Fluorescein derived Schiff base as fluorimetric zinc (II) sensor via ???turn on??? response and its application in live cell imaging

A novel Schiff base L composed of fluorescein hydrazine and a phenol functionalized moiety has been designed and prepared via cost-effective condensation reaction. The L is utilized for selective sensing of Zn2+ over other environmental and biological relevant metal ions in aqueous alcoholic solution under physiological pH range. The binding of Zn(2+ )to the receptor L is found to causes -23 fold fluorescence enhancement OIL. The 1:1 binding mode of the metal complex is established by combined UV-Vis, fluorescence, and HRMS (high-resolution mass spectroscopy) spectroscopic methods. The binding constant (K-a) for complexation and the limit of detection (LOD) of Zn2+ is calculated to be 2.86 x 10(4) M-1 and 1.59 mu M, respectively. Further photophysical investigations including steady-state, time-resolved fluorescence analysis and spectral investigations including NMR (nuclear magnetic resonance), IR (infrared spectroscopy) suggest introduction of CHEF (chelation enhance fluorescence) with the suppression of C=N isomerization and PET (photo-induced electron transfer) mechanism for the strong fluorescent response towards Zn2+. Finally, the sensor L is successfully employed to monitor a real-time detection of Zn2+ by means of TLC (thin layer chromatography) based paper strip. The L is used in the cell imaging study using African green monkey kidney cells (Vero cells) for the determination of exogenous Zn2+ by Immunofluorescence Assay (IFA) process

Rhodamine-azobenzene based single molecular probe for multiple ions sensing: Cu 2+ , Al 3+ , Cr 3+ and its imaging in human lymphocyte cells

A photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) regulated rhodamineazobenzene chemosensor (L) was synthesized for chemoselective detection of Al3+, Cr3+, and Cu2+ by UV-Visible absorption study whereas Al3+ and Cr3+ by Iluorimetric study in EtOH-H2O solvent. L showed a clear fluorescence emission enhancement of 21 and 16 fold upon addition of Al3+ and Cr3+ due to the 1:1 host-guest complexation, respectively. This is first report on rhodamine-azobenzene based Cr3+ chemosensor. The complex formation, restricted imine isomerization, inhibition of PET (photo-induced electron transfer) process with the concomitant opening of the spirolactam ring induced a turn-on fluorescence response. The higher binding constants 6.7 x 10(3) M-1 and 3.8 x 10(3) M-1 for Al(3+ )and Cr3+, respectively and lower detection limits 1 x 10(-6)M and 2 x 10(-6) M for Al3+ and Cr3+, respectively in a buffered solution with high reversible nature describes the potential of L as an effective tool for detecting Al3+ and Cr3+ in a biological system with higher intracellular resolution. Finally, L was used to map the intracellular concentration of Al3+ and Cr3+ in human lymphocyte cells (HLCs) at physiological pH very effectively. Altogether, our findings will pave the way for designing new chemosensors for multiple analytes and those chemosensors will be effective for cell imaging study