Multi-emission composite nano ratiometric fluorescent probe for detecting fluoroquinolone antibiotics and preparation method of multi-emission composite nano ratiometric fluorescent probe

Abstract

The invention discloses a multi-emission composite nano ratiometric fluorescent probe for detecting fluoroquinolone antibiotics and a preparation method of the multi-emission composite nano ratiometric fluorescent probe. The CdTe-Tb-UMP composite nano ratiometric fluorescent probe with double ligands is prepared by taking metal terbium ions (Tb < 3 + >) as central ions and respectively taking uridine monophosphate (UMP) and CdTe quantum dots with red fluorescence emission as bridged ligands. ENR is further coordinated with Tb < 3 + >, energy is transferred to Tb < 3 + > through an antenna effect, so that characteristic green fluorescence of Tb < 3 + > is turned on, and fluorescence of CdTe quantum dots is almost kept unchanged. On the basis, a portable nursing point testing system is further constructed, and the portable nursing point testing system comprises an intelligent mobile phone detector and a wearable fingertip sensor integrated with a micro-fluidic chip and is used for on-site rapid detection of the ENR. The paper-based chip shows rapid and sensitive fluorescence response, and the detection limits of the spectrograph and the paper-based sensor on the ENR are 4.7 nM and 13.1 nM respectively. The probe can be applied to detection of ENR in actual environment water samples, food and drugs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of analysis and environmental food monitoring, and specifically discloses a multi-emission composite nanometer ratio fluorescent probe for detecting fluoroquinolone antibiotics and a preparation method thereof, BACKGROUND

[0002] Fluoroquinolones (FQs) are a class of synthetic broad-spectrum antibiotics. Due to their low price, small side effects, and high antibacterial performance, they are widely used in livestock breeding, disease prevention, and clinical medicine. Enrofloxacin (ENR), as a synthetic third-generation quinolone antibiotic, has the characteristics of low price and excellent antibacterial activity, and has been widely used in the field of animal disease prevention and treatment. However, due to extensive and unrestricted use, ENR residues enter food and the environment, posing a potential threat to the ecosystem and human health. Long-term exposure may cause allergic reactions, teratogenic / carcinogenic mutations, antibiotic resistance, and other problems. In addition, studies have shown that the accumulation of such antibiotics in the human body increases the risk of aortic aneurysm and dissection, and also affects normal heart activity. Therefore, developing a sensitive and accurate method for detecting ENR residues in various foods and environmental media is crucial for protecting public health.

[0003] Currently reported ENR detection methods mainly include high-performance liquid chromatography, chromatography-mass spectrometry, and enzyme-linked immunosorbent methods. However, most of these methods are focused on traditional laboratory methods, which require the use of large instruments, making it difficult to conduct on-site rapid detection of ENR. Therefore, there is still a need to develop a novel, simple, easy-to-operate, and highly sensitive method for detecting ENR. SUMMARY

[0004] The purpose of the present application is to overcome the defects in the prior art and provide a novel, simple, easy-to-operate, and highly sensitive method for on-site rapid detection of fluoroquinolone antibiotics, especially ENR, based on a CdTe-Tb-UMP quantum dot lanthanide nucleotide complex nanometer ratio fluorescent probe.

[0005] The technical solution of the present application is as follows:

[0006] A composite nano-ratio fluorescent probe for detecting fluoroquinolone antibiotics (especially ENR) is provided, which is a CdTe-Tb-UMP composite prepared by mixing cadmium telluride quantum dots (CdTe QDs) with lanthanide nucleotide polymer nanoparticles (Tb-UMP) formed by coordination of terbium ions (Tb3+) and uridine monophosphate (UMP); wherein the CdTe QDs provide red fluorescence emission at 650 nm, the Tb3+ generates characteristic green fluorescence emission at 545 nm after coordination with ENR, and the UMP is used to enhance the fluorescence intensity of the Tb3+; the probe can realize quantitative detection of ENR by measuring the fluorescence intensity ratio (F 545 / F 650 ) at 545 nm and 650 nm under excitation at a wavelength of 290 nm.

[0007] The application further provides application of the composite nano-ratio fluorescent probe in detection of fluoroquinolone antibiotics (especially ENR) in environmental water samples, food samples or medicines.

[0008] The application further provides a preparation method of the composite nano-ratio fluorescent probe, comprising the following steps:

[0009] Step S1, preparing cadmium telluride (CdTe) quantum dots;

[0010] Step S2, preparing the CdTe-Tb-UMP probe: adding CdTe quantum dot solution, Tb 3+ solution and UMP solution into a buffer solution in sequence, and mixing uniformly to obtain the CdTe-Tb-UMP composite fluorescent probe; wherein the mass concentration ratio of Tb 3+ and CdTe quantum dots ranges from 13.59 to 54.36:1; and the mass concentration ratio of Tb 3+ and UMP ranges from 0.14 to 1.68:1. Alternatively, the buffer solution contains 280-320 μM Tb3+, 1-10 mg / L of CdTe QDs and 0.5-2.0 mM of UMP.

[0011] The application further provides a method for detecting fluoroquinolone antibiotics (especially ENR) by using the composite nano-ratio fluorescent probe, which comprises the following steps:

[0012] Step one, adding the probe into a to-be-detected solution containing fluoroquinolone antibiotics;

[0013] Step two, measuring the fluorescence intensity of the mixed solution at 545 nm and 650 nm under excitation at a wavelength of 290 nm;

[0014] Step three, calculating the concentration of ENR according to F 545 / F 650 The linear relationship between the ratio and the fluoroquinolone antibiotic concentration is calculated to obtain the concentration of the fluoroquinolone antibiotic in the to-be-tested solution.

[0015] Further, the to-be-tested solution contains 280-320 μM Tb³⁺, 1-10 mg / L CdTe QDs, and 0.5-2.0 mM UMP. Preferably, the to-be-tested solution contains 300 μM Tb³⁺, 2.5 mg / L CdTe QDs, and 1.0 mM UMP.

[0016] Further, the fluoroquinolone antibiotic concentration ranges from 0.01 to 20 μM, and the response time is 5 min.

[0017] The application also provides a microfluidic paper-based chip for visual detection of enrofloxacin (ENR), comprising: a paper-based chip having a sample inlet, a flow channel, and a sensing area, the flow channel connecting the sensing area and the sample inlet, and the sensing area containing a composite nano-ratio fluorescent probe for detecting enrofloxacin (ENR).

[0018] The application also provides a wearable fingertip sensor comprising the microfluidic paper-based chip.

[0019] Further, the wearable fingertip sensor further comprises double-sided tape, black tape, and light shielding film, and is integrated with a smartphone detector; the sensor realizes rapid, visual, and in-situ detection of ENR through fluorescence color change.

[0020] Further, the smartphone application is used to decompose the fluorescence color into red (R), green (G), and blue (B) values, and to quantify the ENR concentration through the linear relationship between the G / R ratio and the ENR concentration.

[0021] The application provides a preparation method of a double-emission nano-ratio fluorescent probe for detecting ENR and a smartphone-assisted microfluidic chip, wherein CdTe quantum dots are added in the process of forming a lanthanide polymer from Tb-UMP to prepare a CdTe-Tb-UMP ternary complex, i.e., a quantum dot lanthanide nucleotide composite nano-ratio fluorescent probe for detecting ENR. Based on the constructed ratio fluorescent probe, a wearable microfluidic paper-based sensor is prepared, a smartphone is used as a detector, a small, convenient, and portable fluorescent detection dark box device is prepared through 3D printing to realize rapid detection of ENR on site, and rapid, sensitive, and visual detection of ENR is realized.

[0022] As preferred, the application provides a method for detecting ENR based on a composite nano-ratio fluorescent probe constructed from a lanthanide nucleotide nanoparticle, and the construction process of the probe is as follows:

[0023] The composite nano-fluorescent probe is added into the sample solution containing ENR, the mixed solution is incubated after adjusting pH, then the fluorescence intensity of the mixed solution at 545 nm and 650 nm emission wavelengths is measured under the excitation of 290 nm wavelength, the excitation and emission slits are 5 nm and 2.5 nm respectively; according to the fluorescence intensity at 545 nm and 650 nm emission wavelengths, combined with F 545nm / F 650nm The linear relationship between the different concentrations of ENR is obtained, the concentration of ENR in the sample solution is obtained, and the detection of ENR is realized.

[0024] Preferably, in the mixed solution, 30.0 μM Tb 3+ , 20 mM HEPES buffer solution with pH = 6.0, 2.5 mg / L CdTe, 1.0 mM UMP and 0.01-20 μM ENR standard solution are included.

[0025] Preferably, in the above mixed solution, the pH during the determination is 6.0, and the reaction time is 5 min.

[0026] Preferably, the on-site visual detection method of ENR is constructed as follows:

[0027] Preparation and application of paper-based sensor:

[0028] Firstly, the basic structure of the microfluidic paper-based chip is designed by using software. The paper microfluidic chip includes a sample inlet, a flow channel and a sensing area, the diameters of the inlet and the sensing area are 4 mm and 5 mm respectively, and the length of the channel is 9 mm.

[0029] Construction of wearable fingertip sensor: The wearable fingertip sensor is composed of double-sided adhesive tape, black tape for fixing the paper chip, the paper chip itself and light shielding film. The size of the double-sided adhesive tape and the black tape is consistent, with a length of 2 cm and a width of 1 cm. During preparation, firstly, the black double-sided adhesive tape is fixed on the surface of the fixed eye gloves, then the black tape, the chip and the light shielding film are fixed in sequence. The mechanical flexibility of the fingertip sensor is detected.

[0030] Preparation of portable detection box: the structure of the mobile phone detection dark box is designed using Solidworks 2022, and then processed using a commercial 3D printer. A portable device with a size of 15.8 cm × 7.4 cm × 10.0 cm (length × width × height) composed of a smart phone, a 3D printed accessory and a 302 nm ultraviolet lamp is constructed to realize the convenient, visual and on-site detection of ENR. The positions of the ultraviolet lamp, paper-based sensor and camera are reasonably fixed in the 3D accessory to solve the instability limitation in the image acquisition process. The image is taken using a Huawei Mate 30pro smart phone (40 million pixel camera) and analyzed using a color recognition application.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The present application takes metal Tb 3+ as the metal center, and CdTe quantum dots and UMP as bridging ligands, respectively, to prepare a ratio fluorescent probe with double emission response. The β-diketone structure in ENR can coordinate with the central ion Tb 3+ and transfer energy, so that the characteristic green fluorescence of Tb 3+ at 545 nm is turned on; the red fluorescence of CdTe in the system is almost unchanged and can be used as a reference signal; UMP further coordinates with Tb 3+ to form lanthanide nucleotide polymer nanoparticles, greatly improving the fluorescence intensity of the system at 545 nm, and thus significantly improving the sensitivity of ENR detection. With the gradual increase of the concentration of ENR, the fluorescence color of the system changes obviously from red to green, which can realize the on-site visual detection of ENR. By F 545nm / F 650nm ratio, ENR can be quantified, which can obviously eliminate the interference of external factors such as probe concentration, temperature and instrument signal, so that the ratio fluorescent method detection of ENR can be realized. In addition to being able to detect RNR in environmental water samples, the probe can also sensitively detect ENR in food samples, so it has broad application prospects in the field of environmental and food analysis and monitoring. In addition, in order to be able to detect ENR residues on site, a wearable fingertip sensor integrated by a microfluidic chip and a smartphone-based detector is further developed for real-time in-situ detection of ENR, greatly improving the simplicity and practicality of the method.

[0033] The paper-based chip shows a rapid and sensitive fluorescent response, and the detection limit of ENR by the spectrometer and the paper-based sensor is 4.7 nM and 13.1 nM, respectively. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1Fluorescence spectra of different systems of ratiometric fluorescent probe. Among them, HEPES buffer: 20.0 mM, pH = 6.0, Tb 3 + : 300.0 μM, CdTe: 2.5 mg / L, UMP: 1.0 mM, λex= 290 nm.

[0035] Figure 2 To determine the influence of conditions on ENR determination. Among them, (A) [CdTe] / [Tb 3+ ] concentration on the fluorescence intensity of probe at 545 nm, (B) UMP concentration on the fluorescence intensity at 545 nm, (C) pH of the system on the fluorescence intensity at 545 nm, (D) response time on the fluorescence intensity at 545 nm. HEPES buffer: 20.0 mM, pH = 6.0, CdTe: 2.5 mg / L, Tb 3+ : 300.0 μM, UMP: 1.0 mM, pH = 6.0.

[0036] Figure 3 The linear relationship between F 545 / F 650 and ENR concentration. HEPES buffer: 20.0 mM, pH = 6.0, Tb 3+ : 300.0 μM, CdTe: 2.5 mg / L, UMP: 1.0 mM, λex= 290 nm.

[0037] Figure 4 The selectivity of CdTe-Tb-UMP composite nano ratiometric fluorescent probe for ENR detection. Among them, (A) and (B) the influence of the above test components on F 545 / F 650 fluorescence ratio, (C) and (D) the influence of coexisting ENR and test components on F 545 / F 650 fluorescence ratio. Among them, the concentration of ENR is 10 μM, the concentration of ions is 100 μM, the concentration of amino acids, biomolecules and organic pollutants is 100 μM, and the concentration of other types of antibiotics is 50 μM.

[0038] Figure 5Development of wearable fingertip sensor and portable imaging platform. Overview of paper microfluidic chip (A) and wearable fingertip sensor (B). (C) 3D structure design of smartphone detector light path. (D) Schematic diagram of smartphone-based fluorescence detection device. (E) Fluorescence response of paper chip-based sensor device to increasing concentrations of ENR. (F) Detection area for paper chip image RGB analysis. (G) Relationship between G / R reaction and ENR concentration. (H) Schematic diagram of fingertip sensor for detecting FQ. (I) Images of the detection fingertip sensor placed on different meat surfaces without coated FQ under sunlight (a, b, c) and under 302 nm ultraviolet light (d, e, f), and fluorescence images of the detection wearable sensor after touching the sample surface without coated FQs under 302 nm ultraviolet light (g, h, i). DETAILED DESCRIPTION

[0039] The present application will be further described and illustrated in the following with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present application can be combined accordingly without conflict.

[0040] Example 1

[0041] This embodiment first prepared a composite fluorescent probe (CdTe-Tb-UMP probe), which can be used for rapid visual detection of ENR. The preparation method is as follows:

[0042] (1) Preparation of cadmium telluride quantum dots (CdTe) solution, as follows:

[0043] Dissolve 0.228 g of CdCl2·2.5H2O and 0.456 g of sodium citrate in 100 mL of ultrapure water, and add 104 μL of 3-mercaptopropionic acid to the above mixture. Adjust the pH of the solution to 10.5 using 1.0 M NaOH. Then, add 0.044 g of Na2TeO3 to the above solution. Ten minutes later, continue to add 0.08 g of NaBH4, and continue to react the above mixture at 100℃ for 1 hour to prepare CdTe quantum dots with red fluorescence emission. After the solution cools down, add the same volume of anhydrous ethanol solution to the CdTe QD suspension to neutralize the prepared quantum dot solution. Collect the precipitate, wash it with anhydrous ethanol three times, and re-dissolve it in ultrapure water. Dry the CdTe quantum dots by freeze-drying method. Accurately weigh 10.0 mg of CdTe quantum dot solid and dissolve it in 10 mL of ultrapure water to prepare a quantum dot solution with a concentration of 1.0 g / L. Store the solution at 4℃ for later use.

[0044] (2) Preparation of CdTe-Tb-UMP probe as follows:

[0045] To 200 uL 200mM pH=6.0 HEPES buffer solution, 2.5 uL 1.0 g / L CdTe quantum dot solution, 30 uL 10 mM Tb 3+ solution and 100 uL 10 mM UMP solution were added in turn to prepare CdTe-Tb-UMP composite fluorescent probe. The Tb 3+ solution specifically used was Tb(NO3)3.

[0046] To verify the effect of the composite ratio fluorescent probe prepared in this embodiment on ENR, the following detection experiment was also performed:

[0047] (3) Fluorescent detection of CdTe-Tb-UMP probe on enrofloxacin (ENR), as follows:

[0048] Different concentrations of ENR solution were added to the CdTe-Tb-UMP probe solution, and finally diluted to 1.0 mL with ultrapure water, and placed at room temperature for 5 min. The fluorescence intensity of the system at 545 nm and 650 nm was recorded under 290 nm excitation wavelength, and the excitation and emission slit widths were 5.0 nm and 2.5 nm, respectively.

[0049] As Figure 1 shown, the fluorescence response results of CdTe-Tb-UMP composite nanometer ratio fluorescent probe on ENR. As can be seen from the figure, under the excitation of 290 nm, CdTe-Tb-UMP composite nanometer fluorescent probe only emits red fluorescence at 650 nm, and the characteristic spectral peaks of Tb 3+ at 492 nm, 545 nm, 582 nm and 622 nm cannot be observed. After adding ENR, Tb 3+ in the structure of CdTe-Tb-UMP composite nanometer fluorescent probe can selectively coordinate with the β-diketone structure on the surface of ENR structure, and at this time the characteristic fluorescence of Tb 3+ is turned on. Under the effect of the rate effect of ENR, the fluorescence at 650 nm in the probe is quenched. In the presence of UMP, the fluorescence of Tb 3+ in the system is enhanced by 13 times. Based on this, a ratio fluorescent nanometer probe is constructed for sensitive detection of ENR.

[0050] To optimize the determination conditions of CdTe-Tb-UMP composite nanometer ratio fluorescent probe, the detection conditions of the composite probe (including CdTe concentration, Tb 3+ concentration, UMP concentration, pH and response time) were also optimized, and the results are shown in Figure 2 As Figure 2 can be seen, the concentration of CdTe is 2.5 mg / L, the concentration of Tb3+ The optimal determination conditions were 300 μM of the concentration of the probe, 1.0 mM of the concentration of UMP, pH 6.0, and a response time of 5 min.

[0051] Under the optimal experimental conditions, the quantitative detection of ENR by the composite nanofluorescent probe was tested, and the results are shown in Figure 3 When the concentration of ENR was in the range of 0.01-20 μM, the fluorescence ratio F 545 / F 650 showed a good linear relationship with the concentration of ENR, and the linear equation was F 545 / F 650 = 1.68578 [ENR] + 0.05788 (R 2 = 0.9947), and the detection limit (LOD) of ENR was 4.7 nM (3σ / K, where σ is the standard deviation of the determination of the blank solution of the probe for 11 times, and K is the slope of the calibration curve).

[0052] To investigate the selectivity of the CdTe-Tb-UMP probe for ENR, the effects of the following common anions (Na + , K + , Cl - , Ca 2+ , SO4 2- , NO3 - , CO3 2- ), amino acids (tyrosine (Tyr), cysteine (Cys), threonine (Thr), aspartic acid (Asp), serine (Ser), and valine (Val)), antibiotics (streptomycin sulfate (SM), kanamycin (Kan), tetracycline (TC), penicillin (PG), and erythromycin (Ery)), biomolecules (glucose (Glu) and uric acid (UA)), and common organic substances (benzoic acid (BA), o-phthalic acid (o-PA), and p-phthalic acid (p-PA)) on the selectivity of the probe were tested, and the results are shown in Figure 4 As can be seen from the figure, the CdTe-Tb-UMP ratio fluorescent probe has good selectivity and anti-interference ability for the detection of ENR.

[0053] To evaluate the feasibility of the CdTe-Tb-UMP ratio fluorescent probe for the detection of ENR in actual samples, the concentration of ENR in lake water, honey, and milk samples was determined by the standard addition method, and the results are shown in Table 1. The results show that the detection recovery rate of the probe for ENR in the spiked samples was between 90.2-109.3%, and the relative standard deviation was less than 7.9%. The results show that the fluorescent probe can not only realize the trace detection of ENR in water samples, but also can be used for the detection of ENR in food samples.

[0054] Table 1. Analysis results of different samples by composite nanoratio fluorescent probe

[0055] Sample Concentration added / μM Concentration detected / μM Recovery (%) RSD (n=3, %) Lake water 0 ND a ]] / / 0.5 0.54±0.03 108.8 6.2 5.0 5.14±0.41 102.8 7.9 Honey 0 ND a ]] / / 0.5 0.55±0.03 109.3 5.0 5.0 4.51±0.02 90.2 0.3 Milk 0 0.07±0.00 / 4.3 0.5 0.50±0.00 99.1 0.4 5.0 5.33±0.18 106.6 3.3

[0056] ND a = Not detected.

[0057] (3) Detection of ENR by fingertip sensor and smartphone integrated detector, as follows:

[0058] Ratio fluorescence provides accurate ENR detection, however, its reliance on laboratory infrastructure hinders its portability and flexible deployment. To enable on-site detection of ENR residues, the applicant further developed a wearable fingertip sensor integrated with a microfluidic chip and a smartphone detector. As shown in Figure 5 A, the paper microfluidic chip includes a sample inlet, a flow channel, and a sensing zone (detection area), with diameters of 4 mm and 5 mm for the inlet and sensing zone, respectively, and a channel length of 9 mm. Similar to solution-based assays, the chip shows a fluorescence color change from red to green ( Figure 5 A). As shown in Figure 5 B, the wearable fingertip sensor is composed of several layers, including double-sided tape, black tape for fixing the paper chip, the paper chip itself, and an optical shielding film.

[0059] To enable instant monitoring of ENR in food and environmental samples, an accurate, portable, and reliable sensor based on a paper chip was fabricated. To simplify the detection process, the applicant prepared a portable device with dimensions of 15.8 cm x 7.4 cm x 10.0 cm (length x width x height) using 3D printing technology for detection of the paper chip. The device includes a smartphone, a sample holder, a 3D printed accessory, and a 302 nm UV light ( Figure 5 C, D). The relative positions of the light source, sample, and camera are fixed in the 3D printed accessory to minimize instability during image acquisition. A filter (420 nm) is used to reduce background noise caused by excitation light leakage. The device directly records the fluorescence color using the built-in CMOS sensor of the smartphone, eliminating the need to measure fluorescence intensity, which is beneficial for on-site applications.

[0060] To extract quantitative information from the images, the smartphone application (Color Identifier) was used to decompose the fluorescence color into three RGB values (RGB: red, green, and blue values). Figure 5 E shows the color change of the paper chip from red to green as the ENR concentration increases (0-25.0 μM). The RGB values of the chip were obtained and analyzed using the smartphone application ( Figure 5 F and G). A linear response was achieved in the range of 0 to 25 μM, with R2 The value exceeds 0.9746. The corresponding detection limit (LOD, 3σ / k) is 13.1 nM. In addition, in order to verify the feasibility of the portable paper chip, the injection and oral liquid samples were directly diluted and tested as representative real samples. As shown in Table 2, the measurement results are consistent with the labeled values, the recovery rate is between 93.0% and 110.0%, and the RSD is between 1.7% and 2.2%, indicating that the proposed chip can be used to quantify the FQ content in real drug samples and shows great potential for drug quality monitoring.

[0061] Further, by fixing the CdTe-Tb-UMP system on a nitrile glove, a glove-based wearable fingertip sensor was developed to realize the on-site rapid detection of ENR. When the sensor was detected on the surface of meat samples, no obvious color and fluorescence changes were observed in the blank test ( Figure 5 I, a-f). In contrast, when ENR was present in the meat sample, the chip had a significant color change ( Figure 5 I, g-i). The detection performance remained consistent in pork, chicken and fish, as shown in (e.g. Figure 5 I, a-i). This indicates that it is suitable for rapid visual screening of ENR. By integrating with the detector of a smartphone, this fingertip sensor provides a practical platform for on-site monitoring of FQ residues in food and environmental samples, which helps to supervise drug use and reduce antibiotic exposure.

[0062] Table 2. Analysis results of paper-based chip for ENR in different samples

[0063] Sample Labeled / mM Detected / mM Recovery (%) RSD (%) Injection 1 6.96 6.53 ±0.11 93.9 1.7 Injection 1 6.96 6.47 ±0.16 93.0 2.5 oral liquid 1 6.96 7.68±0.15 1.10 2.0 oral liquid 2 6.96 7.64±0.17 1.09 2.2

[0064] The above-described embodiments are only a preferred scheme of the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present application.

Claims

1. A composite nanoratio fluorescent probe for detecting fluoroquinolone antibiotics, characterized in that, The probe is a CdTe-Tb-UMP complex prepared by mixing cadmium telluride quantum dots with lanthanide nucleotide polymer nanoparticles formed by coordination of terbium ions and uridine monophosphate; under excitation of 290 nm wavelength, the probe can detect the ratio of fluorescence intensity at 545 nm and 650 nm F 545 / F 650 Thus, quantitative detection of ENR is realized.

2. The application of the composite nanometer ratio fluorescent probe of claim 1 in the detection of fluoroquinolone antibiotics in environmental water samples, food samples or pharmaceuticals.

3. The preparation method of the composite nanometer ratio fluorescent probe of claim 1, comprising the following steps: Step S1, preparing cadmium telluride quantum dots CdTe; Step S2, preparing CdTe-Tb-UMP probe: adding CdTe quantum dot solution, Tb solution and UMP solution into buffer solution in sequence, and preparing the CdTe-Tb-UMP composite fluorescent probe after mixing uniformly; wherein, 3+ the concentration of CdTe quantum dot solution is 0.5-1.5 mg / mL, the concentration of Tb solution is 0.5-1.5 mg / mL, and the concentration of UMP solution is 0.5-1.5 mg / mL. Tb 3+ The mass concentration ratio of CdTe quantum dots ranges from (13.59-54.36):1; Tb 3+ The mass concentration ratio of UMP ranges from (0.14 to 1.68):

1.

4. A method for detecting fluoroquinolone antibiotics using the composite nanoratio fluorescent probe according to claim 1, characterized in that, comprising the following steps: Step one. Adding the probe to the sample containing fluoroquinolone antibiotics; Step two. Under the excitation wavelength of 290 nm, the fluorescence intensity of the mixed solution at the emission wavelength of 545 nm and 650 nm is measured respectively. Step three. According to F 545 / F 650 The linear relationship between the ratio and the fluoroquinolone antibiotic concentration was calculated to determine the concentration of fluoroquinolone antibiotic in the test solution.

5. The method of claim 4, wherein, The sample contains 280-320 μM Tb³⁺, 1-10 mg / L CdTe QDs and 0.5-2.0 mM UMP.

6. The method of claim 4, wherein, The concentration of fluoroquinolone antibiotics ranges from 0.01 to 20 μM, and the response time is 4-6 min.

7. A microfluidic paper-based chip for visual detection of fluoroquinolone antibiotics in situ, characterized in that, It comprises: A paper-based chip having a sample inlet, a flow channel and a sensing area, the flow channel connecting the sensing area and the sample inlet, and the sensing area having the composite nanometer ratio fluorescent probe for detecting fluoroquinolone antibiotics according to claim 1.

8. A wearable fingertip sensor, characterized by It comprises the microfluidic paper-based chip of claim 7.

9. The wearable fingertip sensor of claim 8, wherein, The wearable fingertip sensor further comprises double-sided tape, black tape and light shielding film, and is integrated with a smartphone detector; the sensor realizes rapid, visual and in-situ detection of fluoroquinolone antibiotics through fluorescence color change.

10. The wearable fingertip sensor of claim 9, wherein, The smartphone application is used to decompose the fluorescence color into red (R), green (G) and blue (B) values, and quantifies the concentration of fluoroquinolone antibiotics through the linear relationship between the G / R ratio and the concentration of fluoroquinolone antibiotics.

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