“Switch-Off-On” Detection of Fe3+ and F− Ions Based on Fluorescence Silicon Nanoparticles and Their Application to Food Samples

An approach to the detection of F− ions in food samples was developed based on a “switch-off-on” fluorescence probe of silicon nanoparticles (SiNPs). The fluorescence of the synthetic SiNPs was gradually quenched in the presence of Fe3+ ion and slightly recovered with the addition of F− ion owing to the formation of a stable and colorless ferric fluoride. The fluorescence recovery exhibited a good linear relationship (R2 = 0.9992) as the concentration of F− ion increased from 0 to 100 μmol·L−1. The detection limit of the established method of F− ion was 0.05 μmol·L−1. The recovery experiments confirmed the accuracy and reliability of the proposed method. The ultraviolet–visible spectra, fluorescence decays, and zeta potentials evidenced the fluorescence quenching mechanism involving the electron transfer between the SiNPs and Fe3+ ion, while the fluorescence recovery resulted from the formation of ferric fluoride. Finally, SiNPs were successfully applied to detect F− ions in tap water, Antarctic krill, and Antarctic krill powder.

Post-Translational Tubulin Modifications in Differentiated Human Neural Stem Cells

The tubulin protein fulfills a variety of cellular functions that range from chromosomal separation to locomotion. The functional diversity of tubulin is achieved through the expression of specific tubulin isotypes in different cell types or developmental time periods. Post-translational modifications (PTMs) of tubulin also are vital for specific intracellular tasks, such as binding and recruiting motor proteins. In neurons, the isotypic expression profile for tubulin is well characterized, and the importance of PTMs for proper neuronal function has gained recent attention due to their implication in neurodegenerative disorders. In contrast, the role of tubulin specializations in the specification of neural cell fate has received minimal attention and studies of tubulin PTMs and isotypes in neuroglia such as astrocytes are relatively few. To bridge this knowledge gap, we undertook an analysis of PTMs in neurons and astrocytes derived from the federally approved H9 hESC-derived human neural stem cell (hNSC) line. In hNSCs, basal cells can be directed to assume neural fate as neurons or astrocytes by specifying different media growth conditions. Immunocytochemical methods, fluorescent antibody probes, and confocal microscopy facilitated image acquisition of fluorescent signals from class III β- tubulin (βIII-tubulin), acetylated tubulin, and polyglutamylated tubulin. Fluorescent probe intensities were assessed with the EBImage package for the statistical programming language R and compared using Student's t-tests. Qualitative analysis indicated that βIII-tubulin, acetylated tubulin, and polyglutamylated tubulin were expressed to some degree in basal hNSCs and their media-differentiated hNSC neuronal and astroglial progeny. In media-differentiated hNSC astrocyte progeny, quantification and statistical analysis of fluorescence probe intensity showed that acetylated tubulin/ βIII-tubulin ratios were greater than the ratio for polyglutamylated tubulin/ βIII-tubulin. These findings represent a snapshot of the dynamic and varied changes tubulin expression profile during the specification of neural cell fate. Results imply that investigations of tubulin PTMs have the potential to advance our understanding of the generation and regeneration of nervous tissue.

Two-photon fluorescence imaging of mitochondria viscosity with water-soluble pyridinium inner salts

Rational design of mitochondrial viscosity probes with water-soluble two-photon (TP) fluorescence probe still remains a challenge in practical biological applications. Herein, three novel water-soluble TP active sulfosalt derivatives (Mito-Z, Mito-H,...

Unravelling the mechanism of glucose binding in a protein-based fluorescence probe: molecular dynamics simulation with a tailor-made charge model

Fluorophores linked to the glucose/galactose-binding protein (GGBP) are a promising class of glucose sensors with potential application in medical devices for diabetes patients. Several different fluorophores at different positions in...

Fluorescent probe for the detection of hypochlorous acid in water samples and cell models

A new fluorescence probe was successfully applied to test strips and imaging analysis of exogenous and endogenous hypochlorite in living cells.