For Fe 3+ Nanochannel devices and electrochemical detection methods for ion concentration detection

Abstract

The application discloses a kind of nanochannel devices for Fe 3+ Ion concentration detection, comprising a nanochannel for containing the electrolyte solution to be measured, the inner surface of the nanochannel is modified with functional molecules, and the functional molecules realize specific binding by chelation, coordination or electrostatic attraction with Fe 3+ Ion, so that the ion current flowing through the nanochannel changes under the applied voltage, realizing the detection of Fe 3+ Ion concentration in the electrolyte solution to be measured. The application also discloses a detection method, and the quantitative detection of Fe 3+ Ion concentration can be achieved by establishing a standard curve, which can quickly, efficiently and quantitatively detect the Fe 3+ Ion concentration in unknown water samples. Since the nanochannel can be recycled and reused, the detection cost is greatly reduced, and it can be used in water quality evaluation, health monitoring and other fields.

Description

Technical Field

[0001] This invention belongs to the technical field of nanodevices and chemical detection, specifically relating to a method for Fe 3+ Nanochannel devices and electrochemical detection methods for ion concentration detection. Background Technology

[0002] With the rapid development of the chemical industry, improper pollution management has made agricultural, industrial wastewater, and urban sewage the main sources of metal ion pollution in water resources. Ferric ions (Fe3+) are a major contributor. 3+ As one of the most common polluting metal ions, high concentrations of Fe in the environment can have destructive impacts on ecosystems and pose a serious threat to human health. Therefore, developing a rapid, accurate, and economical method for the quantitative detection of Fe in the environment and organisms is crucial. 3+ The technology has become extremely important.

[0003] Current Fe 3+ Ion detection techniques, such as fluorescence or spectroscopic probe methods, although capable of quantitatively detecting Fe 3+ While these methods can identify Fe ions, they rely on expensive instruments such as inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES), as well as disposable testing devices such as fluorescent test strips. This not only increases the cost of detection but also limits the widespread adoption of these technologies in field applications due to their operational complexity and high equipment costs. Furthermore, although existing technologies can qualitatively identify Fe ions... 3+ The presence of ions, but they are generally unable to achieve the effect of Fe 3+ Rapid and continuous monitoring of ion concentration is needed. Therefore, a new method that is both economical and capable of sustained and stable operation is required to achieve Fe... 3+ The accurate quantitative detection of ions is of particular importance. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a method for Fe 3+ Nanochannel devices for ion concentration detection and Fe 3+ Electrochemical detection methods for ion concentration.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A type of Fe 3+ A nanochannel device for ion concentration detection includes a nanochannel for containing an electrolyte solution to be tested, wherein the nanochannel is a one-dimensional nanopore or a two-dimensional plane, with one dimension having a size of less than 200 nm; the inner surface of the nanochannel is modified with functional molecules, which interact with Fe... 3+Ions achieve specific binding through chelation, coordination, or electrostatic attraction, causing changes in the ionic current flowing through the nanochannel under applied voltage, thereby controlling the Fe content in the electrolyte solution. 3+ Ion concentration detection.

[0007] Optionally, the functional molecules include tannic acid, deferoxamine, thiophenealdehyde-diaminouracil Schiff base, cyanidin-3-O-glucoside, or anthocyanins. The phenolic hydroxyl groups in the functional molecules exhibit different degrees of deprotonation at different pH values, allowing the inner surface of the nanochannel to possess a positive surface charge, a negative surface charge, or essentially no charge. When a voltage is applied to the nanochannel device, the specifically bound molecules modified on the inner surface bind to Fe through their functional groups. 3+ Ions engage in interactions such as chelation, coordination, and electrostatic attraction, altering the internal surface charge and / or electrochemical properties of the nanochannel, thereby causing changes in the ionic current. Furthermore, the ionic current interacts with Fe... 3+ The ion concentration exhibits a linear relationship. The methods for modifying the inner surface of the nanochannel with different functional molecules include, but are not limited to, chemical bonding, vapor deposition, solution methods, and plasma grafting.

[0008] Optionally, the nanochannels are formed in inorganic or organic polymer materials; the inorganic material includes at least one of glass, silicon, alumina, carbon nanotubes, or graphene; the organic polymer material includes at least one of polyimide, polyethylene terephthalate, polycarbonate, polypyrrole, or polyaniline.

[0009] The nanochannel can be a one-dimensional nanopore or a two-dimensional planar channel, and the radius (or circumcircle radius) of the pore or a certain dimension of the two-dimensional plane is less than 200 nm, preferably less than 150 nm. There can be one or more nanochannels.

[0010] Optionally, the nanochannel is a conical channel, with the radius of the relatively narrow end of the conical nanochannel being less than 150 nm and the radius of the relatively wide end being 200–2000 nm, more preferably 200–500 nm; the radius gradually increases from the relatively narrow end to the relatively wide end.

[0011] Optionally, the system may also include an electrochemical detection system, which includes a working electrode and an auxiliary electrode. The working electrode and the auxiliary electrode are respectively in contact with the electrolyte solution to be tested at both ends of the nanochannel, and a voltage is applied through the working electrode and the auxiliary electrode.

[0012] Optionally, the outer side of the nanochannel also contains the electrolyte solution to be tested, and the electrolyte solution to be tested on the outer side is connected to one end of the nanochannel. In one embodiment, a solution pool is included, the nanochannel is vertically disposed on the solution pool with its bottom end connected to the electrolyte solution to be tested in the solution pool, and its top end is not connected. The working electrode enters from the top end of the nanochannel, and the auxiliary electrode is placed in the solution pool.

[0013] A Fe 3+ The electrochemical detection method for ion concentration uses the above-mentioned method for Fe 3+ A nanochannel device for ion concentration detection involves placing the electrolyte solution to be tested within the nanochannel, applying voltage through an electrochemical detection system, measuring the current response, and comparing the result with a pre-defined standard curve to determine the Fe concentration in the electrolyte solution. 3+ Ion concentration.

[0014] Optionally, the electrolyte solution to be tested includes a basic electrolyte with a concentration of 0.05–1 mM, wherein the basic electrolyte is LiCl, NaCl, or KCl; and the electrolyte solution to be tested contains Fe. 3+ The ion concentration range is 0.01 mM to 1 mM.

[0015] Optionally, the standard curve is prepared by using different Fe... 3+ Electrolyte solution standard samples with varying ion concentrations were tested to determine the corresponding current values, establishing a correlation between current values ​​or current ratios and Fe. 3+ The relationship between ion concentrations; with Fe as an example. 3+ The current value corresponding to the electrolyte solution standard sample with an ion concentration of 0 is the baseline current value, and the current ratio is the ratio of the current value at each concentration to the baseline current value. Optionally, the electrolyte solution standard sample includes a baseline electrolyte with a concentration of 0.05–1 mM. The role of the aforementioned baseline electrolyte is to test whether Fe is present in the nanochannel. 3+ The state of the ions is used as a benchmark; alternatively, the pH of the test solution can be adjusted to allow the functional molecules modified within the nanopores to react with the detected Fe. 3+ Ions exhibit greater specificity, resulting in smaller errors. For example, when the functional molecule is tannic acid, a pH of 5-6 in the electrolyte solution to be tested will affect the Fe... 3+ Ions exhibit a more specific response, showing a linear relationship between concentration and current. If pure water is used without a basic electrolyte, the current fluctuates greatly and is very small under pure water conditions, and the pH is difficult to adjust, easily leading to errors.

[0016] Optionally, the test method is cyclic voltammetry, linear sweep voltammetry, constant potential pulse method, etc., and the applied voltage is +0.5 to +1.5V.

[0017] Optionally, after each detection, a step of returning to the initial state is also included. This step involves cleaning the nanochannels with a cleaning solution containing replacement molecules, which react with Fe... 3+ The binding energy of the ions is higher than that of the functional molecule and Fe. 3+ Binding energy of ions.

[0018] Optionally, the replacement molecule is disodium ethylenediaminetetraacetate (EDTA-2Na), etc.

[0019] The beneficial effects of this invention are as follows:

[0020] Nanochannel devices based on internal surface functionalization modification, through modification of the nanochannel interior with Fe... 3+ Ions can specifically bind to functional molecules, utilizing their functional groups to bind with Fe. 3+ Interactions between ions, such as chelation, coordination, and electrostatic attraction, alter the internal surface charge and / or electrochemical properties of nanochannels, thus demonstrating their influence on Fe. 3+ Specific recognition of ions; this change can be rapidly read by electrochemical measurements, by establishing the relationship between ion current and Fe. 3+ The relationship between ion concentrations allows for the determination of unknown Fe concentrations. 3+ This method enables quantitative ion detection, and the detection process is rapid, accurate, and economical. Nanochannel devices can be stored for extended periods without affecting their detection performance, ensuring the stability and reliability of the detection. It is suitable for applications requiring rapid, on-site Fe detection. 3+ Fe has applications in various fields, such as environmental monitoring, food safety, public health, clinical drug testing, and health monitoring. 3+ Quantitative ion detection provides an economical and effective solution. Attached Figure Description

[0021] Figure 1 This is an embodiment of the invention for Fe 3+ A schematic diagram of the functionalization modification process of nanochannels for ion concentration detection;

[0022] Figure 2 This is an embodiment of the invention for Fe 3+ Schematic diagram of a nanochannel device for ion concentration detection;

[0023] Figure 3 This is an example of an embodiment of the present invention showing the IV curves of a nanochannel device detecting an electrolyte solution containing different metal ions;

[0024] Figure 4 In one embodiment of the present invention, a nanochannel device detects substances containing different amounts of Fe. 3+Schematic diagram of IV curve current values ​​and linear fitting for electrolyte solutions with ion concentrations;

[0025] Figure 5 In one embodiment of the present invention, a nanochannel device detects substances containing different amounts of Fe. 3+ The equilibrium current value and linear fitting diagram of the It curve of an electrolyte solution with ion concentration;

[0026] Figure 6 In one embodiment of the present invention, a nanochannel device is used to repeatedly detect Fe in a water sample. 3+ A schematic diagram of the cyclic stability test results for ion concentration;

[0027] Figure 7 In one embodiment of the present invention, the nanochannel device for Fe 3+ A schematic diagram of the long-term stability test results for ion detection. Detailed Implementation

[0028] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate a better understanding of the invention, and their specific proportions can be adjusted according to design requirements.

[0029] The nanochannels in this embodiment are formed using glass tubes to create nanopores, and the functional molecule used for modification is tannic acid.

[0030] according to Figure 1 The following process can be used to prepare functionalized nanochannels based on tannic acid modification: First, a conical glass nanochannel is prepared using a template method. An etched Pt wire with a conical tip is then encapsulated inside a glass capillary. The Pt wire tip is then exposed by polishing, and aqua regia is used to etch the Pt wire, resulting in an unmodified conical glass nanochannel. The opening radius of the nanochannel tip is in the range of 10–100 nm, and the opening radius at the bottom is approximately 1000 nm. Next, a piranha solution is prepared, and concentrated sulfuric acid and hydrogen peroxide solution (30%) are mixed in a 3:1 volume ratio to clean the inside of the conical glass nanochannel for 25–60 min. Then, it is washed multiple times with deionized water and ethanol. Following this, modification with (3-aminopropyl)triethoxysilane (APTES) is completed, and then an overnight reaction is carried out using 20 mg / mL tannic acid (TA) to obtain the tannic acid-functionalized nanochannel device.

[0031] refer to Figure 2 Tannic acid-functionalized nanochannels were obtained for detecting Fe. 3+ The device for ions includes a nanochannel 1, an electrolyte solution 2 to be tested located inside and outside the nanochannel, a solution tank 3, an electrochemical workstation 4, an Ag / AgCl working electrode 5, and an Ag / AgCl auxiliary electrode 6. Figure 2The nanochannel illustrated is a conical glass nanochannel, with a nano-tip opening 1-1 at one end and a nano-bottom opening 1-2 at the other end, which is connected to a glass capillary. The electrolyte solution 2 to be tested is injected into the nanochannel 1, filling it completely, preferably filling the portion of the glass capillary from the nano-tip opening 1-1 to the nano-bottom opening 1-2. The electrolyte solution 2 to be tested is placed in a solution tank 3. The nano-tip opening 1-1 of the nanochannel 1 is immersed in the electrolyte solution 2 in the solution tank 3, while the other end, the glass capillary opening, is exposed to air. The working electrode 5 is inserted from the glass capillary end of the nanochannel and immersed in the electrolyte solution 2 within the nanochannel 1 through the nano-bottom opening 1-2. The auxiliary electrode 6 is immersed in the electrolyte solution 2 in the solution tank 3, and an electric field is applied through the working electrode 5 and the auxiliary electrode 6. In this embodiment, the working electrode 5 and the auxiliary electrode 6 are connected to an electrochemical workstation 4 for Fe... 3+ Quantitative ion detection test.

[0032] The test electrolyte solutions were based on 1 mM KCl as the base electrolyte solution. 0.1 mM solutions of LiCl, NaCl, CuCl2, MgCl2, AlCl3, and FeCl3 were added to this base to form the test electrolyte solutions. Each test electrolyte solution was used to fill the nanochannel and solution tank, and a voltage was applied through the working electrode. During the experiment, the IV curve scanning range was -1 V to 1 V, and the scan rate was generally 0.01 to 0.1 V / s. In this experiment, the scan rate was 0.05 V / s. IV curves for different electrolyte solutions are referenced. Figure 3 .Depend on Figure 3 It is evident that tannic acid-functionalized nanochannels exhibit enhanced resistance to Fe in electrolyte solutions with different ions. 3+ The specific response of ions. This is because the polyphenolic structural fragments within the tannic acid molecule have different binding affinities for different metal ions, and its affinity for Fe... 3+ The strong chemical coordination between ions, with a very high binding energy, makes Fe... 3+ Ions can be adsorbed in large quantities onto the inner surface of nanochannels, altering the surface charge density and affecting the thickness of the electrical double layer, thereby influencing the Fe... 3+ The interaction between ions and the nanochannel interface affects the IV curve. This is manifested at +1V, where Fe... 3+ The current in an electrolyte solution containing Fe is much greater than that in a solution without Fe. 3+ The remaining electrolyte solution contains ions. Therefore, by virtue of this specificity, it can be used for Fe... 3+ Ultra-trace detection of ions.

[0033] The electrolyte solution to be tested used 1 mM KCl as the base electrolyte solution. 0.05, 0.1, 0.25, 0.5, and 1 mL of 10 mM FeCl3 solution were added to 50 mL of KCl base solution, respectively, to obtain 10, 20, 50, 100, and 200 μM FeCl3 solutions. Different Fe... 3+ The nanochannels and solution tanks were filled with electrolyte solutions of varying ionic concentrations, and a voltage was applied through the working electrode. During the experiment, Fe-free electrolytes were used. 3+ KCl solution was used as the basic electrolyte solution, and mixed solutions of different concentrations of FeCl3 were added as standard samples for the test electrolyte solution. IV performance testing was performed, with the IV curve scanning range from -1V to 1V. In this experiment, the scan rate was 0.05V / s, and different concentrations of FeCl3 were obtained. 3+ IV curves of ionic electrolyte solutions. With a voltage of +1V, the ratio of the ionic current in the test solution to the ionic current in the original solution is used as the ordinate, corresponding to the Fe... 3+ With ion concentration on the x-axis, establish the current ratio and Fe... 3+ The linear relationship between ion concentrations, and the tested Fe 3+ The ion concentration range was 10–200 μM, and the linear correlation R was... 2 =0.9959. Based on this linear relationship, it can be used for Fe 3+ Quantitative detection of ions, refer to Figure 4 As shown.

[0034] In another embodiment, the electrolyte solution to be tested used 1 mM KCl as the base electrolyte solution. 0.05, 0.1, 0.25, 0.5, and 1 mL of 10 mM FeCl3 solution were added to 50 mL of the KCl base solution, respectively, to obtain 10, 20, 50, 100, and 200 μM FeCl3 solutions. Different Fe... 3+ Electrolyte solution standards of varying ion concentrations were filled into nanochannels and solution tanks, respectively. A voltage was applied through the working electrode, and the It curve was detected at +1V to obtain Fe solutions of different concentrations. 3+ The ionic current of the ionic electrolyte solution changes over time. During the test, the ionic current tends to stabilize after 30 seconds. The stable ionic current value is plotted on the ordinate, corresponding to the Fe... 3+ With ion concentration on the x-axis, different Fe values ​​can be established. 3+ Ion concentration, electrolyte ion current, and Fe 3+ A standard curve was obtained to demonstrate the linear relationship between ion concentrations, with the tested concentration range being 10–200 μM, and the linear correlation R0 was [value missing]. 2 =0.9949. Based on this linear relationship, it can be used for unknown solutions of Fe. 3+ Quantitative detection of ions, refer to Figure 5 As shown.

[0035] In the case of unknown concentration of Fe 3+ For quantitative detection of ions, a 1 mM KCl base electrolyte solution is used, and an unknown concentration of the test solution is added to obtain the test electrolyte solution. The ion current value is obtained using the same measurement method as described above. Data processing is performed using the same method as the standard curve measurement process, and the data is substituted into the corresponding standard curve to obtain the corresponding Fe ion current. 3+ Ion concentration.

[0036] In actual testing, better accuracy and consistency can be achieved and errors reduced by controlling the concentration of the base electrolyte solution and the mixing ratio of the base electrolyte solution and the test solution. In the above embodiment, the volume ratio of the base electrolyte solution to the test solution is 50:1. In other embodiments, other volume ratios can be used, with corresponding concentration conversions. Preferably, when detecting unknown concentrations, the concentration of the base electrolyte in the resulting test electrolyte solution should be the same as or similar to the concentration of the base electrolyte in the standard sample used to determine the standard curve.

[0037] Fe was detected in nanochannels during each functionalization modification of tannic acid. 3+ After ionization, Fe 3+ Ions bind to the functional molecule tannic acid. This is achieved by combining with Fe... 3+ EDTA-2Na cleaning solution with higher ion binding energy was used to clean and test Fe. 3+ In ion nanochannels, EDTA-2Na, as a replacement molecule, will replace the Fe atoms bound to tannic acid on the nanochannel surface. 3+ Ions, restoring the nanochannels to undetected Fe 3+ The initial state before ions. Therefore, functionalized nanochannels can repeatedly and quantitatively detect Fe. 3+ Ions, reference Figure 6 As shown.

[0038] The detection function of the functional nanochannel device exhibits long-term stability. After storage for 330 days and 400 days, subsequent tests showed no significant change in the ion current curves of the nanochannel, indicating that the nanochannel possesses excellent long-term stability. Figure 7 As shown.

[0039] In the description of this specification, the references to terms such as "one embodiment," "another embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] The above embodiments are only used to further illustrate one method of Fe... 3+ Nanochannel devices for ion concentration detection and Fe 3+ This invention relates to an electrochemical detection method for ion concentration, but it is not limited to the embodiments described herein. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this invention shall fall within the protection scope of this invention.

Claims

1. A method for Fe 3+ Nanochannel devices for ion concentration detection are characterized by: The device includes a nanochannel for containing a solution of electrolyte to be tested, wherein the nanochannel is a one-dimensional nanopore or a two-dimensional plane, with one dimension having a size of less than 200 nm; the inner surface of the nanochannel is modified with functional molecules; and an electrochemical detection system is also included, comprising a working electrode and an auxiliary electrode, which are respectively in contact with the solution of electrolyte to be tested at both ends of the nanochannel, and a voltage is applied through the working electrode and the auxiliary electrode; the functional molecules interact with Fe... 3+ Ions achieve specific binding through chelation, coordination, or electrostatic attraction, causing changes in the ionic current flowing through the nanochannel under applied voltage, thereby controlling the Fe content in the electrolyte solution. 3+ Ion concentration detection; The functional molecules include tannic acid, deferoxamine, thiophene aldehyde-diaminouracil Schiff base, cyanidin-3-O-glucoside, or anthocyanins. The nanochannels are formed in inorganic or organic polymer materials; the inorganic materials include at least one of glass, silicon, alumina, carbon nanotubes or graphene; the organic polymer materials include at least one of polyimide, polyethylene terephthalate, polycarbonate, polypyrrole or polyaniline.

2. A Fe 3+ An electrochemical detection method for ion concentration, characterized by: Using the Fe as described in claim 1 3+ A nanochannel device for ion concentration detection involves placing the electrolyte solution to be tested within the nanochannel, applying voltage and testing current through an electrochemical detection system, and comparing the result with a pre-determined standard curve to determine the Fe concentration in the electrolyte solution. 3+ Ion concentration.

3. The Fe according to claim 2 3+ An electrochemical detection method for ion concentration, characterized by: The electrolyte solution to be tested includes a basic electrolyte with a concentration of 0.05~1 mM, which includes LiCl, NaCl, and KCl; the electrolyte solution to be tested contains Fe 3+ The ion concentration range is 0.01 mM to 1 mM.

4. The Fe according to claim 2 3+ An electrochemical detection method for ion concentration, characterized in that, The method for preparing the standard curve is as follows: using different Fe... 3+ Electrolyte solution standard samples with varying ion concentrations were tested to determine the corresponding current values, establishing a correlation between current values ​​or current ratios and Fe. 3+ The relationship between ion concentrations; with Fe as an example. 3+ The current value corresponding to the electrolyte solution standard sample with an ion concentration of 0 is the base current value, and the current ratio is the ratio of the current value at each concentration to the base current value.

5. The Fe according to claim 2 3+ An electrochemical detection method for ion concentration, characterized by: The test method is cyclic voltammetry, linear sweep voltammetry, or constant potential pulse method, and the applied voltage is +0.5 ~ +1.5 V.

6. The Fe according to claim 2 3+ An electrochemical detection method for ion concentration, characterized by: After each test, a step of returning to the initial state is also included. This step involves cleaning the nanochannels with a cleaning solution containing replacement molecules, which react with Fe. 3+ The binding energy of the ions is higher than that of the functional molecule and Fe. 3+ Binding energy of ions.

7. The Fe according to claim 6 3+ An electrochemical detection method for ion concentration, characterized by: The replacement molecule is disodium ethylenediaminetetraacetate.

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