Imidazole and imine coated ZnO nanoparticles for nanomolar detection of Al(III) and Zn(II) in semi-aqueous media
Graphical abstract
Introduction
Recently, organic–inorganic hybrid chemosensors that recognize metal ions have gained considerable attention.1, 2, 3, 4, 5, 6 Ease of preparation, a low detection limit, and a broad detection range are advantageous features of organic–inorganic hybrid chemosensors. Aluminum is the third most abundant element in the earth’s crust, and trace amounts of aluminum are required for various normal human biological processes.7 However, excessive intake of aluminum may cause Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis.8, 9, 10 In addition, Aluminum hinders the growth of plants.11 Zinc is another essential transition metal in human physiology,12, 13 playing roles in multiple biological processes including as an essential element of antioxidants and cofactors, gene transcription, neural signal transmission, regulation of metallo-enzymes, and apoptosis.14, 15, 16, 17 A deficiency in zinc may lead to growth retardation, diarrhea, impotence, and delayed sexual maturation.18, 19, 20 Therefore, it is essential to develop chemosensors for the detection of Al(III) and Zn(II) ions.
Fluorogenic chemosensors have enjoyed substantial interest due to their widespread applications in medical and environmental areas. Most of the reported chemosensors for Al(III) and Zn(II) have complex structures that require multistep synthetic routes.21, 22, 23, 24, 25, 26, 27, 28 Therefore, it is essential to develop sensors, which can be easily prepared and have a broad detection range, low detection limit, and a high binding constant.
We previously reported the preparation of dipodal imine-linked ZnO-coated chemosensors, which when decorated with compounds 2 and 3 showed high selectivity for Mg(II)29 and Co(II),30 respectively. To extend the scope of this methodology, two different organic ligands were attached to the surface of ZnO nanoparticles (ZnO-NPs). The best results were obtained using 1-methyl-3-carboxymethylimidazole (1) along with ligands 2 or 3 as shown in Figure 1. Receptors 5 and 6 exhibited selective affinity toward Al(III) and Zn(II), respectively.
Section snippets
Results and discussion
Ligands 1, 2, and 3 were synthesized by literature methods, and the ZnO-NPs were prepared via a sol-gel method.30, 31, 32 Decoration of the organic ligands on the surface of ZnO-NPs was performed through an in situ method. Receptor 4 was obtained by reaction of ligand 1 with Zn(NO3)2 and NaOH. The 1H NMR spectrum of receptor 4 was similar to that of ligand 1 except for signal broadening due to the presence of ZnO-NPs. Transmission electron microscopy (TEM) analysis showed that the modified
Conclusions
Members of a new class of chemosensors 4, 5, and 6, have been prepared. Receptor 5 showed high selectivity for Al(III) ions with a detection limit of 11 nM, whereas receptor 6 selectively recognized Zn(II) with a detection limit of 23 nM. Receptors 5 and 6 displayed sensitive and selective recognition of Al(III) and Zn(II), respectively, even in the presence of other metal ions.
Acknowledgments
This work was supported by the India-Korea Joint Program of Cooperation in Science &Technology (NRF-2011-0027710) and by a CSIR, India Project Grant (01(2417)/10 EMR-II).
References and notes (35)
- et al.
Mater. Lett.
(2008) - et al.
Dyes Pigm.
(2013) Coord. Chem. Rev.
(2002)- et al.
Curr. Opin. Chem. Biol.
(2000) - et al.
Neurobiol. Dis.
(1997) - et al.
Inorg. Chem. Commun.
(2013) - et al.
J. Lumin.
(2014) - et al.
Tetrahedron Lett.
(2009) - et al.
Sens. Actuators, B
(2012) - et al.
Mater. Lett.
(2012)
Eur. J. Inorg. Chem.
Chem. Commun.
Chem. Mater.
Adv. Mater.
ACS Appl. Mater. Interfaces
Chem. Eng. News Arch.
Science
Cited by (9)
Grey level replaces fluorescent intensity: Fluorescent paper sensor based on ZnO nanoparticles for quantitative detection of Cu<sup>2+</sup> without photoluminescence spectrometer
2018, Sensors and Actuators, B: ChemicalCitation Excerpt :As nontoxic and low-cost photoluminescence materials, wurtzite-type ZnO nanostructures are very suitable for fluorescent probes [30]. With different capping agents, especially the imine-linked receptors, fluorescent ZnO nanostructures can selectively test different metal ions, like Al3+, Mg2+, Zn2+, Cr3+, Hg2+, Co2+ and so on [31–36]. It gradually comes to a general consensus that decorating imine-linked receptors is unavoidable to fabricate selective ZnO fluorescent probes.
Supramolecular hybrid of ZnO nanoparticles with benzimidazole based organic ligand for the recognition of Zn<sup>2+</sup> ions in semi-aqueous media
2017, Journal of Photochemistry and Photobiology A: ChemistryCitation Excerpt :Carbon nanotubes modified with glycine-N-8-quinolylamide demonstrated the detection of Zn2+ ions in the micro molar (0.2 μM) range [20]. Lately, Sharma et al. detected Zn2+ ions from imine linked dipodal receptor decorated ZnO nanoparticles [21]. Despite the extensive studies for the detection of Zn2+ ions, reports demonstrated the nanomolar detection of zinc ions from the benzimidazole based organic ligand decorated ZnO nanoparticles are rarely available.
Salen decorated nanostructured ZnO chemosensor for the detection of mercuric ions (Hg<sup>2+</sup>)
2016, Sensors and Actuators, B: ChemicalCitation Excerpt :Merger of these elusive nanomaterials with optical sensing for determination of mercury ions have gained so much prominence [22,29,30]. ZnO has been reported to be an efficient bio- and chemo-sensing material, since it contained mineral elements essential to humans, and exhibited strong bactericidal activity [31,32]. Zhu et al. tested toxic vapors using ZnO nanorods as the optical substrate for fluorescence spectroscopy [33].
3-mercaptopropionic acid surface modification of Cu-doped ZnO nanoparticles: Their properties and peroxidase conjugation
2016, Colloids and Surfaces A: Physicochemical and Engineering AspectsCitation Excerpt :The majority of successful doping has been carried out in the aqueous phase comprising thermal hydrolysis techniques [32], hydrothermal processing [33], and so–gel method [34–36]. Examples of modification of nanocrystalline ZnO with different types of capping ligands have been reported [37–41]. Nevertheless, to the best of our knowledge, there are no reports on the use of capping ligands for functionalization of Cu-doped ZnO nanoparticles.
Development of a simple pyrazine-derived "turn on" Al<sup>3+</sup> fluorescent sensor with high selectivity and sensitivity
2015, Inorganica Chimica ActaCitation Excerpt :Nevertheless, there have been only a few reports about the development of fluorescent chemosensors for Al3+ because of its poor coordination ability [21]. Therefore, it is a great demand to design and synthesize Al3+ selective and sensitive fluorescent chemosensors [22–26]. For a sensor which is based on the photoinduced electron-transfer (PET) mechanism and the chelation-enhanced fluorescence (CHEF) phenomenon, it is evident that the PET from the amine group to the excited singlet state of fluorophore makes the fluorescence of the sensor quenched.