Hg < 2 + > paper-based colorimetric sensor based on alginate oligosaccharide nano-silver and preparation method of Hg < 2 + > paper-based colorimetric sensor

Abstract

The invention discloses a green preparation method and application of alginate oligosaccharide nano-silver, ellipsoidal AOS-AgNPs of about 50 nanometers is prepared through an environment-friendly method, the material has oxidase-like activity, and the activity is remarkably enhanced after the material is combined with mercury ions to form Ag-Hg alloy. Based on the characteristic, an AOS-AgNPs-TMB-Hg < 2 + > detection system is studied and constructed, and 3, 3 ', 5, 5'-tetramethyl benzidine (TMB) is adopted as a chromogenic substrate to realize accurate detection of Hg < 2 + > in a water environment. The system shows excellent performance: the affinity to TMB (Tetramethylbenzidine) is high (Km is equal to 0.547 mM, Vmax is equal to 67.98 mu M / min), the detection linear range is wide (5-100 mu M), the detection limit is as low as 10nM, and the system has strong anti-interference capability. The portable paper-based colorimetric sensor is researched and developed by combining a smart phone technology, and the detection range is expanded to 30-200 [mu] M. The technology breaks through the limitation of a traditional detection method, has high sensitivity, operability and portability, has important application value in the fields of environmental monitoring and agricultural product safety assessment, and provides a new solution for mercury pollution prevention and control.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy metal ion detection, and specifically relates to a Hg 2+ Paper-based colorimetric sensor and preparation method thereof. Background Art

[0002] Mercury, as the most important heavy metal pollutant, enters the environment through various natural and man-made pathways, such as volcanic eruptions, the use of mercury-containing pesticides, and related industrial activities. It accumulates continuously in water, persists, and enters organisms through the food chain, posing a serious threat to human health. Different forms of mercury, including elemental, inorganic, and organic forms, can significantly affect various biological processes in the human body, such as cell proliferation, differentiation, and damage repair, leading to changes in cell structure, and then producing acute or chronic toxicity, causing a variety of diseases. In particular, highly active Hg 2+ Ions can bind to key groups in thioredoxin reductase, blocking the repair of oxidative damage, affecting brain cell function, and in severe cases may lead to death. Therefore, it is necessary to develop a method that can quickly, easily and accurately detect Hg in water or other samples. 2+ The method of determining the content has important practical significance and application value.

[0003] Currently, Hg 2+ The quantitative detection of Hg mainly relies on a series of high-tech methods, such as atomic absorption, emission spectroscopy, fluorescence spectroscopy, inductively coupled plasma mass spectrometry and high performance liquid chromatography. Although these methods are highly sensitive and accurate, they are complex to operate, the equipment is expensive and requires professional personnel to operate, which limits their wide application in on-site and real-time detection. Therefore, it is necessary to develop a simple, efficient, sensitive and environmentally friendly portable Hg 2+ Detection plans are particularly important.

[0004] In recent years, silver-based nanozyme colorimetry has been widely used in Hg 2+ This method shows great potential in the detection of Hg 2+ The color reaction caused by the concentration change can be identified by naked eyes in the visible light range, and the data can be analyzed by smart phones, realizing the Hg 2+ A variety of synthesized and modified silver nanoparticles (AgNPs) have been shown to have oxidase-like catalytic activity and can be used for Hg 2+ In the system where AgNPs and TMB coexist, Hg 2+ The AgNPs interact with the AgNPs to form an Ag-Hg alloy, which enhances the generation of superoxide anions and hydroxyl radicals, improves the oxidase-like activity of the AgNPs, and catalyzes TMB to generate a blue oxidized product oxTMB with a photothermal effect, thereby achieving the photothermal reaction of Hg. 2+ Quantitative detection of .

[0005] AOS, an oligosaccharide derived from the degradation of sodium alginate, is composed of two units: α-L-mannuronic acid and β-D-guluronic acid. It possesses the advantages of low molecular weight, good solubility, safety, non-toxicity, and excellent physiological activity and bioavailability. Its negative surface charge facilitates electrostatic binding with Ag+, making it a suitable template and support for the green synthesis of AgNPs. However, despite its numerous advantages, the use of AOS for the synthesis of AgNPs has not been reported. This provides new insights and directions for our research. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a Hg 2+ Preparation method of paper-based colorimetric sensor.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a Hg 2+ A method for preparing a paper-based colorimetric sensor, characterized in that it comprises:

[0010] The brown algal oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution were mixed and stirred to prepare an AOS-AgNPs solution;

[0011] The AOS-AgNPs solution was ultrasonically dispersed in deionized water to obtain an AOS-AgNPs dispersion;

[0012] The AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution were mixed to obtain a mixed solution;

[0013] Cut the chromatography paper, soak it in the mixture, dry it in the dark, and prepare the test strips to obtain the Hg based on brown algae oligosaccharide nanosilver. 2+ Paper-based colorimetric sensor.

[0014] As a preferred embodiment of the preparation method of the present invention, the brown algae oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution are mixed and stirred, wherein the volume ratio of the brown algae oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution is 600:600:100:1; the concentration of the brown algae oligosaccharide solution is 3 mg / mL, the concentration of the AgNO3 solution is 10 mg / mL, and the concentration of the Vc solution is 10 mg / mL.

[0015] As a preferred embodiment of the preparation method of the present invention, the AOS-AgNPs solution is ultrasonically dispersed in deionized water, wherein the material-liquid ratio of AOS-AgNPs to deionized water is 1 mg: 5-30 mL.

[0016] As a preferred embodiment of the preparation method of the present invention, the AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution are mixed, wherein the concentration of the TMB solution is 10 mM; the concentration of the citric acid-sodium citrate buffer solution is 0.1 M, and the pH is 4.

[0017] As a preferred embodiment of the preparation method of the present invention, the volume ratio of the AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution is 1:1:1-6.

[0018] As a preferred embodiment of the preparation method of the present invention, the immersion in the mixed solution and drying in the dark is carried out for 30 to 60 minutes.

[0019] As a preferred embodiment of the preparation method of the present invention, the drying in the dark is carried out at a temperature of 50°C.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide a Hg 2+ Paper-based colorimetric sensor.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide a Hg 2+ Paper-based colorimetric sensor in Hg 2+ Application in content analysis.

[0022] As a preferred solution of the application of the present invention, wherein: the Hg 2+ Assay involves dipping the test strip into the Hg 2+ After immersing in the solution for 2 minutes, take it out and wait for 5 to 10 minutes. When a color reaction occurs, take a photo with a mobile phone and use ImageJ software to obtain the corresponding RGB value and perform data fitting analysis.

[0023] Beneficial effects of the present invention:

[0024] (1) The AOS-AgNPs prepared by the present invention have excellent stability and dispersibility, as well as oxidase-like activity, and are 2+ The detection provides a new material basis.

[0025] (2) AOS-AgNPs-TMB-Hg provided by the present invention 2+ The detection system can detect Hg in water samples without sample pretreatment. 2+ Direct determination of content is simple, rapid and sensitive.

[0026] (3) Combined with the use of smart phones, the present invention establishes a portable paper-based sensor, broadens its application range in on-site real-time detection, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0028] Figure 1 Preparation of AOS-AgNPs and portable paper-based sensor Hg 2+ Schematic diagram of colorimetric detection;

[0029] Figure 2 Characterization of AOS-AgNPs prepared in Example;

[0030] Figure 3 This is the UV spectrum of AOS-AgNPs prepared in Example;

[0031] Figure 4 Potential diagram of AOS-AgNPs prepared in Example

[0032] Figure 5 XRD pattern of AOS-AgNPs prepared in Example;

[0033] Figure 6 For different concentrations of Hg in the examples 2+ Color development results in the AOS-AgNPs-TMB system;

[0034] Figure 7 is the UV-visible absorption spectrum of different mercury ion concentrations in the embodiment;

[0035] Figure 8is the fitting curve of different mercury ion concentrations in the AOS-AgNPs-TMB system of Example;

[0036] Figure 9 The effects of different metal ions on the AOS-AgNPs-TMB system in the examples are shown in Figure 2. Figure 9 A and 9B are Hg 2+ the effects of absence and presence on the experiment;

[0037] Figure 10 The steady-state kinetic analysis of AOS-AgNPs-based oxidase in the examples;

[0038] Figure 11 This is the Lineweaver-Burk linear fitting diagram of AOS-AgNPs in the embodiment;

[0039] Figure 12 The (G+B) / 2R value of the test paper in the experimental example and the different Hg 2+ Linear fit plot of concentration. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0043] Example 1

[0044] This embodiment provides a Hg 2+ Preparation method of paper-based colorimetric sensor, such as Figure 1 As shown, the specific steps include:

[0045] (1) Prepare 3 mg / mL brown algal oligosaccharide solution with ultrapure water from AOS freeze-dried powder. At the same time, prepare 10 mg / mL V CSolution, 10mg / mL AgNO3 solution. Take 3mL of brown algae oligosaccharide solution, add 3mL of ultrapure water, then add 500μL of AgNO3 solution and 5μL of V c The solution was stirred at room temperature for 1 h. Stirring was stopped when the solution changed from light yellow to yellow-brown.

[0046] (2) Using deionized water as a blank control, AOS, AgNO3, and AOS-AgNPs were scanned in the wavelength range of 200-700 nm by UV-visible spectrophotometer to measure the characteristic absorption peaks; the hydrated particle size and surface charge of AOS-AgNPs were determined by nanoparticle size and Zeta potential analyzer; the AOS-AgNPs solution was dropped onto a 300-mesh copper grid and dried at room temperature, and the sample morphology was observed by HRTEM; the crystal structure of AOS-AgNPs was characterized by X-ray diffractometer from 5 to 90° (10° / min).

[0047] like Figures 2 to 5 As shown, AOS and AgNO3 show characteristic absorption at 230nm and 300nm, respectively, and the generated AOS-AgNPs show a characteristic absorption peak at a wavelength of about 400nm, which is consistent with other types of AgNPs recorded in the literature ( Figure 2 The average hydrated particle size of AOS-AgNPs is about 55 nm and is normally distributed, with a DPI value of 0.242 ( Figure 3 ); Transmission electron microscopy showed that the synthesized AOS-AgNPs were mostly ellipsoidal particles with a size distribution in the range of 25 to 50 nm and good dispersion, which was consistent with the test results of nanoparticle size and Zeta potential analyzer ( Figure 3 The surface potential of AOS is negatively charged, and the absolute value of potential is 25mV, which is consistent with the properties of its anionic polysaccharide. The surface potential of AOS-AgNPs is -15mV, which is consistent with the general characteristic of negative charge on the surface of AgNPs. It is preliminarily proved that the synthesized AOS-AgNPs ( Figure 4 ). X-ray diffraction results show that the characteristic peaks of AOS-AgNPs 2θ values ​​are located at 38.1°, 44.3°, 64.4°, and 77.5° ( Figure 5 ), representing the

[111] ,

[200] ,

[220] , and

[311] planes, respectively. This confirms that AOS-AgNPs are silver nanocrystals with a face-centered cubic (FCC) structure, which is consistent with the results of Sangaonkar et al. Based on the above characterization results, ellipsoidal AOS-AgNPs with a face-centered cubic (FCC) structure of approximately 50 nm were prepared.

[0048] (3) 1 mg of AOS-AgNPs was ultrasonically dispersed in 10 mL of deionized water, and 10 mM TMB solution, 0.1 M (pH = 4) citric acid-sodium citrate buffer solution, and 5, 10, 15, 20, 30, 60, and 100 μM Hg(NO3)2 solutions were prepared. 0.1 mg / mL AOS-AgNPs dispersion was mixed with TMB, citric acid-sodium citrate buffer solution, and seven concentrations of Hg(NO3)2 at a volume ratio of 1:1:6:1. The full wavelength scan was performed and the absorbance at 652 nm was detected.

[0049] (4) Prepare TMB solutions with concentrations of 30, 35, 40, 45, 50, and 60 μM and 30 μM Hg(NO3)2 solutions, respectively. The concentrations of AOS-AgNPs and citric acid-sodium citrate buffer solutions are consistent with those in (3). AOS-AgNPs, TMB, citric acid-sodium citrate buffer solutions, and Hg(NO3)2 solutions of six concentrations are mixed in a volume ratio of 1:1:6:1. The absorbance at 652 nm is measured to calculate the enzyme activity kinetic parameters.

[0050] (5) In order to verify whether other common metal ions interfere with the detection system, 150 μM Zn 2+ 、Mn 2+ 、Cu 2+ Mg 2+ 、Fe 3+ 、Ba + , K + , Ca 2+ , Pb 2+ Solution, used to simulate the possible presence of interfering ions, with 30 μM Hg 2 + The solution was used as a control, and verification was performed using both the external standard method and the internal standard method, specifically:

[0051] 20 μL of each of the above single metal ion solutions were added to the AOS-AgNPs-TMB system consistent with (3), and the absorbance of the solution at 652 nm was measured to evaluate the interference degree of the single ion on the detection system; 2+ In the AOS-AgNPs-TMB system of the solution, 20 μL of other metal ion solutions were added to simulate the coexistence of metal ions, and the absorbance of the solution at 652 nm was measured to evaluate the Hg 2+ In the presence of other ions, whether they will interfere with the detection.

[0052] (6) In order to quickly detect Hg in water samples 2+The AOS-AgNPs-TMB paper-based sensing platform was developed based on the above results. 0.1 mg / mL AOS-AgNPs, 10 mM TMB, and 0.1 M (pH = 4) citric acid-sodium citrate buffer solution were mixed in a volume ratio of 1:1:1. The chromatographic paper was cut into 1 cm × 2 cm pieces and soaked in the mixture for half an hour. The test strips were dried at 50 ° C in the dark to prepare the test strips. The test strips were soaked in 30, 60, 100, 150, and 200 μM Hg 2+ After immersing in the solution for 2 minutes, take it out and wait for 5 to 10 minutes. When a color reaction occurs, take a photo with a mobile phone and use Image J software to obtain the corresponding RGB value and perform data fitting analysis.

[0053] (7) All data were statistically analyzed, standard deviations calculated, and graphed using Origin software.

[0054] Example 2

[0055] The difference between this embodiment and embodiment 1 is that the volume of the single metal ion solution added in step (5) is different. Specifically, 40 μL of each of the above single metal ion solutions was added to the AOS-AgNPs-TMB system consistent with (3), and the absorbance of the solution at 652 nm was measured to evaluate the interference degree of the single ion on the detection system; in the presence of 30 μM Hg 2+ In the AOS-AgNPs-TMB system of the solution, 30 μL of other metal ion solutions were added to simulate the coexistence of metal ions, and the absorbance of the solution at 652 nm was measured to evaluate the Hg 2+ In the presence of ions, whether other ions will interfere with the detection; the remaining steps are the same as in Example 1.

[0056] Example 3

[0057] The difference between this embodiment and embodiment 1 is that the volume of the single metal ion solution added in step (5) is different. Specifically, 40 μL of each of the above single metal ion solutions was added to the AOS-AgNPs-TMB system consistent with (3), and the absorbance of the solution at 652 nm was measured to evaluate the interference degree of the single ion on the detection system; in the presence of 30 μM Hg 2+ 40 μL of other metal ion solutions were added to the AOS-AgNPs-TMB system to simulate the coexistence of metal ions. The absorbance of the solution at 652 nm was measured to evaluate the Hg 2+ In the presence of ions, whether other ions will interfere with the detection; the remaining steps are the same as in Example 1.

[0058] Example 4

[0059] The difference between this embodiment and embodiment 1 is that the volume of the single metal ion solution added in step (5) is different. Specifically, 50 μL of each of the above single metal ion solutions were added to the AOS-AgNPs-TMB system consistent with (3), and the absorbance of the solution at 652 nm was measured to evaluate the interference degree of the single ion on the detection system; in the AOS-AgNPs-TMB system containing 30 μM Hg 2+ In the AOS-AgNPs-TMB system of the solution, 20 μL of other metal ion solutions were added to simulate the coexistence of metal ions, and the absorbance of the solution at 652 nm was measured to evaluate the Hg 2+ In the presence of ions, whether other ions will interfere with the detection; the remaining steps are the same as in Example 1.

[0060] Example 5

[0061] The difference between this embodiment and embodiment 1 is that the volume of the single metal ion solution added in step (5) is different. Specifically, 20 μL of each of the above single metal ion solutions were added to the AOS-AgNPs-TMB system consistent with (3), and the absorbance of the solution at 652 nm was measured to evaluate the interference degree of the single ion on the detection system; in the AOS-AgNPs-TMB system containing 30 μM Hg 2+ In the AOS-AgNPs-TMB system of the solution, 10 μL of other metal ion solutions were added to simulate the coexistence of metal ions, and the absorbance of the solution at 652 nm was measured to evaluate the Hg 2+ In the presence of ions, whether other ions will interfere with the detection; the remaining steps are the same as in Example 1.

[0062] Example 6

[0063] The difference between this embodiment and embodiment 1 is that in step (3), 1 mg of AOS-AgNPs was ultrasonically dispersed into 20 mL of deionized water, and the remaining steps were the same as those in embodiment 1.

[0064] Example 7

[0065] The difference between this embodiment and embodiment 1 is that in step (3), 1 mg of AOS-AgNPs was ultrasonically dispersed into 30 mL of deionized water, and the remaining steps were the same as those in embodiment 1.

[0066] Example 8

[0067] The difference between this embodiment and embodiment 1 is that in step (3), 1 mg of AOS-AgNPs was ultrasonically dispersed into 5 mL of deionized water, and the remaining steps were the same as those in embodiment 1.

[0068] like Figures 6-8 As shown in the AOS-AgNPs-TMB system, with the addition of Hg2+ With the increase of concentration, the color of the solution gradually changes to light blue and then to dark blue ( Figure 6 ), the corresponding absorbance value at 652nm also increases synchronously ( Figure 7 ). The AOS-AgNPs-TMB system was tested for Hg 2+ The lowest detection limit of concentration is 10nM. At the same time, through the analysis and fitting of the absorbance value, it can be known that Hg 2+ When the concentration is in the range of 5 to 100 μM, Hg 2+ The concentration of Hg in water samples is linearly positively correlated with the absorbance of the color system. The linear equation is y = 0.01192x-0.04222, and the correlation coefficient R2 = 0.99982. 2+ content, with good colorimetric detection performance ( Figure 8 ). Hg 2+ The addition of Ag into the detection system promotes the formation of Ag-Hg alloy, which in turn promotes the generation of superoxide anions and hydroxyl radicals, resulting in enhanced oxidase-like activity of AOS-AgNPs, which oxidizes TMB to generate blue oxTMB. This mechanism enables the AOS-AgNPs-TMB system to achieve the detection of Hg 2+ Accurate detection.

[0069] In order to demonstrate that AOS-AgNPs-Hg 2+ It has excellent oxidase-like catalytic activity and is effective for the oxidation of AOS-AgNPs-Hg 2+ The enzyme activity parameters of the system were determined. Figure 10 、 Figure 11 As shown in the figure, as the TMB concentration increased from 30 μM to 60 μM, the reaction rate of the system showed a trend of first rapidly increasing and then gradually slowing down the rate of increase. The correlation coefficient of the enzyme kinetic equation obtained by fitting was R2 = 0.98, indicating that the reaction mechanism of TMB oxidation catalyzed by this system conforms to the typical Michaelis-Menten equation.

[0070] The results of the Lineweaver-Burk method showed that the reciprocal of the reaction rate of AOS-AgNPs nanozyme and the reciprocal of the substrate TMB concentration showed a good linear fitting relationship, and the linear equation y = 8.04748x + 0.01471 was obtained with a correlation coefficient of R2 = 0.95. 2+The Km of the system is 0.547mM and the Vmax is 67.98μM / min. Compared with the Vmax of other silver-based nanozymes, the Vmax values ​​of the 615nm silver nanozyme loaded with carbon microspheres by Zhang et al. and the 4.6nm silver nanozyme modified with bioactive folic acid by Tang et al. are 3.45×10 -8 M·s -1 , 5.2×10 -8 M·s -1 , which is two orders of magnitude smaller than the Vmax value of AOS-AgNPs, and the reaction rate of AOS-AgNPs is faster. This fully proves that AOS-AgNPs has excellent mimic oxidase activity and has a high affinity with the substrate TMB, indicating that this sensing system can realize the detection of Hg in water samples. 2+ Rapid and highly sensitive detection.

[0071]

[0072] Wherein, Vmax: maximum reaction velocity; Km: Michaelis constant; [S]: concentration of reaction substrate.

[0073] In order to further evaluate the AOS-AgNPs-TMB system for Hg 2+ Detection specificity, select Zn 2+ 、Mn 2+ 、Cu 2+ Mg 2+ 、Fe 3+ 、Ba + , K + , Ca 2+ , Pb 2+ Common metal ions such as Hg 2+ The results of external standard method are as follows Figure 9 As shown in A, except Hg 2+ Except for Hg, other ions can hardly be detected in the AOS-AgNPs-TMB system. 2+ After that, the absorbance of each system with the addition of other metal ions is basically the same as that of the system with only Hg 2+ Equal Figure 9 B) The results of the above cross-validation experiments demonstrated that the presence of other common metal ions did not significantly affect Hg 2+ interaction with AOS-AgNPs, and the AOS-AgNPs-TMB system is effective for detecting Hg 2+ Has excellent selection specificity.

[0074] The prepared paper-based sensor was tested under different Hg 2+In the concentration solution test, different degrees of blue are displayed from light to dark; under the condition of keeping the light source unchanged, the color-changing test paper is photographed and the RGB primary color values ​​are extracted with the help of Image J software. 2+ The relationship model between concentrations was fitted using a variety of calculation methods, and the best linear fit was finally achieved through B / (R+G).

[0075] Table 1

[0076] concentration B / (R+G) 6 0.54982 10 0.58127 15 0.61265 20 0.65225 30 0.66304 60 0.7899 100 0.97548

[0077] As shown in Table 1 and Figure 8 As shown, the linear regression equation y=0.00432x+0.54048 was constructed based on the B / (R+G) combination, and the correlation coefficient reached R 2 =0.99, which is in the range of 0-100 μM Hg 2+ Within the detection range, there is a good linear relationship. This experimental result strongly verifies the feasibility of portable paper-based sensors in practical applications.

[0078] Using negatively charged AOS as a template, ellipsoidal AOS-AgNPs with a size of approximately 50 nanometers were prepared. 2+ The oxidase activity of AOS-AgNPs was enhanced to catalyze the color reaction of TMB, and AOS-AgNPs-TMB-Hg 2+ system, applied to Hg in water environment samples 2+ Content detection. The minimum detection limit is 10nM. In the range of 5 to 100μM, the absorbance of this color system is consistent with that of Hg 2+ There is a good linear positive correlation between the concentration of Hg 2+ It has excellent selective specificity and is basically not interfered by other common metal ions. The portable paper-based sensor prepared based on this method has an effective detection range of 30 to 200 μM. 2+ It has great potential application value in the rapid detection of content.

[0079] The present invention successfully prepared a Hg-based oligosaccharide silver nanoparticles (AOS-AgNPs) 2+ A paper-based colorimetric sensor has shown excellent performance and application potential. By using brown algae oligosaccharides with negative surface charges as templates for green synthesis, we obtained AOS-AgNPs with high stability, good dispersion and excellent oxidase-like activity. These nanoparticles reacted with Hg 2+ After binding, it can significantly enhance its oxidase-like activity, thereby catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) to develop color and achieve the purpose of Hg 2+ Sensitive detection.

[0080] AOS-AgNPs-TMB-Hg of the present invention 2+ The detection system exhibits a wide linear range (5-100 μM), a low detection limit (10 nM), and excellent anti-interference ability against other coexisting ions, ensuring high selectivity and accuracy. Furthermore, combined with smartphone applications, the portable paper-based sensor we developed not only simplifies the operational process but also enhances the convenience of on-site real-time detection, making it a promising candidate for applications in water environment monitoring, agricultural product testing, and other fields.

[0081] In summary, the Hg 2+ Paper-based colorimetric sensor and its preparation method not only solve the problem of Hg 2+ It solves the problem of complex and time-consuming detection, and also improves the sensitivity and accuracy of detection, providing a new technical means for the rapid detection of heavy metal ions, which has important practical value and social significance.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A Hg-based brown algae oligosaccharide nanosilver 2+ The preparation method of the paper-based colorimetric sensor is characterized by: include, The brown algal oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution were mixed and stirred to prepare an AOS-AgNPs solution; The AOS-AgNPs solution was ultrasonically dispersed in deionized water to obtain an AOS-AgNPs dispersion; The AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution were mixed to obtain a mixed solution; Cut the chromatography paper, soak it in the mixture, dry it in the dark, and prepare the test strips to obtain the Hg based on brown algae oligosaccharide nanosilver. 2+ Paper-based colorimetric sensor.

2. The preparation method according to claim 1, wherein: The brown algae oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution are mixed and stirred, wherein the volume ratio of the brown algae oligosaccharide solution, ultrapure water, AgNO3 solution, and Vc solution is 600:600:100:1; the concentration of the brown algae oligosaccharide solution is 3 mg / mL, the concentration of the AgNO3 solution is 10 mg / mL, and the concentration of the Vc solution is 10 mg / mL.

3. The preparation method according to claim 1, wherein: The AOS-AgNPs solution is ultrasonically dispersed in deionized water, wherein the material-liquid ratio of AOS-AgNPs to deionized water is 1 mg: 5-30 mL.

4. The preparation method according to claim 1, wherein: The AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution are mixed, wherein the concentration of the TMB solution is 10 mM; the concentration of the citric acid-sodium citrate buffer solution is 0.1 M, and the pH is 4.

5. The preparation method according to claim 4, wherein: The volume ratio of the AOS-AgNPs dispersion, TMB, and citric acid-sodium citrate buffer solution is 1:1:1-6.

6. The preparation method according to claim 1, wherein: The process of soaking the mixture in the mixed solution and drying the mixture in a dark place is carried out, wherein the soaking time is 30 to 60 minutes.

7. The preparation method according to claim 6, wherein: The light-proof drying process is carried out at a temperature of 50°C.

8. Hg based on brown algal oligosaccharide nanosilver prepared by the preparation method according to any one of claims 1 to 7 2+ Paper-based colorimetric sensor.

9. A Hg-based brown algae oligosaccharide nanosilver 2+ Paper-based colorimetric sensor in Hg 2+ Application in content analysis.

10. The use according to claim 9, characterized in that: The Hg 2+ Assay involves dipping the test strip into the Hg 2+ After immersing in the solution for 2 minutes, take it out and wait for 5 to 10 minutes. When a color reaction occurs, take a photo with a mobile phone and use ImageJ software to obtain the corresponding RGB value and perform data fitting analysis.

Images