An ultra-sensitive fluorescence multi-channel and colorimetric probe based on salicylaldehyde hydrazone for Al³⁺ recognition with a 3:1 binding ratio†

Zhongyan Zhang‡ ^abc, Sha Wang‡^a, Muxi Wang^a, Hongming Li^a, Qingjian Liang^d, Jiawei Tang^a, Jian Sun*^e, Li-Jun Ma*^abc and Hong Liu^c
aSchool of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China. E-mail: mlj898021@scnu.edu.cn
^bKey Laboratory of Analytical Chemistry for Biomedicine, South China Normal University, Guangzhou 510006, P. R. China
^cKey Laboratory of Theoretical Chemistry of Environment Ministry of Education, South China Normal University, Guangzhou, 510006, P. R. China
^dCollege of Pharmacy, Xinjiang Key Laboratory of Biopharmaceuticals and Medical Devices, Xinjiang Medical University, Urumqi 830017, China
^eCollege of Pharmacy, Xinjiang Medical University, Urumqi, 830011, China. E-mail: jiansun@ciac.ac.cn

First published on 19th August 2024

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1. Introduction

Aluminum is the most abundant metallic element in the Earth's crust and is widely used in the aerospace industry, food processing and therapeutic drugs due to its excellent ductility and oxide corrosion resistance.^1–3 Unfortunately, because the ionic structure is very similar to several metals such as Fe³⁺ and Ca²⁺,⁴ the large accumulation of Al³⁺ and the long metabolic cycle⁵ will lead to the retarded growth of plants⁶ and many diseases of mammals due to its ion competition, such as Alzheimer's disease, osteoporosis, small cell hypochromicity and anemia.^7–11 Aluminum is currently considered a neurotoxic substance, and imbalanced aluminum intake can lead to many serious diseases.¹² The World Health Organization (WHO) established the maximum permissible content of Al³⁺ ions in drinking water to be 7.41 μM.¹³ Therefore, rapid, efficient, reliable, highly sensitive, and selective detection of Al³⁺ is of great significance and has attracted great attention.^2–4,12

Many methods have been devised to date to detect Al³⁺. Atomic absorption spectrometry (AAS), high performance liquid chromatography (HPLC), inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS) have been widely used for the analysis and quantitative detection of Al³⁺.^14–17 Compared to the traditional testing methods, fluorescence probes have been extensively studied in recent years due to their advantages of being easily operable, having high sensitivity and specificity, and being cost-effective.^18–22 An aluminum ion is a hard acid, so groups containing O and N with hard base properties are often ideal candidates for the design of fluorescence probes for Al³⁺.^23–27 However, the relatively weak coordination and strong hydration ability make the detection of Al³⁺ easily affected by matrix interference from Zn²⁺ or Cu²⁺, leading to limited selectivity and sensitivity.^22,24 In addition, the dependence on organic solvents is another drawback of many existing fluorescence probes, which seriously hinders their further application in the environment and biological systems.^1,23 Thus, the design of Al³⁺ specific fluorescence probes still poses challenges.^1,22,28

In a study, a fluorescence compound SBN based on salicylaldehyde hydrazine was synthesized for the fluorescence analysis of Al³⁺.²⁹ The introduction of the salicylaldehyde hydrazine groups not only significantly improves the water-solubility of the fluorescence compounds, but more importantly, the hydroxyl and carbon–nitrogen double bonds contained in it and its analogues have the potential to specifically complex with Al³⁺.^{13,17,23,30,31} Meanwhile, the presence of pyridine and benzene rings with appropriate steric hindrance effects in the fluorescence compound is beneficial for constructing spatial barriers, which enhances the selectivity and stability of chelating metal ions. Mechanism studies have shown that the particular molecular structure of SBN enables it to form stable complexes with Al³⁺ with a binding ratio of 3:1, thereby exhibiting specific recognition of Al³⁺ in aqueous solutions. The special structure of 3SBN–Al³⁺ enables SBN to exhibit multi-channel recognition of Al³⁺, and the dual-channel fluorescence bioimaging of Al³⁺ in living cells using SBN confirms the enormous potential of the probe in analyzing biological systems.

2. Experimental section

The detailed information on reagents, apparatus, experiment methods, preparation of fluorescence test paper, cell culture and computational details used in the study is listed in the ESI.†

SBN was synthesized by Schiff base reaction, as shown in Scheme 1. 0.2740 g (2.0 mmol) of nicotinic acid hydrazide and 0.3866 g (2.0 mmol) of 4-(diethylamino)salicylaldehyde were dissolved in 40 mL ethanol. The mixture was reacted at room temperature and stirred for 6 h. The formed yellow precipitate was filtrated off and vacuum dried after washing with ethanol 3 times, to obtain SBN as a yellow solid in 20.62% yield (0.1238 g). ¹H NMR (600 MHz, DMSO-d₆, δ/ppm), 11.95 (s, 1H), 11.33 (d, J = 9.3 Hz, 1H), 9.07 (s, 1H), 8.80 (t, J = 32.4 Hz, 1H), 8.43 (s, 1H), 8.34–8.23 (m, 1H), 7.58 (dd, J = 7.7, 4.8 Hz, 1H), 7.24 (d, J = 8.8 Hz, 1H), 6.29 (dd, J = 8.8, 2.5 Hz, 1H), 6.14 (d, J = 2.4 Hz, 1H), 3.36 (m, 4H), 1.12 (t, J = 6.9 Hz, 6H). ¹³C NMR (151 MHz, DMSO-d₆, δ/ppm) δ: 161.19, 160.21, 152.65, 150.83, 150.78, 148.96, 135.75, 132.08, 129.45, 124.08, 106.78, 104.20, 97.92, 44.27, 13.01. HRMS: 313.1667, calcd for [SBN + H⁺] (C₁₇H₂₁N₄O₂), 313.1665 (see Fig. S1–S3 in the ESI†).

3. Results and discussion

3.1. SBN as a dual channel fluorescence probe for Al³⁺

In order to explore the selectivity of SBN to metal ions, at the excitation wavelength of 365 nm, 16 common metal ions were added to SBN aqueous solution respectively. As shown in Fig. 1(A), the SBN solution itself shows almost no fluorescence emission at all due to the photoinduced electron transfer (PET) between the nitrogen atom on the Schiff base group and fluorophores.²⁴ When 3.0 μM Al³⁺ is added to the SBN solution, the fluorescence intensity of the solution is significantly enhanced, and a new strong fluorescence emission band is generated at 459 nm. Obviously, the coordination between Al³⁺ and the Schiff base group inhibits the PET process, resulting in the significant enhancement of the fluorescence emission of SBN. However, the addition of 6.0 μM Ag⁺, Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Hg²⁺, K⁺, Na⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ cannot cause fluorescence enhancement of SBN solution. The result shows that SBN is a highly selective fluorescence enhancement probe for Al³⁺. Interestingly, when the excitation wavelength is 425 nm, SBN can still highly selectively recognize Al³⁺ and produce fluorescence, as shown in Fig. 1(B). However, the addition of Al³⁺ leads to strong fluorescence emission of SBN at 512 nm. The result shows that SBN can highly selectively recognize Al³⁺ through dual channel fluorescence emission at 459 and 512 nm.

When excited with a wavelength of 365 nm, with the continuous addition of Al³⁺, a new fluorescence emission at 459 nm is generated and continuously enhanced, causing the color of the SBN solution to change from colorless to blue, as shown in Fig. 1(C). When the concentration of Al³⁺ was increased to 7.0 μM, the fluorescence intensity of the resulting solution was increased by 259 times, which shows that SBN can recognize Al³⁺ with high sensitivity. In addition, when excited with a wavelength of 425 nm, the fluorescence enhanced recognition signal of SBN for Al³⁺ appears at 512 nm; this is accompanied by an obvious fluorescence color change from colorless to bright green, which can also offer highly sensitive recognition for Al³⁺ through the change in fluorescence color of the SBN solution, as shown in Fig. 1(D). When the concentration of Al³⁺ is 4.0 μM, the fluorescence emission of SBN reaches the strongest level, which is about 41 times.

As shown in Fig. 1(E) and (F), based on the fluorescence titration experiment and the formula LOD = 3S/ρ, the LOD of SBN for Al³⁺ was measured and calculated.^23,24 The calculated LODs of SBN for Al³⁺ at 459 nm (λ_ex = 365 nm) and 512 nm (λ_ex = 425 nm) are 0.54 nM and 2.16 nM, respectively. The LODs are considerably lower than the maximum content of Al³⁺ allowed in drinking water by the WHO (7.41 μM).¹³ Therefore, SBN is a dual fluorescence emission recognition channel probe for Al³⁺ with ultra-high sensitivity. Furthermore, when the fluorescence test papers covering SBN were immersed in an aqueous solution of Al³⁺ (LOD of 7.41 μM as dictated by the WHO), the test paper covering SBN changes from light blue to bright cyan under 365 nm UV light, as shown in the inset of Fig. 1(E). These results well-proved SBN is able to be utilized for the fluorescence detection of Al³⁺ in actual water samples.

The anti-interference performance is an important indicator of ion fluorescence probes, and the competition experiments of 15 common metal ions on the recognition of Al³⁺ by SBN were also studied. As shown in Fig. 2(A) and (B), the coexistence of the 15 common metal ions (Na⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ag⁺, Cd²⁺, Ba²⁺, Hg²⁺ and Pb²⁺), at concentrations twice that of Al³⁺, have negligible effects on the response of SBN to Al³⁺ at two different excitation wavelengths. The results show that SBN has a strong anti-interference ability for the detection of Al³⁺, and has potential in the identification of Al³⁺ in water samples. In order to explore the response time and photostability of SBN to the Al³⁺ dual-channel fluorescence response, the changes in the fluorescence emission intensity of SBN aqueous solution at 459 and 512 nm with time before and after adding Al³⁺ were tested, as shown in Fig. 2(C) and (D). The fluorescence intensity of SBN aqueous solution reached the maximum within 5 minutes after the addition of Al³⁺, which was relatively rapid, and it remained stable within 1 hour. Therefore, SBN is a fluorescence probe with a fast and stable response to Al³⁺. In addition, SBN showed a good reversibility and a wide range of pH from 5.0 to 7.0 for the fluorescence recognition to Al³⁺, as shown in Fig. 2(E) and (F).

3.2. Recognition mechanism of SBN toward Al³⁺

In order to explore the binding information between SBN and Al³⁺, a Job's plot curve and the fitting of the binding ratio based on fluorescence titration experiments were explored. As shown in Fig. 3(A), keeping the total concentration of SBN and Al³⁺ at 20.0 μM, then changing the concentration ratio of the two, when the concentration ratio of Al³⁺ and SBN is 1:3, the fluorescence intensity of SBN reaches the maximum value.³² Therefore, the combination ratio of Al³⁺ and SBN is 1:3. The fitting of the above fluorescence titration data in Fig. 1(D) using the Benesi–Hildebrand (B–H) equation³³ also shows a binding ratio of 1:3 with a binding constant of 6.197 × 10¹⁷ M⁻³ and a correlation coefficient R² of 0.991, as shown in Fig. 3(B).

Moreover, the binding information of SBN with Al³⁺ was further explored by using HRMS analysis. As shown in Fig. 3(C), multiple component peaks belonging to 3SBN–Al³⁺ were measured within the range of m/z 950 to 1060. The HRMS spectra of SBN–Al³⁺ exhibit peaks at m/z 957.4642, 977.4373, 983.4217, 995.4151, 999.3967, 1017.4270 and 1051.3358, which can be assigned to [3SB + Al³⁺ − 3H⁺] (calc. = 957.4088), [3SB + Al³⁺ + H₂O − 3H⁺] (calc. = 977.4350), [3SB + Al³⁺ + Na⁺] (calc. = 983.4215), [3SB + Al³⁺ + 2H₂O − H⁺] (calc. = 995.4456), [3SB + Al³⁺ + K⁺] (calc. = 999.3960), [3SB + Al³⁺ + 2H₂O + Na⁺ − 2H⁺] (calc. = 1017.3784), and [3SBN⁻ + Al³⁺ + 3H₂O + K⁺ − 2H⁺] (calc. = 1051.4120), respectively. At the same time, the strong peak observed at m/z = 313.1667, corresponds to SBN + H⁺ (calc. = 313.1665). Thus, the HRMS analysis further confirmed that probe SBN can chelate Al³⁺ to form a 1:3 complex.

The binding mode of SBN to Al³⁺ was also explored by ¹H NMR titration experiment, as shown in Fig. 3(D). When Al³⁺ was added, the chemical shifts of the hydrogen atoms H_h, H_i and H_j on the benzene ring were upfield shifted by 0.1662, 0.0965, and 0.1144 ppm, respectively, indicating a significant coordination between phenolic hydroxyl groups and Al³⁺. Simultaneously, the chemical shift of H_f was upfield shifted by 0.1325 ppm, which shows the combination of Al³⁺ and a carbon nitrogen double bond. In addition, the hydrogen atoms H_a, H_b, H_c, and H_d on the pyridine ring exhibited irregular upfield shifts of −0.093, 0.0811, 0.0022 and 0.1269 ppm, respectively, implying the significant change in the chemical microenvironment of the pyridine ring in the SBN–Al³⁺ complex.

Based on the results of HRMS and fluorescence spectra, the binding model of the 3SBN–Al³⁺ complex was further investigated using the DFT calculation in the Gaussian 09 package.^34,35 As shown in Fig. 3(E), in the optimized structure of the 3SBN–Al³⁺ complex, one Al³⁺ ion combines with the hydroxyl oxygen and Schiff base nitrogen atoms in three SBN molecules to form three chelating rings; the Al³⁺–O bond lengths are 1.847, 1.829 and 1.868 Å, and the Al³⁺–N bond lengths are 2.021, 2.022 and 2.122 Å, respectively, all within the range of typical coordination bond distances.^36,37 Meanwhile, two distinct π–π forms between the pyridine ring and the benzene ring were discovered, with distances of 3.147 and 3.208 Å, respectively. These results indicated that in the combination between Al³⁺ and hydroxyl groups, the nitrogen atom of the Schiff base causes the aggregation of three SBN molecules, resulting in stable π–π stacking forms of the pyridine and benzene rings in different SBN molecules. The result well illustrates the reason for the dual channel fluorescence recognition of Al³⁺ by SBN. The combination of Al³⁺ and SBN molecules suppresses the PET effect, and the fluorescence recognition signal at 512 nm corresponds to the π–π stacking forms of the aromatic rings, while the signal at 459 nm corresponds to the non-aggregated part of the benzene ring. In addition, the π–π stacking of the pyridine and benzene rings in the optimized structure of the 3SBN–Al³⁺ complex induced the irregular chemical shifts of hydrogen atoms on the pyridine ring in the ¹H NMR titration.

The molecular orbital diagrams of the SBN and 3SBN–Al³⁺ complex were shown in Fig. 3(F). The local HOMO electron of SBN is delocalized through a phenol ring, diethyl amine group and acylhydrazine group. In the local transition, the delocalized electron (HOMO) of SBN is transited to the pyridine ring moiety (LUMO). The transition of the HOMO to the LUMO of SBN showed the PET process, resulting in the fluorescence quenching.³¹ In the 3SBN–Al³⁺ complex, the delocalized electron (HOMO) on the phenol ring of the complex is transited to the π–π stacking moiety of the pyridine and benzene rings (LUMO), which inhibits the electron transfer from the HOMO (donor) to the fluorophore, resulting in the significant fluorescent emission enhancement belonging to the monomer and aggregate of the fluorophore. The results are consistent with the reported PET mechanism of the fluorescent probe for metal ions.^23,24,31 In addition, the energy gap of the 3SBN–Al³⁺ complex (5.411 eV) is lower that of SBN (5.686 eV), which is more beneficial to the conversion of SBN into the 3SBN–Al³⁺ complex. Therefore, SBN does not exhibit fluorescence emission due to the PET process, but the PET effect is suppressed in the composite formed by Al³⁺ and the probe in a 1:3 binding ratio, resulting in strong fluorescence emission of the monomer and aggregate of the fluorophore.

3.3 SBN as a colorimetric probe for Al³⁺

The change in the UV-vis absorption spectra of SBN caused by Al³⁺ was also measured. As shown in Fig. 4(A), with the continuous addition of Al³⁺, the UV-vis absorption spectra of SBN exhibited an obvious hyperchromicity with four absorption peaks at 267, 304, 316 and 402 nm. The UV-vis absorption intensity of SBN at 402 nm increased by 2.6 times and tended to saturate after adding 7.0 μM Al³⁺, which is consistent with that shown by the fluorescence spectra, both showing a strong binding between SBN and Al³⁺ with a binding ratio of 3:1. In addition, when the concentration of Al³⁺ was increased to 7.0 μM, a 28 nm red shift from 374 nm to 402 nm was observed, which caused the solution color to change from colorless to yellow. The selectivity of SBN for the UV-vis recognition of Al³⁺ was also measured. As shown in Fig. 4(B), when 16 common metal ions were added to an aqueous solution of SBN, only Al³⁺ caused the hyperchromicity and red shift of SBN. The result indicated that SBN is a highly selective colorimetric probe for Al³⁺.

The competition experiments of common metal ions on the recognition of Al³⁺ by SBN were also conducted. As shown in Fig. 4(C), the coexistence of most of the common metal ions (Na⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ag⁺, Cd²⁺, Ba²⁺, Hg²⁺ and Pb²⁺) have negligible effects on the UV-vis recognized absorption spectra of SBN toward Al³⁺. Based on the UV-vis absorption data of the Al³⁺ titration probe, the detection limit of SBN was calculated to be 31.4 nM using the formula LOD = 3S/ρ,²³ which is also well below the LOD of 7.41 μM as dictated by the WHO,¹³ as shown in Fig. S4 in the ESI.† The experimental results show that SBN is also a highly sensitive colorimetric probe of Al³⁺ with a strong anti-interference ability. The Job's plot curve based on the UV-vis experiments was explored.^32,33 As shown in Fig. 4(D), keeping the total concentration of SBN and Al³⁺ at 20.0 μM, then changing the concentration ratio of the two, when the concentration ratio of Al³⁺ and SBN is 1:3, the UV-vis absorption intensity of SBN reaches the maximum value. Therefore, the combination ratio of Al³⁺ and SBN is 1:3.

The fluorescence excitation spectra of SBN in the presence of different concentrations of Al³⁺ at different emission wavelengths were also measured. As shown in Fig. 4(E), when 459 nm was selected as the emission wavelength, the single SBN solution did not show a significant excitation peak. However, with the continuous addition of Al³⁺, four excitation peaks at 260, 308, 316, and 367 nm were generated and gradually enhanced. The result is consistent with the UV-vis absorption spectra, showing a clear interaction between the probe and Al³⁺, which is also consistent with the fluorescence emission spectra, showing a significant PET effect. When 512 nm was selected as the emission wavelength, as the concentration of Al³⁺ increased, three new peaks at 308, 319 and 378 nm were clearly measured, while a shoulder peak near 428 nm was also observed, as shown in Fig. 4(F). The experimental result further proves the generation of new fluorescence components in the SBN–Al³⁺ system, which can correspond to the π–π conjugated part of the fluorescence groups on the probes in the 3SBN–Al³⁺ complex. In addition, the excitation spectra of SBN can also serve as a source of fluorescence response signals for Al³⁺. Based on the two fluorescence excitation spectra of SBN toward Al³⁺, the detection limits of SBN were calculated to be 3.29 and 2.50 nM using the formula LOD = 3S/ρ,²³ indicating that SBN also has dual channel ultra-sensitive detection signals for Al³⁺ in the fluorescence excitation spectra, as shown in Fig. S5 and S6 in the ESI.†

3.4 Cellular imaging of Al³⁺ with 1

To further demonstrate the applicability of SBN for the detection of Al³⁺ in a biological matrix, the fluorescence bio-imaging of Al³⁺ in GS cells of Epinephelus coioides was examined. As shown in Fig. 5, GS cells of Epinephelus coioides were incubated with SBN (20.0 μM) for 30 min at 37 °C, and washed with PBS three times. At this point, GS cells of Epinephelus coioides incubated with SBN exhibit weak fluorescence, which indicates that SBN can easily migrate into the cells. Thereafter, Al³⁺ (20.0 μM) was added and incubated for another 30 min. The cells were washed with PBS three times to remove excess Al³⁺.³⁸ Significantly, in the presence of Al³⁺, GS cells of Epinephelus coioides incubated with SBN exhibit strong fluorescence at both excitation wavelengths (λ_ex values are 365/425 nm), which shows that SBN can be applied to fluorescence dual channel monitoring of Al³⁺ in the cytoplasm of live cells.

4. Conclusion

Based on salicylaldehyde hydrazone, a multi-channel responsive fluorescence probe SBN for Al³⁺ was synthesized. SBN can chelate Al³⁺ to form complexes with a 3:1 binding ratio, which contain both individual and π–π stacking fluorescence groups. Meanwhile, the complexation of Al³⁺ can suppress the PET effect between the fluorescence group and the carbon nitrogen double bond in the SBN molecule, thereby exhibiting fluorescence enhanced recognition signals. Therefore, the composite structure formed between SBN and Al³⁺ with a 3:1 binding ratio can generate multi-channel recognition signals from individual or aggregated fluorophores. When the excitation wavelengths are 365 nm and 425 nm, the ultra-sensitive fluorescence emission recognition signals for Al³⁺ are 459 nm and 512 nm, respectively, which come from the fluorescence emissions of the fluorophore monomer and aggregate. At the same time, when 459 nm and 512 nm are selected as emission wavelengths, the two different excitation spectra of SBN are also able to recognize Al³⁺. Under visible light, SBN can recognize Al³⁺ by directly observing color changes with the naked eye. In addition, the detection of Al³⁺ by SBN has ultra-high sensitivity, high selectivity, a fast response time, stable optical signal, good anti-interference ability, and can be used for multi-channel fluorescence recognition of Al³⁺ in biological systems. The current research is of great significance for the development of multi-channel fluorescence recognition ion probes.

Data availability

The authors confirm that the data supporting the findings of this study are available within the article and/or its ESI.†

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This work was partially supported by the National Natural Science Foundation of China (No. 22273027 and 22373024).

References

1. S. Gui, Y. Huang, F. Hu, Y. Jin, G. Zhang, L. Yan, D. Zhang and R. Zhao, Anal. Chem., 2015, 87, 1470–1474 CrossRef CAS PubMed .
2. D. Zhen, C. Liu, Q. Deng, S. Zhang, N. Yuan, L. Li and Y. Liu, Chin. Chem. Lett., 2023, 109249 Search PubMed .
3. L. Wu, S. Yao, H. Xu, T. Zheng, S. Liu, J. Chen, N. Li and H. Wen, Chin. Chem. Lett., 2022, 33, 541–546 CrossRef CAS .
4. S. Y. Li, D. B. Zhang, J. Y. Wang, R. M. Lu, C. H. Zheng and S. Z. Pu, Sens. Actuators, B, 2017, 245, 263–272 CrossRef CAS .
5. G. Berthon, Coord. Chem. Rev., 2002, 228, 319–341 CrossRef CAS .
6. R. W. Gensemer and R. C. Playle, Crit. Rev. Environ. Sci. Technol., 1999, 29, 315–450 CrossRef CAS .
7. D. R. Crapper, S. S. Krishnan and A. J. Dalton, Science, 1973, 180, 511–513 CrossRef CAS PubMed .
8. D. P. Perl and A. R. Brody, Science, 1980, 208, 297–299 CrossRef CAS PubMed .
9. J. L. Domingo, Neurotoxicol. Teratol., 1995, 17, 515–521 CrossRef CAS PubMed .
10. G. H. Mayor, T. O. Lohr and T. V. Sanchez, J. Environ. Pathol., Toxicol. Oncol., 1985, 6, 43–50 CAS .
11. W. A. Durai, A. Ramu and A. Dhakshinamoorthy, Inorg. Chem. Commun., 2020, 121, 108191 CrossRef .
12. T. T. Kim Cuc, P. Q. Nhien, T. M. Khang, H. Y. Chen, C. H. Wu, B.-T. B. Hue, Y.-K. Li, J. I. Wu and H.-C. Lin, ACS Appl. Mater. Interfaces, 2021, 13, 20662–20680 CrossRef CAS PubMed .
13. Y. Sang, K. Wang, X. Kong, F. Cheng, C. zhou and W. Li, Sens. Actuators, B, 2022, 362, 131780 CrossRef CAS .
14. H. Lian, Y. Kang, S. Bi, Y. Arkin, D. Shao, D. Li, Y. Chen, L. Dai, N. Gan and L. Tian, Talanta, 2004, 62, 43–50 CrossRef CAS PubMed .
15. M. A. Kamyabi and A. Aghaei, Spectrochim. Acta, Part B, 2017, 128, 17–21 CrossRef CAS .
16. H. Karami, M. F. Mousavi, Y. Yamini and M. Shamsipur, Anal. Chim. Acta, 2004, 509, 89–94 CrossRef CAS .
17. C.-X. Wang, B. Wu, W. Zhou, Q. Wang, H. Yu, K. Deng, J.-M. Li, R.-X. Zhou and S.-W. Huang, Sens. Actuators, B, 2018, 271, 225–238 CrossRef CAS .
18. G. Kumar, A. Srivastava and P. Kumar, ACS Chem. Neurosci., 2023, 14, 2792–2801 CrossRef CAS PubMed .
19. G. Sun and H. Fang, J. Phys. Chem. A, 2023, 127, 1857–1865 CrossRef CAS PubMed .
20. S. Tang, X. Wu, P. Zhao, K. Tang, Y. Chen, J. Fu, H. Lei, Z. Yang and Z. Zhang, Anal. Chem., 2022, 94, 17223–17231 CrossRef CAS PubMed .
21. W. Li, C. Jiang, S. Lu, F. Wang, Z. Zhang, T. Wei, Y. Chen, J. Qiang, Z. Yu and X. Chen, Sens. Actuators, B, 2020, 321, 128490 CrossRef CAS .
22. Y. Zhang, Y. Fang, N.-Z. Xu, M.-Q. Zhang, G.-Z. Wu and C. Yao, Chin. Chem. Lett., 2016, 27, 1673–1678 CrossRef CAS .
23. Z. Ou, M. Wang, Z. Zhang, J. Liang, J. Tang, X. Lei, L. Yang, H. Liu and L.-J. Ma, Microchem. J., 2023, 195, 109386 CrossRef CAS .
24. X. Lei, Y. Zou, Q. Liang, W. Xu, S. Lao, B. Yang, L. Li, L. Yang, H. Liu and L.-J. Ma, J. Photochem. Photobiol., A, 2022, 428, 113854 CrossRef CAS .
25. Z. Li, X. Peng, Y. Chen, L. Xiao and X. Duan, Polyhedron, 2023, 236, 116370 CrossRef CAS .
26. P. Yin, Q. Niu, J. Liu, T. Wei, T. Hu, T. Li, X. Qin and J. Chen, Sens. Actuators, B, 2021, 331, 129418 CrossRef CAS .
27. Y. Wu, X. Wen and Z. Fan, Food Anal. Methods, 2019, 12, 1736–1746 CrossRef .
28. J. Shen, X. Wen and Z. Fan, Sens. Actuators, B, 2023, 381, 133436 CrossRef CAS .
29. L.-J. Ma, S. Wang, H. Liu, J.-S. Xu, P.-T. Lu, X. Liu and S.-Y. Liu, Chinese Invention Pat., ZL2020111074042, 2020 Search PubMed .
30. T. J. Dathees, G. Narmatha, G. Prabakaran, S. Seenithurai, J.-D. Chai, R. S. Kumar, J. Prabhu and R. Nandhakumar, Food Chem., 2024, 445, 138967 CrossRef CAS PubMed .
31. Y. Li, Q. Niu, T. Wei and T. Li, Anal. Chim. Acta, 2019, 1049, 196–212 CrossRef CAS PubMed .
32. Y.-J. Liu, F.-F. Tian, X.-Y. Fan, F.-L. Jiang and Y. Liu, Sens. Actuators, B, 2017, 240, 916–925 CrossRef CAS .
33. J. Kumar, M. J. Sarma, P. Phukan and D. K. Das, Dalton Trans., 2015, 44, 4576–4581 RSC .
34. J.-D. Chai and M. Head-Gordon, J. Chem. Phys., 2008, 128, 084106 CrossRef PubMed .
35. J.-D. Chai and M. Head-Gordon, Phys. Chem. Chem. Phys., 2008, 10, 6615–6620 RSC .
36. F. Wang, J. H. Moon, R. Nandhakumar, B. Kang, D. Kim, K. M. Kim, J. Y. Lee and J. Yoon, Chem. Commun., 2013, 65, 7228–7230 RSC .
37. S. S. Samanta, P. K. Giri, S. Giri, A. Ghosh and A. Misra, J. Mol. Struct., 2023, 1278, 134927 CrossRef CAS .
38. L.-J. Ma, Q. Liang, R. Feng, Z. Lv, F. Cui, L. Li, L. Yang, H. Liu and F. Sun, J. Photochem. Photobiol., A, 2021, 408, 113086 CrossRef CAS .

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Footnotes

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4tc02315c

‡ These co-first authors contributed equally to this work.

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