A fluorescence detection method based on polydopamine nanoparticles and pH regulation of bisphenol s

Abstract

The application discloses a kind of based on polydopamine nanoparticle and pH regulation bisphenol S fluorescence detection method, belong to analytical detection technical field.The method for detecting bisphenol S based on pH regulation of the application includes as follows: taking sample to be measured and water and pH=9.0 phosphate buffer solution are mixed and oscillate uniformly, the fluorescence spectrum of the sample under 310nm excitation is determined, with 460nm fluorescence intensity and according to standard curve, the content of bisphenol S in the sample to be measured is calculated;The application enhances the fluorescence emission and characteristic absorption of bisphenol S by simple pH regulation method, realizes the high sensitivity detection of bisphenol S, the method does not need to prepare complex material with complicated process, has the advantages of sensitive, fast and simple, has good detection capacity to bisphenol S in actual sample.

Description

Technical Field

[0001] This invention relates to a fluorescence detection method for bisphenol S based on polydopamine nanoparticles and pH regulation, belonging to the field of analytical detection technology. Background Technology

[0002] After bisphenol A (BPA) was identified as a harmful endocrine disruptor and its use in food packaging, baby bottles, thermal paper, and other products was restricted or banned, various BPA structural analogs, including BPA S, BPA F, and tetrabromobisphenol A, gradually replaced BPA in industrial production to avoid threats to consumer health and reduce environmental impact. However, with the widespread use of these alternatives and the deepening of research on them, multiple studies have shown that BPA S has similar hormone activity, cytotoxicity, neurotoxicity, and reproductive and developmental toxicity to BPA. Furthermore, BPA S has a longer biological half-life and stronger resistance to biodegradation, allowing it to enter the human body through multiple routes of exposure and accumulate, ultimately leading to serious harms such as obesity, immune dysfunction, and reproductive defects.

[0003] Currently available techniques for detecting bisphenol S include liquid chromatography and its associated methods, ultraviolet spectrophotometry, electrochemical methods, chemiluminescence methods, and fluorescence spectroscopy. Among these, liquid chromatography-tandem mass spectrometry (LC-MS / MS) is the national standard-specified method for determining the migration of bisphenol S in food, food contact materials, and products, with detection limits and quantitation limits as low as 0.03 μg / kg and 0.10 μg / kg, respectively. Although LC-MS / MS offers extremely high specificity and sensitivity, its high requirements for expensive instruments and skilled operators, cumbersome sample pretreatment procedures, and long analysis times cannot be ignored. Therefore, a series of new technologies have been proposed to achieve accurate and rapid detection of bisphenol S, such as electrochemical sensors that modify glassy carbon electrodes with different materials, and fluorescent sensors that combine metal-organic frameworks, molybdenum disulfide nanosheets, gold nanoparticles, and fluorescent materials. However, most electrochemical sensors require the use of at least two materials to achieve functional complementarity in electrode modification. High-performance fluorescent sensors also mostly use nucleic acid aptamers to improve their specific recognition ability of bisphenol S. The use of composite materials and biological materials has also increased the complexity and cost of detection methods to some extent. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a method for detecting bisphenol S using polydopamine nanoparticles (DPA-PDs) as fluorescent probes supplemented by pH control. This method prepares DPA-PDs via a simple one-step hydrothermal method using dopamine hydrochloride as a precursor. After deprotonation in an alkaline environment, the fluorescence emission and characteristic absorption band of bisphenol S are enhanced, and the red-shifted characteristic absorption band overlaps with the excitation and emission spectra of DPA-PDs. Therefore, in an alkaline environment, as the concentration of bisphenol S increases, the 310 nm fluorescence emission of DPA-PDs is quenched due to the internal filtration effect, while the 460 nm fluorescence emission of bisphenol S gradually increases. This allows for high-sensitivity detection of bisphenol S using the 460 nm fluorescence intensity or the ratio of 460 nm fluorescence intensity to 310 nm fluorescence intensity. This method is simple to operate and has high sensitivity and accuracy.

[0005] To achieve the above objectives, the following technical solution is provided:

[0006] The first objective of this invention is to provide a method for detecting bisphenol S based on pH regulation, the method comprising the following:

[0007] Take the sample to be tested, mix it with water and phosphate buffer solution with pH=9.0, and shake it evenly. Measure the fluorescence spectrum of the sample under 310 nm excitation. Calculate the content of bisphenol S in the sample based on the fluorescence intensity at 460 nm and the standard curve.

[0008] In one embodiment, the concentration of the phosphate buffer solution is 0.1–0.5 mol / L.

[0009] In one embodiment, the volume ratio of the sample to be tested to water and phosphate buffer is 1:1 to 2:7.

[0010] In one embodiment, the standard curve is established by: mixing a series of concentrations of bisphenol S with water and phosphate buffer solution and shaking until homogeneous, and measuring the fluorescence spectrum of each sample under 310 nm excitation; constructing a standard curve with the fluorescence intensity of bisphenol S at 460 nm as the ordinate and the concentration of bisphenol S as the abscissa.

[0011] A second objective of this invention is to provide a fluorescence detection method for bisphenol S based on polydopamine nanoparticles and pH regulation, the method comprising the following:

[0012] (1) Construction of quantitative relationship model

[0013] The polydopamine nanoparticle DPA-PDs fluorescent probe system was shaken with a series of bisphenol S solutions of known concentrations to obtain standard samples. The emission spectra of each standard sample were measured under 290 nm excitation. A quantitative relationship model was established with the bisphenol S concentration as the abscissa and the fluorescence intensity at 460 nm or the ratio of the fluorescence intensity at 460 nm to the fluorescence intensity at 310 nm as the ordinate.

[0014] (2) Determination of bisphenol S content in the sample

[0015] The polydopamine nanoparticle DPA-PDs fluorescent probe system was mixed with the test solution and shaken to obtain the test sample. Then the emission spectrum of the test sample under 290nm excitation was measured. The content of bisphenol S in the test sample was calculated based on the fluorescence intensity at 460nm or the ratio of the fluorescence intensity at 460nm to the fluorescence intensity at 310nm and the quantitative relationship model constructed in step (1).

[0016] In one embodiment, the preparation of the DPA-PDs fluorescent probe system includes the following:

[0017] Dopamine hydrochloride was dissolved in water and then transferred to a high-pressure reactor for hydrothermal reaction to obtain a crude product. The crude product was filtered through a filter membrane to obtain a DPA-PDs solution. The DPA-PDs solution was mixed with water and an alkaline buffer solution to obtain the DPA-PDs fluorescent probe system.

[0018] In one embodiment, the mass-to-volume ratio of dopamine hydrochloride to water is 0.1:10-30 g / mL.

[0019] In one embodiment, the hydrothermal reaction is carried out at a temperature of 180–200°C for 8–12 hours.

[0020] In one embodiment, the alkaline buffer solution is a sodium hydroxide-adjusted phosphate buffer solution with a pH value greater than 7, a concentration of 0.1–0.2 mol / L, and a volume accounting for 50–90% of the total volume of the DPA-PDs fluorescent probe system; preferably, the pH value is 9.

[0021] In one embodiment, the concentration corresponding to the DPA-PDs solution having an absorbance of 0.700 at 284 nm in the UV-Vis absorption spectrum is defined as 1 unit.

[0022] In one embodiment, the concentration of DPA-PDs in the DPA-PDs fluorescent probe system described in steps (1) and (2) is 0.1-0.5 units; the DPA-PDs fluorescent probe system accounts for 90% of the total sample volume.

[0023] In one embodiment, the DPA-PDs fluorescent probe system includes a DPA-PDs solution, water, and an alkaline buffer solution in a volume ratio of 1 to 5:1:7.

[0024] A third objective of this invention is to provide an application of the above-described method in the detection of bisphenol S.

[0025] Beneficial effects:

[0026] (1) This invention prepares polydopamine nanoparticles (DPA-PDs) via a hydrothermal method using dopamine hydrochloride as a precursor, and enhances the fluorescence emission and characteristic absorption of bisphenol S by combining a simple pH control method. In an alkaline environment, the fluorescence emission of DPA-PDs is quenched by bisphenol S due to the internal filtration effect, while the fluorescence emission of bisphenol S gradually increases with increasing concentration. The detection limit of the single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S is as low as 0.075 μmol / L, and the detection limit of the ratiometric fluorescence sensing model constructed based on the emission intensity ratio of DPA-PDs to bisphenol S is as low as 0.257 μmol / L.

[0027] (2) The detection method established by this invention does not require the preparation of composite materials with complicated processes. It has good selectivity for bisphenol S in a series of bisphenol compounds and has the advantages of being sensitive, fast and simple. Attached Figure Description

[0028] Figure 1 The spectral characteristics of the polydopamine nanoparticles prepared in Example 1 of the present invention are shown in the following figures: (A) Three-dimensional fluorescence spectrum of polydopamine nanoparticles; (B) Ultraviolet-visible absorption spectrum, excitation spectrum (λem = 310 nm) and emission spectrum (λex = 280 nm) of polydopamine nanoparticles.

[0029] Figure 2 Example 2 of this invention presents a single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S; (A) Emission spectra of bisphenol S at different concentrations; (B) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-700 μmol / L); (C) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-100 μmol / L), and linear fitting results in the range of 0.5-100 μmol / L; (D) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-10 μmol / L).

[0030] Figure 3The ratiometric fluorescence sensing model constructed in Example 3 of this invention includes: (A) Emission spectra of the system at different concentrations of bisphenol S; (B) Relationship between fluorescence quenching rate at 310 nm and bisphenol S concentration (0-500 μmol / L); (C) Relationship between fluorescence enhancement at 460 nm and bisphenol S concentration (0-500 μmol / L); (D) Relationship between the ratio of emission intensity at 460 nm and 310 nm and bisphenol S concentration (0-500 μmol / L); (E) Relationship between fluorescence enhancement at 460 nm and bisphenol S concentration. (F) Relationship curves between concentrations (0-100 μmol / L) and linear fitting results in the range of 1-70 μmol / L; (G) Relationship curves between the ratio of emission intensity at 460 nm and 310 nm and bisphenol S concentration (0-100 μmol / L), and linear fitting results in the range of 10-100 μmol / L;

[0031] Figure 4 The following are spectral characteristic diagrams of bisphenol S under different pH environments in Example 4 of the present invention: (A) Fluorescence emission spectrum of bisphenol S under corresponding optimal excitation wavelengths in different pH environments; (B) UV-Vis absorption spectrum of bisphenol S under different pH environments; (C) Relationship curve between peak wavelength of characteristic absorption peak of bisphenol S and pH value; (D) Relationship curve between absorbance of characteristic absorption peak of bisphenol S and pH value; (E) Fluorescence emission spectrum of polydopamine nanoparticles under 280 nm excitation in different pH environments (inset shows the relationship curve between fluorescence intensity at 310 nm and pH value); (F) UV-Vis absorption spectrum of polydopamine nanoparticles under different pH environments.

[0032] Figure 5 The following are data analysis diagrams under different detection conditions of the present invention: (A) Emission spectra of polydopamine nanoparticles, bisphenol S, and a mixture of polydopamine nanoparticles and bisphenol S under 290 nm excitation; (B) UV-Vis absorption spectra of polydopamine nanoparticles, bisphenol S, and a mixture of polydopamine nanoparticles and bisphenol S; (C) UV-Vis absorption spectrum of bisphenol S, excitation spectrum and emission spectrum of polydopamine nanoparticles; (D) Time-resolved fluorescence spectra of polydopamine nanoparticles before and after the addition of bisphenol S.

[0033] Figure 6The following is a data graph showing the selectivity and anti-interference capabilities of Example 5 of the present invention: (A) fluorescence quenching rate at 310 nm, (B) fluorescence enhancement at 460 nm, and (C) the ratio of emission intensity at 460 nm to 310 nm when bisphenol S and a potential interfering agent are added respectively; when bisphenol S and a potential interfering agent are added simultaneously, the following are the system's (D) fluorescence quenching rate at 310 nm, (E) fluorescence enhancement at 460 nm, and (F) the ratio of emission intensity at 460 nm to 310 nm.

[0034] Figure 7 The following are linear model diagrams established in Sprite samples according to Example 6 of the present invention: (A) Linear model diagram established based on the fluorescence enhancement at 460 nm; (B) Linear model diagram established based on the ratio of emission intensity at 460 nm and 310 nm. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The specific embodiments described below further illustrate the present invention.

[0036] Example 1

[0037] The preparation of polydopamine nanoparticles (DPA-PDs) includes the following:

[0038] 0.1 g of dopamine hydrochloride was dissolved in 10 mL of deionized water, and the resulting transparent solution was transferred to a 15 mL high-pressure reactor lined with polytetrafluoroethylene. The mixture was heated at 200 °C for 8 h to obtain the crude product. After naturally cooling to room temperature, the crude product was filtered through a 0.22 μm filter membrane. The filtered DPA-PDs solution was stored at 4 °C for later use.

[0039] The concentration corresponding to a DPA-PDs solution with an absorbance of 0.700 at 284 nm in the UV-Vis absorption spectrum was defined as 1 unit.

[0040] like Figure 1 As shown, the UV-Vis absorption spectra of DPA-PDs exhibit characteristic absorption peaks at 220 nm and 280 nm. The three-dimensional fluorescence spectrum of DPA-PDs shows only one emission center, and DPA-PDs exhibit wavelength-independent fluorescence emission at 310 nm, corresponding to an optimal excitation wavelength of 280 nm.

[0041] Example 2

[0042] A pH-controlled method for detecting bisphenol S, the method comprising the following steps:

[0043] (1) Construction of standard curve

[0044] Mix 200 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) and shake well. Then, add 100 μL of bisphenol S solution of different concentrations (1, 3, 5, 7, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000 μmol / L) respectively. For the blank control group, add an equal volume of deionized water and shake well again. Measure the fluorescence spectrum of each sample under 310 nm excitation. Construct a standard curve with the fluorescence intensity of bisphenol S at 460 nm as the ordinate and the concentration of bisphenol S as the abscissa.

[0045] (2) Detection of bisphenol S in the sample to be tested

[0046] Take 100 μL of the sample to be tested, mix it with 200 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH=9.0) and shake it evenly. Measure the fluorescence spectrum of the sample under 310 nm excitation and calculate the content of bisphenol S in the sample to be tested according to the standard curve constructed in step (1).

[0047] The results are as follows Figure 2 As shown, the intrinsic fluorescence intensity of bisphenol S at 460 nm is positively correlated with the concentration of bisphenol S in the range of 0-200 μmol / L. Figure 2 B), and the two showed a higher linear correlation in the range of 0-100 μmol / L; the linear fitting results showed that, under 310 nm excitation, the fluorescence intensity of bisphenol S at 460 nm was linearly correlated with the concentration of bisphenol S in the range of 0.5-100 μmol / L (R). 2 The detection limit was calculated to be 0.075 μmol / L (0.9950); however, when the concentration of bisphenol S exceeded 200 μmol / L and increased further, the effect of the internal filtration gradually strengthened, and the fluorescence intensity at 460 nm no longer maintained a monotonically increasing trend. Figure 2 B).

[0048] Example 3

[0049] A method for detecting bisphenol S combining polydopamine nanoparticles and pH regulation, the method comprising the following steps:

[0050] (1) Construction of standard curve

[0051] 100 μL of DPA-PDs solution (concentration of 1 unit), 100 μL of deionized water, and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken thoroughly. Then, 100 μL of bisphenol S solution with different concentrations (1, 3, 5, 7, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000 μmol / L) were added to each sample. The blank control group was prepared by adding an equal volume of deionized water. The mixture was shaken thoroughly again. The fluorescence spectra of each sample were measured under 290 nm excitation. The fluorescence spectrum was plotted on the x-axis as the concentration of bisphenol S solution and on the y-axis as IL. 460 / I 310 A standard curve is constructed using the ratio as the ordinate;

[0052] (2) Detection of bisphenol S in the sample to be tested

[0053] Take 100 μL of the sample to be tested, mix it with 100 μL of DPA-PDs solution, 100 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH=9.0) and shake it evenly. Measure the fluorescence spectrum of the sample under 290 nm excitation and calculate the content of bisphenol S in the sample to be tested according to the standard curve constructed in step (1).

[0054] The results are as follows Figure 3 As shown, with increasing bisphenol S concentration, the fluorescence emission at 310 nm attributed to DPA-PDs was gradually quenched, while the emission peak at 460 nm attributed to the intrinsic fluorescence of bisphenol S gradually increased. Figure 3 A). Regarding the fluorescence quenching rate at 310 nm, the quenching rate approaches saturation when the bisphenol S concentration is greater than or equal to 200 μmol / L; however, in the range of 0-20 μmol / L, the correlation between the fluorescence quenching rate caused by bisphenol S and the bisphenol S concentration is poor, ultimately making it difficult to find a curve with a good linear correlation (R0) in the relationship between the fluorescence quenching rate and the bisphenol S concentration at 310 nm. 2 The range is close to or greater than 0.99.

[0055] Although there is no significant linear correlation between the quenching rate of the emission peak at 310 nm and the bisphenol S concentration, the ratio of emission intensity at 460 nm to that at 310 nm (I 460 / I 310 The correlation between the concentration of bisphenol S and the concentration of bisphenol S is a two-stage linear relationship within the range of ≤100 μmol / L. For example... Figure 3 As shown in F and 3G, I 460 / I 310The concentration of bisphenol S showed a linear correlation in the ranges of 1-10 μmol / L and 10-100 μmol / L, and the calculated detection limit was 0.257 μmol / L.

[0056] Furthermore, although the single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S has a lower detection limit (Example 2), the ratiometric fluorescence sensing model constructed by introducing DPA-PDs (I... 460 / I 310 This avoids the irregular changes in fluorescence intensity at 460 nm caused by the internal filtration effect when the bisphenol S concentration is greater than 200 μmol / L, and has a better qualitative discrimination effect in the high concentration range (e.g., Figure 3 C or Figure 2 B and Figure 3 (as shown in D).

[0057] Example 4: pH Condition Optimization

[0058] Following the method in Example 2, 200 μL of deionized water, 100 μL of bisphenol S solution, or 100 μL of DPA-PDs solution were mixed with 700 μL of phosphate buffer solution and shaken thoroughly. The concentration of bisphenol S solution was 5 mmol / L, the concentration of DPA-PDs solution was 1 unit, the concentration of phosphate buffer solution was 0.1 mol / L, and the pH values ​​were 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, and 12.0, respectively. The fluorescence spectra of each sample were measured under excitation at 290 nm.

[0059] The results are as follows Figure 4 As shown in Figure B, with increasing pH, the two characteristic absorption peaks of bisphenol S exhibit a consistent trend. The two characteristic absorption peaks, originally located at 234 nm (characteristic absorption peak 1) and 259 nm (characteristic absorption peak 2), will red-shift to approximately 260 nm and 292 nm, respectively, and the intensity of the absorption peaks will first decrease and then increase. The red-shift of characteristic absorption peak 1 mainly occurs as the pH increases from 7.0 to 9.0, with the pH inflection point of the absorbance change at 8.0; while the red-shift of characteristic absorption peak 2 is completed as the pH increases from 6.0 to 8.0, with the pH inflection point of the absorbance change at 7.0. Regarding fluorescence characteristics (… Figure 4 A) When the system pH is less than 7.0, the emission peak of bisphenol S is located at 500 nm; as the pH increases to 10.0, the emission peak gradually blue-shifts and the fluorescence emission intensity significantly increases, corresponding to an optimal excitation wavelength changing from 280 nm to 310 nm; when the pH further increases, the emission peak continues to blue-shift to 394 nm and the full width at half maximum (FWHM) significantly decreases, while the intensity further increases. It is speculated that the unique response of the spectral characteristics of bisphenol S to pH is related to its deprotonation process in an alkaline environment. For DPA-PDs, Figure 4E indicates that the system pH only affects the fluorescence emission intensity of DPA-PDs without affecting the peak position. The fluorescence emission intensity of DPA-PDs gradually decreases with increasing pH and is almost completely quenched at pH ≥ 11.0. When pH is greater than 8.0, the characteristic absorption peak of DPA-PDs at 280 nm undergoes a redshift with increasing pH, and a new broad absorption band at 434 nm is added to its absorption spectrum at pH ≥ 11.0. Figure 4 F). Taking into account the influence of pH regulation on the spectral characteristics of DPA-PDs and bisphenol S, pH 9.0 was selected as the detection environment for bisphenol S. This not only fully enhances the intrinsic fluorescence and characteristic absorption of bisphenol S, but also avoids the complete quenching of the fluorescence emission of DPA-PDs under strongly alkaline conditions.

[0060] At pH 9.0, bisphenol S significantly quenched the fluorescence emission of DPA-PDs at 310 nm and produced its intrinsic fluorescence emission peak at 460 nm. Figure 5 A). Figure 5 The UV-Vis absorption spectrum shown in Figure B indicates that the absorption spectrum (red line) of the DPA-PDs and bisphenol S mixture is basically consistent with the superimposed spectrum (green line) of the two monomer absorption spectra. This means that no non-fluorescent ground-state complex is generated in the DPA-PDs and bisphenol S mixture, ruling out the existence of a static quenching mechanism. Comparing the spectral characteristics of bisphenol S and DPA-PDs reveals that the characteristic absorption peak 2 of bisphenol S at 292 nm overlaps with both the excitation and emission spectra of DPA-PDs. Figure 5 C), which is also close to the selected excitation wavelength (290 nm), suggests the existence of two fluorescence quenching mechanisms characterized by donor-acceptor spectral overlap: internal filtering and resonant energy transfer. Furthermore, Figure 5 The time-resolved fluorescence spectrum shown in D indicates that the fluorescence lifetime of DPA-PDs remained essentially unchanged before and after the addition of bisphenol S. Therefore, the contribution of the resonance energy transfer mechanism to the fluorescence quenching of DPA-PDs was ruled out. It can be determined that bisphenol S mainly quenched the fluorescence of DPA-PDs based on the internal filtering effect. Bisphenol S competes with DPA-PDs for the absorption of excitation light and the absorption of fluorescence emission from DPA-PDs.

[0061] Example 5: Selectivity and Anti-interference Capability

[0062] In addition to the four bisphenol compounds (bisphenol A, bisphenol AF, bisphenol b, and bisphenol F), phenol and catechol, as well as common water ions (Na+), were also selected as potential interfering substances. + K + Ca 2+ Mg 2+ Zn2+ SO4 2- ).

[0063] In the selectivity experiment, following the method in Example 3, 100 μL of DPA-PDs solution (concentration of 1 unit), 100 μL of deionized water, 100 μL of bisphenol S solution or interfering agent solution, and 700 μL of phosphate buffer solution (0.1 mol / L, pH 9) were mixed and shaken thoroughly. The concentration of bisphenol S solution was 100 μmol / L, the concentration of organic interfering agent solution was 500 μmol / L, and the concentration of ionic interfering agent solution was 5 mmol / L. The fluorescence spectra of each sample were measured under excitation at 290 nm.

[0064] In the anti-interference ability experiment, following the method in Example 3, 100 μL of DPA-PDs solution (concentration of 1 unit), 100 μL of bisphenol S solution, 100 μL of interfering agent solution, and 700 μL of phosphate buffer solution (0.1 mol / L, pH 9) were mixed and shaken until homogeneous. The concentration of bisphenol S solution was 100 μmol / L, the concentration of organic interfering agent solution was 500 μmol / L, and the concentration of ionic interfering agent solution was 5 mmol / L. The fluorescence spectrum of each sample was measured under excitation at 290 nm.

[0065] Depend on Figure 6 The results show that relying solely on the fluorescence quenching rate of the emission peak at 310 nm is insufficient for the specific detection of bisphenol S; however, the ratio of fluorescence enhancement at 460 nm caused by bisphenol S to the emission intensities at both 460 nm and 310 nm is significantly higher than that of other potential interfering substances, even when the concentration of bisphenol S is lower than that of these potential interfering substances. Although bisphenol AF, Ca... 2+ With Zn 2+ It can also induce fluorescence enhancement at 460 nm, but the corresponding fluorescence enhancement is much lower than that of bisphenol S (BPS). Figure 6 (B) Furthermore, when these interfering substances coexist with bisphenol S, they do not significantly interfere with the fluorescence enhancement at 460 nm induced by bisphenol S. These results indicate that the bisphenol S detection method based on DPA-PDs and pH regulation proposed in this invention exhibits good selectivity and anti-interference ability for bisphenol S.

[0066] Example 6

[0067] The method for detecting bisphenol S in real samples based on DPA-PDs and pH control includes the following steps:

[0068] Bottled drinking water, Sprite, plastic bottles, plastic cups, and food plastic bags were selected as actual samples for the experiment. Bottled drinking water and Sprite, as actual samples, did not require pretreatment. 0.1g of each of the three plastic products (plastic bottle, plastic cup, and food plastic bag) was washed with ultrapure water and dried. Then, each product was added to a beaker containing 100mL of ultrapure water, covered with aluminum foil, and heated at 80℃ for 1 hour. After cooling to room temperature, the plastic products were removed, and the water sample was used as the actual sample.

[0069] For the four actual samples—bottled drinking water, plastic bottles, plastic cups, and food plastic packaging bags—100 μL of LPA-PDs solution (concentration of 1 unit), 100 μL of deionized water, and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken thoroughly. Then, 100 μL of the actual sample was added to each sample and shaken thoroughly again. Replacing the deionized water with an equal volume of bisphenol S solution yielded spiked samples. The fluorescence spectra of each sample were measured under 290 nm excitation. The bisphenol S content in the test samples was calculated based on the standard curve model constructed in Example 3.

[0070] For Sprite samples, an additional model needs to be built. Figure 7 100 μL of DPA-PDs solution (concentration of 1 unit) and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken thoroughly. Then, 100 μL of Sprite sample and 100 μL of bisphenol S solution of different concentrations were added and shaken thoroughly again. The fluorescence spectra of each sample were measured under 290 nm excitation, and a standard curve model was constructed according to Example 3.

[0071] The detection results of five actual samples with different spiking concentrations based on the linear model between the fluorescence enhancement at 460 nm and the ratio of emission intensity at 460 nm and 310 nm and the bisphenol S concentration are shown in Tables 1 and 2, respectively.

[0072] Table 1 shows the detection of bisphenol S in actual samples based on the fluorescence enhancement at 460 nm.

[0073]

[0074]

[0075] Table 2 shows the detection of bisphenol S in actual samples based on the ratio of emission intensity at 460 nm to 310 nm.

[0076]

[0077] For the fluorescence enhancement model at 460 nm, the recoveries ranged from 92.6% to 111%, and the relative standard deviations (RSDs) ranged from 2.74% to 22.1%. For the ratio of emission intensities at 460 nm to 310 nm, the recoveries ranged from 96.6% to 110%, and the RSDs ranged from 1.05% to 11.7%. These results indicate that both models are feasible in real samples. However, the matrix of the Sprite sample somewhat interferes with the stability of the fluorescence enhancement model at 460 nm (e.g., the RSD in Sprite reached 22.1% in Table 1, while the RSD of the Sprite sample in Table 2 was less than 10%).

[0078] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A fluorescence detection method for bisphenol S based on polydopamine nanoparticles and pH regulation, characterized in that, The method includes the following: (1) Construction of quantitative relationship model The polydopamine nanoparticle DPA-PDs fluorescent probe system was shaken with a series of bisphenol S solutions of known concentrations to obtain standard samples. The emission spectra of each standard sample were measured under 290 nm excitation. A quantitative relationship model was established with the concentration of bisphenol S as the abscissa and the fluorescence intensity at 460 nm or the ratio of the fluorescence intensity at 460 nm to the fluorescence intensity at 310 nm as the ordinate. (2) Determination of bisphenol S content in the sample The polydopamine nanoparticle DPA-PDs fluorescent probe system was mixed with the test solution and shaken to obtain the test sample. Then the emission spectrum of the test sample under 290 nm excitation was measured. The content of bisphenol S in the test sample was calculated based on the fluorescence intensity at 460 nm or the ratio of the fluorescence intensity at 460 nm to the fluorescence intensity at 310 nm and the quantitative relationship model constructed in step (1). The DPA-PDs fluorescent probe system accounts for 90% of the total sample volume; The DPA-PDs fluorescent probe system includes DPA-PDs solution, water, and alkaline buffer solution in a volume ratio of 1~5:1:

7. The preparation of the DPA-PDs fluorescent probe system includes the following steps: Dopamine hydrochloride was dissolved in water and then transferred to a high-pressure reactor for hydrothermal reaction to obtain a crude product. The crude product was filtered through a filter membrane to obtain a DPA-PDs solution. The DPA-PDs solution was mixed with an alkaline buffer solution to obtain the DPA-PDs fluorescent probe system. The pH value of the alkaline buffer solution is 9.

0.

2. The method according to claim 1, characterized in that, The mass-to-volume ratio of dopamine hydrochloride to water is 0.1:10~30; g / mL.

3. The method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 180~200℃ for 8~12 hours.

4. The method according to claim 1, characterized in that, The alkaline buffer solution is a phosphate buffer solution adjusted with sodium hydroxide, with a concentration of 0.1~0.2 mol / L, and its volume accounts for 50-90% of the total volume of the DPA-PDs fluorescent probe system.

5. The method according to claim 1, characterized in that, The concentration corresponding to a DPA-PDs solution with an absorbance of 0.700 at 284 nm in the UV-Vis absorption spectrum was defined as 1 unit.

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