CN111992224A

CN111992224A - Two-dimensional cobalt oxide stable rhodium nano mimic enzyme and preparation method and application thereof

Info

Publication number: CN111992224A
Application number: CN202010791132.6A
Authority: CN
Inventors: 严正权; 赵齐; 胡蕾; 祁玉基
Original assignee: Qufu Normal University
Current assignee: Qufu Normal University
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2020-11-27
Anticipated expiration: 2040-08-07
Also published as: CN111992224B

Abstract

The invention relates to the technical field of catalytic detection of nano mimic enzyme, in particular to a two-dimensional cobalt oxide stable rhodium nano mimic enzyme and a preparation method and application thereof. Based on the ultra-large specific surface area of the two-dimensional cobalt oxide, the good catalytic performance of the rhodium nanoparticles and the excellent synergistic enhancement effect between the two, the preparation method is characterized in that a surfactant CTAB (cetyl trimethyl ammonium bromide) is used for assisting the one-pot reduction preparation, so that when cobalt ions form ultra-thin two-dimensional cobalt oxide, the rhodium ions are reduced into rhodium nanoparticles and adsorbed on the surface of the two-dimensional cobalt oxide, and the 2D CoO @ Rh NC (rhodium-on-cobalt) stable rhodium nano mimic enzyme is obtained. The 2D CoO @ Rh NC is successfully applied to visible colorimetric detection of p-aminophenol in an environmental water sample or urea in a water sample, soil and urine, and has the advantages of simplicity in operation, good selectivity, high sensitivity, strong visibility and the like.

Description

Two-dimensional cobalt oxide stable rhodium nano mimic enzyme and preparation method and application thereof

Technical Field

The invention relates to the technical field of catalytic detection of nano mimic enzyme, in particular to a two-dimensional cobalt oxide stable rhodium nano mimic enzyme and a preparation method and application thereof.

Background

The nano mimic enzyme serving as an efficient bionic catalyst has low cost and high stability, can catalyze various reactions under mild conditions, has higher substrate specificity, selectivity and catalytic efficiency, and is widely applied to the fields of photodynamic therapy, bionic catalysis, biosensing, environmental analysis and detection and the like.

Urea is an important nitrogen-containing organic compound and is widely applied to the field of agriculture. P-aminophenol is used in the pharmaceutical industry for the synthesis of paracetamol, clofibrate, etc., and the U.S. and chinese pharmacopoeias limit the maximum content of p-aminophenol in a drug to 50 ppm. Therefore, the development of a method for detecting urea and p-aminophenol efficiently, conveniently and sensitively has important significance.

Disclosure of Invention

Aiming at the defects in the prior art, the technical problem to be solved by the invention is to provide a two-dimensional cobalt oxide stable rhodium nano mimic enzyme and a preparation method and application thereof, wherein the two-dimensional cobalt oxide stable rhodium nano mimic enzyme (2D CoO @ Rh NC) is prepared by a surfactant CTAB assisted one-pot reduction method, and the catalytic activity of the oxidation mimic enzyme and the visibility and sensitivity of colorimetric detection of urea and p-aminophenol are improved.

The technical scheme adopted by the invention for realizing the purpose is as follows: a two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme is prepared by a surfactant CTAB assisted one-pot reduction method based on the ultra-large specific surface area of two-dimensional cobalt oxide, the good catalytic performance of rhodium nanoparticles and the excellent synergistic enhancement effect of the two-dimensional cobalt oxide and the good catalytic performance of the rhodium nanoparticles, so that when cobalt ions form ultra-thin two-dimensional cobalt oxide, the rhodium ions are reduced into rhodium nanoparticles and adsorbed on the surface of the two-dimensional cobalt oxide, and the two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme, 2D CoO @ Rh NC, is obtained.

The invention comprises a preparation method of a two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme, which comprises the following steps:

(1) weighing Co (NO)₃)₂·9H₂O、RhCl₃·3H₂Adding O and hexadecyl trimethyl ammonium bromide into a beaker, adding water, and then, carrying out ultrasonic stirring to fully dissolve;

(2) at room temperature, NaBH is added₄Dissolving in water, slowly dripping into the mixed solution obtained in the step (1), and fully stirring for reaction;

(3) and (3) centrifugally separating the reaction mixed solution, fully washing the obtained solid with ethanol and deionized water, and drying in vacuum to obtain black two-dimensional cobalt oxide stable rhodium nano mimic enzyme, 2D CoO @ Rh NC.

Further, the synthesis mechanism of the 2D CoO @ Rh NC is as follows:

the high concentration surfactant CTAB is easy to form a positively charged double-layer CTAB micelle, and is prepared from NaBH₄Hydrolysis of the resulting negatively charged OH^–And positively charged Co²⁺The nano-particles are sequentially adsorbed on the surfaces of the double molecular layers by virtue of strong electrostatic action to form curved Co oxide nano-sheets; due to Rh³⁺/Rh⁰Has a much higher redox potential than Co²⁺/Co0, in the presence of sodium borohydride (NaBH) as reducing agent₄) In the presence of Rh³⁺Is reduced into rhodium nano particles and is uniformly adsorbed on the surface of the Co oxide nano sheet to form the two-dimensional cobalt oxide stable rhodium nano mimic enzyme.

Further, said Co (NO)₃)₂·9H₂O，RhCl₃·3H₂O, CTAB and NaBH₄The molar ratio of (1), (0.1-0.3), (1-2), (2-3), and the reaction time of the step (2) is 5-15 min.

Further, the preparation method comprises the following specific steps:

(1) weighing 1mmol Co (NO)₃)₂·9H₂O、0.2mmol RhCl₃·3H₂O and 1.4mmol CTAB in a 100mL small beaker, 25mLH was added₂O, ultrasonic stirring for 30min for full dissolution;

(2) 2.6mmol of NaBH₄Dissolving in 15mLH₂Slowly dripping the mixture into the mixed solution obtained in the step (1), and fully stirring and reacting for 10min at room temperature;

(3) after centrifugal separation, the solid is fully washed by ethanol and deionized water, and vacuum drying is carried out at 60 ℃ to obtain the black 2D CoO @ Rh NC mimic enzyme.

The invention comprises application of a two-dimensional cobalt oxide stable rhodium nano mimic enzyme, and the two-dimensional cobalt oxide stable rhodium nano mimic enzyme can be used for colorimetric detection of urea and p-aminophenol simultaneously.

Further, the detecting step is:

(1) preparing a standard solution: preparing 2D CoO @ Rh NC mimic enzyme;

(2) preparation of actual samples:

randomly measuring 1 part of each water sample in different environments, filtering the water samples for three times by a 4-micron microporous filtering membrane, and distilling and concentrating to obtain water samples in different environments;

randomly weighing 1 part of each soil sample in different environments, ultrasonically leaching the soil samples with water for 1 week, and filtering the soil samples for three times through a 4-micron microporous filtering membrane to obtain different soil samples;

sampling to obtain one part of urine of adults at different time, and filtering for three times by a 4-micron microporous filtering membrane for later use;

(3) determination of urea and p-aminophenol in the sample:

putting a 2D CoO @ Rh NC mimic enzyme standard solution into a centrifuge tube, adding a sample to be detected and TMB, fixing the volume by using a disodium hydrogen phosphate-citric acid buffer solution with the pH value of 3.5, uniformly mixing, standing at room temperature for a period of time, and measuring an absorption spectrum within the range of 250-800 nm;

calculating the urea content in the sample to be detected according to the linear relation between the logarithm of the absorbance ratio at the wavelength of 652nm and 436nm and the urea concentration; and calculating the concentration of the p-aminophenol in the sample to be detected according to a linear equation between the logarithm of the absorbance ratio at 283nm and at 652nm or at 371nm and the concentration of the p-aminophenol.

Further, the reaction conditions in the step (3) are as follows: c. C_{2D CoO@Rh NC}＝20μg/mL，pH＝3.5，c_TMB0.05mM and reaction time of 50 min;

the 2D CoO @ Rh NC-TMB reaction system in the step (3) has specific selective spectral response to urea and p-aminophenol, and is accompanied by visible blue to brown yellow or blue to colorless color change;

the linear ratio relationship of the absorption spectrum intensity of the 2D CoO @ Rh NC-TMB reaction system in the step (3) to the concentration of urea or p-aminophenol exists.

Further, the reaction mechanism of the detection is as follows:

the CoO @ Rh NC mimic enzyme has high-efficiency oxidation mimic enzyme activity, can catalyze and oxidize TMB in the presence of air at room temperature to generate blue oxTMB, has special reduction performance on p-aminophenol, and can selectively reduce the blue oxide oxTMB into colorless TMB; the urea can reduce the blue oxide oxTMB into colorless TMB and further form brown yellow imine through the action of free amino and carbonyl; thereby realizing the colorimetric detection of urea and p-aminophenol simultaneously by enzyme catalysis.

The two-dimensional cobalt oxide stable rhodium nano mimic enzyme, the preparation method and the application thereof have the beneficial effects that:

based on the ultra-large specific surface area of the two-dimensional cobalt oxide and the good catalytic performance of rhodium nanoparticles, especially the excellent synergistic enhancement effect between the two, the invention prepares a two-dimensional cobalt oxide stable rhodium nano mimic enzyme (2D CoO @ Rh NC) by the reduction of a surfactant CTAB assisted one-pot method, optimizes the experimental conditions on the basis of discussing the catalytic activity mechanism of the two-dimensional cobalt oxide stable rhodium nano mimic enzyme, applies the 2D CoO @ Rh NC mimic enzyme to the colorimetric detection of urea and p-aminophenol, effectively detects the visibility of urea in water environment, soil and urine and p-aminophenol in an environmental water sample, avoids the interference of other components in the sample, and has strong visibility, simple and convenient operation, good selectivity and high sensitivity. The dual-mode ratiometric probe can also effectively reduce background interference absorption, and improve the accuracy and precision of detection results.

Drawings

FIG. 1 is a schematic diagram of the synthetic route of 2D CoO @ Rh NC according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the mechanism for simultaneous colorimetric detection of urea and p-aminophenol in 2D CoO @ Rh NC according to an embodiment of the present invention;

in fig. 3:

(a) a structural representation TEM image of the 2D CoO @ Rh NC of the embodiment of the invention;

(b) the structural representation HR-TEM image of the 2D CoO @ Rh NC of the embodiment of the invention;

(c) the structural representation EDS diagram of the 2D CoO @ Rh NC of the embodiment of the invention;

(d) a 3RD diagram of the structural representation of the 2D CoO @ Rh NC in the embodiment of the invention;

in fig. 4:

(a) the ultraviolet-visible absorption spectrogram and the corresponding color change chart of a 2D CoO @ Rh NC-TMB system, a cobalt oxide-TMB system, a rhodium nano-TMB system and a 2D CoO @ Rh NC-TMB system in the embodiment of the invention are shown in the specification;

(b) the time response curve graph of the 2D CoO @ Rh NC-TMB system of the embodiment of the invention at 652nm is shown;

in fig. 5:

(a) is a line graph of the influence of different pH values on 2D CoO @ Rh NC catalytic oxidation TMB in the embodiment of the invention;

(b) is a bar graph of the influence of the rhodium-cobalt molar ratio in different composite materials of the embodiment of the invention on 2D CoO @ Rh NC catalytic oxidation TMB;

(c) is a line graph of the influence of different temperatures on 2D CoO @ Rh NC catalytic oxidation TMB in the embodiment of the invention;

(d) is a bar graph of the effect of different temperatures on 2D CoO @ Rh NC catalytic oxidation TMB in the examples of the invention;

(e) is a line graph of the influence of different TMB contents on 2D CoO @ Rh NC catalytic oxidation TMB in the embodiment of the invention;

(f) is a line graph of the effect of different reaction times on 2D CoO @ Rh NC catalytic oxidation TMB in the examples of the invention;

FIG. 6 shows the effect of a common interfering substance on colorimetric identification of urea and p-aminophenol in a 2D CoO @ Rh NC-TMB system and the corresponding color change thereof in an embodiment of the present invention;

in fig. 7:

(a) UV-vis spectral titration curves for colorimetric identification of urea and corresponding color changes (c) for embodiments of the invention_Urea：6,9,15,30,45,60,75,90,105,120,135,150,165μM)；

(b) The linear relation curve of lg (A652/A436) and urea with different concentrations in the embodiment of the invention is shown;

(c) UV-vis spectral titration curves for colorimetric identification of p-aminophenol and their corresponding color changes (c) for embodiments of the present invention_{P-aminophenol}：1.7,3.3,15,25,35,45,55,65,75,85,95,105μM)；

(d) Is the linear relation curve of Lg (A283/A652) and Lg (A283/A371) and c-p-aminophenol in the embodiment of the invention.

A specific embodiment;

the invention is further explained in detail with reference to the drawings and the specific embodiments;

example 1:

a two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme is prepared by a surfactant CTAB assisted one-pot reduction method based on the ultra-large specific surface area of two-dimensional cobalt oxide, the good catalytic performance of rhodium nanoparticles and the excellent synergistic enhancement effect of the two-dimensional cobalt oxide and the good catalytic performance of the rhodium nanoparticles, so that when cobalt ions form ultra-thin two-dimensional cobalt oxide, the rhodium ions are reduced into rhodium nanoparticles and adsorbed on the surface of the two-dimensional cobalt oxide, and the two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme, 2D CoO @ Rh NC, is obtained.

The synthesis mechanism of the 2D CoO @ Rh NC is as follows:

the high concentration surfactant CTAB is easy to form a positively charged double-layer CTAB micelle, and is prepared from NaBH₄Hydrolysis of the resulting negatively charged OH^–And positively charged Co²⁺By virtue of being strongThe electrostatic action is absorbed on the surface of the bilayer in sequence to form a curved Co oxide nanosheet; due to Rh³⁺/Rh⁰Has a much higher redox potential than Co²⁺/Co⁰In the reducing agent sodium borohydride (NaBH)₄) In the presence of Rh³⁺Is reduced into rhodium nano particles and is uniformly adsorbed on the surface of the Co oxide nano sheet to form the two-dimensional cobalt oxide stable rhodium nano mimic enzyme.

The Co (NO)₃)₂·9H₂O，RhCl₃·3H₂O, CTAB and NaBH₄The molar ratio of (1), (0.1-0.3), (1-2), (2-3), and the reaction time of the step (2) is 5-15 min.

The detection steps are as follows:

(1) preparing a standard solution: preparing 2D CoO @ Rh NC mimic enzyme, urea, p-aminophenol and TMB standard solution;

(2) preparation of actual samples:

(3) determination of urea and p-aminophenol in the sample:

The reaction conditions in the step (3) are as follows: c. C_{2D CoO@Rh NC}＝20μg/mL，pH＝3.5，c_TMB0.05mM and reaction time of 50 min;

The reaction mechanism of the detection is as follows:

Example 2:

a preparation method of two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme,

preparation of 2D CoO @ Rh NC:

0.291g (1mmol) of Co (NO) was weighed₃)₂·9H₂O、0.0418g(0.2mmol)RhCl₃·3H₂O and 0.5g (1.4mmol) cetyltrimethylammonium bromide (CTAB) in a 100mL small beaker, 25mLH was added₂O, ultrasonic stirring for 30min for full dissolution; 0.1g (2.6mmol) of NaBH₄Dissolving in 15mLH₂Slowly dropping the solution into the mixed solution, fully stirring and reacting for 10min at room temperature, centrifugally separating, fully washing the solid with ethanol and deionized water, and drying in vacuum at 60 ℃ to obtain black 2D CoO stable Rh nano simulationEnzyme (the synthetic route is shown in figure 1).

The structure of 2D CoO @ Rh NC was structurally characterized by TEM, EDS, 3RD, etc., as shown in FIG. 3. TEM shows that rhodium nanoparticles are uniformly modified on the ultrathin two-dimensional cobalt oxide, and further EDS proves that elements such as Rh, Co, O and the like exist in the composite material; the main characteristic diffraction peaks of the (220) (311) (400) (511) (400) plane and the (111) plane of the simple substance rhodium, which are both attributed to the cobalt oxide, appear in the 3RD spectrogram, and further prove that the rhodium nano-modified on the two-dimensional cobalt oxide nano-chip.

A two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme for colorimetric detection of urea and p-aminophenol simultaneously,

a detection step:

(1) preparation of 2D CoO @ Rh NC mimic enzyme standard solution

And ultrasonically dispersing the 2D CoO @ Rh NC mimic enzyme into deionized water to prepare a 2D CoO @ Rh NC mimic enzyme standard solution with the concentration of 0.1mg/mL, and storing the solution at room temperature for later use.

(2) Preparation of the actual samples

Randomly measuring 1 part of each 1000.0mL environmental water sample (such as Yihe water, Polygon river water, apartment tap water and the like), filtering for three times by a 4-micrometer microporous filtering membrane, distilling and concentrating to 10.0mL to prepare different environmental water samples, and storing at room temperature for later use;

randomly weighing 1 part of each of 10.0g of soil samples (field soil and the like in different places), ultrasonically leaching the soil samples for 1 week by using 100.0mL of water, filtering the soil samples for three times by using a 4-micron microporous filtering membrane to obtain different soil samples, respectively marking the soil samples as a soil sample 1 and a soil sample 2, and storing the soil samples at room temperature for later use;

sampling to obtain urine of adult at different time (morning, noon and evening), filtering with 4 μm microporous filter membrane for three times, and storing at room temperature.

(3) Determination of urea and p-aminophenol in a sample

Adding 200 mu L (0.1mg/mL) of a sample to be detected and 100 mu L (1.5mM) of TMB into a 5mL centrifuge tube by taking 600 mu L (0.1mg/mL) of 2D CoO @ Rh NC simulated enzyme standard solution, then diluting to 3mL by using a disodium hydrogen phosphate-citric acid buffer solution with the pH of 3.5, mixing uniformly, standing for 50min at room temperature, and measuring the absorption spectrum within the range of 250-800 nm.

FIG. 2 is a reaction mechanism diagram of detection.

The results show that: for the colorimetric detection of urea, the log lg of the absorbance ratio at 652nm and 436nm of the system (A)₆₅₂/A₄₃₆) With urea concentration (c)_Urea) The linear relationship is good within the range of 6.0-165.0 mu M, the correlation coefficient (R) is 0.9988, and the detection limit is 1.1 mu M. By the linear equation lg (A)₆₅₂/A₄₃₆)＝0.00898c_Urea0.41603, calculating the content of urea in the sample to be tested. Under the optimal test condition, the method is successfully applied to the detection of urea in an environmental water sample and a soil sample, as shown in table 1, the recovery rate of urea in the sample is 96.7-100.9%, and the relative error (RSD) is less than 4.2%; further applied to the detection of urea in urine at different times (morning, noon and evening), as shown in table 2, the recovery rate of urea in the sample is 96.1-103.6%, and the relative error (RSD) is less than 3.3%.

As shown in FIG. 7, for the colorimetric detection of p-aminophenol, the logarithm lg (A) of the absorbance ratio at 283nm, 371nm and 652nm of the system₂₈₃/A₆₅₂) Or lg (A)₂₈₃/A₃₇₁) And concentration of p-aminophenol (c)_{P-aminophenol}) The molecular weight of (A) is within the range of 1.7-105.0 mu M, and the linear relation is good, and the detection limit is 0.68 mu M and 0.72 mu M. According to the linear equation: lg (A)₂₈₃/A₆₅₂)＝-0.03632+0.01219c_{P-aminophenol}And lg (A)₂₈₃/A₃₇₁)＝-0.20103+0.01254c_{P-aminophenol}And the concentration of the p-aminophenol in the sample to be detected can be calculated. Under the best test condition, the method is successfully applied to the detection of the p-aminophenol in an environmental water sample (table 3), the recovery rate of the p-aminophenol in the sample is 96.0-105.8%, and the relative error (RSD) is less than 2.9%.

Table 1 detection of urea in environmental water sample and soil sample (n ═ 5)^a

^apH 3.5,c_{2D CoO@Rh NC}＝20μg/mL.

^bThe actual value is the measured value in the table multiplied by 10^-2(the sample is concentrated 100 times before the measurement)

Table 2 System test results for urea in urine at different times (n ═ 5)^a

^apH 3.5,c_{2D CoO@Rh NC}＝20μg/mL.

^bThe actual value is the value measured in the table X10 (the sample is diluted 10 times before the measurement)

Table 3 detection of p-aminophenol in an environmental water sample by the system (n ═ 5)^a

^apH 3.5,c_{2D CoO@Rh NC}＝20μg/mL.

^bThe actual value is the measured value in the table multiplied by 10^-2(the sample was concentrated 100-fold before testing).

Example 3:

and (3) detecting the activity of a 2D CoO @ Rh NC mimic enzyme catalytic oxidation TMB standard sample:

(1) preparation of 2D CoO @ Rh NC mimic enzyme standard solution

Ultrasonically dispersing the 2D CoO @ Rh NC mimic enzyme into deionized water to prepare a 2D CoO @ Rh NC mimic enzyme standard solution with the concentration of 0.1mg/mL, and storing the solution at room temperature for later use.

(2) Preparation of TMB Standard solution

0.3651g (1.5mmol) of TMB was weighed out and dissolved in 1000.0mL of deionized water to prepare a 1.5mM TMB standard solution, which was stored at room temperature and diluted to the desired concentration at the time of use.

(3) Activity of 2D CoO @ Rh NC mimic enzyme for catalytic oxidation of TMB standard sample

And (3) adding 100 mu L (1.5mM) of TMB into a 5mL centrifuge tube from 600 mu L (0.1mg/mL) of 2D CoO @ Rh NC mimic enzyme standard solution, diluting to 3mL with a pH 3.5 disodium hydrogen phosphate-citric acid buffer solution, mixing uniformly, standing at room temperature for 50min, measuring an absorption spectrum within a range of 250-800 nm, and observing the change of the solution color.

As shown in fig. 4: the 2D CoO @ Rh NC mimic enzyme is capable of catalyzing the oxidation of TMB, producing distinct uv-visible characteristic absorption peaks at 652nm and 371nm, accompanied by a distinct color change, from colorless to blue.

Example 4:

and (2) carrying out simultaneous colorimetric detection on urea and p-aminophenol standard solutions by using two-dimensional cobalt oxide stabilized rhodium nano mimic enzyme:

(1) preparation of 2D CoO @ Rh NC mimic enzyme standard solution

(2) Preparation of urea, p-aminophenol and TMB standard solution

0.0601g (1.0mmol) of urea, 0.1091g (1.0mmol) of p-aminophenol and 0.3651g (1.5mmol) of TMB are weighed and respectively dissolved in 1000.0mL of deionized water to respectively prepare 1.0mM of urea, 1.0mM of p-aminophenol and 1.5mM of TMB standard solution, and the standard solution is stored at room temperature and diluted to the required concentration when in use.

(3) Determination of urea and p-aminophenol in standard solutions

Adding 1.0mM urea or p-aminophenol standard samples with different volumes and 100 mu L (1.5mM) TMB into 600 mu L (0.1mg/mL) of 2D CoO @ Rh NC simulated enzyme standard solution in a 5mL centrifuge tube, fixing the volume to 3mL by using disodium hydrogen phosphate-citric acid buffer solution with the pH value of 3.5, uniformly mixing, standing at room temperature for 50min, measuring an absorption spectrum within the range of 250-800 nm, calculating the relation between the spectral intensity and the concentration of the urea or p-aminophenol standard sample, and recording different color change characteristics.

Example 5:

the two-dimensional cobalt oxide stabilizes the rhodium nanometer mimic enzyme and simultaneously detects the optimization of the experimental conditions of urea and p-aminophenol by colorimetry,

in order to obtain the optimal catalytic activity of the 2D CoO @ Rh NC, the influence of factors such as different pH values, the rhodium-cobalt molar ratio of the composite material, the temperature, the TMB concentration, the reaction time and the like on the oxidation mimic enzyme is measured,

as shown in fig. 5: determining the optimized test conditions as follows: c. C_{2D CoO@Rh NC}＝20μg/mL，pH＝3.5，Mol_Rh/Mol_Co＝1:5，c_TMB0.05mM, room temperature, 50 min.

Example 6:

exploration of common coexisting interferent K⁺,Ca²⁺,Mg²⁺,Cl^-Influence of phenylalanine, alanine, glycine, threonine, glucose, acetone, formaldehyde, naphthaldehyde, uric acid, phenol, aniline on the detection of urea and p-aminophenol

As shown in fig. 6: the result shows that common coexisting interfering substances have no obvious influence on colorimetric identification of urea and p-aminophenol by a 2D CoO @ Rh NC-TMB system.

The invention starts from the reaction principle and discusses the mechanism of the two-dimensional cobalt oxide-rhodium nano composite material (2D CoO @ Rh NC) for imitating enzyme catalytic oxidation of TMB and the specific visible colorimetric action of added urea and p-aminophenol. On the basis, the optimal test conditions are further determined to be influenced by factors such as pH value, rhodium-cobalt molar ratio of the composite material, temperature, TMB concentration, reaction time and the like: c. C_{2D CoO@Rh NC}＝20μg/mL，pH＝3.5，Mol_Rh/Mol_Co＝1:5，c_TMB0.05mM, room temperature, 50 min. The common coexisting interferent has no obvious interference on the detection of the urea and the p-aminophenol, and can visually detect the p-aminophenol and the urea in a water sample, a soil sample and a urine sample in an environmental water sample. Wherein, the linear regression equation of the urea colorimetric detection is lg (A)₆₅₂/A₄₃₆) 0.00898-0.41603, the linear range of detection is 6.0-165.0 mu M, the correlation coefficient (R) is 0.9988, the detection limit is 1.1 mu M, the recovery rate of urea in a sample is 96.1-103.6%, and the relative error (RSD) is less than 4.2%.

The linear regression equation of colorimetric detection of p-aminophenol is lg(A₂₈₃/A₆₅₂)＝-0.03632+0.01219c(R²0.9727) and lg (a)₂₈₃/A₃₇₁)＝-0.20103+0.01254c(R²0.9827), the linear range of detection is 1.7-105.0 mu M, the detection limit is 0.68 mu M and 0.72 mu M, the recovery rate of p-aminophenol in the sample is 96.0-105.8%, and the relative error (RSD) is less than 2.9%.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.

Claims

1. A two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme is characterized in that: based on the ultra-large specific surface area of the two-dimensional cobalt oxide, the good catalytic performance of the rhodium nanoparticles and the excellent synergistic enhancement effect between the two, the preparation method is characterized in that a surfactant CTAB (cetyl trimethyl ammonium bromide) is used for assisting the one-pot reduction preparation, so that when cobalt ions form ultra-thin two-dimensional cobalt oxide, the rhodium ions are reduced into rhodium nanoparticles and adsorbed on the surface of the two-dimensional cobalt oxide, and the 2D CoO @ RhNC (rhodium-on-cobalt) nano mimic enzyme with two-dimensional cobalt oxide stability is obtained.

2. A method of preparing a two-dimensional cobalt oxide-stabilized rhodium nanomimic enzyme of claim 1, wherein said preparing step comprises:

3. The method for preparing a two-dimensional cobalt oxide-stabilized rhodium nanomodulase according to claim 2, wherein the synthesis mechanism of the 2D CoO @ Rh NC is as follows:

the high concentration surfactant CTAB is easy to form a positively charged double-layer CTAB micelle, and is prepared from NaBH₄Hydrolysis of the resulting negatively charged OH^–And positively charged Co²⁺The nano-particles are sequentially adsorbed on the surfaces of the double molecular layers by virtue of strong electrostatic action to form curved Co oxide nano-sheets; due to Rh³⁺/Rh⁰Has a much higher redox potential than Co²⁺/Co⁰Rh in the presence of a reducing agent sodium borohydride³⁺Is reduced into rhodium nano particles and is uniformly adsorbed on the surface of the Co oxide nano sheet to form the two-dimensional cobalt oxide stable rhodium nano mimic enzyme.

4. The method for preparing the two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme according to claim 2, which is characterized in that: the Co (NO)₃)₂·9H₂O，RhCl₃·3H₂O, CTAB and NaBH₄The molar ratio of (1), (0.1-0.3), (1-2), (2-3), and the reaction time of the step (2) is 5-15 min.

5. The method for preparing the two-dimensional cobalt oxide stable rhodium nanometer mimic enzyme according to claim 2, wherein the preparation method comprises the following steps:

(1) weighing 1mmol Co (NO)₃)₂·9H₂O、0.2mmol RhCl₃·3H₂O and 1.4mmol CTAB in a 100mL small beaker, 25mL H was added₂O, ultrasonic stirring for 30min for full dissolution;

(2) 2.6mmol of NaBH₄Dissolved in 15mL of H₂Slowly dripping the mixture into the mixed solution obtained in the step (1), and fully stirring and reacting for 10min at room temperature;

6. Use of a two-dimensional cobalt oxide-stabilized rhodium nanomodulase having the structure of claim 1 or prepared by the method of any one of claims 2 to 5, wherein: the two-dimensional cobalt oxide stable rhodium nano mimic enzyme can be used for colorimetric detection of urea and p-aminophenol simultaneously.

7. The use of a two-dimensional cobalt oxide-stabilized rhodium nanomodulase as claimed in claim 6, wherein the detection step is:

(1) preparing a standard solution: preparing 2D CoO @ Rh NC mimic enzyme;

(2) preparation of actual samples:

(3) determination of urea and p-aminophenol in the sample:

8. The use of a two-dimensional cobalt oxide-stabilized rhodium nanomodulase of claim 7, wherein:

the reaction conditions in the step (3) are as follows: c. C_2DCoO@RhNC＝20μg/mL，pH＝3.5，c_TMBThe reaction time was 50min at 0.05 mM.

9. The use of a two-dimensional cobalt oxide-stabilized rhodium nanomodulase of claim 7, wherein:

10. Use of a two-dimensional cobalt oxide-stabilized rhodium nanomodulase according to any one of claims 6 or 7, wherein the reaction mechanism for detection is: