Double-signal ratio type up-conversion luminescent probe, preparation method thereof and application of double-signal ratio type up-conversion luminescent probe in oxalate detection

Abstract

The invention relates to the technical field of analytical chemistry, and particularly discloses a double-signal ratio type up-conversion luminescent probe, a preparation method thereof and application of the double-signal ratio type up-conversion luminescent probe in oxalate detection, and the double-signal ratio type up-conversion luminescent probe comprises up-conversion nanoparticles UCNPs and an iron-chromium cyanine R compound. The upconversion nanoparticles UCNPs are combined with the iron-chromium cyanine R compound to construct a double-emission-peak regulation and control system, when the system is used for oxalate detection, oxalate can be chelated with Fe < 3 + > in the iron-chromium cyanine R compound, blue shift of an induced absorption spectrum is achieved, green and red emission peaks of the UCNPs are synchronously regulated and controlled, and the detection sensitivity is high. The fluorescent-colorimetric bimodal high-sensitivity detection of the oxalate is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and in particular to a dual-signal ratiometric up-conversion luminescent probe, a preparation method thereof, and application thereof in oxalate detection. Background Art

[0002] Oxalate (chemical formula C2O4 2- ) is widely present in soil and agricultural products. Excessive oxalate in the soil will 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 will reduce the bioavailability of minerals such as calcium, and long-term intake may be harmful to human health. Accurately detecting the content of oxalate in soil and agricultural products is of great practical significance for assessing soil fertility, ensuring the safety of agricultural products, guiding agricultural production regulation and environmental risk management.

[0003] Currently, methods for oxalate detection 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 ability 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 molecules or material systems that can specifically interact with target substances and enable qualitative identification and quantitative determination of target substances based on changes in fluorescence signals, occupy a key position in the field of analytical chemistry. These probes exhibit exceptional detection performance, demonstrating ultrahigh sensitivity for accurate identification of trace analytes. They also possess excellent selectivity for specific differentiation of target analytes. Their rapid response kinetics meet the needs of real-time in situ monitoring, and their simple operation process facilitates the construction of visual detection platforms. These characteristics have led to their widespread application in numerous fields, including bioanalysis, environmental monitoring, and medical diagnostics. However, traditional fluorescent probe systems still have inherent limitations, mainly manifested in insufficient photostability and susceptibility to photobleaching. At the same time, under short-wavelength excitation conditions, background fluorescence interference is significant, which seriously restricts the further improvement of its analytical performance.

[0004] Upconversion nanoparticles (UCNPs), a class of inorganic nanomaterials with unique optical properties, derive their luminescence mechanism from 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, exhibiting anti-Stokes luminescence. Consequently, UCNP-based nanoprobes offer unique advantages. Their near-infrared light excitation effectively reduces autofluorescence interference in complex matrix samples, while their excellent photostability and resistance to photobleaching effectively minimize signal attenuation during detection, providing reliable support for long-term, continuous monitoring.

[0005] Upconversion nanofluorescent probes usually use upconversion nanoparticles as energy donors and chromophores as recognition units to regulate the upconversion emission signal. Generally, one upconversion emission peak is selected as the detection signal, and another fixed emission peak is selected as the reference signal. However, due to the low upconversion quantum yield and the low energy transfer efficiency between the energy donor and the acceptor, the signal contrast of the upconversion luminescent probe before and after the addition of the test substance is difficult to effectively enhance. The contrast (i.e., the ratio of the signal intensity of the probe before and after the reaction) is the determining factor for the sensitivity of all chemical reaction-based probes. In contrast, the change of the dual signal ratio provides a feasible approach to improving the probe signal contrast. However, the position of the chromophore absorption peak is relatively fixed, making it difficult to flexibly adjust to achieve the regulation of multiple upconversion emission peaks. This makes the construction of a dual-signal ratio-type upconversion luminescent probe with high signal contrast a difficult problem that needs to be overcome in this field. Summary of the Invention

[0006] Based on this, the purpose of the present invention is to provide a dual-signal ratiometric upconversion luminescence probe, a preparation method thereof, and an application in oxalate detection. By combining core-shell structure upconversion nanoparticles UCNPs with iron-chrome cyanine R complexes, a dual-emission peak regulation system is constructed. The blue shift of the absorption spectrum induced by oxalate is utilized to synchronously regulate the green and red emission peaks of UCNPs, thereby realizing fluorescence-colorimetric dual-modal highly sensitive detection of oxalate.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The present invention first provides a dual-signal ratiometric upconversion luminescent probe, which comprises upconversion nanoparticles UCNPs and an iron-chrome cyanine R complex.

[0008] The present invention combines upconversion nanoparticles UCNPs with the iron-chrome cyanine R complex to construct a dual emission peak regulation system. When used for oxalate detection, oxalate can react with Fe in the iron-chrome cyanine R complex. 3+Chelation induces a blue shift in the absorption spectrum, synchronously regulates the green and red emission peaks of UCNPs, and dual signal regulation improves the signal contrast of the probe, realizing the fluorescence-colorimetric dual-modal highly sensitive detection of oxalate.

[0009] As a further improvement of the above solution of the present invention, in order to improve the dispersibility and stability of the upconversion nanoparticles UCNPs in aqueous solution, the UCNPs are subjected to the following treatment: after removing the surface oleic acid ligands of the UCNPs by acid treatment, the hydrophilic molecules are coated on the surface.

[0010] As a further improvement of the above solution 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.

[0011] As a further improvement of the above solution of the present invention, the UCNPs are NaYF4:Yb / Er@NaYF4 upconversion nanoparticles. 3+ The molar concentration of Er is 20%, 3+ The molar concentration of Y is 2%, 3+ The molar concentration of UCNPs is 78% to ensure that the UCNPs produce dual emission peaks at 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°C, and the reaction time is 30-60 minutes. Preferably, the preparation method of UCNPs comprises the following steps: (1) NaYF4:Yb / Er upconversion nanoparticles are prepared by reacting yttrium chloride, ytterbium chloride, erbium chloride, oleic acid, 1-octadecene, ammonium fluoride, and sodium hydroxide; the entire reaction process is carried out in a protective atmosphere (such as argon) to prevent oxidation and reduce impurity formation; (2) NaYF4:Yb / Er@NaYF4 upconversion nanoparticles with a 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 impurity formation.

[0012] The present invention also provides a method for preparing the dual-signal ratiometric upconversion luminescent probe as described above, comprising the following steps: mixing an upconversion nanoparticle solution, an iron salt solution, and an chromocyanine R (ECR) solution.

[0013] As a further improvement of the above-mentioned 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, and 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 chrome cyanine R solution is 4.4-5.8 mM.

[0014] As a further improvement of the above scheme of the present invention, the method further adds a surfactant and / or a buffer solution. Since the ion association complex is hydrophobic, in order to make it stably exist in the aqueous solution, the surfactant added in the present invention can chelate the excess Fe 3+ Buffer solutions accept and release H + , stabilize the pH value of the probe solution within a certain range and prevent large changes in the pH value.

[0015] As a further improvement of the above solution of the present invention, the surfactant is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide; and / or the buffer solution is an acetic acid-sodium acetate buffer solution (HAc-NaAc) with a pH of 4-5.

[0016] The present invention also provides a detection device, which includes the dual-signal ratiometric up-conversion luminescence probe as described above.

[0017] The present invention also provides an application of the aforementioned dual-signal ratiometric upconversion luminescence probe in the detection of oxalate, which can be specifically applied to the detection of oxalate in soil and agricultural products.

[0018] As a further improvement of the above-mentioned scheme of the present invention, the application includes the following steps: adding the sample to be tested to the dual-signal ratiometric upconversion luminescence probe, using an ultraviolet-visible spectrophotometer to monitor the absorption spectrum changes of the system in real time, and simultaneously detecting the changes in UCL signal intensity by a UCL spectrometer equipped with a laser, and establishing a quantitative relationship between oxalate concentration and spectral signal by analyzing the dynamic changes of the absorption peak position and intensity and the UCL signal intensity, thereby realizing highly sensitive dual-modal detection of oxalate.

[0019] As a further improvement of the above solution of the present invention, the dual-signal ratiometric up-conversion luminescence probe is used for fluorescence detection at an excitation wavelength of 980 nm and an emission wavelength of 500-700 nm. 540 / I 655 is a quantitative signal; And / or, the dual-signal ratiometric up-conversion luminescence probe is used for colorimetric analysis within an absorption wavelength range of 400-700 nm, with A 526 / A 656 is a quantitative signal.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention combines core-shell upconversion nanoparticles UCNPs with iron-chrome cyanine R complexes to construct a dual-emission peak regulation system. Oxalate can be used to induce a blue shift in the absorption spectrum and synchronously regulate the green and red emission peaks of UCNPs, thereby achieving highly sensitive fluorescence-colorimetric dual-modal detection of oxalate.

[0021] The dual-signal ratiometric up-conversion luminescent probe provided by the present invention detects oxalate, and the oxalate reacts with the Fe in the iron-chrome cyanine R complex. 3+ Chelation induced the absorption spectrum to shift from 656 nm to 526 nm, and synchronously regulated the 540 nm green emission quenching and 655 nm red emission recovery of UCNPs. 540 / I 655 ) to achieve fluorescence detection, through the absorbance ratio (A 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.

[0022] The core-shell structured UCNPs used in the present invention have high crystallinity and excellent photostability. The near-infrared light excitation characteristics can reduce the interference of spontaneous fluorescence in complex matrices. Through the dual-emission peak synergistic regulation strategy, a high-contrast ratio probe is constructed to achieve an oxalate detection limit as low as 4.2 nM, which is 3-10 times higher than the sensitivity of traditional single-channel detection methods. The linear range is 0-220 μM, and the spiked recovery rate in complex matrices reaches 98.62%-122.64%, with strong anti-interference ability.

[0023] The present invention constructs a luminescence-colorimetry dual-mode readout system, which realizes dual signal verification and visual detection through upconversion luminescence (UCL) color change (green→yellow→red) and absorption spectrum migration (blue→purple→red). It can not only obtain high-precision data through instrument analysis, but also complete on-site rapid detection of oxalate by observing the color change with the naked eye, realizing full-scene coverage from laboratory instrument analysis to on-site real-time detection, greatly improving the convenience and intuitiveness of oxalate detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Structural characterization diagram of NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; 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 NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (C) is the size distribution diagram of NaYF4:Yb / Er upconversion nanoparticles prepared in Example 1; Figure 1 (D) is the size distribution diagram of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (E) is a high-resolution TEM image of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 1 (F) XRD patterns of NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in Example 1; Figure 2 Schematic diagram of the mechanism of detecting oxalate using a dual-signal ratiometric upconversion luminescence probe proposed in the present invention; Figure 3 This is the dual-signal output principle diagram of the dual-signal ratiometric up-conversion luminescence probe; Figure 3 (A) Upconversion energy transfer pathway diagram of UCNPs; Figure 3 (B) Schematic diagram of the energy transfer upconversion luminescence mechanism of UCNPs; Figure 3 (C) is the UCL spectrum and absorbance spectrum of the dual-signal ratiometric upconversion luminescence probe before and after the addition of oxalate. Figure 3 (C) The inset shows the UCL images before (green) and after (red) the addition of oxalate to the probe; Figure 4 Containing different Fe 3+ The absorbance of the dual-signal ratiometric upconversion luminescence probe after adding oxalate; Figure 5 The absorbance of the dual-signal ratiometric upconversion luminescence probe containing different ECR concentrations after adding oxalate; Figure 6 The absorbance of the dual-signal ratiometric upconversion luminescence probe containing different DTAB concentrations after adding oxalate; Figure 7 The absorbance of the dual-signal ratiometric upconversion luminescence probe after adding oxalate in buffer solutions with different pH values; Figure 8 The sensitivity analysis results of the dual-signal ratiometric upconversion luminescence probe prepared in Example 1 for oxalate detection; Figure 8 (A) is the UCL spectrum change diagram in the range of oxalate concentration 0-220 μM, Figure 8 The inset in (A) shows the change of UCL color with oxalate concentration; Figure 8 (B) is I 540 / I655 Exponential function fitting curve of intensity ratio and oxalate concentration; Figure 8 (C) is ln(I 540 / I 655 ) and the linear fitting curve of oxalate concentration; Figure 8 (D) is the UV-vis spectrum change of the probe of the present invention in the range of oxalate concentration from 0 to 220 μM, Figure 8 The inset in (D) shows the color change of the probe solution with oxalate concentration; Figure 8 (E) is A 526 / A 656 Exponential function fitting curve of intensity ratio and oxalate concentration; Figure 8 (F) is ln(A 526 / A 656 ) and the linear fitting curve of oxalate concentration; Figure 8 (G) is the linear fitting curve of UCL intensity at 540 nm and oxalate concentration; Figure 8 (H) is the linear fitting curve of UCL intensity at 655 nm and oxalate concentration; Figure 8 (I) is I 540 / I 655 , I 540 , I 655 Signal contrast of three detection signals; Figure 9 The results of the selectivity and anti-interference ability analysis of the dual-signal ratiometric upconversion luminescence probe prepared in Example 1 for oxalate detection are shown in FIG. Figure 9 (A) is a graph showing the selectivity (red bar) and anti-interference (blue bar) test results of the probe in the presence of interfering substances in fluorescence mode; Figure 9 (B) is the test result of the selectivity (red bar) and anti-interference (blue bar) of the probe in the colorimetric mode in the presence of interfering substances; 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 DESCRIPTION

[0025] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] Example 1 This example provides a dual-signal ratiometric upconversion luminescence probe, which is prepared by mixing 200 μL of a hydrophilic UCNPs solution (concentration of 10 mg / mL), 40 μL of a FeCl3 solution (concentration of 5 mM), 25 μL of an ECR solution (concentration of 5 mM), 200 μL of a DTAB solution (concentration of 1.5 mM), and 1335 μL of a HAc-NaAc buffer solution (pH = 4.5) to obtain a dual-signal ratiometric upconversion luminescence probe.

[0028] The hydrophilic UCNPs of this example were obtained by subjecting NaYF4:Yb / Er@NaYF4 upconversion nanoparticles to the following treatment: placing the NaYF4:Yb / Er@NaYF4 upconversion nanoparticles in 60 mL of hydrochloric acid solution with a pH of 1, ultrasonically treating for 1 h, centrifuging, washing twice with ultrapure water, and then dispersing in 20 mL of ultrapure water to obtain a UCNPs solution; dissolving 300 mg of PAA in 30 mL of ethylene glycol, heating to 110°C and maintaining for 1 h, then adding the UCNPs solution, vigorously stirring for 30 min, then heating to 240°C and maintaining for 2 h, cooling, and collecting the UCNPs-PAA composite material by centrifugation, washing three times with deionized water, and finally dispersing 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 future use. In this embodiment, NaYF4:Yb / Er@NaYF4 upconversion nanoparticles are prepared by existing methods. For details, please refer to Example 1 of patent publication number CN119269488B for the preparation of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles, which will not be described in detail here.

[0029] Figure 1 (A) is a low-resolution TEM image of NaYF4:Yb / Er upconversion nanoparticles prepared in this example; Figure 1 (B) is a low-resolution TEM image of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this example; Figure 1 (C) is the size distribution diagram of NaYF4:Yb / Er upconversion nanoparticles prepared in this example; Figure 1 (D) is the size distribution diagram of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this example; Figure 1 (E) is a high-resolution TEM image of NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this example; Figure 1 (F) is the XRD pattern of NaYF4:Yb / Er upconversion nanoparticles and NaYF4:Yb / Er@NaYF4 upconversion nanoparticles prepared in this example.

[0030] 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 example both exhibit a uniform spherical structure, and the particle size increases from 26.06 nm to 28.12 nm.

[0031] Depend on Figure 1 (E) It can be seen that the core-shell structured UCNPs prepared in this example have clear lattice fringes and the interplanar spacing is about 0.515 nm, corresponding to the (100) crystal plane of hexagonal NaYF4.

[0032] Figure 1 The XRD pattern of (F) is highly consistent with the standard card of hexagonal NaYF4 (PDF 16-0334), proving the successful synthesis of UCNPs in this example.

[0033] Example 2 The difference between this embodiment and embodiment 1 is that in this embodiment, 40 μL of 2.5 mM FeCl 3 solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0034] Example 3 The difference between this embodiment and embodiment 1 is that in this embodiment, 40 μL of a 3.75 mM FeCl 3 solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0035] Example 4 The difference between this embodiment and embodiment 1 is that in this embodiment, 40 μL of a 6.25 mM FeCl 3 solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0036] Example 5 The difference between this embodiment and embodiment 1 is that in this embodiment, 40 μL of a 7.5 mM FeCl 3 solution is used in the preparation of the dual-signal ratiometric up-conversion luminescence probe solution.

[0037] Example 6 The difference between this embodiment and embodiment 1 is that in this embodiment, 40 μL of 8.75 mM FeCl 3 solution is used in the preparation of the dual-signal ratiometric up-conversion luminescent probe solution.

[0038] Example 7 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of an ECR solution with a concentration of 4.4 mM is used when preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0039] Example 8 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of an ECR solution with a concentration of 4.6 mM is used when preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0040] Example 9 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of an ECR solution with a concentration of 4.8 mM is used when preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0041] Example 10 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of 5.2 mM ECR solution is used in preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0042] Example 11 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of an ECR solution with a concentration of 5.4 mM is used when preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0043] Example 12 The difference between this embodiment and embodiment 1 is that in this embodiment, 25 μL of 5.8 mM ECR solution is used in preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0044] Example 13 The difference between this embodiment and embodiment 1 is that in this embodiment, 200 μL of 0.5 mM DTAB solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0045] Example 14 The difference between this embodiment and embodiment 1 is that in this embodiment, 200 μL of 1 mM DTAB solution is used in preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0046] Example 15 The difference between this embodiment and embodiment 1 is that in this embodiment, 200 μL of 2 mM DTAB solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0047] Example 16 The difference between this embodiment and embodiment 1 is that in this embodiment, 200 μL of 2.5 mM DTAB solution is used in preparing the dual-signal ratiometric up-conversion luminescent probe solution.

[0048] Example 17 The difference between this embodiment and embodiment 1 is that in this embodiment, 200 μL of 3 mM DTAB solution is used in preparing the dual-signal ratiometric up-conversion luminescence probe solution.

[0049] Example 18 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 3.5.

[0050] Example 19 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 4.

[0051] Example 20 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 5.

[0052] Example 21 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 5.5.

[0053] Example 22 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 6.

[0054] Example 23 The difference between this embodiment and embodiment 1 is that the pH value of the HAc-NaAc buffer solution used in this embodiment when preparing the dual-signal ratiometric up-conversion luminescence probe solution is 6.5.

[0055] Application Example 1 Study on the mechanism of oxalate detection To 1800 μL of the dual-signal ratiometric upconversion luminescence probe solution prepared in Example 1, 200 μL of sodium oxalate solution (220 μM) was added. After reacting for 5 seconds, UCL spectroscopy (excitation wavelength of 980 nm) and UV-visible absorption spectroscopy were performed using a UCL spectrometer and a UV-visible spectrophotometer, respectively.

[0056] Combine Figure 2 After oxalate is added to the dual-signal ratiometric upconversion luminescence probe solution, oxalate can react with the iron-chrome cyanine R complex (Fe 3+ -ECR) undergoes a specific binding reaction, inducing Fe 3+ The -ECR complex dissociates, a process that significantly changes the optical properties of the dual-signal ratiometric upconversion luminescence probe system. Its absorption peak shifts from 656 nm to the shorter wavelength, eventually stabilizing at 526 nm. This change in the absorption spectrum simultaneously triggers a dynamic response in the fluorescence emission of UCNPs. The green luminescence intensity at 540 nm shows a significant quenching phenomenon, while the red luminescence intensity at 655 nm gradually recovers.

[0057] 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 luminescence. When oxalate is introduced into the system, Fe 3+ The -ECR complex dissociates, and the released ECR's absorption spectrum forms a new overlapping region with the 540 nm green emission spectrum of UCNPs. Through this dynamic conversion of the absorption-emission spectrum overlap region, precise control of the dual emission peak intensities is achieved, providing a dual optical signal output mechanism for the visual detection of oxalate.

[0058] Application Example 2 200 μL of sodium oxalate solution (220 μM) was added to 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1-23, respectively. After reacting for 5 seconds, UV-visible absorption spectrum detection was performed using a UV-visible spectrophotometer. The results were as follows: Figure 4-Figure 7 shown.

[0059] according to Figure 4-Figure 7 The results show that: as the Fe 3+ With the increase of concentration, the absorbance gradually increased and then showed a downward trend. 3+ When the concentration is 100 μM, the corresponding absorbance is the highest, indicating that Fe 3+The best concentration is 100 μM; with the increase of ECR ​​concentration in the detection solution, the absorbance gradually increases and then gradually decreases. When the ECR concentration in the detection solution is 62.5 μM, the corresponding absorbance is the highest, indicating that the best concentration of ECR ​​in the detection solution is 62.5 μM; with the increase of DTAB concentration in the detection solution, the absorbance gradually increases and then tends to decrease. When the DTAB concentration in the detection solution is 150 μM, the corresponding absorbance is the highest, indicating that the best concentration of DTAB in the detection solution is 150 μM; with the increase of pH of the buffer solution, the absorbance gradually increases and then gradually decreases. When the pH of the buffer solution is 4.5, the corresponding absorbance is the highest, indicating that the best concentration of the buffer solution is 4.5; Example 1 is the optimal value after comprehensive consideration.

[0060] Application Example 3 Sensitivity analysis of oxalate detection To 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1, 200 μL of sodium oxalate solution of different concentrations was added. The sodium oxalate concentration ranged from 0 to 220 μM. After 5 seconds of reaction, UCL spectrometer and UV-visible spectrophotometer were used to perform UCL spectroscopy (excitation wavelength of 980 nm) and UV-visible absorption spectroscopy, respectively. The luminescence intensity ratio (I 540 / I 655 ), and the absorbance ratio at 526 nm and 656 nm in the UV-visible absorption spectrum (A 526 / A 656 A quantitative analysis model for oxalate concentration was established using a dual-parameter ratio method, effectively reducing background interference and improving detection sensitivity and accuracy.

[0061] like Figure 8 As shown in Figure 2, with the increase of oxalate concentration, the color of UCL gradually changes from green to red ( Figure 8 A illustration), I 540 / I 655 Decreases exponentially ( Figure 8 B), the linear relationship is good after logarithmization (R 2 =0.981, Figure 8 C), the detection limit is 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 ratiometric upconversion luminescence probe of the present invention is improved by 3-10 times compared with that of a single channel ( Figure 8 I).

[0062] Application Example 4 Analysis of selectivity and anti-interference ability of oxalate detection Take 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1, add 200 μL of sodium oxalate solution (220 μM) and 200 μL of interfering substance aqueous solution (1100 μM, five times the concentration of oxalate), respectively. The interfering substance aqueous solution contains Cl - 、SO4 2- 、NO 3- 、CH3COO - , Ca 2+ 、Zn 2+ 、Al 3+ , ascorbic acid, glucose, and glutathione to verify the selective response of the dual-signal ratiometric upconversion luminescence probe of the present application to oxalate.

[0063] At the same time, an anti-interference test was set up. 1800 μL of the dual-signal ratiometric upconversion luminescent probe solution prepared in Example 1 was taken, and 200 μL of a mixed solution of sodium oxalate (220 μM) and the above-mentioned interfering substance (1100 μM) was added. The fluorescence intensity of the system was measured by a UCL spectrometer (excitation wavelength 980 nm). The ratio of luminescence to colorimetric intensity (I 540 / I 655 , A 526 / A 656 ) was used as an indicator to compare and analyze the effect of the presence or absence of oxalate on the probe signal response. The experiment was repeated three times, and the average value was taken. Origin 2021 software was used for data processing and error analysis.

[0064] like Figure 9 As shown, after the addition of the interfering substance, the UCL color of the dual-signal ratiometric upconversion luminescence probe solution remained green and the solution remained blue, while the addition of oxalate caused obvious changes in 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 ratiometric upconversion luminescence probe of the present application has excellent selectivity and anti-interference ability.

[0065] Application Example 5 Detection of oxalate in actual samples Weigh 5.0 g of soil sample passed through a 100-mesh sieve into a 50-mL centrifuge tube, add 20 mL of ultrapure water, and ultrasonically extract the sample 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, collect the supernatant, and filter it through a 0.45 μm water filter membrane for later use.

[0066] Celery and tomatoes were selected as vegetable samples. After washing and drying fresh celery and tomatoes, 10.0 g of the edible parts of each were taken and placed in a high-speed tissue grinder to grind into a uniform slurry. 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 tube was vortexed for 10 min, ultrasonic-assisted extraction was performed for 20 min, and centrifuged at 8000 r / min for 10 min. The supernatant was collected and the extraction was repeated once. The supernatants were combined and filtered through a 0.22 μm filter membrane for later use.

[0067] The dual-signal ratiometric upconversion luminescence probe prepared in Example 1 was used to detect oxalate in soil, celery, and tomato samples at different spike concentrations (0, 50, 100, and 150 μM) using a luminescence detection system. The recovery rate was calculated as follows: recovery rate = (amount detected after spike addition - amount detected before spike addition) / amount of oxalate standard solution added to evaluate the accuracy and reliability of the detection method. The results are shown in Table 1.

[0068] Table 1. Recovery data of spiked oxalate detected by probe in real samples

[0069] The results in Table 1 show that the spiked recoveries for soil samples ranged from 98.62% to 101.61%, for celery samples from 105.65% to 122.64%, and for tomato samples from 103.81% to 110.68%, with an overall recovery range of 98.62% to 122.64%. Furthermore, the relative standard deviations (RSDs) for each sample were strictly controlled within 5%. This data demonstrates that the dual-signal ratiometric upconversion luminescence probe of this invention maintains excellent detection accuracy and repeatability in diverse and complex matrices, effectively verifying its reliability in practical applications.

[0070] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0071] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A dual-signal ratiometric upconversion luminescence probe, characterized in that: The dual-signal ratiometric up-conversion luminescent probe comprises up-conversion nanoparticles and an iron-chrome cyanine R complex.

2. The dual-signal ratiometric up-conversion luminescence probe according to claim 1, characterized in that: The upconversion nanoparticles are processed as follows: the upconversion nanoparticles are treated with acid and then coated with hydrophilic molecules on the surface.

3. The dual-signal ratiometric up-conversion luminescence probe according to claim 2, characterized in that: The acid treatment uses hydrochloric acid with a pH of 0.8-1.2; and / or the hydrophilic molecule is polyacrylic acid.

4. A method for preparing a dual-signal ratiometric upconversion luminescence probe according to any one of claims 1 to 3, characterized in that: It includes the following steps: The upconversion nanoparticle solution, the iron salt solution, and the chrome cyanine R solution were mixed.

5. The method for preparing a dual-signal ratiometric upconversion luminescence probe according to claim 4, 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, and 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 chrome cyanine R solution is 4.4-5.8 mM.

6. The method for preparing a dual-signal ratiometric upconversion luminescence probe according to claim 4, characterized in that: The method further includes the addition of a surfactant and / or a buffer solution.

7. The method for preparing a dual-signal ratiometric upconversion luminescence probe according to claim 6, wherein: The surfactant is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide; and / or the buffer solution is an acetic acid-sodium acetate buffer solution with a pH of 4-5.

8. A detection device, characterized in that: The method comprises the dual-signal ratiometric up-conversion luminescence probe according to any one of claims 1 to 3.

9. Use of the dual-signal ratiometric up-conversion luminescent probe according to any one of claims 1 to 3 in the detection of oxalate.

10. The use according to claim 9, characterized in that The application is to perform fluorescence detection within an excitation wavelength of 980 nm and an emission wavelength of 500-700 nm. 540 / I 655 is a quantitative signal; And / or, the application is to perform colorimetric analysis within an absorption wavelength of 400-700 nm, with A 526 / A 656 is a quantitative signal.

Images