Ni-Fc MOF nanomaterials as Hg 2+ Application of detection probes

Abstract

This invention discloses Ni-Fc MOF nanomaterials as Hg 2+ The application of the detection probe, the preparation method of the Ni-Fc MOF nanomaterial includes: 1,1-ferrocene dicarboxylic acid and water-soluble Ni at 110–130 °C. 2+ The Ni-Fc MOF nanomaterials were prepared by salt reaction. This invention is based on Hg... 2+ Sensitive and selective activation of oxidase activity by probes from flower-shaped Ni-Fc MOF nanomaterials was achieved, and a Hg assay was established using flower-shaped nanozymes as recognizers and 3,3',5,5'-tetramethylbenzidine as a signal generator. 2+ Colorimetric sensing method.

Description

Technical Field

[0001] This invention relates to novel applications of Ni-Fc MOF nanomaterials, specifically to Ni-Fc MOF nanomaterials as Hg 2+ Application of detection probes. Background Technology

[0002] Hg 2+ Trace detection methods mainly focus on high-performance liquid chromatography (HPLC), inductively coupled plasma mass spectrometry (ICP-MS), and atomic absorption / emission spectroscopy (AAS / AES). While these methods offer high sensitivity and good selectivity, they often involve complex pretreatment processes, are time-consuming, require expensive instruments and specialized operators, making them unsuitable for environmental monitoring and food quality and safety evaluation. This limits their further application in routine analysis. Therefore, developing a suitable alternative for Hg detection that not only possesses comparable sensitivity and selectivity to the aforementioned methods but also avoids their drawbacks is crucial. 2+ Detection methods are essential. To achieve this goal, colorimetric analysis methods based on nanozymes have been developed. Nanozymes are a class of nanomaterials that can mimic natural enzymes and have been widely used in fields such as biosensing, tumor therapy, antibacterial agents, and environmental remediation.

[0003] Due to the outstanding advantages of nanozymes, such as simple preparation, high stability, and excellent catalytic performance, the colorimetric detection of Hg based on nanozymes has become a popular application. 2+ Pioneering research has been established. In previous studies, Hg 2+ The regulation of the catalytic activity of noble metal nanozymes (such as Au, Pt, Ag, etc.) enables the incorporation of these noble metal nanozymes into Hg. 2+ In colorimetric detection, its regulation mechanism is Hg. 2+ They adsorb onto the surface of noble metals and form corresponding alloys. However, the aggregation of noble metal nanoparticles and their high cost limit their application in Hg... 2+ Further applications in detection. To overcome these limitations, some non-noble metal nanozyme complexes, such as MPA-CeO2, ZnS@β-CD, NH2-MIL-101(Fe)@Cu / CeO2, and NSC / Co6Ni3S8, have also been used to prepare Hg. 2+ The colorimetric probes used for detection. However, in these non-noble metal nanozyme complexes, only one component on the hybrid is actually catalytically active. Undoubtedly, this strategy of binding nanozymes to other functional molecules may block the pathway of the target analyte to the active site, thus reducing the sensitivity of the nanozyme for target analyte detection. In addition, currently reported methods for detecting Hg... 2+The colorimetric sensing probe mainly utilizes the peroxidase activity of nanozymes (and inevitably adds hydrogen peroxide to the reaction system), which undoubtedly increases the possibility of functional molecules on the surface of nanozymes binding to interfering substances in complex sample matrices, making it difficult to guarantee its selectivity and anti-interference performance. Summary of the Invention

[0004] To address the shortcomings or deficiencies of existing technologies, this invention provides Ni-Fc MOF nanomaterials as Hg 2+ The application of the detection probe, the preparation method of the Ni-Fc MOF nanomaterial includes: 1,1-ferrocene dicarboxylic acid (Fc(COOH)2) and water-soluble Ni at 110–130 °C. 2+ The Ni-Fc MOF nanomaterials were prepared by salt reaction.

[0005] The preferred embodiment is that the 1,1-ferrocene dicarboxylic acid and Ni 2+ The molar ratio is 1:1.

[0006] An optional approach is that the preparation method of the Ni-Fc MOF nanomaterial includes: an organic solvent solution of 1,1-ferrocene dicarboxylic acid and a water-soluble Ni 2+ The Ni-Fc MOF nanomaterials were prepared by mixing the salt aqueous solution and reacting it at 110–130 °C.

[0007] An alternative is that the water-soluble Ni 2+ The salt can be selected from NiCl2, Ni(NO3)2, Ni2SO4 or NiBr2.

[0008] The nanomaterials used in this invention are 1,1′-ferrocene dicarboxylic acid and nickel chloride hexahydrate as precursors. A novel flower-shaped nanozyme probe can be prepared using a simple one-step hydrothermal method with oxygenation, without the need for hazardous chemical reagents. This invention is based on Hg... 2+ Sensitive and selective activation of oxidase activity by probes from flower-shaped Ni-Fc MOF nanomaterials was achieved. A Hg assay was established using flower-shaped nanozymes as recognizers and 3,3',5,5'-tetramethylbenzidine (TMB) as a signal generator. 2+ Colorimetric sensing method.

[0009] This invention also provides the above-mentioned Ni-Fc MOF nanomaterials and Hg 2+ The mixture is used as an oxidase.

[0010] This invention also provides an Hg 2+ The detection method provided for Hg 2+The detection method involves adding the aforementioned Ni-Fc MOF nanomaterials and chromogenic oxidase substrate to the analyte, mixing thoroughly to obtain the detection system, and detecting the Hg content in the analyte by analyzing the color development of the detection system. 2+ The tested substances, such as water, food, pollutants, or industrial waste, also require Hg testing. 2+ The sample to be tested.

[0011] Optionally, the chromogenic oxidase substrate is selected from TMB, ABTS (2,2-azido-bis(3-ethyl-benzothiazol-6-sulfonic acid) diammonium salt), or OPD (o-phenylenediamine). The pH of the detection system is 2-4, and the detection temperature is 30-40℃. Further optionally, the color development of the detection system is analyzed using a UV spectrophotometer.

[0012] This invention relates to Hg 2+ The lowest detection limit is 6.47 nM, enabling high-sensitivity detection of Hg. 2+ It can be used as a general method for rapid and convenient detection of Hg in real samples. 2+ Residue. And it can selectively identify Hg. 2+ It remains and has no specific signal response to other heavy metal ions. Attached Figure Description

[0013] Figure 1 Characterization of the flower-like Ni-Fc MOF nanozyme prepared in this invention: (a) and (b) are scanning electron microscope images, (c) is a transmission electron microscope image, (d) is an elemental distribution map, (e) is an X-ray single crystal diffraction pattern, (f) is a Fourier transform infrared spectrum, and (g), (h) and (i) are XPS photoelectron spectra.

[0014] Figure 2 For Hg 2+ Evaluation of oxidase activity triggered by Ni-Fc MOF nanoflowers; (a) TMB + different nanozymes + Hg 2+ The UV-Vis absorption spectra of the nanoflowers are shown in the insets from left to right: Ni-Fc MOF nanoflowers, carbon nanoflowers, TiO2 nanoflowers, ZnO nanoflowers, MnO2 nanoflowers, WS2 nanoflowers, and CoFe2O4 nanoflowers. (b) TMB, TMB+Ni-Fc MOF, and TMB+Hg are also shown. 2+ and TMB+Ni-Fc MOF+Hg 2+ The UV-Vis absorption spectrum of TMB+Ni-FcMOF+Hg is shown in (c). 2+ OPD+Ni-Fc MOF+Hg 2+ ABTS+Ni-Fc MOF+Hg 2+The UV-Vis absorption spectra are shown, with the dashed line representing the blank control and the inset representing the corresponding reaction solutions. (d) and (e) represent Ni-Fc MOF+Hg, respectively. 2+ Mie dynamics analysis and Lineweaver-Burk plot;

[0015] Figure 3 The Ni-Fc MOF nanoflowers prepared in this invention are used to detect Hg. 2+ Investigation of the sensing mechanism; (a) Ni-Fc MOF / Hg 2+ XPS analysis of the Hg 4f region, (b) Ni-Fc MOF / Hg 2+ XPS analysis of the O1s region of Ni-Fc MOF, (c) with the addition of Hg 2+ Ni in Ni-Fc MOF nanoflowers 2+ / Ni 3+ The relative content of (d)Ni-Fc MOF / Hg 2+ The free radical scavenging test of the composite system was conducted using isopropanol (IPA, 1% aqueous solution), p-benzoquinone (PBQ, 200 μM), and sodium azide (NaN3, 200 μM).

[0016] Figure 4 The Ni-Fc MOF nanoflowers prepared in this invention are used to detect Hg. 2+ The detection system was studied; (a), (b), and (c) represent the effects of pH, temperature, and reaction time on the sensing system, respectively.

[0017] Figure 5 The Ni-Fc MOF nanoflowers prepared in this invention are used to detect Hg. 2+ Sensitivity and specificity analysis; (a) for Ni-Fc MOF / TMB system at different concentrations of Hg 2+ UV-Vis absorption spectra under stress (inset shows photographs of the corresponding reaction solutions), (b) shows Hg concentrations in the range of 0-70 μM. 2+ The absorbance values ​​are shown in (c), which is the standard curve, and (d) is the absorbance bar graph of different interfering ions at 652 nm.

[0018] Figure 6 The Ni-Fc MOF nanoflowers prepared in this invention are used to detect Hg. 2+ Stability and reusability; (a) relative enzyme activity of 5 batches of Ni-Fc MOF nanoflowers, (b) Hg after 5 cycles 2+ The relative enzyme activity of the / Ni-Fc MOF system, (c) Hg at different storage times 2+ Relative enzyme activity of the / Ni-Fc MOF system; Detailed Implementation

[0019] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0020] This invention presents a mercury ion visualization colorimetric sensing platform using Ni-Fc MOF nanomaterials as the recognizer and 3,3',5,5'-tetramethylbenzidine (TMB) as the signal generator. The Ni-Fc MOF nanomaterials used in this invention possess excellent hydrophilicity, a large specific surface area, and multiple active sites, enabling effective directional migration of electrons / holes. This ensures that the active sites on the nanomaterial surface are fully exposed and in full contact with the reactants. (Hg) 2+ As a "trigger switch," it can selectively activate the oxidase activity of the probe Ni-Fc MOF nanomaterial, even under harsh environments, for Hg. 2+ The response also exhibits excellent stability.

[0021] Compared to other materials such as MPA-CeO2, ZnS@β-CD, NH2-MIL-101(Fe)@Cu / CeO2, and NSC / Co6Ni3S8, this invention eliminates the need for additional hydrogen peroxide in the sensing system, reducing its complexity. Furthermore, the Ni-Fc MOF nanomaterial used in this invention possesses a bimetallic hybrid valence state (Ni... 2+ / Ni 3+ and Fe 2+ / Fe 3+ This facilitates the separation of photons and the transfer of electrons, thereby improving the response rate of the sensing system.

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of the present invention, not all of them, and do not impose any limitations on the present invention. Any use of the technical solutions of this embodiment, including simple variations thereof, falls within the scope of protection of the present invention. The experimental reagents used in this invention are all commercially available and have not undergone further processing; the instruments and equipment are all commonly used. Unless otherwise specified, all reagent concentrations are molar concentrations.

[0023] Example 1: Method for preparing this Ni-Fc MOF nanomaterial

[0024] This embodiment provides a method for preparing Ni-Fc MOF, including the following steps:

[0025] First, dissolve 1 mmol of Fc(COOH)2 in 16 mL of DMF solution to obtain solution A; dissolve 1 mmol of NiCl2·6H2O in 8 mL of ultrapure water to obtain solution B; then, sonicate solutions A and B separately for 15 min, and after the two reagents are completely dissolved, mix them and purge with oxygen for 10 min.

[0026] Next, the mixture was transferred into a 50 mL Teflon-lined stainless steel autoclave and reacted at 125 °C for 12 h.

[0027] Then, after the reactants were allowed to cool naturally to room temperature, the resulting brown sample was taken out and washed three times with ethanol to remove excess impurities.

[0028] The material obtained in this embodiment was characterized as follows:

[0029] (1) Scanning electron microscopy and transmission electron microscopy: such as Figure 1 As shown in a, 1b, and 1c, the Ni-Fc MOF nanomaterials obtained in this embodiment exhibit a flower-like structure composed of superimposed two-dimensional scale-like sheets; elemental distribution diagram ( Figure 1 d) shows that C, O, Ni and Fe elements are uniformly distributed within the crystal structure, confirming the successful preparation of Ni-Fc MOF nanoflowers; quantitative data show that the C content in Ni-FcMOF nanoflowers is very high (47.74%, Wt%), indicating that this bimetallic Ni-Fc MOF material is mainly supported by a carbon framework.

[0030] (2) X-ray single-crystal diffraction pattern: such as Figure 1 As shown in Figure e, the typical diffraction peaks of Ni-Fc MOF nanoflowers are located at 6.21°, 11.57°, 12.48°, 14.70°, 16.29°, 17.62° and 18.78°, which are consistent with the (200), (003), (400), (001), (201), (401) and (600) crystal planes of the existing Zn-Fc MOF crystal structure, indicating that Ni-Fc MOF nanoflowers have high crystal purity.

[0031] (3) Fourier transform infrared spectroscopy: such as Figure 1 As shown in f, Ni-Fc MOF nanoflowers are at 3442 cm⁻¹ -1 The presence of a strong characteristic absorption band at this location is mainly attributed to the OH stretching vibration, indicating that Ni-Fc MOF nanoflowers possess a certain degree of hydrophilicity. This property is beneficial for their application in analytical sensing. Furthermore, the characteristic absorption band of Ni-Fc MOF nanoflowers was found to be mainly concentrated in the 1750-400 cm⁻¹ range. -1 Between, 1650cm -1 and 1190cm -1The two characteristic absorptions at 1575 cm⁻¹ are mainly attributed to the stretching vibrations of C=O and CO in the -COOH group, while the absorption at 1575 cm⁻¹ is... -1 The shoulder peak at 1489 cm⁻¹ is considered to be the stretching vibration of C=O in the COO- group, which is mainly related to the coordination number of the oxygen atom and nickel atom in the carboxylic acid group of the ferrocene unit. -1 1396cm -1 and 1035cm -1 The characteristic peaks are distributed on the C=C stretching vibration, CH bending vibration, and CC deformation vibration of the organic ligands, respectively. Notably, the 780 cm⁻¹ peak... -1 and 489cm -1 The peak values ​​belong to the stretching vibrations of the Cp-Fe bonds and the deformation vibrations of the Fe-O bonds, while 530 cm⁻¹... -1 The peak values ​​belong to the tensile vibrations of Ni-O, and these results provide strong evidence for the successful preparation of Ni-Fc MOF nanoflowers.

[0032] (4) XPS photoelectron spectroscopy: such as Figure 1 As shown in g, 1h, and 1i, the Ni-Fc MOF nanoflowers are composed of C (69.41%, at.%), O (20.29%, at.%), Ni (5.41%, at.%), and Fe (4.56%, at.%) elements. In the Ni 2p spectrum, the peaks at 855.7 eV, 856.9 eV, 873.1 eV, and 874.9 eV can be attributed to Ni. 2+ 2p3 / 2, Ni 3+ 2p3 / 2, Ni 2+ 2p1 / 2 and Ni 3+ 2p1 / 2 binding energy. In the Fe2p spectrum, the peaks at 711.1 eV, 714.2 eV, 723.9 eV, and 726.9 eV represent Fe2 binding energies. 2 + 2p3 / 2, Fe 3+ 2p3 / 2, Fe 2+ 2p1 / 2 and Fe 3+ 2p¹ / ² binding energy. The above XPS results indicate that the metal center of the Ni-Fc MOF nanoflower possesses a hybrid element valence state (Ni). 2+ / Ni 3+ and Fe 2+ / Fe 3+ This is beneficial for the separation of photons and the transfer of electrons.

[0033] Example 2: Ni-Fc MOF Sensing of Hg 2+

[0034] This embodiment uses several common nanomaterials and the Ni-Fc MOF nanomaterials prepared in Example 1 to study Hg. 2+ Triggering the activity of their respective oxidases, common nanomaterials include carbon nanoflowers [1] TiO2 nanoflowers [2] ZnO nanoflower [3] MnO2 nanoflowers [4] WS2 nanoflower [5] CoFe2O4 nanoflowers [6] The preparation methods of the above-mentioned common nanomaterials are given in the references.

[0035] Protocol: Add 50 μL TMB and 50 μL Hg respectively. 2+ (Exogenous Hg in the embodiments of this article) 2+ Both were derived from mercuric chloride) and 50 μL of the corresponding nanomaterial aqueous solution were added to 650 μL of acetate buffer (0.1 M, pH 3.0). TMB and Hg 2+ The final concentrations of the nanomaterials were 1 mM, 100 μM, and 50 μg / mL, respectively; after 60 min of complete reaction, the ultraviolet-visible spectra were recorded in the range of 300–800 nm.

[0036] Result: As Figure 2 As shown in a, only Ni-Fc MOF+Hg 2+ The +TMB group reaction solution exhibited a visible blue signal, with two typical oxidation peaks at 367 nm and 652 nm, while other nanomaterials reacted with Hg. 2+ The composite system cannot catalyze TMB; the reaction solution is colorless, indicating that Hg... 2+ The activation of oxidase activity in Ni-Fc MOF nanoflowers is specific. Furthermore, this result also indicates that carbon nanoflowers, TiO2 nanoflowers, ZnO nanoflowers, MnO2 nanoflowers, WS2 nanoflowers, and CoFe2O4 nanoflowers do not possess Hg-sensing capabilities. 2+ Performance.

[0037] Example 3: Ni-Fc MOF / Hg 2+ Evaluation of oxidase activity and analysis of sensing mechanism in composite system

[0038] plan:

[0039] The Ni-Fc MOF nanomaterial solution (50 μL, 200 μg / mL), TMB solution (50 μL, 10 mM), and acetate buffer (650 μL, pH 3.0) prepared in Example 1 were mixed as a solution for detecting Hg. 2+ Working solution;

[0040] Subsequently, 100 μM Hg was added to the above working solution. 2+ Standard solution; after reacting for 60 min, record the UV-Vis spectrum in the range of 300–800 nm using a UV spectrophotometer.

[0041] In addition, the inventors also conducted a control experiment, replacing TMB with two chromogenic substrates, ABTS (2,2-azino-bis(3-ethyl-benzothiazol-6-sulfonic acid) diammonium salt) and OPD (o-phenylenediamine), to further verify the Ni-Fc MOF / Hg ratio. 2+ Oxidase activity of the complex system. The concentrations of ABTS and OPD were both 10 mM.

[0042] Finally, the apparent kinetics of the catalytic reaction system were studied in the TMB concentration range of 0.1–1.0 mM, and the Michaelis constant (Km) was calculated using double reciprocal curves. m ) and maximum reaction rate (V max Regarding the sensing mechanism, the inventors focused on Ni-Fc MOF / Hg 2+ XPS analysis was performed on the Hg 4f and O1s regions of the composite system. The Hg content was investigated. 2+ The valence state change of Ni during the binding process with Ni-Fc MOF was investigated. Free radical scavenging experiments were also conducted using isopropanol (IPA, 1% aqueous solution), p-benzoquinone (PBQ, 200 μM), and sodium azide (NaN3, 200 μM). Specifically, 50 μL of Ni-Fc MOF nanoflower solution, 50 μL of TMB solution, 650 μL of acetate buffer, and 50 μL of Hg were mixed. 2+ After the standard solution was reacted with 50 μL of different free radical scavengers for 60 min, the absorbance at 652 nm was recorded using a UV spectrophotometer to systematically study the types of free radicals generated in the catalytic reaction system.

[0043] result:

[0044] (1) In this experiment, the oxidase activity of the Ni-Fc MOF nanoflowers prepared in Example 1 was first studied using the common chromogenic substrate TMB as a signal generator. The study found that the Ni-Fc MOF nanoflowers themselves do not possess the ability to oxidize TMB to generate blue oxidation products, such as... Figure 2 As shown in Figure b. Surprisingly, Hg... 2+ It can act as a signaling activator to trigger the oxidase activity of Ni-Fc MOF nanoflowers. For example... Figure 2 As shown in b, Ni-Fc MOF+Hg 2+ The +TMB group exhibited two typical oxidation peaks at 367 nm and 652 nm, while Ni-Fc MOF or Hg alone showed... 2+ It can hardly catalyze TMB, indicating that Hg2+ The mixed solution of Ni-Fc and MOF exhibits excellent oxidase activity. Furthermore, Hg was also found... 2+ A mixed solution of Ni-Fc MOF can also catalyze ABTS or OPD, forming corresponding green and yellow oxidation products, with maximum absorption peaks at 419 nm and 417 nm, respectively. Figure 2 c) This further confirms Hg 2+ It can act as a "trigger switch" to activate the oxidase activity of Ni-Fc MOF nanoflowers.

[0045] (2) Ni-Fc MOF / Hg 2+ Calculation of enzyme activity parameters for the complex system: To further evaluate Hg 2+ The oxidase activity of Ni-FcMOF was activated, and the apparent steady-state kinetics of TMB oxidation in this reaction system were determined by varying the concentration of TMB using the initial rate method. Figure 2 As shown in d, Ni-Fc MOF nanoflowers and Hg were obtained within the TMB concentration range of 0.1–1.0 mM. 2+ Kinetic curves of the composite system were obtained. The relationship between the onset rate of the catalytic process and the substrate concentration was found to be in excellent agreement with the Michaelis-Menten kinetic model. Subsequently, the Michaelis constant (Km) was calculated. m ) and maximum reaction rate (V max The results were 2.3797 mM and 4.6247 × 10⁻⁶ mM, respectively. -8 M / s( Figure 2 e).

[0046] (3) Hg 2+ Sensing mechanism for triggering Ni-Fc MOF nanoflower oxidase activity: via XPS photoelectron spectroscopy and free radical quenching assays ( Figure 3 The inventor discovered Hg 2+ The sensing mechanism that triggers the activity of Ni-Fc MOF nanoflower oxidase is mainly due to Hg 2+ The combination of Ni and O elements to form Hg-O bonds causes surface chemical changes in Ni-Fc MOF nanoflowers, leading to Ni... 3+ The increased content promotes the production of ·OH and O2. ·- The formation of ·OH and O2. ·- Increased concentration of Hg catalyzes the colorless TMB to undergo a blue color reaction. Therefore, within a certain concentration range, the concentration of Hg in the sensing system... 2+ The higher the concentration, the more obvious the corresponding color reaction, and the stronger the corresponding detection signal.

[0047] Example 4: Ni-Fc MOF nanoflowers paired with Hg 2+ Detection performance analysis

[0048] (1) Add 50 μL of TMB and 50 μL of Hg respectively. 2+ 50 μL of Ni-Fc MOF was added to 650 μL of acetate buffer (0.1 M, pH 3.0), along with TMB and Hg. 2+ The final concentrations of Ni-Fc MOF were 1 mM, 100 μM and 50 μg / mL, respectively. After reacting for 60 min, the UV-Vis spectra were recorded in the range of 300–800 nm. The pH value was set to 2–12. The temperature was set to 4℃, 25℃, 35℃, 45℃, 55℃ and 65℃.

[0049] The results are as follows Figure 4 As shown, with the increase of pH and reaction temperature in the reaction system, Hg 2+ The activated oxidase activity showed a trend of first increasing and then decreasing, reaching its maximum under the reaction conditions of pH=3 and 35℃. Furthermore, Ni-Fc MOF+Hg 2+ The absorbance of the +TMB system at 652 nm as a function of time is shown in the curve, Hg 2+ The activated oxidation reaction reached equilibrium after 40 minutes, indicating that the substrate in the reaction system was basically completely consumed within 40 minutes.

[0050] (2) A mixture of Ni-Fc MOF nanoflower dispersion (50 μL, 200 μg / mL), chromogenic oxidase substrate TMB solution (50 μL, 10 mM), and acetate buffer (650 μL, pH 3.0) was used as a Hg detection solution. 2+ The working solution was prepared; subsequently, a series of Hg solutions of different concentrations were added to the above working solution. 2+ Standard solution; after incubation at 35℃ for 40 min, the above mixed solution was measured using a UV spectrophotometer to obtain different Hg values. 2+ The concentration of ultraviolet absorbance values ​​was calculated and a scatter plot was plotted.

[0051] The results are as follows Figure 5 As shown, see Figure 5 a, with Hg 2+ Concentration is plotted on the x-axis, and absorbance at 652 nm on the y-axis. The relationship between absorbance and Hg is analyzed. 2+ Concentrations were plotted as a scatter plot, such as... Figure 5 As shown in b. Additionally:

[0052] Sensitivity: Combination Figure 5 c. This example provides the standard curve for linear fitting. Within the range of 0.015–37.5 μM, Hg 2+ The concentration and absorbance showed a good linear relationship, and the fitted linear equation was Abs=0.00805×C(Hg) 2+)+0.03622(R 2 =0.9943), LOD is 6.47 nM. Compared with other colorimetric methods for Hg detection... 2+ Compared with other methods, the colorimetric sensing platform based on Ni-Fc MOF nanoflowers has a lower detection limit and a wider linear range, indicating that the proposed colorimetric detection method has certain advantages.

[0053] Selectivity: Combination Figure 5 d, some common metal ions, including Al 3+ Mn 2+ Cr 3+ Cu 2+ Mg 2+ Ni 2+ Cd 2+ Co 2+ K + Ca 2+ Pb 2+ Na + Fe 2+ This will not trigger the oxidase activity of Ni-Fc MOF nanoflowers (the detection system for each ion is the same as the detection system in part (2) of this example, and the specific ions are sourced from common soluble salts), while Hg 2+ The / Ni-FcMOF / TMB system exhibits a typical oxTMB characteristic peak at 652 nm, indicating that Hg 2+ The oxidase activity triggered by Ni-Fc MOF nanoflowers is specific.

[0054] (3) Batch processing stability: such as Figure 6 As shown in Figure a, based on the detection system of this embodiment (2), under the same Hg 2+ At a concentration (50 μM), the oxidase activity of five batches of Ni-Fc MOF nanoflowers prepared using the same method as in Example 1 showed no significant difference, confirming that Ni-Fc MOF nanoflowers have excellent batch stability.

[0055] (4) Reusability: Based on the detection system in part (2) of this embodiment, the reusability of Ni-Fc MOF nanoflowers was evaluated through a recovery test. The Ni-Fc MOF nanoflowers, used as catalysts, were recovered by centrifugation at the end of each reaction for use in the next round of testing. Figure 6 b shows that after 5 cycles, Hg 2+ The oxidase activity of the / Ni-Fc MOF system still reached more than 80% of the original enzyme activity, indicating that the catalytic system has good reusability.

[0056] (5) Storage stability: Based on the detection system in part (2) of this embodiment, it was found that as the storage time increases, Hg... 2+ The catalytic activity of the / Ni-Fc MOF system decreased slightly, but remained above 90%. Figure 6 c) This indicates that the surface chemical state and composition of Ni-Fc MOF nanoflowers did not change during long-term storage, providing a guarantee for the further application of the colorimetric sensing platform.

[0057] Example 5:

[0058] To verify the practicality of the colorimetric sensing platform in actual sample testing, standard addition and recovery tests were conducted on tap water and drinking water. Tap water was obtained from the laboratory, while drinking water was purchased from a supermarket. The operation steps of the addition and recovery test were the same as those for establishing the standard curve, as shown in the detection system (2) of Example 4 (where the amount of water sample added was 50 μL).

[0059] The results obtained by the inventors through experiments are shown in Table 1. The recovery rates for tap water and drinking water were 93.80%–105.42%, with relative standard deviations (RSD) ranging from 0.20% to 3.37%. Therefore, this invention can detect Hg in actual water samples. 2+ The results were basically consistent with those of the spiked samples, reflecting its good practical application value.

[0060] Table 1. Actual Sample Testing Tests

[0061]

[0062]

[0063] The results above are the average of three repeated trials. Different letters in the column represent significant differences (P≤0.05).

[0064] It should be noted that, in the specific protocol, for samples containing Hg, a preliminary test needs to be conducted before adding the spike to determine whether the sample itself contains Hg. 2+ The concentration, the actual test amount after spiking is the sample detection value and the Hg content in the sample itself. 2+ The difference in concentration.

[0065] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0067] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

[0068] References:

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Claims

1. Ni-Fc MOF nanomaterials as Hg 2+ The application of the detection probe, and the preparation method of the Ni-Fc MOF nanomaterial includes: 110-130 °C, 1,1 ferrocene dicarboxylic acid and water-soluble Ni 2+ salt reaction to prepare the Ni-Fc MOF nanomaterials; The detection method of Hg 2+ includes adding Ni-Fc MOF nanomaterial and chromogenic oxidase substrate in the object to be detected, mixing to obtain a detection system, and detecting Hg 2+ in the object to be detected by analyzing the color development of the detection system. The preparation method of the Ni-Fc MOF nanomaterial includes: 1,1-ferrocene dicarboxylic acid and water-soluble Ni at 110–130 °C. 2+ The Ni-Fc MOF nanomaterials were prepared by salt reaction; the pH value of the detection system was 2-4, and the detection temperature was 30-40℃.

2. The application according to claim 1, characterized in that, The 1,1-ferrocene dicarboxylic acid and Ni 2+ The molar ratio is 1:

1.

3. The application according to claim 1, characterized in that, The preparation method of the Ni-Fc MOF nanomaterial includes: an organic solvent solution of 1,1-ferrocene dicarboxylic acid and a water-soluble Ni 2+ The Ni-Fc MOF nanomaterials were prepared by mixing the salt aqueous solution and reacting it at 110–130 °C.

4. The application according to claim 1, characterized in that, The water-soluble Ni 2+ The salt is selected from NiCl2, Ni(NO3)2, Ni2SO4 or NiBr2.

5. A type of Hg 2+ The detection method is characterized by, The method involves adding Ni-Fc MOF nanomaterials and a chromogenic oxidase substrate to the analyte, mixing them thoroughly to obtain a detection system, and detecting Hg in the analyte by analyzing the color development of the detection system. 2 + ; The preparation method of the Ni-Fc MOF nanomaterial includes: 1,1-ferrocene dicarboxylic acid and water-soluble Ni at 110–130 °C. 2+ The Ni-Fc MOF nanomaterials were prepared by salt reaction; the pH value of the detection system was 2-4, and the detection temperature was 30-40℃.

6. The Hg according to claim 5 2+ The detection method is characterized by, The objects to be tested are water, food, pollutants, or industrial waste.

7. The Hg according to claim 5 2+ The detection method is characterized by, The chromogenic oxidase substrate is selected from TMB, ABTS, or OPD.

8. The Hg according to claim 5 2+ The detection method is characterized by, The color development of the detection system was analyzed using an ultraviolet spectrophotometer.

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