Dual-signal ratio type upconversion luminescence probe, preparation method thereof and application in oxalate detection

Abstract

The application relates to the technical field of analytical chemistry, and particularly discloses a double-signal ratio type upconversion luminescence probe, a preparation method thereof and application thereof in oxalate detection, wherein the double-signal ratio type upconversion luminescence probe comprises upconversion nanoparticles (UCNPs) and an iron-chromium cyanine R complex. 3+ The application constructs a double-emission-peak regulation system by combining the upconversion nanoparticles (UCNPs) with the iron-chromium cyanine R complex, and when the double-signal ratio type upconversion luminescence probe is used for oxalate detection, oxalate can be combined with Fe 3+ in the iron-chromium cyanine R complex to induce a blue shift of an absorption spectrum, and the green and red emission peaks of the UCNPs are simultaneously regulated, so that the double-mode high-sensitivity fluorescence-colorimetric detection of oxalate is realized.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry, and in particular to a dual-signal ratio-type upconversion luminescent probe, its preparation method, and its application in oxalate detection. Background Technology

[0002] Oxalate (chemical formula C2O4) 2- Oxalate is widely present in soil and agricultural products. Excessive oxalate in soil can affect the activity of metal ions and the absorption of nutrients by crops, thereby interfering with soil ecology and plant growth. Excessive oxalate in agricultural products can reduce the bioavailability of minerals such as calcium, and long-term intake may harm human health. Accurate detection of oxalate content in soil and agricultural products is of great practical significance for assessing soil fertility, ensuring the safety of agricultural products for consumption, guiding agricultural production regulation, and managing environmental risks.

[0003] Currently, methods for detecting oxalate include high-performance liquid chromatography (HPLC), ion chromatography (IC), ultraviolet-visible spectrophotometry (UV-Vis), and fluorescence spectroscopy. However, existing methods still have room for improvement in terms of anti-interference capability in complex samples, detection throughput, and cost-effectiveness. There is an urgent need to develop detection technologies that combine high sensitivity, high selectivity, and practicality. Fluorescent probes, as a class of molecular or material systems capable of specifically interacting with target substances and achieving qualitative and quantitative determination of target substances based on changes in fluorescence signals, occupy an important position in analytical chemistry. These probes exhibit excellent detection performance, demonstrating ultra-high detection sensitivity, enabling precise identification of trace analytes. They also possess excellent selectivity, specifically distinguishing target analytes. Their rapid response kinetics meet the needs of real-time in-situ monitoring, and their simple operation facilitates the construction of visual detection platforms. These characteristics have led to their widespread application in many fields such as bioanalysis, environmental monitoring, and medical diagnostics. However, traditional fluorescent probe systems still have inherent limitations, mainly manifested in insufficient photostability, easy photobleaching, and significant background fluorescence interference under short-wavelength excitation conditions, which seriously restricts the further improvement of their analytical performance.

[0004] Upconversion nanoparticles (UCNPs), as a class of inorganic nanomaterials with unique optical properties, exhibit luminescence based on a multiphoton absorption process under near-infrared light excitation. This process involves the continuous absorption of multiple low-energy long-wavelength photons, leading to energy level transitions and the emission of high-energy short-wavelength photons, thus displaying anti-Stokes luminescence characteristics. Therefore, UCNP-based nanoprobes possess unique advantages. Their near-infrared light excitation effectively reduces autofluorescence interference in complex matrix samples, while their excellent photostability and resistance to photobleaching effectively reduce signal attenuation during detection, providing reliable assurance for long-term, continuous monitoring.

[0005] Upconversion fluorescent nanoprobes typically use upconversion nanoparticles as energy donors and chromophores as recognition units to modulate the upconversion emission signal. Generally, one upconversion emission peak is selected as the detection signal, and another fixed emission peak is used as the reference signal. However, due to the low upconversion quantum yield and inefficient energy transfer between the energy donor and acceptor, the signal contrast of the upconversion luminescent probe is difficult to enhance effectively before and after the addition of the analyte. Contrast (the ratio of the probe's signal intensity before and after the reaction) is a decisive factor in the sensitivity of all chemical reaction-based probes. In contrast, changing the dual-signal ratio provides a feasible approach to improve probe signal contrast. However, the relatively fixed position of the chromophore absorption peak makes it difficult to flexibly adjust to achieve multi-upconversion emission peak modulation. This makes constructing dual-signal ratio upconversion luminescent probes with high signal contrast a pressing challenge in this field. Summary of the Invention

[0006] Based on this, the purpose of this invention is to provide a dual-signal ratio-type upconversion luminescent probe, its preparation method, and its application in oxalate detection. By combining core-shell structured upconversion nanoparticles (UCNPs) with an iron-chromium anthocyanin R complex, a dual emission peak modulation system is constructed. By utilizing the blue shift of the absorption spectrum induced by oxalate, the green and red emission peaks of UCNPs are simultaneously modulated to achieve highly sensitive fluorescence-colorimetric dual-modality detection of oxalate.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention first provides a dual-signal ratio-based upconversion luminescent probe, which includes upconversion nanoparticles UCNPs and an iron-chromium anthocyanin R complex.

[0009] This invention constructs a dual emission peak regulation system by combining upconversion nanoparticles (UCNPs) with an iron-chromium anthocyanin R complex. When used for oxalate detection, oxalate can bind with Fe in the iron-chromium anthocyanin R complex. 3+Chelation induces a blue shift in the absorption spectrum, simultaneously modulates the green and red emission peaks of UCNPs, and enhances the signal contrast of the probe through dual-signal modulation, thus achieving highly sensitive fluorescence-colorimetric dual-modality detection of oxalate.

[0010] As a further improvement of the above-mentioned scheme of the present invention, in order to improve the dispersibility and stability of the upconversion nanoparticles UCNPs in aqueous solution, the UCNPs are treated as follows: after removing the surface oleic acid ligands by acid treatment, hydrophilic molecules are coated on the surface of the UCNPs.

[0011] As a further improvement to the above-described scheme of the present invention, the acid treatment uses hydrochloric acid with a pH of 0.8-1.2; and / or, the hydrophilic molecule is polyacrylic acid.

[0012] As a further improvement to the above-described scheme of the present invention, the UCNPs are NaYF4:Yb / Er@NaYF4 upconversion nanoparticles. Preferably, in the UCNPs, Yb 3+ The molar concentration is 20%, Er 3+ The molar concentration of Y is 2%. 3+ The molar concentration is 78% to ensure that the UCNPs produce dual emission peaks of 540 nm (green) and 655 nm (red) under 980 nm near-infrared light excitation. Preferably, the UCNPs are prepared by a solvothermal method using yttrium chloride, ytterbium chloride, erbium chloride, oleic acid, 1-octadecene, ammonium fluoride, and sodium hydroxide as raw materials. Preferably, the reaction temperature of the solvothermal method is 100-300℃, and the reaction time is 30-60 min. Preferably, the preparation method of the UCNPs includes the following steps:

[0013] (1) NaYF4:Yb / Er upconversion nanoparticles were prepared by reacting yttrium chloride, ytterbium chloride, erbium chloride, oleic acid, 1-octadecene, ammonium fluoride and sodium hydroxide; the entire reaction process was carried out in a protective atmosphere (such as argon) to prevent oxidation and reduce the generation of impurities;

[0014] (2) NaYF4:Yb / Er@NaYF4 upconversion nanoparticles with core-shell structure were prepared by reacting NaYF4:Yb / Er upconversion nanoparticles, yttrium chloride, oleic acid, 1-octadecene, ammonium fluoride and sodium hydroxide. The entire reaction process was carried out in a protective atmosphere (such as argon) to prevent oxidation and reduce the generation of impurities.

[0015] The present invention also provides a method for preparing the dual-signal ratio-type upconversion luminescent probe as described above, which includes the following steps: mixing upconversion nanoparticle solution, iron salt solution, and chromian cyanide R (ECR) solution.

[0016] As a further improvement to the above-described scheme of the present invention, the concentration of the upconversion nanoparticle solution is 10 mg / mL; and / or, the concentration of the iron salt solution is 2.5-8.75 mM, wherein the iron salt solution is at least one of ferric sulfate solution, ferric nitrate solution, and ferric chloride solution; and / or, the concentration of the chromocyanine R solution is 4.4-5.8 mM.

[0017] As a further improvement to the above-described scheme of the present invention, the method also incorporates a surfactant and / or a buffer solution. Since ion-pair compounds are hydrophobic, the surfactant added in this invention is used to chelate excess Fe to ensure their stable existence in aqueous solution. 3+ ; Buffer solutions accept and release H+ + This stabilizes the pH of the probe solution within a certain range, preventing significant pH changes.

[0018] As a further improvement to the above-described scheme of the present invention, the surfactant is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide; and / or, the buffer solution is an acetate-sodium acetate buffer solution (HAc-NaAc) with pH=4-5.

[0019] The present invention also provides a detection device comprising a dual-signal ratio upconversion luminescent probe as described above.

[0020] This invention also provides an application of the dual-signal ratio-type upconversion luminescent probe as described above in the detection of oxalate. Specifically, it can be applied to the detection of oxalate in soil and agricultural products.

[0021] As a further improvement to the above-mentioned solution of the present invention, the application includes the following steps: adding the sample to be tested to the dual-signal ratio-type upconversion luminescent probe, using a UV-Vis spectrophotometer to monitor the changes in the absorption spectrum of the system in real time, and simultaneously detecting the changes in UCL signal intensity using a UCL spectrometer equipped with a laser. By analyzing the position and intensity of the absorption peak and the dynamic changes in the UCL signal intensity, a quantitative relationship between oxalate concentration and spectral signal is established, thereby achieving highly sensitive dual-modal detection of oxalate.

[0022] As a further improvement to the above-described scheme of the present invention, the dual-signal ratio-type upconversion luminescent probe performs fluorescence detection within the excitation wavelength of 980 nm and the emission wavelength of 500-700 nm, with I... 540 / I 655 For quantitative signals;

[0023] And / or, the dual-signal ratiometric upconversion luminescent probe is used for colorimetric analysis within an absorption wavelength range of 400-700 nm, with A 526 / A 656 It is a quantitative signal.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention constructs a dual emission peak modulation system by combining core-shell upconversion nanoparticles (UCNPs) with an iron-chromium anthocyanin R complex. This system can utilize the blue shift of the oxalate-induced absorption spectrum to simultaneously modulate the green and red emission peaks of UCNPs, thereby achieving highly sensitive fluorescence-colorimetric dual-modal detection of oxalate.

[0026] The dual-signal ratio-based upconversion luminescent probe provided by this invention detects oxalate ions and the Fe in the iron-chromium anthocyanin R complex. 3+ Chelation induces a blue shift in the absorption spectrum from 656 nm to 526 nm, simultaneously modulating the 540 nm green emission quenching and 655 nm red emission recovery of UCNPs, through the intensity ratio of the two emission peaks (I0). 540 / I 655 Fluorescence detection is achieved by measuring the absorbance ratio (A / B). 526 / A 656 ) to achieve colorimetric detection, and I 540 / I 655 The signal ratio responds exponentially to the concentration of the analyte, breaking through the sensitivity bottleneck of the single-signal mode.

[0027] The core-shell structured UCNPs used in this invention have high crystallinity and excellent photostability. Their near-infrared excitation characteristics can reduce autofluorescence interference in complex matrices. Through a dual-emission peak synergistic modulation strategy, a high-contrast ratio probe is constructed, achieving a detection limit of oxalate as low as 4.2 nM. This is 3-10 times more sensitive than traditional single-channel detection methods, with a linear range of 0-220 μM. The spiked recovery rate in complex matrices reaches 98.62%-122.64%, and the anti-interference ability is strong.

[0028] This invention constructs a dual-mode readout system based on luminescence and colorimetry. It achieves dual signal verification and visual detection through upconversion luminescence (UCL) color changes (green→yellow→red) and absorption spectral shifts (blue→violet→red). It can not only obtain high-precision data through instrument analysis, but also complete the rapid on-site detection of oxalate by observing color changes with the naked eye. It realizes full-scenario coverage from laboratory instrument analysis to on-site real-time detection, which greatly improves the convenience and intuitiveness of oxalate detection. Attached Figure Description

[0029] Figure 1 The structural characterization diagrams of NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1 are shown. Figure 1(A) is a low-resolution TEM image of NaYF4:Yb / Er upconversion nanoparticles prepared in Example 1; Figure 1 (B) is a low-resolution TEM image of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (C) is a size distribution diagram of the NaYF4:Yb / Er upconversion nanoparticles prepared in Example 1; Figure 1 (D) is a size distribution diagram of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (E) is a high-resolution TEM image of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (F) shows the XRD patterns of NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1.

[0030] Figure 2 This is a schematic diagram illustrating the mechanism of a dual-signal ratio-type upconversion luminescent probe for detecting oxalate proposed in this invention.

[0031] Figure 3 This is a schematic diagram of the dual-signal output principle of a dual-signal ratio-type upconversion luminescent probe. Figure 3 (A) is a diagram of the upconversion energy transfer pathway of UCNPs; Figure 3 (B) is a schematic diagram of the energy transfer upconversion luminescence mechanism of UCNPs; Figure 3 (C) shows the UCL and absorbance spectra of the dual-signal ratiometric upconversion luminescent probe before and after the addition of oxalate. Figure 3 The inset in (C) shows UCL images before (green) and after (red) the addition of oxalate to the probe;

[0032] Figure 4 For containing different Fe 3+ The absorbance of a dual-signal ratiometric upconversion luminescent probe after the addition of oxalate;

[0033] Figure 5 The absorbance of dual-signal ratiometric upconversion luminescent probes containing different ECR concentrations after the addition of oxalate is shown.

[0034] Figure 6 The absorbance of dual-signal ratiometric upconversion luminescent probes containing different DTAB concentrations after the addition of oxalate is shown.

[0035] Figure 7 The absorbance of a dual-signal ratiometric upconversion luminescent probe containing buffer solutions of different pH values ​​after the addition of oxalate is shown.

[0036] Figure 8The results show the sensitivity analysis of the dual-signal ratio-type upconversion luminescent probe prepared in Example 1 for oxalate detection. Figure 8 (A) shows the UCL spectrum changes in the range of oxalate concentration from 0 to 220 μM. Figure 8 The illustration in (A) shows the change in UCL color with oxalate concentration; Figure 8 (B) is I 540 / I 655 The intensity ratio is fitted to an exponential function curve of oxalate concentration; Figure 8 (C) is ln(I) 540 / I 655 Linear fitting curve of oxalate concentration; Figure 8 (D) shows the UV-vis spectrum changes of the probe of the present invention in the range of 0-220 μM oxalate concentration. Figure 8 The illustration in (D) shows the change in the color of the probe solution as the concentration of oxalate ions; Figure 8 (E) is A 526 / A 656 The intensity ratio is fitted to an exponential function curve of oxalate concentration; Figure 8 (F) is ln(A) 526 / A 656 Linear fitting curve of oxalate concentration; Figure 8 (G) is the linear fitting curve of UCL intensity and oxalate concentration at 540 nm. Figure 8 (H) is the linear fitting curve of UCL intensity and oxalate concentration at 655 nm. Figure 8 (I) is I 540 / I 655 I 540 I 655 Signal contrast of the three detection signals;

[0037] Figure 9 The results of the analysis of the selectivity and anti-interference ability of the dual-signal ratio-type upconversion luminescent probe prepared in Example 1 for oxalate detection are presented. Figure 9 (A) is a graph showing the test results of the probe's selectivity (red bar) and anti-interference (blue bar) in fluorescence mode in the presence of interfering substances; Figure 9 (B) shows the test results of the probe's selectivity (red bar) and anti-interference (blue bar) in colorimetric mode in the presence of interfering substances; where 1-blank, 2-oxalate, 3-Cl - ,4-SO4 2- 5-NO 3- 6-CH3COO - 7-Ca 2+ ,8-Zn 2 + ,9-Al 3+,10-ascorbic acid,11-glucose,12-glutathione. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0040] Example 1

[0041] This embodiment proposes a dual-signal ratio-based upconversion luminescent probe, which is prepared by mixing 200 μL of hydrophilic UCNPs solution (concentration 10 mg / mL), 40 μL of FeCl3 solution (concentration 5 mM), 25 μL of ECR ​​solution (concentration 5 mM), 200 μL of DTAB solution (concentration 1.5 mM), and 1335 μL of HAc-NaAc buffer solution (pH=4.5) evenly to obtain the dual-signal ratio-based upconversion luminescent probe.

[0042] The hydrophilic UCNPs in this embodiment were obtained by treating NaYF4:Yb / Er@NaYF4 upconversion nanoparticles as follows: NaYF4:Yb / Er@NaYF4 upconversion nanoparticles were placed in 60 mL of hydrochloric acid solution with pH=1, sonicated for 1 h, centrifuged, washed twice with ultrapure water, and dispersed in 20 mL of ultrapure water to obtain a UCNPs solution; 300 mg of PAA was dissolved in 30 mL of ethylene glycol, heated to 110 °C and held for 1 h, then the UCNPs solution was added, stirred vigorously for 30 min, then heated to 240 °C and held for 2 h, cooled, centrifuged to collect the UCNPs-PAA composite material, washed three times with deionized water, and finally dispersed in 20 mL of ultrapure water to obtain a hydrophilic UCNPs solution with a concentration of 10 mg / mL, which was stored at 4 °C for later use. In this embodiment, the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles were prepared using existing methods. For details, please refer to Example 1 of the patent with publication number CN119269488B for the preparation of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles. Further details will not be provided here.

[0043] Figure 1(A) is a low-resolution TEM image of the NaYF4:Yb / Er upconversion nanoparticles prepared in this embodiment; Figure 1 (B) is a low-resolution TEM image of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this embodiment; Figure 1 (C) is a size distribution diagram of the NaYF4:Yb / Er upconversion nanoparticles prepared in this embodiment; Figure 1 (D) is a size distribution diagram of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this embodiment; Figure 1 (E) is a high-resolution TEM image of the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this embodiment; Figure 1 (F) shows the XRD patterns of the NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this embodiment.

[0044] Depend on Figure 1 As can be seen from (A)-(D), the NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this embodiment both exhibit a uniform spherical structure, with the particle size increasing from 26.06 nm to 28.12 nm.

[0045] Depend on Figure 1 (E) It can be seen that the core-shell structured UCNPs prepared in this embodiment have clear lattice stripes and a crystal plane spacing of about 0.515 nm, corresponding to the (100) crystal plane of hexagonal phase NaYF4.

[0046] Figure 1 The XRD pattern of (F) corresponds highly to the standard card (PDF 16-0334) of hexagonal NaYF4, proving the successful synthesis of UCNPs in this embodiment.

[0047] Example 2

[0048] The difference between this embodiment and Embodiment 1 is that this embodiment uses 40 μL of 2.5 mM FeCl3 solution when preparing the dual-signal ratio-type upconversion luminescent probe solution.

[0049] Example 3

[0050] The difference between this embodiment and Embodiment 1 is that this embodiment uses 40 μL of 3.75 mM FeCl3 solution when preparing the dual-signal ratio-type upconversion luminescent probe solution.

[0051] Example 4

[0052] The difference between this embodiment and Embodiment 1 is that this embodiment uses 40 μL of 6.25 mM FeCl3 solution when preparing the dual-signal ratio-type upconversion luminescent probe solution.

[0053] Example 5

[0054] The difference between this embodiment and Embodiment 1 is that this embodiment uses 40 μL of 7.5 mM FeCl3 solution when preparing the dual-signal ratio-type upconversion luminescent probe solution.

[0055] Example 6

[0056] The difference between this embodiment and Embodiment 1 is that this embodiment uses 40 μL of 8.75 mM FeCl3 solution when preparing the dual-signal ratio-type upconversion luminescent probe solution.

[0057] Example 7

[0058] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 4.4 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0059] Example 8

[0060] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 4.6 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0061] Example 9

[0062] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 4.8 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0063] Example 10

[0064] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 5.2 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0065] Example 11

[0066] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 5.4 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0067] Example 12

[0068] The difference between this embodiment and Embodiment 1 is that this embodiment uses 25 μL of 5.8 mM ECR solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0069] Example 13

[0070] The difference between this embodiment and Embodiment 1 is that this embodiment uses 200 μL of 0.5 mM DTAB solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0071] Example 14

[0072] The difference between this embodiment and Embodiment 1 is that this embodiment uses 200 μL of 1 mM DTAB solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0073] Example 15

[0074] The difference between this embodiment and Embodiment 1 is that this embodiment uses 200 μL of 2 mM DTAB solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0075] Example 16

[0076] The difference between this embodiment and Embodiment 1 is that this embodiment uses 200 μL of 2.5 mM DTAB solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0077] Example 17

[0078] The difference between this embodiment and Embodiment 1 is that this embodiment uses 200 μL of 3 mM DTAB solution when preparing the dual-signal ratio upconversion luminescent probe solution.

[0079] Example 18

[0080] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 3.5 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0081] Example 19

[0082] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 4 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0083] Example 20

[0084] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 5 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0085] Example 21

[0086] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 5.5 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0087] Example 22

[0088] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 6 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0089] Example 23

[0090] The difference between this embodiment and Embodiment 1 is that the HAc-NaAc buffer solution used in this embodiment has a pH of 6.5 when preparing the dual-signal ratio upconversion luminescent probe solution.

[0091] Application Example 1

[0092] Mechanism study of oxalate detection

[0093] Add 200 μL of sodium oxalate solution (220 μM) to 1800 μL of the dual-signal ratio-type upconversion luminescent probe solution prepared in Example 1. After reacting for 5 s, perform UCL spectroscopy (excitation wavelength of 980 nm) and UV-Vis absorption spectroscopy using a UCL spectrometer and a UV-Vis spectrophotometer, respectively.

[0094] Combination Figure 2 When oxalate is added to the solution of a dual-signal ratio-based upconversion luminescent probe, the oxalate can react with the iron-chromium anthocyanin R complex (Fe... 3+ -ECR undergoes a specific binding reaction, inducing Fe 3+ The dissociation of the -ECR complex significantly alters the optical properties of the dual-signal ratiometric upconversion luminescent probe system. Its absorption peak shifts blue from 656 nm towards shorter wavelengths, eventually stabilizing at 526 nm. This change in the absorption spectrum simultaneously triggers a dynamic response in the fluorescence emission of UCNPs. The green emission intensity at 540 nm exhibits a significant quenching phenomenon, while the red emission intensity at 655 nm gradually recovers.

[0095] like Figure 3 As shown, when oxalate is not involved, Fe 3+The absorption spectrum of the -ECR complex significantly overlaps with the 655 nm red emission spectrum of UCNPs. This spectral overlap effect leads to energy transfer quenching of the red emission. When oxalate is introduced into the system, Fe... 3+ The dissociation of the -ECR complex releases ECR, whose absorption spectrum overlaps with the 540 nm green emission spectrum of UCNPs. This dynamic conversion of the absorption-emission spectral overlap region enables precise control of the intensity of the dual emission peaks, providing a dual optical signal output mechanism for the visual detection of oxalate.

[0096] Application Example 2

[0097] 200 μL of sodium oxalate solution (220 μM) was added to 1800 μL of the dual-signal ratiometric upconversion luminescent probe solutions prepared in Examples 1-23, respectively. After reacting for 5 s, UV-Vis absorption spectroscopy was performed using a UV-Vis spectrophotometer, and the results are as follows: Figures 4-7 As shown.

[0098] according to Figures 4-7 The results show that: with the increase of Fe in the detection solution 3+ As the concentration increases, the absorbance gradually increases, then tends to decrease. This is especially true for Fe in the detection solution. 3+ The highest absorbance was observed at a concentration of 100 μM, indicating that Fe in the detection solution was high. 3+ The optimal concentration was 100 μM. As the ECR concentration in the detection solution increased, the absorbance gradually increased and then gradually decreased, with the highest absorbance observed at an ECR concentration of 62.5 μM, indicating that the optimal ECR concentration was 62.5 μM. Similarly, as the DTAB concentration in the detection solution increased, the absorbance gradually increased and then gradually decreased, with the highest absorbance observed at a DTAB concentration of 150 μM, indicating that the optimal DTAB concentration was 150 μM. Furthermore, as the pH of the buffer solution increased, the absorbance gradually increased and then gradually decreased, with the highest absorbance observed at a pH of 4.5, indicating that the optimal pH of the buffer solution was 4.5. Example 1 represents the optimal value after comprehensive consideration.

[0099] Application Example 3

[0100] Sensitivity analysis of oxalate detection

[0101] 200 μL of sodium oxalate solution of different concentrations (0–220 μM) was added to 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1. After reacting for 5 s, UCL spectroscopy (excitation wavelength 980 nm) and UV-Vis absorption spectroscopy were performed using a UCL spectrometer and a UV-Vis spectrophotometer, respectively. Subsequently, the ratio of luminescence intensity at 540 nm to 655 nm in the UCL spectrum (IL) was calculated based on the spectral characteristic peaks. 540 / I 655 ), and the ratio of absorbance at 526 nm to 656 nm in the UV-Vis absorption spectrum (A 526 / A 656 A quantitative analysis model for oxalate concentration was established using the two-parameter ratio method, which effectively reduced background interference and improved detection sensitivity and accuracy.

[0102] like Figure 8 As shown, with increasing oxalate concentration, the color of UCL gradually changes from green to red. Figure 8 (A illustration), I 540 / I 655 It shows an exponential decline ( Figure 8 B), after logarithmic transformation, the linear relationship is good (R). 2 =0.981, Figure 8 C), with a detection limit as low as 4.2 nM; in colorimetric mode, the solution changes from blue to red ( Figure 8 D illustration), A 526 / A 656 Exponential response ( Figure 8 E), LOD is 520 nM; and the signal contrast (S / B) of the dual-signal ratio upconversion luminescent probe of this invention is 3-10 times higher than that of the single channel. Figure 8 I).

[0103] Application Example 4

[0104] Selectivity and anti-interference ability analysis of oxalate detection

[0105] Take 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1, and add 200 μL of sodium oxalate solution (220 μM) and 200 μL of interfering aqueous solution (1100 μM, five times the concentration of oxalate), respectively. The interfering aqueous solution contains Cl. - SO4 2- NO 3- CH3COO - Ca 2+ Zn 2+ Al 3+The selective response of the dual-signal ratiometric upconversion luminescent probe to oxalate was verified by ascorbic acid, glucose, and glutathione.

[0106] Simultaneously, an anti-interference test was conducted. 1800 μL of the dual-signal ratio-type upconversion luminescent probe solution prepared in Example 1 was taken, and 200 μL of a mixed solution of sodium oxalate (220 μM) and the aforementioned interfering agent (1100 μM) was added. The fluorescence intensity of the system was measured using a UCL spectrometer (excitation wavelength 980 nm), with the luminescence-to-colorimetric intensity ratio (Ig) used as the metric. 540 / I 655 A 526 / A 656 Using oxalate as an indicator, the influence of the presence or absence of oxalate on the probe signal response was compared and analyzed. The experiment was repeated three times, and the average value was taken. Origin 2021 software was used for data processing and error analysis.

[0107] like Figure 9 As shown, after the addition of the interfering agent, the UCL color of the dual-signal ratiometric upconversion luminescent probe solution remained green, while the solution remained blue. However, the addition of oxalate caused significant changes in both fluorescence and colorimetric signals. Figure 9 (A, 9B); In the anti-interference experiment, when the interfering substance coexists with oxalate, the signal response is consistent with that of oxalate alone, proving that the dual-signal ratio-type upconversion luminescent probe of this application has excellent selectivity and anti-interference ability.

[0108] Application Example 5

[0109] Detection of oxalate in actual samples

[0110] Weigh 5.0 g of soil sample that has passed through a 100-mesh sieve into a 50 mL centrifuge tube, add 20 mL of ultrapure water, and sonicate in a 40 kHz ultrasonic instrument for 30 min to fully dissolve the oxalate in the soil; then centrifuge at 8000 r / min for 15 min, take the supernatant, filter it through a 0.45 μm aqueous filter membrane and set it aside.

[0111] Vegetable samples were selected from celery and tomatoes. Fresh celery and tomatoes were washed and dried, and 10.0 g of edible parts of each were taken and ground into a uniform slurry in a high-speed tissue homogenizer. 2.0 g of the slurry was weighed into a 50 mL centrifuge tube and 15 mL of 2% (v / v) formic acid aqueous solution was added. The mixture was vortexed for 10 min, ultrasonically extracted for 20 min, centrifuged at 8000 r / min for 10 min, and the supernatant was collected. The extraction was repeated once, and the supernatants were combined and filtered through a 0.22 μm filter membrane for later use.

[0112] In a luminescent detection system, the dual-signal ratiometric upconversion luminescent probe prepared in Example 1 was used to detect the oxalate content in soil, celery, and tomato samples at different spiking concentrations (0, 50, 100, and 150 μM). The recovery rate was calculated as: Recovery rate = (detected amount after spiking - detected amount before spiking) / amount of oxalate standard solution added, to evaluate the accuracy and reliability of the detection method. The results are shown in Table 1.

[0113] Table 1. Spiked recovery data of oxalate in real samples by probe detection

[0114]

[0115] Table 1 shows that the spiked recoveries for soil samples were 98.62%–101.61%, for celery samples 105.65%–122.64%, and for tomato samples 103.81%–110.68%, with the overall recoveries remaining stable at 98.62%–122.64%. Furthermore, the relative standard deviations (RSDs) for each sample were strictly controlled within 5%. This data fully demonstrates that the dual-signal ratiometric upconversion luminescent probe of this invention maintains good detection accuracy and repeatability when facing different complex matrices, effectively verifying its reliability in practical applications.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A dual-signal ratio-based upconversion luminescent probe, characterized in that, The dual-signal ratiometric upconversion luminescent probe comprises upconversion nanoparticles and an iron-chromium anthocyanin R complex; wherein... The upconversion nanoparticles have a green emission peak at 540 nm and a red emission peak at 655 nm. The dual-signal ratio upconversion luminescent probe is configured such that, in the absence of oxalate, the iron-chromium anthocyanin R complex quenches the red emission peak; in the presence of oxalate, the oxalate reacts with the iron-chromium anthocyanin R complex, inducing a blue shift in the absorption spectrum, quenching the green emission peak, and restoring the intensity of the red emission peak, thereby achieving a ratio of 1 / 2 emission peak intensity. 540 / I 655 To achieve fluorescence detection of oxalate, and I 540 / I 655 The signal ratio exhibits an exponential response relationship with oxalate concentration; The upconversion nanoparticles are NaYF4:Yb / Er@NaYF4 upconversion nanoparticles, wherein Yb 3+ The molar concentration is 20%, Er 3+ The molar concentration of Y is 2%. 3+ The molar concentration is 78%; the upconversion nanoparticles are treated as follows: the upconversion nanoparticles are treated with acid and then coated with hydrophilic molecules on the surface; the acid treatment uses hydrochloric acid with pH=0.8-1.2; the hydrophilic molecules are polyacrylic acid.

2. A method for preparing the dual-signal ratio-type upconversion luminescent probe as described in claim 1, characterized in that, It includes the following steps: Mix the upconversion nanoparticle solution, iron salt solution, and chromocyanine R solution.

3. The method for preparing a dual-signal ratio-type upconversion luminescent probe according to claim 2, characterized in that, The concentration of the upconversion nanoparticle solution is 10 mg / mL; and / or, the concentration of the iron salt solution is 2.5-8.75 mM, wherein the iron salt solution is at least one of ferric sulfate solution, ferric nitrate solution, and ferric chloride solution; and / or, the concentration of the chromocyanine R solution is 4.4-5.8 mM.

4. The method for preparing a dual-signal ratio-type upconversion luminescent probe according to claim 2, characterized in that, The method also incorporates surfactants and / or buffer solutions.

5. The method for preparing a dual-signal ratio-type upconversion luminescent probe according to claim 4, characterized in that, The surfactant is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide; and / or the buffer solution is an acetate-sodium acetate buffer solution with pH=4-5.

6. A detection device, characterized in that, It includes the dual-signal ratio upconversion luminescent probe as described in claim 1.

7. The application of a dual-signal ratio-type upconversion luminescent probe as described in claim 1 in oxalate detection.

8. The application according to claim 7, characterized in that, The application described involves fluorescence detection with an excitation wavelength of 980 nm and an emission wavelength in the range of 500-700 nm, using I... 540 / I 655 For quantitative signals; And / or, the application is to perform colorimetric analysis in the absorption wavelength range of 400-700 nm, using A 526 / A 656 It is a quantitative signal.

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