DNA-guided organic small molecule constructs for the detection of heavy metal ions

Abstract

The present invention discloses a method for detecting heavy metal ions by a DNA-guided organic small molecule construct, comprising the following steps: mixing an Alq3 solution with an ss-DNA aqueous solution to obtain an ssDNA-Alq3 solution; mixing an ssDNA-Alq3 solution with a buffer solution at a ratio of 1:1 to obtain a detection liquid; mixing the detection liquid with a heavy metal ion solution at a ratio of 1:1 and reacting; comparing the fluorescence intensity of the detection liquid before the reaction with the fluorescence intensity of the detection liquid after the reaction, and then obtaining the content of heavy metal ions in the heavy metal ion solution; wherein the concentration of the heavy metal ion solution is 25ppb to 400ppb. The technical scheme of the present invention can be prepared by preparing ssDNA-Alq3 mixed aggregates, and the detection of heavy metal ion solutions by using ssDNA-Alq3 mixed aggregates. Compared with traditional detection means, the detection method of the present invention is simpler, less time-consuming, faster in response, and more obvious in detection effect; it can quickly detect heavy metal ions.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal detection, and particularly relates to a method for detecting heavy metal ions by a DNA-directed organic small molecule construct. Background Art

[0002] Environmental pollution is a major problem faced by today's society. Heavy metals are highly toxic at trace levels, and their pollution poses a huge threat to the environment and public health worldwide. Exploring an efficient and sensitive method for detecting heavy metals has become an inevitable trend under high demand. Currently, some relatively traditional detection and analysis methods, such as inductively coupled plasma mass spectrometry, atomic absorption spectrometry, ultraviolet-visible spectrophotometry, X-ray fluorescence spectrometry, etc., are widely used to analyze the heavy metal pollution degree of water bodies. However, these methods usually rely on large machines, the cost of instrument maintenance is relatively high, and the sample preparation process is cumbersome during detection. Therefore, traditional detection technologies have great limitations.

[0003] Aluminum tris(8-hydroxyquinoline) (Alq3) was first mentioned in 1987 and used in the preparation of materials for organic light-emitting diodes. Since then, research on Alq3 has mainly focused on improving the brightness and long-term stability of Alq3. In particular, the preparation of one-dimensional nanowires and nanorods has attracted extensive attention. In 2013, the research group of Dong June Ahn first discovered that Alq3 can self-assemble in a single-stranded DNA solution to form a DNA-doped hexagonal prism construct.

[0004] In summary, how to set up a new method for detecting heavy metal ions by a DNA-directed organic small molecule construct to quickly detect the content of metal ions in a solution is an urgent problem to be solved by those skilled in the art currently. Summary of the Invention

[0005] The main purpose of the embodiments of the present invention is to propose a method for detecting heavy metal ions by a DNA-directed organic small molecule construct, aiming to prepare a new type of hybrid aggregate for rapid detection of heavy metal ions.

[0006] The technical solution for the present invention to solve the above technical problems is to provide a method for detecting heavy metal ions by a DNA-directed organic small molecule construct, including the following steps:

[0007] Mix an Alq3 solution with an aqueous ss-DNA solution to obtain an ssDNA-Alq3 solution;

[0008] Mix the ssDNA-Alq3 solution and a buffer solution in a ratio of 1:1 to obtain a detection solution;

[0009] Mix the detection solution and the heavy metal ion solution evenly in a 1:1 ratio and react; compare the fluorescence intensity of the detection solution before the reaction with that after the reaction, and then obtain the content of heavy metal ions in the heavy metal ion solution;

[0010] Among them, the concentration of the heavy metal ion solution is 25 ppb to 400 ppb.

[0011] In an embodiment of the present invention, the buffer solution is 2-(N-morpholino)ethanesulfonic acid buffer solution.

[0012] In an embodiment of the present invention, the step of mixing the Alq3 solution and the aqueous solution of ss-DNA to obtain the ssDNA-Alq3 solution includes:

[0013] Dissolve the Alq3 powder in tetrahydrofuran to obtain an Alq3 solution with a concentration of 1 mg / ml;

[0014] Prepare an aqueous solution of ss-DNA with a concentration of 500 nmol / l, mix it with the Alq3 solution in an 8:1 ratio, stir, and let it stand at room temperature for more than 10 h.

[0015] In an embodiment of the present invention, the step of mixing the ssDNA-Alq3 solution and the buffer solution in a 1:1 ratio to obtain the detection solution includes:

[0016] Mix the ssDNA-Alq3 solution and the buffer solution in a 1:1 ratio;

[0017] Let it stand for 30 min to obtain the detection solution.

[0018] In an embodiment of the present invention, the step of mixing the detection solution and the heavy metal ion solution evenly in a 1:1 ratio and reacting; comparing the fluorescence intensity of the detection solution before the reaction with that after the reaction, and then obtaining the content of heavy metal ions in the heavy metal ion solution includes:

[0019] Mix the detection solution and the heavy metal ion solution evenly in a 1:1 ratio and react;

[0020] After 30 min, compare the fluorescence intensity of the detection solution before the reaction with that after the reaction, and then obtain the content of heavy metal ions in the heavy metal ion solution.

[0021] In an embodiment of the present invention, the detection solution is used to detect lead ions, and the DNA sequence used in the aqueous solution of ss-DNA is: 5′-GGTTGGTGTGGTTGG-3′.

[0022] In an embodiment of the present invention, the detection solution is used to detect arsenic ions, and the DNA sequence used in the ss-DNA aqueous solution is as follows:

[0023] 5′-ATGCAAACCCTTAAGAAAGTGGTCGTCCAAAAAACCATTG-3′.

[0024] In an embodiment of the present invention, the detection solution is used to detect cadmium ions, and the DNA sequence used in the ss-DNA aqueous solution is: 5′-GGGTTCACAGTCCGTT-3′.

[0025] In an embodiment of the present invention, the detection solution is used to detect mercury ions, and the DNA sequence used in the ss-DNA aqueous solution is: 5’-TTCTTTCTTCCCCTTGTTTGTT-3′.

[0026] The technical solution of the present invention, by preparing the ssDNA-Alq3 mixed aggregate and using the detection of the ssDNA-Alq3 mixed aggregate for heavy metal ion solutions, compared with traditional detection means, the detection method of the present invention is simpler, takes less time, has a fast response, and the detection effect is more obvious; it can quickly detect heavy metal ions. And after the ssDNA-Alq3 mixed aggregate is combined with the buffer solution, it can overcome the influence of the complex acidic background in heavy metal ions on the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0028] Figure 1 It is a flowchart of the steps of Embodiment 1 of the method for detecting heavy metal ions by the DNA-guided organic small molecule construct of the present invention;

[0029] Figure 2 It is a schematic diagram of the preparation of the ssDNA-Alq3 of the present invention;

[0030] Figure 3 It is the fluorescence spectrum and standard curve of the detection of lead ions by the detection solution of the present invention;

[0031] Figure 4 It is the fluorescence spectrum and standard curve of the detection of arsenic ions by the detection solution of the present invention;

[0032] Figure 5Fluorescence spectrum and standard curve of the detection solution for cadmium ion detection according to the present invention;

[0033] Figure 6 Fluorescence spectrum and standard curve of the detection solution for mercury ion detection according to the present invention;

[0034] Figure 7 Flow chart of the steps of Example 2 of the method for detecting heavy metal ions by the DNA-directed organic small molecule construct according to the present invention. Detailed implementation mode

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0037] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meanings of "several" and "multiple" are at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0040] Example 1

[0041] As Figure 1 shown, a method for detecting heavy metal ions by a DNA-directed organic small molecule construct includes the following steps:

[0042] S10: Mix the Alq3 solution with the ss-DNA aqueous solution to obtain the ssDNA-Alq3 solution;

[0043] Understandably, Alq3 is aluminum octahydroxyquinoline, and the DNA sequence of the ss-DNA used is:

[0044] 5′-GGTTGGTGTGGTTGG-3′;

[0045] 5′-ATGCAAACCCTTAAGAAAGTGGTCGTCCAAAAAACCATTG-3′;

[0046] 5′-GGGTTCACAGTCCGTT-3′;

[0047] or 5’-TTCTTTCTTCCCCTTGTTTGTT-3′.

[0048] As Figure 2 shown, Alq3 can self-assemble in the single-stranded DNA solution to form a DNA-doped hexagonal prism construct. Aptamers are a class of DNA or RNA molecules that can specifically bind to target molecules screened by the systematic evolution of ligands by exponential enrichment (SELEX) technology. Aptamers have high specificity. When an aptamer specifically binds to a target, the spatial configuration of the aptamer changes and a stable spatial structure can be formed. With the development of nucleic acid selection technology, aptamers of many substances have been screened out, and many aptamers that can specifically bind to metal ions have also been screened out and widely used in the detection of heavy metal ions in various fields. By combining the functionality of DNA with the luminescence properties of Alq3 small molecules, the ssDNA-Alq3 hybrid aggregates prepared by using different DNA sequences can achieve qualitative analysis and quantitative detection of heavy metal ions.

[0049] S20: Mix the ssDNA-Alq3 solution with the buffer solution at a ratio of 1:1 to obtain the detection solution;

[0050] Understandably, combining the functionality of DNA with the luminescent properties of Alq3 small molecules can achieve qualitative analysis and quantitative detection of heavy metal ions. However, the mixed aggregates of ssDNA-Alq3 have the disadvantage of being acid- and alkali-resistant; by mixing the ssDNA-Alq3 solution with a buffer solution to obtain a test solution, when the test solution is mixed with a heavy metal ion solution, ssDNA-Alq3 will not be destroyed by the acidic background solution.

[0051] Specifically, the buffer solution is 2-(N-morpholino)ethanesulfonic acid, which is a zwitterionic buffer solution, in which alkaline components and acidic components coexist. When a small amount of acidic substances is added to the solution, the alkaline component in the buffer pair reacts and neutralizes with it. When a small amount of alkaline substances is added to the solution, the acidic component in the buffer pair reacts and neutralizes with it. When the buffer solution is mixed with the ssDNA-Alq3 solution, the ssDNA-Alq3 solution can effectively overcome the disadvantage of the ssDNA-Alq3 solution being acid-resistant when detecting heavy metal ion solutions; thereby enabling the ssDNA-Alq3 solution to stably determine the content of heavy metal ions in heavy metal ion solutions. The reason why the buffer solution is first mixed with the ssDNA-Alq3 solution is that heavy metal ions will be hydrolyzed and then precipitated if they are in a neutral environment for a long time, affecting the final detection results.

[0052] S30: Evenly mix the detection liquid and the heavy metal ion solution in a ratio of 1:1 and react; compare the fluorescence intensity of the detection liquid before the reaction with the fluorescence intensity of the detection liquid after the reaction, and then obtain the content of heavy metal ions in the heavy metal ion solution;

[0053] Wherein, the concentration of the heavy metal ion solution is 25ppb to 400ppb.

[0054] The principle of ssDNA-Alq3 detection of heavy metal ions: DNA with certain specific base sequences can specifically recognize heavy metal ions; after binding, the structure and spatial conformation of single-stranded DNA will change; they are folded into some specific secondary and tertiary structures through the superposition of aromatic rings, electrostatic effects, the interaction of van der Waals forces and the action of hydrogen bonds in the chain; when the DNA molecules on the surface of the Alq3 construct form a specific conformation with the heavy metal ions, it leads to the transfer of electrons (from Alq3 molecules to heavy metal ions), thereby reducing the fluorescence intensity of the mixed aggregates. By comparing the fluorescence intensity before and after the reaction, the content of heavy metal ions can be calculated. The addition of buffer solution can overcome the complex pH environment in heavy metal detection samples.

[0055] The preparation method of the ssDNA-Alq3 hybrid aggregate of the present invention is simple and has good specificity; through the detection of heavy metal ion solutions by the ssDNA-Alq3 hybrid aggregate, compared with traditional detection methods, the detection method of the present invention is more convenient, time-consuming, has a fast response, and the detection effect is more obvious; it can quickly detect heavy metal ions. And after the ssDNA-Alq3 hybrid aggregate binds to the MES buffer solution, it can overcome the influence of the complex acidic background in heavy metal ions on the detection.

[0056] As Figure 3 shown, the DNA sequence of the ss-DNA used is 5′-GGTTGGTGTGGTTGG-3′, which is used to detect lead ions in the solution; through Figure 3 it can be seen that Figure 3 a is the fluorescence spectrogram, Figure 3 b is the standard curve graph, with the concentration of lead ions as the abscissa and the fluorescence intensity of the ssDNA-Alq3 hybrid aggregate as the ordinate, the drawn standard curve; its correlation coefficient R 2 is 0.9945, indicating that the drawn curve has good linearity and feasibility, indicating that this method can be used to detect lead ions.

[0057] As Figure 4 shown, the DNA sequence of the ss-DNA used is 5′-ATGCAAACCCTTAAGAAAGTGGTCGTCCAAAAAACCATTG-3′, which is used to detect arsenic ions, through Figure 4 it can be seen that Figure 4 a is the fluorescence spectrogram, Figure 4 b is the standard curve graph, with the concentration of arsenic ions as the abscissa and the fluorescence intensity of the ssDNA-Alq3 hybrid aggregate as the ordinate, the drawn standard curve; its correlation coefficient R 2 is 0.9917, indicating that the drawn curve has good linearity and feasibility, indicating that this method can be used to detect arsenic ions.

[0058] As Figure 5 shown, the DNA sequence of the ss-DNA used is 5′-GGGTTCACAGTCCGTT-3′, which is used to detect cadmium ions, through Figure 5 it can be seen that Figure 5 a is the fluorescence spectrogram, Figure 5 b is the standard curve graph, with the concentration of cadmium ions as the abscissa and the fluorescence intensity of the ssDNA-Alq3 hybrid aggregate as the ordinate, the drawn standard curve; its correlation coefficient R 2 is 0.9957, indicating that the drawn curve has good linearity and feasibility, indicating that this method can be used to detect cadmium ions.

[0059] As Figure 6As shown, the DNA sequence of the ss-DNA used is 5’-TTCTTTCTTCCCCTTGTTTGTT-3’, which is used to detect mercury ions. By Figure 6 it can be seen that Figure 6 a is the fluorescence spectrum diagram, Figure 6 b is the standard curve diagram. With the concentration of mercury ions as the abscissa and the fluorescence intensity of the ssDNA-Alq3 mixed aggregate as the ordinate, the standard curve is plotted; the correlation coefficient R 2 is 0.9991, indicating that the plotted curve has good linearity and feasibility, demonstrating that this method can be used to detect mercury ions.

[0060] Example 2

[0061] As Figure 7 shown, a method for detecting heavy metal ions using a DNA-directed organic small molecule construct includes the following steps:

[0062] S11: Dissolve Alq3 powder in tetrahydrofuran to obtain an Alq3 solution with a concentration of 1 mg / ml;

[0063] S12: Prepare an aqueous ss-DNA solution with a concentration of 500 nmol / l, mix it with the Alq3 solution in a ratio of 8:1, stir, and let it stand at room temperature for more than 10 h;

[0064] S21: Mix the ssDNA-Alq3 solution with the buffer solution in a ratio of 1:1;

[0065] S22: Let it stand for 30 min to obtain the detection solution;

[0066] S31: Mix the detection solution with the heavy metal ion solution evenly in a ratio of 1:1 and react;

[0067] S32: After 30 min, compare the fluorescence intensity of the detection solution before the reaction with that after the reaction to obtain the content of heavy metal ions in the heavy metal ion solution.

[0068] When the detection solution is used to detect lead ions, the DNA sequence used in the aqueous ss-DNA solution is: 5′-GGTTGGTGTGGTTGG-3′.

[0069] When the detection solution is used to detect arsenic ions, the DNA sequence used in the aqueous ss-DNA solution is: 5′-ATGCAAACCCTTAAGAAAGTGGTCGTCCAAAAAACCATTG-3′.

[0070] When the detection solution is used to detect cadmium ions, the DNA sequence used in the ss-DNA aqueous solution is: 5′-GGGTTCACAGTCCGTT-3′.

[0071] When the detection solution is used to detect mercury ions, the DNA sequence used in the ss-DNA aqueous solution is: 5’-TTCTTTCTTCCCCTTGTTTGTT-3′.

[0072] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for detecting heavy metal ions using a DNA-guided organic small molecule construct, wherein the heavy metal ions are lead ions, arsenic ions, cadmium ions or mercury ions, characterized in that: The steps include: Mixing an Alq3 solution with an ss-DNA aqueous solution to obtain a ssDNA-Alq3 solution, wherein the Alq3 is octahydroxyquinoline aluminum; The ssDNA-Alq3 solution and the buffer solution were mixed in a ratio of 1:1 and allowed to stand for 30 min to obtain a detection solution; The detection liquid and the heavy metal ion solution are mixed evenly in a ratio of 1:1, and reacted; the fluorescence intensity of the detection liquid before the reaction is compared with the fluorescence intensity of the detection liquid after the reaction, and then the content of heavy metal ions in the heavy metal ion solution is obtained; Wherein, the concentration of the heavy metal ion solution is 25ppb~400ppb; When the detection solution is used to detect lead ions, the DNA sequence in the ss-DNA aqueous solution is: 5′-GGTTGGTGTGGTTGG-3′; When the detection solution is used to detect arsenic ions, the DNA sequence in the ss-DNA aqueous solution is: 5′-ATGCAAACCCTTAAGAAAGTGGTCGTCCAAAAAACCATTG-3′; When the detection solution is used to detect cadmium ions, the DNA sequence in the ss-DNA aqueous solution is: 5′-GGGTTCACAGTCCGTT-3′; When the detection solution is used to detect mercury ions, the DNA sequence in the ss-DNA aqueous solution is: 5'-TTCTTTCTTCCCCTTGTTTGTT-3'; The buffer solution is a 2-(N-morpholino)ethanesulfonic acid buffer solution.

2. The method for detecting heavy metal ions by using a DNA-guided organic small molecule construct according to claim 1, characterized in that: The step of mixing the Alq3 solution and the ss-DNA aqueous solution to obtain the ssDNA-Alq3 solution comprises: Dissolve Alq3 powder in tetrahydrofuran to obtain an Alq3 solution with a concentration of 1 mg / ml; A ss-DNA aqueous solution with a concentration of 500 nmol / l was prepared, and mixed with the Alq3 solution at a ratio of 8:1, stirred, and allowed to stand at room temperature for more than 10 hours.

3. The method for detecting heavy metal ions by using a DNA-guided organic small molecule construct according to claim 1, characterized in that: The steps of uniformly mixing the detection liquid and the heavy metal ion solution in a ratio of 1:1 and reacting them; comparing the fluorescence intensity of the detection liquid before the reaction with the fluorescence intensity of the detection liquid after the reaction to obtain the content of heavy metal ions in the heavy metal ion solution include: The test solution and the heavy metal ion solution are mixed evenly in a ratio of 1:1 and reacted; After 30 minutes, the fluorescence intensity of the detection solution before the reaction was compared with the fluorescence intensity of the detection solution after the reaction, and then the content of heavy metal ions in the heavy metal ion solution was obtained.

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