Portable seawater antibiotic ratio fluorescence sensing device and method based on hydrogen bond network enhanced lanthanide MOF

Abstract

Marine pollution caused by antibiotic abuse has become a global environmental challenge, wherein trace detection of quinolone antibiotics (such as fleroxacin FLE, norfloxacin NOR and enrofloxacin ENR) is particularly key. The invention develops a high-stability fluorescence sensor based on a lanthanide series metal organic framework (Ln-MOF (at) BTEC), and by introducing a hydrogen bond network strengthening strategy, the performance of the material in a seawater high-salt environment is remarkably improved. The fluorescence decay rate of the material in simulated seawater within 60 min is as low as 2.67%, which is 21.49% in 30 min compared with that of a base material, and the stability is obviously improved. In addition, the ratio proportional fluorescence sensing can effectively and instantaneously respond to FLE, NOR and ENR in the presence of numerous interferents in a seawater system, and the detection limits within the range of 0-10 [mu] M are 80.7 nM, 21.03 nM and 28.22 nM respectively. Meanwhile, an intelligent mobile phone platform is successfully integrated to realize visual field detection, and the standard addition recovery rate in Dalian coastal areas and seawater in culture areas reaches 83-115% (RSDlt; the research provides a novel solution with high stability and high sensitivity for marine antibiotic pollution monitoring.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring technology and relates to a portable seawater antibiotic ratio fluorescence sensing device and method based on hydrogen bond network enhanced lanthanide MOF. Background Technology

[0002] In recent years, the widespread detection of quinolone antibiotics (FQs) in marine environments, along with their potential ecological risks and drug resistance gene-driven effects, has made them a new type of pollutant of great concern. Achieving on-site, rapid, and accurate quantification of trace residues in complex marine matrices is a key technological requirement that urgently needs to be addressed in marine environmental monitoring and risk assessment.

[0003] Existing detection technologies fall short of meeting this demand. While traditional chromatography-mass spectrometry (GC-MS) methods offer high precision, their bulky equipment, complex sample pretreatment, and reliance on fixed laboratories make them unsuitable for rapid on-site screening in shipboard, shore-based, or sudden pollution incidents. In contrast, sensing technologies based on specific fluorescence responses are considered an ideal pathway for on-site detection due to their potential for high sensitivity, rapid response, and instrument portability. Among these, metal-organic frameworks (MOFs) show great potential in constructing fluorescence sensing platforms due to their designable structure, tunable pores, and excellent luminescence properties.

[0004] However, directly applying MOF-based fluorescence sensing to the detection of quinolone antibiotics in the unique medium of seawater presents many challenges. For example, the Al-MOF or similar conventional MOF materials disclosed in patent CN112505012A for antibiotic detection suffer from difficulties in the coordination bonds between the metal nodes and organic ligands under high Na+ concentrations. + Ca 2+ Mg 2+In the presence of competing ions, the material is easily damaged, leading to dissociation of the material framework or loss of fluorescence activity, thus compromising the reliability of the detection signal. While patent CN116970185A modifies MOFs to enhance the adsorption of specific metal ions, it does not systematically address the common chemical and fluorescence stability issues in complex saline matrices. Furthermore, even with good selectivity and stability, converting the fluorescence response into a readily observable and objectively quantifiable result for on-site personnel is a crucial missing element in existing technologies. For example, the paper- or carbon-dot-based methods mentioned in patents CN114994002A and CN113390840A ultimately rely on naked-eye colorimetry under natural light. This method is highly susceptible to ambient light and the observer's subjective judgment, achieving only rough qualitative or semi-quantitative results, failing to meet the need for precise quantification of pollutant concentrations. Existing technologies lack a dedicated portable device capable of standardizing excitation and acquisition conditions to convert subtle color / fluorescence changes into stable digital signals.

[0005] This invention addresses the aforementioned gaps and needs by proposing a collaborative and innovative technical solution. A novel Tb / Eu-BTC@BTEC material, enhanced through hydrogen bonding networks and designed with dual emission ratio fluorescence, is designed to achieve highly sensitive, selective, and interference-resistant internal reference detection of fleroxacin (FLE), norfloxacin (NOR), and enrofloxacin (ENR) concentrations in seawater. The Tb / Eu-BTC@BTEC fluorescence extraction and quantification device, by providing a standardized excitation and imaging environment, converts the concentration-dependent color changes generated by the material into precisely quantifiable digital image signals. This invention provides a complete and reliable technical pathway for the on-site, rapid, and visually accurate quantitative detection of quinolone antibiotics in seawater. Summary of the Invention

[0006] The purpose of this invention is to provide a portable seawater antibiotic ratio fluorescence sensing device and method based on a hydrogen-bonded network-enhanced lanthanide MOF. This is achieved by strengthening the structure with Tb through a hydrogen-bonded network. 3+ / Eu 3+ MOF materials with dual emission ratio fluorescence properties will be used to overcome the challenges of stability and selectivity in high-salinity seawater. Simultaneously, a portable fluorescence extraction device will be developed to provide a standardized optical acquisition environment, eliminating ambient light interference and enabling digital quantitative analysis of fluorescence signals. Ultimately, a complete integrated materials-device platform will be constructed to achieve rapid, visual, and accurate quantitative detection of fleroxacin (FLE), norfloxacin (NOR), and enrofloxacin (ENR) in seawater.

[0007] The technical solution of this invention:

[0008] A portable seawater antibiotic ratio fluorescence sensing method based on hydrogen bond network-enhanced lanthanide MOFs, comprising the following steps:

[0009] (1) Preparation of Tb / Eu-BTC@BTEC composite material:

[0010] Tb(NO3)3·6H2O, Eu(NO3)3·6H2O, H3BTC, and H4BTEC were ultrasonically dissolved in DMF, and then mixed with ultrapure water to obtain a mixed solution. The mixed solution was transferred to a reaction vessel, heated to 100-110℃ and maintained for 20-28 h. Unreacted ligands and metal ions were then removed by vacuum filtration, sequentially passing through ethanol, water, and ethanol. Finally, the mixture was dried at 50-70℃ for 8-12 h to obtain the Tb / Eu-BTC@BTEC composite material.

[0011] The mass ratio of Tb(NO3)3·6H2O, Eu(NO3)3·6H2O, H3BTC and H4BTEC is 36.2 : 1 : 16.8 : 2.24.

[0012] The volume ratio of DMF to ultrapure water was 5.7 : 34.3;

[0013] The concentration of Tb(NO3)3·6H2O in the mixed solution was 4.08 g / L;

[0014] (2) Construction of a portable seawater antibiotic ratio fluorescence sensor:

[0015] The portable seawater antibiotic ratio fluorescence sensor includes:

[0016] The device's light-shielding system is a sealed cuboid structure made of opaque material using 3D printing technology. It consists of an assemblable upper device body and a lower base. The upper surface of the upper device body is equipped with a mobile phone camera interface and a power supply fixing slot. The lower base is a sample placement area. The mobile phone camera interface can be adapted to the camera size of different smartphone models to ensure a tight fit after installation and completely block external light.

[0017] Light source array system: Integrated into the device's light shielding system, it is a multi-band light source array composed of multiple independently controlled LED beads (such as 295nm, 310nm, 365nm, 385nm). Users can select a single wavelength or perform wavelength combination irradiation by independent switches according to the optimal excitation requirements of the fluorescent material, so as to realize the "on-demand customization" of the excitation spectrum and improve the applicability of the device.

[0018] Smartphone and image processing unit: The smartphone serves as an image acquisition and processing terminal, capturing sample fluorescence images in a light-protected environment through an application and extracting the RGB values ​​of the target area of ​​the image.

[0019] (3) Integration and application of the detection system:

[0020] Step 1: Establishing the standard curve;

[0021] A series of standard solutions of target antibiotics (fluroxacin, norfloxacin, and enrofloxacin) with known concentrations were prepared. Tb / Eu-BTC@BTEC composite material was added to each solution, maintaining a dispersion concentration of 1 g / L. After mixing, the solutions were placed in transparent sample tubes and positioned in the sample placement area of ​​a portable seawater antibiotic ratio fluorescence sensor. The smartphone camera was tightly fitted to the camera interface of the portable seawater antibiotic ratio fluorescence sensor, and the color extraction software was activated. The desired wavelength excitation light source (e.g., 365 nm) was selected and activated. The smartphone camera was used to capture the sample fluorescence image via the application. The sample area was then manually selected within the fluorescence image, and the average RGB value of that area was manually obtained using an image analysis tool. The average RGB value was converted to a B / R value (the ratio of the blue channel intensity to the red channel intensity). With antibiotic concentration as the x-axis (X) and B / R value as the y-axis, a standard curve equation Y = kX + b and a correlation coefficient (R²) were obtained through linear fitting. 2 Record the equation and parameters for use in on-site testing.

[0022] Step 2: On-site sample testing;

[0023] Take a seawater sample, add Tb / Eu-BTC@BTEC composite material, control the dispersion concentration of Tb / Eu-BTC@BTEC composite material to 1 g / L, mix well, and then put it into a transparent sample tube and place it in the sample placement area of ​​the portable seawater antibiotic ratio fluorescence sensor; tightly connect the smartphone camera to the camera interface of the portable seawater antibiotic ratio fluorescence sensor, and open the color extraction software; select and turn on the same wavelength excitation light source as in step two (e.g., 365 nm). Use the application to control the smartphone camera to capture the sample fluorescence image and obtain the RGB values;

[0024] Step 3: Signal conversion and quantitative analysis;

[0025] The RGB values ​​obtained in step two are converted into B / R values ​​and substituted into the standard curve equation Y=kX+b pre-defined in step one to calculate the concentration of the target antibiotic in the seawater sample (X = (Y - b) / k).

[0026] Step 4: Recording and Outputting Results;

[0027] Record and output the calculated antibiotic concentration values ​​to complete the on-site testing.

[0028] The beneficial effects of this invention are:

[0029] A standardized and digital on-site visual quantitative solution was constructed: Addressing the issues of large subjective errors in naked-eye colorimetry and strong ambient light interference, this invention provides a standardized environment for excitation and imaging through a sealed, light-shielding design and a programmable multi-band light source array, completely eliminating the influence of external light and human interpretation. Combined with smartphone color recognition applications, subtle changes in fluorescence color are converted into precise RGB digital signals (B / R ratio), and a quantitative relationship with antibiotic concentration is established, achieving a leap from "visual judgment" to "digital quantification."

[0030] The system achieves the goal of rapid, portable, and efficient on-site testing: the entire testing system (materials + device) is easy to operate, requires no complex pretreatment, and responds quickly, completing the analysis of a single sample within minutes. The device is compact and portable, requiring only a smartphone to operate, overcoming the limitations of traditional large instruments that cannot be used on-site, and meeting the core requirements of rapid, portable, and low-cost operation for shipborne, shore-based, and emergency monitoring.

[0031] The system demonstrates excellent performance in practical applications, validating the feasibility of the technical solution. As shown in the examples, spiked recovery experiments on real seawater samples using this system showed recoveries of fleroxacin (FLE), norfloxacin (NOR), and enrofloxacin (ENR) ranging from 93.16% to 112.50%, 93.10% to 110.00%, and 94.50% to 116.40%, respectively, with relative standard deviations (RSDs) all below 5.94%. Furthermore, the limits of detection (LODs) reached 110.6 nM, 53.2 nM, and 66.2 nM, respectively. This fully demonstrates the reliability and practical value of the system for accurate quantitative detection in real seawater environments. Attached Figure Description

[0032] Figure 1 The images show the microstructure of the materials. (a)-(c) are scanning electron microscope (SEM) images of the H4BTEC-modified Tb / Eu-BTC material; (d)-(f) are SEM images of the Tb / Eu-BTC composite material.

[0033] Figure 2 This is a schematic diagram of the main structure of the portable fluorescence extraction and quantification device described in this invention. (a) is a front view, (b) is a side view, (c) is a top view, and (d) is a perspective view.

[0034] Figure 3 This is a schematic diagram of the base structure of the device described in this invention.

[0035] Figure 4 This is a photograph showing the actual portable fluorescence extraction and quantification device described in this invention.

[0036] Figure 5 The images show the results of quantitative visual detection of FLE in simulated seawater using the device of this invention under 365nm excitation. (a) shows the CIE 1931 chromaticity coordinates corresponding to different FLE concentrations, illustrating the regular color change from red to pink; (b) shows the linear fitting curve between the blue / red channel intensity ratio (B / R) calculated from the RGB values ​​extracted from the image and the FLE concentration, demonstrating the quantitative reliability of the visual signal.

[0037] Figure 6 The results of visual quantitative detection of NOR in simulated seawater using the device of the present invention are shown in the figure. (a) is the CIE colorimetric diagram corresponding to different concentrations of NOR; (b) is the linear fitting curve of B / R value and NOR concentration.

[0038] Figure 7 The results of visual quantitative detection of ENR in simulated seawater using the device of the present invention are shown in the figure. (a) is the CIE colorimetric diagram corresponding to different concentrations of ENR; (b) is the linear fitting curve of B / R value versus ENR concentration.

[0039] In the diagram: 1-Smartphone; 2-Device light shielding system; 3-Light source array system; 4-Mobile phone camera interface; 5-Power supply mounting slot; 6-Sample placement area. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0041] Example 1: Detection of fleroxacin (FLE) in seawater using the system of the present invention

[0042] (1) Preparation of Tb / Eu-BTC@BTEC composite material;

[0043] First, the Tb / Eu-BTC@BTEC composite material was prepared. 0.163 g of Tb(NO3)3·6H2O, 0.0045 g of Eu(NO3)3·6H2O, 0.0756 g of Trimesic acid (H3BTC), and 0.0101 g of 1,2,4,5-Benzenetetracarboxylic acid (H4BTEC) were weighed and dissolved ultrasonically in 5.7 mL of DMF. Then, 34.3 mL of ultrapure water was added and mixed thoroughly. The mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 100-110 °C for 20-28 hours. After the reaction, the product was collected by vacuum filtration and washed sequentially with ethanol, ultrapure water, and ethanol to remove unreacted ligands and metal ions. Finally, the obtained solid was dried at 50-70 °C for 8-12 hours to obtain the Tb / Eu-BTC@BTEC composite material. Figure 1 Tb / Eu-BTC@BTEC under scanning electron microscopy Figure 1 ac) and Tb / Eu-BTC ( Figure 1 The comparison between the two clearly shows that H4BTEC modifies Tb / Eu-BTC.

[0044] (2) Design of a portable fluorescence sensing platform;

[0045] A closed cuboid structure formed in one piece using 3D printing technology, consisting of an assemblable upper unit ( Figure 2 ) and the lower base ( Figure 3 The main body has a mobile phone camera interface 4 and a power supply mounting slot 5 on its upper surface; the base serves as the sample placement area 6. The interface 4 is designed according to the size of the mobile phone camera to ensure a tight fit after installation and complete isolation from external light. The light source array uses a 365nm emission band. The smartphone acts as the image acquisition terminal, extracting the RGB values ​​of the target area of ​​the image.

[0046] (3) Development of the standard curve;

[0047] Using simulated seawater as a matrix, 2 mL of fleroxacin (FLE) standard solutions with concentrations of 0, 4, 8, 12, 16, and 20 μM were prepared. 2 mg of Tb / Eu-BTC@BTEC composite material (dispersion concentration 1 g / L) was added to each standard solution, and the mixture was ultrasonically mixed. The mixed samples were then placed sequentially in the sample placement area of ​​the portable fluorescence extraction and quantification device described in this invention.

[0048] Connect the smartphone camera to the device's camera interface and open the color recognition application. Select and turn on the 365 nm ultraviolet light source in the device's light source array system. Control the camera to capture fluorescence images of the sample via the application. Based on this method, the RGB values ​​and CIE colorimetric properties of the FLE were obtained in the concentration range of 0–20 μM. Figure 5 a.

[0049] The RGB values ​​of each sample were converted by calculating the intensity ratio (B / R value) of the blue and red channels. Plotting the concentration (X, μM) of the FLE standard solution on the x-axis and the corresponding B / R value (Y) on the y-axis, a standard curve equation was obtained through linear fitting: Y = 0.0208X + 0.3926, R... 2 = 0.9818 (attached) Figure 5 b). Based on this equation and the signal fluctuations of the blank sample, the limit of detection (LOD) for FLE using this method was calculated to be 110.6 nM (3σ / k criterion). This serves as a quantitative basis for rapid on-site detection.

[0050] (4) Actual sample testing

[0051] Spiking and recovery experiments were conducted using seawater samples from Dalian, China, as examples of real samples. As shown in Table 1, FLE, NOR, and ENR were not found in these samples before their addition.

[0052] surface Initial parameters of seawater samples

[0053]

[0054] Based on this, a spiked recovery experiment was conducted to test the sensor's practicality. The image acquisition and signal extraction steps were repeated to obtain the average RGB value of the sample and convert it to a B / R value (denoted as Y_sample). Y_sample was substituted into the pre-defined standard curve equation Y = 0.0208X + 0.3926 from step (2) to calculate the concentration of fleroxacin in seawater. As shown in Table 2, in actual seawater samples, the recovery rate of FLE was 93.16%–112.50%, with a relative standard deviation (RSD) of less than 5.94%.

[0055] surface Spiking experiment of FLE in actual seawater sample dispersion system using a portable device

[0056]

[0057] Example 2: Detection of Norfloxacin (NOR) in seawater using the system of the present invention

[0058] (1) Preparation of Tb / Eu-BTC@BTEC composite material;

[0059] First, the Tb / Eu-BTC@BTEC composite material was prepared. 0.163 g of Tb(NO3)3·6H2O, 0.0045 g of Eu(NO3)3·6H2O, 0.0756 g of Trimesic acid (H3BTC), and 0.0101 g of 1,2,4,5-Benzenetetracarboxylic acid (H4BTEC) were weighed and dissolved ultrasonically in 5.7 mL of DMF. Then, 34.3 mL of ultrapure water was added and mixed thoroughly. The mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 100-110 °C for 20-28 hours. After the reaction, the product was collected by vacuum filtration and washed sequentially with ethanol, ultrapure water, and ethanol to remove unreacted ligands and metal ions. Finally, the obtained solid was dried at 50-70 °C for 8-12 hours to obtain the Tb / Eu-BTC@BTEC composite material.

[0060] (2) Design of a portable fluorescence sensing platform;

[0061] The sealed cuboid structure, integrally formed using 3D printing technology, consists of an assemblable upper unit and a lower base. The upper surface of the main body features a mobile phone camera interface 4 and a power supply mounting slot 5; the base serves as the sample placement area 6. The interface 4 is designed according to the size of the mobile phone camera to ensure a tight fit after installation and complete isolation from external light. The light source array utilizes a 365nm emission wavelength. The smartphone acts as the image acquisition device, extracting the RGB values ​​of the target area in the image.

[0062] (3) Development of the standard curve;

[0063] Using simulated or representative seawater as a matrix, prepare 2 mL of norfloxacin (NOR) standard solutions with concentrations of 0, 4, 8, 12, 16, and 20 μM. Add 2 mg of Tb / Eu-BTC@BTEC composite material (dispersion concentration 1 g / L) to each standard solution and mix ultrasonically. Place the mixed samples sequentially into the sample placement area of ​​the portable fluorescence extraction and quantification device described in this invention.

[0064] The smartphone camera was tightly fitted to the device's camera interface, and the color recognition application was opened. The 365 nm ultraviolet light source in the device's light source array system was selected and turned on. The camera was controlled via the application to capture fluorescence images of the sample. Based on this method, the RGB values ​​and CIE colorimetric properties of NOR in the concentration range of 0–20 μM were obtained. Figure 6 a.

[0065] The RGB values ​​of each sample were converted by calculating the intensity ratio (B / R value) of the blue and red channels. Plotting the concentration of the NOR standard solution (X, μM) on the x-axis and the corresponding B / R value (Y) on the y-axis, a standard curve equation was obtained through linear fitting: Y = 0.0233X + 0.5077 (e.g., according to the attached...). Figure 6 (b) Obtain the fitted curve. A significant linear relationship exists between the fluorescence signal of the material and the pollutant concentration (Rb). 2 = 0.9996). Based on this equation and the signal fluctuation of the blank sample, the detection limit (LOD) of this method for NOR was calculated to be 53.2 nM (using the 3σ / k criterion). This serves as a quantitative basis for rapid on-site detection.

[0066] (4) Actual sample testing;

[0067] Spiking and recovery experiments were conducted using seawater samples from Dalian, China, as real samples. As shown in Table 1, FLE, NOR, and ENR were not detected in these samples before their addition. Based on this, the practicality of the sensor was tested using a spiked recovery experiment. The image acquisition and signal extraction steps described above were repeated to obtain the average RGB value of the sample and convert it to a B / R value (denoted as Y_sample). Substituting Y_sample into the pre-defined standard curve equation Y = 0.0233X + 0.5077 from step (2), the concentration of norfloxacin in seawater was calculated. As shown in Table 3, the recovery rate of NOR in the actual seawater samples was 93.10%–110.00%, with a relative standard deviation (RSD) of less than 5.59%.

[0068] surface Portable device for spiking NOR in actual seawater sample dispersion systems

[0069]

[0070] Example 3: Detection of enrofloxacin (ENR) in seawater using the system of the present invention.

[0071] (1) Preparation of Tb / Eu-BTC@BTEC composite material

[0072] First, the Tb / Eu-BTC@BTEC composite material was prepared. 0.163 g of Tb(NO3)3·6H2O, 0.0045 g of Eu(NO3)3·6H2O, 0.0756 g of Trimesic acid (H3BTC), and 0.0101 g of 1,2,4,5-Benzenetetracarboxylic acid (H4BTEC) were weighed and dissolved ultrasonically in 5.7 mL of DMF. Then, 34.3 mL of ultrapure water was added and mixed thoroughly. The mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 100-110 °C for 20-28 hours. After the reaction, the product was collected by vacuum filtration and washed sequentially with ethanol, ultrapure water, and ethanol to remove unreacted ligands and metal ions. Finally, the obtained solid was dried at 50-70 °C for 8-12 hours to obtain the Tb / Eu-BTC@BTEC composite material.

[0073] (2) Design of a portable fluorescence sensing platform;

[0074] The enclosed cuboid structure, formed in one piece using 3D printing technology, consists of an assemblable upper unit (attached). Figure 2 ) and lower base (with) Figure 3 The main body has a mobile phone camera interface 4 and a power supply mounting slot 5 on its upper surface; the base serves as the sample placement area 6. The interface 4 is designed according to the size of the mobile phone camera to ensure a tight fit after installation and complete isolation from external light. The light source array uses a 365nm emission band. The smartphone acts as the image acquisition terminal, extracting the RGB values ​​of the target area of ​​the image.

[0075] (3) Development of the standard curve;

[0076] Using simulated or representative seawater as a matrix, prepare 2 mL of enrofloxacin (ENR) standard solutions with concentrations of 0, 3, 6, 9, 12, and 15 μM. Add 2 mg of Tb / Eu-BTC@BTEC composite material (dispersion concentration 1 g / L) to each standard solution and mix ultrasonically. Place the mixed samples sequentially into the sample placement area of ​​the portable fluorescence extraction and quantification device described in this invention.

[0077] The smartphone camera was tightly fitted to the device's camera interface, and the color recognition application was opened. The 365 nm ultraviolet light source in the device's light source array system was selected and turned on. The camera was controlled via the application to capture fluorescence images of the sample. Subsequently, the sample area was selected in the image. Based on this method, the RGB values ​​of ENR in the concentration range of 0–15 μM and the CIE colorimetric values ​​were obtained. Figure 7 a.

[0078] The RGB values ​​of each sample were converted by calculating the intensity ratio (B / R value) of the blue and red channels. Plotting the concentration of the ENR standard solution (X, μM) on the x-axis and the corresponding B / R value (Y) on the y-axis, a standard curve equation was obtained through linear fitting: Y = 0.0149X + 0.5133 (e.g., according to the attached...). Figure 7 (b) The fitted curve was obtained. A significant linear relationship exists between the fluorescence signal of the material and the pollutant concentration (R² = 0.9846). Based on this equation and the signal fluctuation of the blank sample, the limit of detection (LOD) for ENR using this method was calculated to be 66.2 nM (using the 3σ / k criterion). This serves as a quantitative basis for rapid on-site detection.

[0079] (4) Actual sample testing;

[0080] Spiking and recovery experiments were conducted using seawater samples from Dalian, China, as real samples. As shown in Table 1, FLE, NOR, and ENR were not detected in these samples before their addition. Based on this, the practicality of the sensor was tested using a spiked recovery experiment. The image acquisition and signal extraction steps described above were repeated to obtain the average RGB value of the sample and convert it to a B / R value (denoted as Y_sample). Substituting Y_sample into the pre-defined standard curve equation Y = 0.0149X + 0.5133 in step (2), the concentration of enrofloxacin in the seawater was calculated. As shown, in actual seawater samples, the recovery rate of ENR was 94.50%–116.40%, with a relative standard deviation (RSD) of less than 4.89%.

[0081] surface Portable device for ENR spiking experiments in actual seawater sample dispersion systems

[0082]

[0083] The above are embodiments of the present invention. The above embodiments and specific parameters are only for clearly illustrating the invention verification process and are not intended to limit the patent protection scope of the present invention. The patent protection scope of the present invention shall still be determined by its claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the protection scope of the present invention.

Claims

1. A portable seawater antibiotic ratio fluorescence sensing method based on hydrogen-bonded network-enhanced lanthanide MOFs, characterized in that, The steps are as follows: (1) Preparation of Tb / Eu-BTC@BTEC composite material: Tb(NO3)3·6H2O, Eu(NO3)3·6H2O, H3BTC, and H4BTEC were ultrasonically dissolved in DMF, and then mixed with ultrapure water to obtain a mixed solution. The mixed solution was transferred to a reaction vessel, heated to 100-110℃ and maintained for 20-28 h. Unreacted ligands and metal ions were then removed by vacuum filtration, sequentially passing through ethanol, water, and ethanol. Finally, the mixture was dried at 50-70℃ for 8-12 h to obtain the Tb / Eu-BTC@BTEC composite material. (2) Construction of a portable seawater antibiotic ratio fluorescence sensor: (3) Integration and application of the detection system: Step 1: Establishing the standard curve; Step 2: On-site sample testing; Take a seawater sample, add Tb / Eu-BTC@BTEC composite material, control the dispersion concentration of Tb / Eu-BTC@BTEC composite material to 1 g / L, mix well, put it into a transparent sample tube and place it in the sample placement area of ​​the portable seawater antibiotic ratio fluorescence sensor; tightly fit the smartphone camera with the mobile phone camera interface of the portable seawater antibiotic ratio fluorescence sensor, and open the color extraction software; select and turn on the same wavelength excitation light source as in step two; use the application to control the mobile phone camera to capture the sample fluorescence image and obtain the RGB value; Step 3: Signal conversion and quantitative analysis; The RGB values ​​obtained in step two are converted into B / R values ​​and substituted into the standard curve equation Y = kX + b pre-defined in step one to calculate the concentration of the target antibiotic in the seawater sample. Step 4: Recording and Outputting Results; Record and output the calculated antibiotic concentration values ​​to complete the on-site testing.

2. The portable seawater antibiotic ratio fluorescence sensing method according to claim 1, characterized in that, In step (1), the mass ratio of Tb(NO3)3·6H2O, Eu(NO3)3·6H2O, H3BTC and H4BTEC is 36.2 : 1 : 16.8 : 2.24; The volume ratio of DMF to ultrapure water was 5.7 : 34.3; The concentration of Tb(NO3)3·6H2O in the mixed solution was 4.08 g / L.

3. The portable seawater antibiotic ratio fluorescence sensing method according to claim 1, characterized in that, The portable seawater antibiotic ratio fluorescence sensor includes: The device's light-shielding system is a sealed cuboid structure made of opaque material using 3D printing technology. It consists of an assemblable upper device body and a lower base. The upper surface of the upper device body is equipped with a mobile phone camera interface and a power supply fixing slot. The lower base is a sample placement area. The mobile phone camera interface can be adapted to the camera size of different smartphone models to ensure a tight fit after installation and completely block external light. Light source array system: Integrated into the device's light shielding system, it is a multi-band light source array composed of multiple independently controlled LED beads; users can select a single wavelength or perform wavelength combination irradiation by independently switching according to the optimal excitation requirements of the fluorescent material. Smartphone and image processing unit: The smartphone serves as an image acquisition and processing terminal, capturing sample fluorescence images in a light-protected environment through an application and extracting the RGB values ​​of the target area of ​​the image.

4. The portable seawater antibiotic ratio fluorescence sensing method according to claim 1, characterized in that, The specific steps for establishing the standard curve in step one are as follows: A series of target antibiotic standard solutions with known concentrations were prepared, and Tb / Eu-BTC@BTEC composite material was added to each solution. The dispersion concentration of the Tb / Eu-BTC@BTEC composite material was controlled at 1 g / L. After mixing, the solutions were placed in transparent sample tubes and placed in the sample placement area of ​​a portable seawater antibiotic ratio fluorescence sensor. The smartphone camera was tightly connected to the camera interface of the portable seawater antibiotic ratio fluorescence sensor, and the color extraction software was opened. The required wavelength excitation light source was selected and turned on. The smartphone camera was used to capture the sample fluorescence image through the application. Then, the sample area was manually selected in the sample fluorescence image, and the average RGB value of the sample area was manually obtained using an image analysis tool. The average RGB value was converted into a B / R value (the ratio of the intensity of the blue channel to the red channel). With the antibiotic concentration as the x-axis and the B / R value as the y-axis, the standard curve equation Y = kX + b and the correlation coefficient R were obtained through linear fitting. 2 .

Images