A Single and Simple Receptor as a Multifunctional Chemosensor for the Al 3 + /Cu 2 + ions and Its Live Cell Imaging Applications (original) (raw)
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Journal of Luminescence, 2019
A new 2-hydroxynaphthalen based Schiff base colorimetric and fluorescence chemosensor, H 2 L {(E)-4-((2-hydroxynaphthalen-1-yl)methyleneamino)benzoic acid}, for selective sensing of Al 3+ ions has been synthesized and characterize by different physico-chemical and spectroscopic techniques. The probe shows enhanced fluorescence and significant color change from bright yellow to colorless in the presence of Al 3+ ions in methanol-water (9:1 v/v) solution, without interference from other metal ions. The binding mode of H 2 L with Al 3+ was studied by UV-vis, fluorescence titration, job's plot analysis, and ESI-MS. The probe acts as a bidentate ligand and interacts with Al 3+ ions with a binding constant of K b = 1.546 × 10 5 M-1. The limit of detection for Al 3+ is found to be 6.4 × 10 −7 M. The cytotoxicity of the probe has been evaluated by MTT assay on MCF-7 cell line, indicating more than 92% cell viability in the concentration range of 1.25-50 μM with no serious cytotoxicity on cells. Live cell imaging study clearly indicates that the 2 accumulation of Al 3+ in living cells can be detected by H 2 L.
A naphthalene based sulfonamide Schiff base, (E)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-N-(5methylisoxazol-3-yl)benzenesulfonamide (HL) has been found to be a flourescence turn-on probe for selective detection of Al 3+ in aqueous system. Structure of the probe has been established by FTIR, 1 H NMR, mass spectra and X-ray single crystal study. The probe has shown 24 times flourescence enhancement in presence of Al 3+ . The limit of detection (LOD) obtained by 3s method is 33.2 nM. The probable co-ordination environment of L-Al 2+ complex has been supported by mass spectral data and DFT computational study. By TD-DFT calculation UV-Vis spectra of HL and L-Al 2+ complex has been predicted and that has well correlated with experimental data. Cell imaging study reveals that the probe can be used for the intracellular detection of Al 3+ in cultured Vero cell. Antimicrobial activity of HL has also been evaluated and probable mode of binding inside the DHPS cavity has been predicted by docking study. This sensor is unique with reference to two other predecessors because of its biocompatibility of sulfonamide derivative and nonmutagenicity.
Sensors and Actuators B: Chemical, 2018
A new Schiff base tcph, derived from 2-thiophene carboxylic acid hydrazide, has been synthesized and characterized by various spectroscopic techniques. The molecular structure of the compound has also been determined by X-ray crystallography. The tcph acts as a selective Al 3+ and F − induced OFF-ON-OFF type of probe in aqueous media. The 1:1 binding stoichiometry between probe and Al 3+ has been established from Job's plot and further supported by ESI-MS studies. The limit of detection of Al 3+ ions is determined by 3 methods, which is found to be 1.35 × 10 −9 M. The coordination environment for the tcph-Al 3+ complex is delineated by NMR titration and DFT calculations. Detailed insights of probe-metal interaction mechanism have been studied by density functional theory (DFT) as well as time dependent-DFT calculations. MTT assay of the probe on live SiHa cells suggests no serious cytotoxicity in cells even at higher concentration. The probe tcph and its tcph-Al 3+ complex have also been successfully applied to detect Al 3+ and F − ions in living cells (SiHa cells), respectively.
The design and development of fluorescent chemosensors have recently been the focus of consider-able attention for the sensitive and specific detection of environmentally and biologically relevant metalions in aqueous solutions and in living cells. Herein, we report photophysical results for a 1H-pyrrole-2-carboxaldehyde-substituted rhodamine 6G derivative (RCS) that possesses specific binding affinitytoward Al3+and Cu2+at micromolar concentration levels. In an N,N-dimethylformamide (DMF) andwater (v/v = 2/8) medium, the RCS chemosensor exhibits a substantially enhanced absorbance inten-sity at 532 nm and a color change from colorless to pink for Cu2+; it also exhibits significant “off–on”fluorescence at 557 nm, accompanied by a color change from colorless to fluorescent-yellow upon bind-ing to Al3+. The RCS sensor exhibits extremely high fluorescence enhancement upon complexation withAl3+, and it can be used as a “naked eye” sensor. Through fluorescence titration at 557 nm, we confirmedthat RCS exhibits a fluorescence response with a remarkable enhancement in emission intensity resultingfrom the complexation between RCS and Al3+, whereas no emission appeared in the case of competitivemetal ions (Cu2+, Al3+, Li+, Na+, K+, Cs+, Mg2+, Ca2+, Fe2+, Co2+, Ag+, Zn2+, Cd2+, Hg2+and Pb2+) in a DMF andwater (v/v = 2/8) solution. The reversible ring-opening mechanism of the rhodamine spirolactam inducedby Al3+/Cu2+binding and the 1:1 stoichiometric structure between RCS and Al3+were adequately sup-ported by Job-plot evaluation, optical titration and FT-IR analysis. The lowest detection limit for Al3+is3.20 × 106M−1in a DMF and water (v/v = 2/8) solution. Al3+-induced chelation-enhanced fluorescence(CHEF) is associated with spirolactam ring opening of the rhodamine unit. Finally, RCS was successfullyapplied for the bio-imaging of Al3+in living HeLa cells and for fluorescence imaging of a microfluidicsystem.
A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (R6CN) was designed, synthesized and characterized as a reversible switch. R6CN displayed high selectivity toward Al 3+ from various metal ions, including Al 3+ , Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Hg 2+ , Pb 2+ and the resultant complex [R6CN-Al 3+ ]. The ring-opening mechanism of the rhodamine spirolactam was induced by Al 3+ binding, and the 1:1 stoichiometric structure between R6CN and Al 3+ was adequately supported by the Job-plot evaluation, optical titration, FT-IR and 1 H NMR results. Theoretical calculations and modeling simulations were performed using Material Studio 4.3 suite (VAMP), and the results supported the formation of a 1:1 complex between R6CN and Al 3+. The fluorescence quantum yield of R6CN-Al 3+ (˚ f = 92.33%) was very high compared to that of the bare ligand. The detection limit for Al 3+ was 4.28 × 10 −9 M, and a significant color change from almost colorless to pale-pink occurred in the presence of Al 3+. In turn, the R6CN-Al 3+ complex acted as a selective chemosensor toward N 3 − among various anions, including F − , Cl − , Br − , I − , NO 3 − , CH 3 COO − , ClO 4 − , CN − , SCN − , HSO 4 − , HPO 4 − and PF 6 − , in acetonitrile media. Moreover, the R6CN-Al 3+ complex also exhibited a high selectivity and sensitivity toward the azide anion upon the addition of Al 3+ , and the color reversed back to colorless when the two ions were present together in solution. At last, R6CN was productively applied to the PEGDMA polymer to sense Al 3+ ions, which was analyzed using FT-IR, fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.
We have synthesized a novel 2-chloronicotinaldehyde-functionalized rhodamine B derivative (RBCN)that acts as an “OFF–ON” chemosensor. RBCN specifically binds Al3+in the presence of a large excessof competing metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+andPb2+) and exhibits visible changes in its electronic and fluorescent spectral behavior. These spectralchanges are significant in the visible region of the spectrum and thus enable detection with the nakedeye. Upon coordination with Al3+, the promoted ring opening of the rhodamine spirolactam ring in theRBCN chemosensor evokes a fluorescence turn-on response via the chelation-enhanced fluorescence pro-cess. The probe exhibited good brightness and fluorescence enhancement in which the lower detectionlimit for Al3+was 2.86 × 10−8M. The ring-opening mechanism of the rhodamine spirolactam inducedby Al3+binding and the 1:1 stoichiometric structure between RBCN and Al3+were supported by Job’splot evaluation, UV–vis, fluorescence titrations, FT-IR and1H NMR spectroscopic studies. Finally, theo-retical calculations and modeling simulations were conducted using Material Studio 4.3 suite to simulatethe formation of a 1:1 complex between RBCN and Al3+. However, the fluorescence and colorimetricresponse of the RBCN-Al3+complex was quenched by the addition of azide (N3−) anion, which abstractsthe Al3+ion from the complex and turns off the sensor, confirming that the recognition process isreversible.
ACS omega, 2019
Four rhodamine 6G-based chemosensors (H 3 L1−H 3 L4) are designed for selective detection of Al 3+ ion. They are characterized using various spectroscopic techniques and X-ray crystallography. All absorption and emission spectral studies have been performed in 10 mM N-(2-hydroxyethyl)piperazine-N′-ethanesulfonic acid (HEPES) buffer solution at pH 7.4 in H 2 O/ MeOH (9:1, v/v) at 25°C. In absorption spectra, chemosensors exhibit an intense band around 530 nm in the presence of Al 3+ ion. Chemosensors (H 3 L1−H 3 L4) are nonfluorescent when excited around 490 nm. The presence of Al 3+ ion enhances the emission intensity (555 nm) many times. The formation of complexes 1−4 is established with the aid of different spectroscopic techniques. The limit of detection value obtained in the nanomolar range confirms the high sensitivity of the probes toward Al 3+ ion. It has been observed that the presence of aliphatic spacers in the diamine part and different halogen substituents in the salicylaldehyde part strongly influences the selectivity of the chemosensors toward Al 3+ ion. The propensity of the chemosensors to identify intracellular Al 3+ ions in triple-negative human breast cancer cell line MDA-MB-468 by fluorescence imaging is also examined in this study.
Sensors and Actuators B: Chemical, 2015
A novel Schiff base receptor (E)-1-(4-((4-(diethylamino)-2-hydroxybenzylidene)amino)phenyl)-3,4-diphenyl-1H-pyrrole-2,5-dione (BASB) was synthesized and characterized. The receptor BASB exhibited a selective "off-on" recognition towards Al 3+ , Cr 3+ and Fe 3+ among the various tested metal ions. It showed significant color change from colorless to yellow, with the appearance of a new charge transfer absorption band at 425 nm. The detection limits for Al 3+ , Cr 3+ and Fe 3+ were found to be 2.16×10-6 M, 1.27×10-8 M and 5.03×10-8 M respectively. The binding stoichiometry between BASB and Al 3+ was observed to be 2:1 whereas, Cr 3+ and Fe 3+ showed 1:1 binding stoichiometry based on the Job's plot analysis. Further, a Boolean type molecular logic gate system of BASB was developed in the presence of Al 3+ and Fas chemical inputs.
Acta Chimica Slovenica
Six different Schiff bases to be used as turn-on fluorescent probes based on photoinduced electron transfer (PET) mechanism for the recognition of aluminum ions were successfully synthesized and characterized. The binding abilities of synthesized compounds with different metal cations were investigated by absorption and emission spectra. From the spectrophotometric experiments, it were seen that compound SK-1 displayed an excellent fluorescence response towards targeted aluminum ions probably due to its suitable chelating structure. Furthermore, such compound SK-1 also showed high sensitivity and selectivity response towards aluminum ions over other competing ions. In addition, the potential biological applications of SK-1 to detect aluminum ions in living cells were also investigated and results showed that fluorescence sensor SK-1 could be a promising probe for determining and/or monitoring aluminum ions in both biological and/or chemical samples.