Luminol-Eu3+-Gd3+-functionalized mesoporous silica for ultrasensitive detection of tetracycline antibiotics and smartphone-assisted sensing analysis

An organic-inorganic hybrid nanoprobe, namely LML-D-SBA@Eu3+-Gd3+, was constructed, with SBA-15 acting as the carrier material, and luminol and Eu3+ acting as fluorescence channels to achieve ratiometric signals that eliminate external interference (accurate detection). Gd3+ was used as a sensitizer to amplify the red emission of Eu3+ (ultrasensitive detection). In TCs detection, the luminol emission at 428 nm was quenched due to the photoinduced electron transfer mechanism, and the Eu3+ emission at 617 nm was sensitized due to the synergistic energy transfer from TCs and Gd3+ to Eu3+. The fluorescence intensity at 617 and 428 nm showed ratiometric changes as indicated by notable color changes from blue to red. The detection limits for TC and OTC were 0.21 and 0.08 ng/mL, respectively. To realize a facile, rapid, and cost-effective detection, we constructed a portable intelligent sensing platform based on smartphones, and it demonstrated great potential for on-site detection of TCs.

A new carbazole based fluorescent probe with AIE characteristic for detecting and imaging hydrazine in living cells, mungbean sprouts, Arabidopsis thaliana, and practical samples

In this study, we report a new carbazole-malononitrile fluorescent probe CBC with an interesting aggregation-induced emission (AIE) characteristic. Probe CBC could rapidly and selectively detect hydrazine (N2H4) in ～100% aqueous media, and also exhibit an exceedingly low detection limit of 6.3 nM for sensitively detecting N2H4. The sensing mechanism of CBC towards N2H4 has been well demonstrated through the spectra of 1H NMR, HRMS and FTIR. Interestingly, probe CBC was applied to visualize and detect gaseous and aqueous N2H4 with sensitive color changes. Importantly, probe CBC was applied to effectively detect N2H4 in practical samples such as soil, human serum, human urine, plants, foods and beverages, as well as sensitively sense and image N2H4 in biological systems including living mungbean sprouts, Arabidopsis thaliana, and HeLa cells.

A turn on fluorescent assay for real time determination of β-galactosidase and its application in living cell imaging

In recent years, fluorescent probes based on chemical reactions have been widely investigated as a powerful and noninvasive method for the diagnosis of diseases. β-Galactosidase (β-gal), a typical lysosomal glycosidase, over expressed in senescent cells and primary ovarian cancer cells, which has been considered as an important biomarker cell senescence and primary ovarian cancers. Fluorescent probes for the determination of β-gal provide an excellent choice for visualization of cell senescence. In this work, a turn on fluorescent probe (HBT-gal) for β-gal activity was developed based on the enzymatic hydrolysis of glycosidic bonds. HBT-gal showed little fluorescence in aqueous buffer excited at 415 nm, while emitted green fluorescence centered at ∼ 492 nm upon incubated with β-gal. The sensing scheme showed high selectivity and sensitivity for β-gal activity with a limit of detection calculated as low as 0.19 mU/mL. Moreover, HBT-gal was successfully applied to image β-gal activity in senescent Hep G2 cells treated with H₂O₂. Therefore, probe HBT-gal demonstrated a potential usage for the determination of cell senescence using β-gal as a biomarker.

The preparation of a special fluorescent probe with an aggregation-induced emission effect for detecting hydrazine in water

A novel phenyl-carbazole fluorescent molecule, PCBI, with an AIE effect is used as an excellent special probe for the detection of N2H4 in a DMF–H2O system.