively, and the fluorescence potentials of selected compounds were determined using immunofluorescence microscopy. The fluorescence intensity of molecules and 3D interactive surface plot images of cells were analyzed using ImageJ software. Cell imaging analyses showed that BX-6 and BX-13, like ThT, specifically stain the cell nucleolus. Moreover, molecular docking studies showed that the compounds could identify the RNA-rich nucleolus by binding with high affinity to the guanine region in the RNA structure. The results suggest that the compounds may be an initial route in developing specific biosensor compounds for nucleolus imaging.

Observation of single-molecule Raman spectroscopy enabled by synergic electromagnetic and chemical enhancement

There has been a long fundamental pursuit to enhance and levitate the Raman scattering signal intensity of molecule by a huge number of ~ 14–15 orders of magnitude, to the level comparable with the molecule fluorescence intensity and truly entering the regime of single-molecule Raman spectroscopy. In this work we report unambiguous observation of single-molecule Raman spectroscopy via synergic action of electromagnetic and chemical enhancement for rhodamine B (RhB) molecule absorbed within the plasmonic nanogap formed by gold nanoparticle sitting on the two-dimensional (2D) monolayer WS2 and 2 nm SiO2 coated gold thin film. Raman spectroscopy down to an extremely dilute value of 10–18 mol/L can still be clearly visible, and the statistical enhancement factor could reach 16 orders of magnitude compared with the reference detection sample of silicon plate. The electromagnetic enhancement comes from local surface plasmon resonance induced at the nanogap, which could reach ~ 10–11 orders of magnitude, while the chemical enhancement comes from monolayer WS2 2D material, which could reach 4–5 orders of magnitudes. This synergic route of Raman enhancement devices could open up a new frontier of single molecule science, allowing detection, identification, and monitor of single molecules and their spatial–temporal evolution under various internal and external stimuli.