Phthalate detection method based on aptamer-induced gold nanorod aggregation

Abstract

The invention relates to a phthalate detection method based on gold nanorods and aptamers, which comprises the following steps: firstly, synthesizing positively charged gold nanorods, and neutralizing positive charges on the surfaces of AuNRs by using negatively charged aptamers to aggregate the AuNRs; auNRs aggregation is regulated and controlled through the action of DEHP and the aptamer, rapid visual detection of DEHP is achieved, and the detection limit can reach 4.2 nM. The detection sensitivity is high. The method is simple, convenient and rapid in operation process and high in sensitivity, does not need complex sample pretreatment and large-scale instruments and equipment, has strong practicability, has been used for detecting DEHP content in various actual water samples and food samples, and has wide application prospects in the aspects of food safety evaluation and environmental monitoring.

Description

Technical Field

[0001] The present invention specifically provides a phthalate detection method based on aptamer-induced gold nanorod aggregation, and is mainly designed in the fields of new materials and environmental monitoring. Background Art

[0002] Phthalate acid esters (PAEs) are the most widely used plasticizers, enhancing the flexibility and elasticity of plastics, thereby improving the quality of plastic polymers. DEHP, one of the most widely used PAEs, is a toxic plasticizer made from octanol or isooctanol and phthalic acid. It is commonly found in many consumer products, such as food packaging, medical devices, and children's toys. Studies have reported DEHP concentrations as high as 18.10 mg / kg in soil near industrial waste sites. Furthermore, DEHP has been detected in human serum, reflecting its widespread exposure and potential for bioaccumulation. Therefore, a reliable and sensitive detection method is urgently needed to ensure environmental and biological safety.

[0003] To date, various methods have been developed for the determination of DEHP, primarily including high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). However, the limitations of complex sample preparation, sophisticated instrumentation, and skilled personnel are insufficient to meet the demands of rapid and on-site detection. Therefore, the development of innovative sensors for rapid, sensitive, and field-deployable detection is crucial. Given the potential threat of DEHP to human health, establishing efficient, sensitive, and highly specific DEHP detection methods is of great scientific significance and application value.

[0004] Among them, AuNRs have attracted much attention due to their unique optical properties. The surface plasmon resonance (SPR) characteristics of AuNRs cause them to exhibit strong characteristic absorption peaks in the visible-near infrared region, and the position and intensity of these absorption peaks are highly sensitive to the size, aspect ratio, and refractive index of the surrounding medium of the nanorods. This property makes AuNRs an ideal material for constructing optical sensors. By combining the optical properties of AuNRs with the molecular recognition ability of nucleic acid aptamers, and based on the difference in solution color of AuNRs in the presence or absence of DEHP, which is affected by the aptamer and exhibits aggregation or dispersion, it is expected to construct a new DEHP visualization detection platform. This sensing system not only enables highly sensitive detection of DEHP, but also enables visual detection through visual observation of color changes, providing a promising technical solution for rapid on-site screening of DEHP. Summary of the Invention

[0005] The present invention aims to provide a visual detection method for DEHP based on AuNRs and nucleic acid aptamers. This method utilizes the surface plasmon resonance (SPR) effect of gold nanorods and the specific recognition ability of nucleic acid aptamers. The binding of nucleic acid aptamers to DEHP induces the aggregation or dispersion of AuNRs, resulting in changes in solution color and absorbance, enabling rapid, sensitive, and specific detection and quantitative analysis of DEHP. The technical solution of the present invention is as follows: In a 96-well microtiter plate, the sample solution is added to a DEHP aptamer solution (prepared in Tris-HCl buffer), mixed and incubated for a specified period of time. Finally, a positively charged AuNRs solution is added for color development. Because the DEHP in the sample binds to the aptamer, the aptamer is unable to induce AuNR aggregation, resulting in a wine-red solution, allowing the sample signal to be measured.

[0006] The sample solution was replaced by the same volume of Tris-HCl buffer solution, and the rest of the operation was the same. At this time, the solution was blue-gray, and the blank signal was measured.

[0007] By comparing the color changes of AuNRs solutions in the presence of different concentrations of DEHP, a visual semi-quantitative detection of DEHP was achieved. The absorbance of the solution was measured using a UV-visible spectrophotometer, enabling rapid and accurate detection of DEHP.

[0008] Compared with the prior art, the present invention has the following advantages: The present invention has high selectivity for DEHP and has relatively high selectivity for the same type of phthalates and other endocrine disruptors and common ions.

[0009] The operation process of the present invention is simple and quick, does not require complicated sample pretreatment and large-scale instruments and equipment, and is highly practical.

[0010] It can be used to detect the DEHP content in a variety of actual water samples and food samples, and has broad application prospects in food safety assessment and environmental monitoring. DETAILED DESCRIPTION Example

[0011] In a 96-well microtiter plate, 3.6 mL of a 1 mM DEHP aptamer DNA solution and 75 mL of a river water sample solution were pipetted into a Tris-HCl buffer solution, maintaining the incubation volume at 210 mL. The remaining volume was then filled with Tris-HCl buffer and incubated for 20 minutes. Finally, 150 mL of the AuNRs solution was added for color development. The final volume of the mixed solution was 360 mL. A control group was treated with the same volume of Tris-HCl buffer instead of the DEHP solution, and all other procedures were identical to those of the experimental group. After color development, absorbance spectra were scanned using a UV spectrophotometer for both the control and experimental groups, and the color was photographed and recorded using a digital camera. Example

[0012] In a 96-well microtiter plate, 3.6 mL of a 1 mM DEHP aptamer DNA solution and 75 mL of tap water sample solution were pipetted into a Tris-HCl buffer solution, maintaining the incubation volume at 210 mL. The remaining volume was then filled with Tris-HCl buffer and incubated for 20 minutes. Finally, 150 mL of the AuNRs solution was added for color development. The final volume of the mixed solution was 360 mL. A control group was treated with the same volume of Tris-HCl buffer instead of DEHP solution, and all other procedures were the same as for the experimental group. After color development, absorbance spectra were scanned using a UV spectrophotometer for both the control and experimental groups, and the color was photographed and recorded using a digital camera. Example

[0013] In a 96-well microtiter plate, 3.6 mL of a 5 mM DEHP aptamer DNA solution and 75 mL of tap water sample solution were pipetted into a Tris-HCl buffer solution, maintaining the incubation volume at 210 mL. The remaining volume was then filled with Tris-HCl buffer and incubated for 20 minutes. Finally, 150 mL of the AuNRs solution was added for color development. The final volume of the mixed solution was 360 mL. A control group was treated with the same volume of Tris-HCl buffer instead of DEHP solution, and all other procedures were the same as for the experimental group. After color development, absorbance spectra were scanned using a UV spectrophotometer for both the control and experimental groups, and the color was photographed and recorded using a digital camera.

[0014] The above examples were used to detect DEHP concentrations in food samples and environmental water samples. The results were consistent with the values ​​determined by standard methods or the certified values ​​of standard substances, indicating that the determination results were reliable.

Claims

1. A method for detecting phthalates based on aptamer-induced gold nanorod aggregation, characterized in that The following steps are involved: (1) The gold nanorods (AuNRs) are synthesized by a seed growth method using cetyltrimethylammonium bromide (CTAB) as a surfactant, and silver ions are introduced to adjust the aspect ratio, ultimately obtaining AuNRs with an aspect ratio of 1.5-4.5; (2) The negatively charged di(2-ethylhexyl) phthalate (DEHP) aptamer was mixed and incubated with the positively charged AuNRs in a buffer solution to induce the aggregation of AuNRs, causing the solution color to change from wine red to blue-gray; (3) DEHP was added to the solution in (2). The presence of DEHP dispersed the aggregated AuNRs, and the solution changed from blue-gray to purple again. (4) Visual detection of DEHP is achieved through the color change of the gold nanorod solution or the intensity change of the longitudinal surface plasmon resonance absorption peak in the UV-visible absorption spectrum.

2. The method according to claim 1, characterized in that The negatively charged aptamer can neutralize the positive charge on the surface of AuNRs, causing the AuNRs to aggregate.

3. The method according to claim 1, wherein the AuNRs have an aspect ratio of 1.5-4.

5.

4. The method according to claim 1, characterized in that The aptamer concentration was 1-10 nM.

5. The method according to claim 1, characterized in that This method can be used to detect DEHP in samples such as drinking water, river water, bottled beverages, food packaging leachate and environmental wastewater.