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CN-122012077-A - Preparation method of magnetic fluorescent probe for detecting lead ions in tea beverage

CN122012077ACN 122012077 ACN122012077 ACN 122012077ACN-122012077-A

Abstract

The invention discloses a preparation method of a magnetic fluorescent probe for detecting lead ions in tea beverage, belonging to the technical field of functional materials and food safety detection. The preparation method of the invention takes ferroferric oxide nano powder as a magnetic core, catalyzes tetradentate amine monomer and linear dialdehyde monomer to generate Schiff base condensation reaction on the surface of the magnetic core by a solvothermal method to form a covalent organic framework shell layer connected by imine bond (-C=N-), and the magnetic fluorescent probe is prepared after magnetic separation, washing and drying. The magnetic fluorescent probe prepared by the invention has the fluorescence quantum yield of more than 15% and the fluorescence intensity attenuation rate of less than 5%, and the fluorescence is strong and stable under 500 nm light. When the method is used for detecting the tea beverage, the external magnet can be utilized for rapid separation, and the high-sensitivity and high-selectivity quantitative detection of the nM level of lead ions in the tea beverage can be realized by measuring the change of the fluorescence intensity of the external magnet. The magnetic fluorescent probe prepared by the invention is simple and quick to operate and has strong anti-interference capability.

Inventors

  • ZHANG CHENGFENG
  • ZONG JIANFA
  • ZHANG CHENGJUN

Assignees

  • 合肥芯宇生物科技有限公司

Dates

Publication Date
20260512
Application Date
20251230

Claims (4)

  1. 1. The preparation method of the magnetic fluorescent probe for detecting lead ions in tea beverage is characterized by comprising the following operation steps: Preparation of covalent organic framework shell layers (1.1) Mixing 10 mg ferroferric oxide nano powder, 15-25 mg tetradentate amine monomer, 15-25 mg linear dialdehyde monomer, 2-5 mL mixed solvent, 0.01-0.05 mL acetic acid and 0.5mL lead nitrate solution with concentration of 50mg/mL by ultrasonic to obtain ultrasonic mixture; The mixed solvent is prepared by uniformly mixing trimethylbenzene and N, N-dimethylformamide according to the volume ratio of 1:1; (1.2) in an oven, under the nitrogen atmosphere, enabling tetradentate amine monomer and linear dialdehyde monomer to generate Schiff base condensation reaction on the surface of ferroferric oxide nano powder to obtain a covalent organic framework shell layer; Preparation of magnetic fluorescent probes (2.1) Washing the covalent organic framework shell material 3 times by using N, N-dimethylformamide, and then washing the covalent organic framework shell material 3 times by using tetrahydrofuran organic reagent; (2.2) vacuum drying to obtain the purified magnetic fluorescent probe of the covalent organic framework shell layer; The magnetic fluorescent probe is a powdery crystal, is a covalent organic framework crystal taking an imine bond (-C=N-) as a basic connecting unit, and has particle size smaller than 20nm and shows superparamagnetism and magnetic guidance, and the surface of the crystal is coated with silicon dioxide, so that the colloid stability and biocompatibility of the crystal in a complex matrix are improved, and the occurrence of nonspecific adsorption is prevented; the magnetic fluorescent probe generates strong and stable fluorescence under a 500nM wavelength light source, the fluorescence quantum yield is 19%, the fluorescence intensity attenuation rate is 1.8%, the detection limit is at the nM level, and the magnetic fluorescent probe is stable under the conditions of ethanol, acetone and dichloromethane organic reagents and 300 ℃ high temperature; When the magnetic fluorescent probe is used for detection, the magnetic fluorescent probe is dispersed in phosphate buffer solution with the pH value of 6.0 to prepare detection liquid with the concentration of 1 mg/mL.
  2. 2. The method for preparing the magnetic fluorescent probe for detecting lead ions in tea beverage according to claim 1, wherein in the step (1.1), the ultrasonic condition is that the ultrasonic power is 350W for 20 minutes.
  3. 3. The method for preparing a magnetic fluorescent probe for detecting lead ions in tea beverage according to claim 1, wherein in the step (1.2), the condensation reaction condition is that the temperature is 150 ℃ and the time is 72 hours.
  4. 4. The method for preparing the magnetic fluorescent probe for detecting lead ions in tea beverage according to claim 1, wherein in the step (2.2), the vacuum drying condition is that the temperature is 60 ℃, the vacuum degree is 95kPa, and the time is 12 hours.

Description

Preparation method of magnetic fluorescent probe for detecting lead ions in tea beverage Technical Field The invention relates to the technical field of analytical chemistry and food safety detection, in particular to a preparation method of a fluorescent probe, and especially relates to a magnetic fluorescent probe for rapidly and highly selectively detecting lead ions in tea beverages and a preparation method thereof. Background Tea beverages are popular beverages worldwide, and safety is of paramount importance. Heavy metal lead ions (Pb 2+) can remain in tea leaves due to industrial pollution, planting environment and other factors, and finally enter tea drinks. The heavy metal lead ions can be strongly combined with functional groups (particularly mercapto-SH) on various enzymes, proteins and biomolecules after entering human cells to destroy the normal structure and functions of organic macromolecules and initiate a series of toxic reactions, and mainly comprises the following steps of 1, damaging brain development, leading to reduced intelligence quotient, numbness of hands and feet, slow reaction, abnormal behaviors and the like, 2, inhibiting hemoglobin synthesis, interfering with iron utilization, increasing erythrocyte membrane brittleness, and causing anemia, erythrocyte weakness and the like, 3, damaging kidney, causing renal tubular dysfunction, interstitial nephritis, renal fibrosis and other symptoms, 4, replacing calcium in bones to deposit in bones, and releasing a large amount of lead in the bones into blood to cause heavy metal poisoning if fracture or osteoporosis occurs. At present, the method for detecting heavy metal ions in tea beverage samples mainly comprises the following steps of 1. An Atomic Absorption Spectrometry (AAS) and an inductively coupled plasma mass spectrometry (ICP-MS), wherein the method is a gold standard for detecting heavy metals in a laboratory, has the advantages of high sensitivity and good accuracy, but has the limitations that instruments and equipment are expensive and heavy, a complex sample pretreatment process is required, the operation is required by professionals in a laboratory environment, and the method is difficult to be used for on-site rapid detection, real-time monitoring and large-scale screening, and the application scene is greatly limited. 2. Electrochemical analysis, such as anodic stripping voltammetry, is relatively simple and has high sensitivity. However, the disadvantage is that the electrode surface is easily contaminated, frequent pretreatment and regeneration steps are required, and reproducibility is sometimes poor. The detection process is also relatively complicated, and has certain technical requirements for operators. 3. The method is simple and convenient to operate, and is expected to realize rapid detection. However, the traditional organic micromolecular fluorescent dye has the defects of weak fluorescence intensity, poor light stability (easy photobleaching), small Stokes shift and the like. More importantly, the selectivity and the sensitivity of the heavy metal ions are often difficult to be compatible, and the heavy metal ions are easily interfered by other coexisting ions in a sample, so that the detection result is unreliable. When the fluorescent probe technology is directly applied to a tea beverage system with complex components, serious challenges are faced, and the technical bottleneck mainly exists, namely, the first, serious substrate interference problem. The tea beverage is a complex mixture system, wherein natural components such as tea polyphenol, tea pigment (such as theaflavin and thearubigin), alkaloid, protein, saccharide and the like are contained in the tea beverage, and the tea beverage can generate strong background fluorescence, or quench fluorescent signals of a probe through mechanisms such as internal filtering effect, fluorescence resonance energy transfer and the like, so that the signal to noise ratio is obviously reduced, and the detection sensitivity and accuracy are greatly reduced. Second, selectivity and interference immunity are insufficient. Many fluorescent probes reported at present have insufficient specific coordination between recognition sites and lead ions, are easily interfered by the coexisting ions, generate false positive or false negative signals, and have poor reliability of detection results. Third, the stability of the probe in a practical environment is poor. The pH range of tea beverages is wide (e.g., lemon tea is slightly acidic), while many probe molecules are structurally unstable in non-neutral pH environments and are subject to decomposition or property changes, thereby affecting reproducibility and accuracy of the assay. In view of the above, there is a lack of a magnetic nano-fluorescent probe capable of specifically adapting to a complex system of tea beverages in the prior art. Disclosure of Invention In order to realize the urgent need of rapidly, accuratel