Abstract
Background: The traditional methods for the detection and quantification of Cu2+ and Fe3+ heavy metal ions are usually troublesome in terms of high-cost, non-portable, time-consuming, specialized personnel and complicated tools, so their applications in practical analyses is limited. Therefore, the development of cheap, fast and simple-use techniques/instruments with high sensitivity/selectivity for the detection of heavy metal ions is highly demanded and studied.
Methods: In this study, a fluorene-based fluorescent ''turn-off'' sensor, methyl 2-(2-((((9H-fluoren-9- yl)methoxy)carbonyl)amino)-3- phenylpropanamido) acetate (probe FLPG) was synthesized via onepot reaction and characterized by 1H-NMR, 13C-APT-NMR, HETCOR, ATR-FTIR and elemental analysis in detailed. All emission spectral studies of the probe FLPG have been performed in CH3CN/HEPES (9/1, v/v, pH=7.4) media at rt. The quantum (Φ) yield of probe FLPG decreased considerably in the presence of Cu2+ and Fe3+. The theoretical computation of probe FLPG and its complexes were also performed using density functional theory (DFT). Furthermore, bio-imaging experiments of the probe FLPG was successfully carried out for Cu2+ and Fe3+ monitoring in living-cells.
Results: The probe FLPG could sense Cu2+ and Fe3+ with high selectivity and sensitivity, and quantitative correlations (R2>0.9000) between the Cu2+/Fe3+ concentrations (0.0−10.0 equiv). The limits of detection for Cu2+ and Fe3+ were found as 25.07 nM and 37.80 nM, respectively. The fluorescence quenching in the sensor is managed by ligand-to-metal charge transfer (LMCT) mechanism. Job’s plot was used to determine the binding stoichiometry (1:2) of the probe FLPG towards Cu2+ and Fe3+. The binding constants with strongly interacting Cu2+ and Fe3+ were determined as 4.56×108 M-2 and 2.02×103+ M-2, respectively, via the fluorescence titration experiments. The outcomes of the computational study supported the fluorescence data. Moreover, the practical application of the probe FLPG was successfully performed for living cells.
Conclusion: This simple chemosensor system offers a highly selective and sensitive sensing platform for the routine detection of Cu2+ and Fe3+, and it keeps away from the usage of costly and sophisticated analysis systems.
Keywords: Fluorescence sensor, fluorene, iron, copper, DFT, bio-imaging.
Graphical Abstract
[http://dx.doi.org/10.1016/j.microc.2019.104423]
[http://dx.doi.org/10.1016/j.tet.2015.06.081]
[http://dx.doi.org/10.1016/j.tetlet.2011.08.092]
[http://dx.doi.org/10.1016/j.ica.2019.05.046]
[http://dx.doi.org/10.1016/j.saa.2020.118236] [PMID: 32179460]
[http://dx.doi.org/10.1016/j.microc.2020.105075]
[http://dx.doi.org/10.1016/j.jphotochem.2019.111982]
[http://dx.doi.org/10.1016/j.molliq.2016.07.047]
[http://dx.doi.org/10.1016/j.tetlet.2017.08.078]
[http://dx.doi.org/10.1093/ajcn/88.3.855S] [PMID: 18779308]
[PMID: 17259340]
[http://dx.doi.org/10.1016/j.jphotochem.2018.07.021]
[http://dx.doi.org/10.1007/s00277-018-3407-5] [PMID: 29959467]
[http://dx.doi.org/10.1093/jn/130.2.489S]
[http://dx.doi.org/10.1016/j.ica.2018.04.028]
[http://dx.doi.org/10.1016/j.snb.2015.10.086]
[http://dx.doi.org/10.1016/j.snb.2015.08.125]
[http://dx.doi.org/10.3233/JAD-2009-1010] [PMID: 19387120]
[http://dx.doi.org/10.1080/03630260701699912] [PMID: 18274986]
[http://dx.doi.org/10.1016/S0165-0173(98)00012-5] [PMID: 9729418]
[http://dx.doi.org/10.1023/A:1012006404144]
[http://dx.doi.org/10.1002/chin.200023130]
[http://dx.doi.org/10.1166/sl.2010.1330]
[http://dx.doi.org/10.1016/j.saa.2010.12.065] [PMID: 21257342]
[http://dx.doi.org/10.1007/s10895-016-1972-3] [PMID: 27995460]
[http://dx.doi.org/10.1016/j.jphotochem.2019.111982]
[http://dx.doi.org/10.14723/tmrsj.44.69]
[http://dx.doi.org/10.1016/j.snb.2016.12.067]
[http://dx.doi.org/10.1039/C8AY02526F]
[http://dx.doi.org/10.1063/1.448799]
[http://dx.doi.org/10.1063/1.464913]
[http://dx.doi.org/10.1016/S0040-4039(02)00754-2]
[http://dx.doi.org/10.1021/ja071088k] [PMID: 17429976]
[http://dx.doi.org/10.1039/C8DT04042G] [PMID: 30511078]
[http://dx.doi.org/10.1021/acsomega.9b01432] [PMID: 31552323]
[http://dx.doi.org/10.1016/j.talanta.2019.120615] [PMID: 31987182]
[http://dx.doi.org/10.1016/j.saa.2017.01.064] [PMID: 28182986]
[http://dx.doi.org/10.1016/j.saa.2020.118119] [PMID: 32032858]
[http://dx.doi.org/10.1016/j.ica.2019.119191]
[http://dx.doi.org/10.1016/j.snb.2008.05.019]
[http://dx.doi.org/10.1016/j.jlumin.2013.06.013]
[http://dx.doi.org/10.1016/j.saa.2017.04.056] [PMID: 28456087]
[http://dx.doi.org/10.1016/S0076-6879(82)87029-8] [PMID: 7176926]