A fluorescent carbon dot based on ampicillin sodium, its preparation method and application

Abstract

This invention belongs to the field of carbon-based material preparation technology, specifically relating to a fluorescent carbon dot based on ampicillin sodium, its preparation method, and its application. In this invention, ampicillin sodium is dispersed in distilled water, followed by carbonization treatment using a solvothermal method. After separation and purification, water-soluble N-doped fluorescent carbon dots emitting blue fluorescence are obtained. The prepared carbon dots exhibit excellent optical behavior, excellent photostability, and excellent water solubility. The prepared carbon dots can be used to detect Fe in real environmental water samples and living cells. 3+ and Cu 2+ It exhibits good selectivity and high sensitivity. Compared with other carbon dot-based fluorescence sensing methods, the detection method of this invention is comparable to or superior to them.

Description

Technical Field

[0001] This invention belongs to the field of carbon-based material preparation technology, specifically relating to a fluorescent carbon dot based on ampicillin sodium, its preparation method, and its application. Background Technology

[0002] Heavy metal ion pollution, including iron, copper, lead, and cadmium, poses a significant threat to human health, agricultural production, and the environment. Among these metal ions, Fe... 3+ Iron is the most abundant essential trace element in the human body. It plays a crucial role in various biological processes, including oxygen binding and transport, cell proliferation and differentiation, DNA repair, photosynthesis, and electron transport. A deficiency of iron in the body... 3+ Iron can affect hemoglobin synthesis in red blood cells, leading to a decrease in red blood cell volume and oxygen-carrying capacity, resulting in iron-deficiency anemia. Furthermore, excessive iron in the body... 3+ It can lead to arteriosclerosis, physiological and metabolic disorders, etc. Similarly, Cu 2+ Cu is another important element in the human body, maintaining the cellular respiratory system, bone formation redox processes, and biosynthesis. 2+ Both deficiency and excess of Fe can lead to a range of serious health problems, such as Alzheimer's disease, Meniere's disease, Wilson's disease, and Parkinson's disease. The U.S. Environmental Protection Agency recommends a Fe content of [missing information - likely related to Fe levels in drinking water]. 3+ and Cu 2+ The maximum permissible concentrations are 0.3 mg / L and 1.3 mg / L, respectively. Therefore, the design and synthesis of Fe with excellent selectivity and sensitivity is crucial. 3+ and Cu 2+ Probes for Fe in environmental and medical applications 3+ and Cu 2+ Rapid and accurate visual detection is of great significance.

[0003] Currently, it is used to detect Fe 3+ and Cu 2+ The main methods include mass spectrometry, X-ray fluorescence spectrometry, voltammetry, and electrochemical methods. However, the high cost of instruments and operation, as well as the complex pretreatment process, limits their practical application. Summary of the Invention

[0004] To address the above problems, this invention provides a method for preparing ampicillin carbon dots, comprising the following steps:

[0005] (1) Dissolve ampicillin sodium in water, sonicate for 30 minutes, then react the mixture at 180°C for 12 hours, and cool to obtain a yellow suspension;

[0006] (2) The yellow suspension was filtered through a 0.22 μm filter membrane. The filtered solution was then placed in a dialysis bag and dialyzed for 24 hours to obtain a purified solution.

[0007] (3) The purified solution was freeze-dried for 24 hours to obtain ampicillin carbon dot powder.

[0008] Furthermore, the mass-to-volume ratio of ampicillin sodium and water in step (1) is 0.56 g: 30 mL.

[0009] Furthermore, the reaction conditions described in step (1) are to carry out the reaction in a high-pressure reactor lined with polytetrafluoroethylene.

[0010] Furthermore, the dialysis molecular weight cutoff in step (2) is 500 Da.

[0011] The present invention also provides an ampicillin carbon dot, which is prepared by the above-described method.

[0012] This invention also provides the above-mentioned ampicillin carbon dots for detecting real environmental water samples and intracellular Fe. 3+ and Cu 2+ Applications in this area.

[0013] The present invention has the following beneficial effects:

[0014] This invention disperses ampicillin sodium in distilled water, then carbonizes the ampicillin sodium using a solvothermal method. After separation and purification, water-soluble N-doped fluorescent carbon dots (ACDs) emitting blue fluorescence are obtained. The prepared ACDs exhibit excellent optical behavior, excellent photostability, and excellent water solubility. Based on the synergistic effect of internal filtration (IFE) and static quenching, the ACDs are utilized to target Fe... 3+ and Cu 2+ Multivariate sensing was employed, with detection limits of 0.31 μM and 0.26 μM, respectively. Furthermore, by analyzing Fe in real water samples and living cells... 3+ and Cu 2+ The successful detection validates the practicality of ACDs. These findings confirm that the proposed ACDs can serve as a fluorescence sensor for Fe. 3+ and Cu 2+ Effective detection is needed to detect Fe in the environment and biological systems. 3+ and Cu 2+ Real-time monitoring offers a promising future. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 (a) UV absorption and fluorescence spectra of ACDs, with insets showing images of ACDs under visible light (left) and UV light (right); (b) Emission spectra of ACDs under different excitations;

[0017] Figure 2 (a) ACD sTEM image (inset shows HRTEM image and size distribution); (b) FT-IR image; (c) XPS full spectrum; (d) C1s; (e) N 1s and (f) O 1s spectra;

[0018] Figure 3 (a) Effect of different pH values ​​on the fluorescence of ACDs; (b) Effect of different concentrations of NaCl solution on the fluorescence of ACDs;

[0019] Figure 4 (a) Fluorescence emission spectra of ACDs solutions with different ions added; (b) Relative fluorescence intensity of ACDs solutions with different ions added; (c) Images of ACDs solutions under UV light with different ions added.

[0020] Figure 5 (a) Fe at different concentrations 3+ Fluorescence spectra of ACDs added; (b) F0 / F and Fe 3+ Linear relationship between concentrations (0.9-80 μM); (c) Cu at different concentrations 2+ Fluorescence spectra of ACDs added; (b) F0 / F with Cu 2+ Linear relationship between concentrations (0.8-90 μM);

[0021] Figure 6 Other metal ions (100 μM) for detecting (a) Fe 3+ and (b)Cu 2+ Interference;

[0022] Figure 7 (a) Cytotoxicity of ACDs at different concentrations (0-1000 μg / mL) on HeLA cells; (b) Cytotoxicity of ACDs and ACDs-Fe 3+ and ACDs-Cu 2+ Bright-field and fluorescence images of HeLa cells treated with the complex;

[0023] Figure 8Schematic diagram of the quenching mechanism of ACDs. (a) Addition of Fe to ACDs solution 3+ and Cu 2+ (b) Fe fluorescence lifetime; 3+ and Cu 2+ (c) The overlap between the ultraviolet absorption spectrum of ACDs and the fluorescence spectrum of ACDs; 3+ Cu 2+ And the addition of different concentrations of Fe to ACDs 3+ and Cu 2+ The following is the ultraviolet absorption spectrum. Detailed Implementation

[0024] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods used in the embodiments are conventional methods, and the reagents used are commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] Example 1

[0030] 1.1 Synthesis of Ampicillin Carbon Dots (ACDs)

[0031] ACDs were synthesized via a one-step hydrothermal method using ampicillin sodium as a raw material. First, 0.56 g of ampicillin sodium was dissolved in 30 mL of water and sonicated for 30 minutes. The mixture was then placed in a polytetrafluoroethylene-lined autoclave and reacted at 180 °C for 12 hours. After cooling, a yellow suspension was obtained. The yellow suspension was then filtered through a 0.22 μm filter membrane to remove larger particles or undissolved impurities. The filtered solution was placed in a dialysis bag (molecular weight cutoff 500 Da) and dialyzed for 24 hours to remove unreacted raw material and smaller impurities. Finally, the purified solution after dialysis was freeze-dried for 24 hours to obtain dried ACD powder.

[0032] 1.2Fe 3+ and Cu 2+ Detection

[0033] Fe 3+ and Cu 2+ The detection method was constructed based on selective experiments. To study the application of ACDs in ion detection, common metal ions (K+, K ... + Ag + Na + ,Fe 3+ Zn 2+ Al 3+ ,Mn 2+ Pb 2+ Mg 2+ Cu 2+ ,Cr 3+ Hg 2+ and Co 2+ A 0.1 M solution was prepared, and 10 μL of the metal ion solution was mixed with 990 μL of LACDs (100 μg / mL) solution. The fluorescence spectra of the mixed solution before and after ion addition were recorded in the excitation wavelength range of 350 nm, and the corresponding fluorescence emission intensity was recorded at 450 nm. Then, Fe... 3+ and Cu 2+ The effects of ACDs on Fe were investigated at different concentrations (0 to 300 μM). 3+ and Cu 2+ Sensitivity was assessed. All fluorescence measurements were performed at room temperature. The limit of detection was estimated using the formula LOD = 3σ / K, where “σ” is the standard deviation of the blank sample and “K” is the slope of the standard curve.

[0034] 1.3 Cytotoxicity and Bioimaging of ACDs

[0035] The cytotoxicity of ACDs was investigated using a CCK-8 assay kit, with HeLa cells selected as the cell line. HeLa cells were cultured to the logarithmic growth phase and seeded into 96-well plates at a density of 5000 cells per well, and incubated overnight at 37°C in a 5% CO2 incubator. After 24 hours, cells were treated with 100 μL of fresh Dulbecco's Modified Eagle Medium (DMEM), containing 0, 50, 100, 150, 200, 400, 800, and 1000 μg / mL of ACDs. After 24 hours of incubation, each well was washed three times with PBS (0.01 M, pH 7.4). Then, 100 μL of culture medium and 10 μL of CCK-8 were added to each well. After incubating the 96-well cell culture plates in an incubator for 1 hour, the OD value was measured at 450 nm using a microplate reader. The viability of HeLa cells was calculated based on the OD values.

[0036] For cell imaging, HeLa cells were seeded at a density of 5000 cells per well in 24-well plates and incubated for 24 hours. Next, 500 μL of LACDs solution (100 μg / mL) was added, followed by a further 12 hours of incubation. Fe was then added to the cells. 3+ and Cu 2+ Incubate for 2 hours. Then wash the cells three times with PBS. Finally, observe the cells using a fluorescence microscope.

[0037] Results and Discussion of Example 2

[0038] 2.1 Characterization of ACDs

[0039] The optical properties of ACDs are mainly studied through ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy. Aqueous solutions of ACDs are pale yellow and emit bright blue fluorescence under 365 nm ultraviolet light. Figure 1 (Illustration a). In the UV-Vis absorption spectrum, Amp shows a distinct absorption peak at 264 nm. However, after Amp is converted into ACDs, the absorption peak shifts from 264 nm to 251 nm, which can be attributed to the π-π transition of C=C. * The transition indicates the formation of a graphite-carbon structure in the core of ACDs. The strong absorption of ACDs at 350 nm is due to the n-π* transition of the C=O bond, and the fluorescence excitation band of ACDs overlaps with its absorption band at 350 nm. Figure 1 b shows the fluorescence behavior of ACDs at different excitation wavelengths (290-400 nm). When the excitation wavelength changes from 290 nm to 400 nm, the position of the maximum emission peak shows a slight red shift. When the excitation wavelength is 350 nm, the fluorescence intensity of ACDs reaches its maximum value.

[0040] From transmission electron microscopy Figure 2 As can be seen, ACDs are approximately spherical and disperse well in water. The high-resolution TEM image clearly shows lattice fringes with a spacing of 0.20 nm, which are consistent with the lattice fringes on the surface of graphitic carbon (100) structure. Figure 2 The illustration shows the particle size statistics of ACDs particles, with a particle size range of 3-5.8 nm and an average size of 4.6 nm.

[0041] Characteristic peaks in the FT-IR of ACDs ( Figure 2 (b) This reveals the main functional groups on the surface of ACDs. ACDs and Amp have a surface area of ​​3500–3100 cm⁻¹. -1 Strong and broad absorption peaks are observed in the range of 1620-1770 cm⁻¹, consistent with the stretching vibrations of OH and NH, which can be attributed to the intermolecular hydrogen bonds in Amp and ACD. -1 The peak value at 1400-1460 cm is attributed to the stretching vibrations of C=O and C=C and the bending vibrations of NH; -1 The peak at that point corresponds to CN and CH. The NH bending vibration peak in the Amp spectrum is approximately 1770 cm⁻¹. -1 and 1690cm -1 However, it disappeared in the ACD spectrum. This is likely due to the C=C(1630) reaction caused by Amp during the carbonization process. -1 ) tensile vibration.

[0042] XPS spectra showed that ACDs had three distinct peaks at ~284 (C1s), ~400 (N1s), and ~532 eV (O1s). Figure 2 c). For example Figure 2 As shown in the inset, the percentages of C, N, and O in ACD are 61.86%, 9.29%, and 28.85%, respectively. (C1s spectrum) Figure 2 d) The surface of ACD contains three different types of carbon atoms: CC / C=C (284.0 eV), CN / CO (284.9 eV) and C=O (287.6 eV). Figure 2 The N1s spectrum in e is resolved at 399.0 eV and 400.5 eV, corresponding to pyrrole N and graphite N, respectively. O1s spectrum ( Figure 2 f) Absorption peaks were observed at 530.4 eV and 531.1 eV, corresponding to C=O and CO, respectively. XPS analysis results were in agreement with FT-IR. Characterization results indicated the presence of hydrophilic groups such as hydroxyl, amino, and carboxyl groups on the surface of ACDs.

[0043] 2.2 Stability Study of ACDs

[0044] The stability of fluorescent materials often significantly impacts their application in real-world environments. Therefore, we investigated the effects of pH and ionic strength on the stability of fluorescent materials (ACDs). Figure 3 As shown in Figure a, the fluorescence intensity of the ACD solution exhibits different responses at different pH values ​​(1-12). With increasing pH (1-10), the fluorescence intensity gradually increases, while there is no significant change in fluorescence intensity when the pH value is greater than 10. The pH responsiveness of ACDs may be related to the presence of amines on the ACD surface. Amines, acting as Lewis bases, react with acids to form ammonium salts, thereby disrupting the surface state of ACDs and causing the fluorescence intensity of ACDs to be quenched under acidic conditions. Figure 3 As shown in b, the fluorescence intensity of the ACD remained unchanged even at a NaCl concentration of 1 M, indicating that the ACD can emit stably even under high salt conditions. This demonstrates that the fluorescence properties of the ACD are unaffected by changes in the surrounding ionic environment. This stability is beneficial for the potential applications of the ACD.

[0045] 2.3ACDs on Fe 3+ and Cu 2+ Detection

[0046] The oxygen-containing functional groups on the surface of ACDs can improve their water solubility, and due to the coordination between oxygen functional groups and metal ions, ACDs have the potential for application in metal ion detection. Therefore, we investigated the effects of various metal ions on the fluorescence intensity of ACDs. Figure 4 As shown in (a) and (b), when 100M of different cations K are added... + Ag + Na + Zn 2+ Al 3+ Mn 2+ Pb 2+ Mg 2+ Cr 3+ Hg 2+ and Co 2+ At that time, the fluorescence intensity of ACD did not change, only Fe... 3+ and Cu 2+ This can significantly reduce the fluorescence intensity of ACDs, likely due to the presence of numerous oxygen-containing functional groups on the surface of ACDs, particularly carboxyl and hydroxyl groups. Furthermore, it can be clearly observed that, except for Cu... 2+ and Fe 3+ In the presence of all metal ions except those present, the blue fluorescence of ACD remains unchanged under ultraviolet light. Figure 4 c). These results indicate that ACDs are effective in detecting Cu. 2+ and Fe 3+ It has a high degree of selectivity.

[0047] Furthermore, the effects of ACDs on Fe were investigated. 3+ and Cu 2+ The fluorescence response curve. From Figure 5 a and Figure 5 c. As can be seen, at the optimal emission peak of ACDs at 450 nm, with Fe... 3+ and Cu 2+ As the concentration gradually increases, the fluorescence intensity of the ACDs solution gradually decreases. For example... Figure 5 As shown in b, Fe 3+ Within the concentration range of 0.9-80 μM, ACDs exhibited a good linear relationship in their fluorescence response, with a correlation coefficient (R0). 2 The coefficient of variation is 0.9956, and the linear equation is F0 / F = 1.01264 + 0.01193C. Fe 3+ Where F0 and F are the amounts of Fe added to the ACDs solution, respectively. 3+ Fluorescence intensity before and after. For Cu 2+ ,like Figure 5 As shown in d, Cu 2+ Within the concentration range of 0.8-90 μM, ACDs exhibited a good linear relationship in their fluorescence response, with a correlation coefficient (R0). 2 The coefficient of variation is 0.9932, and the linear equation is F0 / F = 1.03775 + 0.0146C. Cu 2+ The detection limits were 0.31 μM and 0.26 μM, respectively, which are lower than the limits for Fe in drinking water specified above. 3+ (5.37 μM) and Cu 2+ The content of (20 μM) is summarized in Tables 1 and 2. 3+ and Cu 2+ Some literature on fluorescence sensors. It is clear that Fe based on ACDs... 3+ and Cu 2+ The fluorescence sensor is comparable to or better than previously published sensors.

[0048] To further understand the practical applications of ACDs, Fe 3+ and Cu 2+ The applicability of the detection was investigated, and interference experiments with some coexisting metal ions (100 μM) were performed. For example... Figure 6 As shown in a and b, the coexistence of other ions affects Fe. 3+ / Cu 2+ The fluorescence of ACDs was not significantly affected. These results confirm that ACDs can be used as fluorescent probes to sense Fe in an aqueous environment. 3+ and Cu 2+ High selectivity.

[0049] 2.4 Cytotoxicity and Bioimaging Studies of ACDs

[0050] As a potential biomarker, the cytotoxicity and biocompatibility of adenosine dichlorophenate (ACDs) must be considered. The MTT assay was used to determine the cytotoxicity of ACDs. Figure 7 As shown in Figure a, after treating HeLa cells with 1000 μg / mL ACDs for 24 hours, the cell viability remained above 90%, indicating that ACDs have low cytotoxicity and good application prospects, and therefore can be used for bioimaging.

[0051] Subsequently, fluorescence imaging of ACDs was investigated to assess Fe in HeLa cells. 3+ and Cu 2+ Visualization. For example... Figure 7 As shown in b, ACDs did not significantly alter or damage cell shape, indicating that ACDs have relatively low toxicity and good biocompatibility. Cells were excited and observed in blue, green, and red channels, respectively, and it was found that the cells emitted only bright blue fluorescence, while green and red fluorescence were negligible. Next, Fe... 3+ and Cu 2+ Cells were treated for 30 minutes to study Fe. 3+ and Cu 2+ Effects on cell fluorescence imaging. The study found that adding Fe to cultured cells... 3+ and Cu 2+ Subsequently, the fluorescence of the cells was significantly quenched, but the cell morphology remained intact. These findings indicate that ACDs have good membrane permeability and can be used to label Fe. 3+ and Cu 2+ .

[0052] 2.5 Detection of actual samples

[0053] To verify the feasibility of ACDs in detecting real samples, Fe in tap water and drinking water was analyzed. 3+ and Cu 2+ Tests were conducted. As shown in Table 3, Fe in tap water and drinking water 3+ and Cu 2+ The recoveries ranged from 98.00% to 102.40%, with corresponding relative standard deviations (RSDs) below 4.42%. These results indicate that the synthesized ACDs can be used as a detection method for Fe in real samples. 3+ and Cu 2+ A good candidate.

[0054] 2.6ACDs on Fe 3+ and Cu 2+ Detection mechanism

[0055] Fe 3+ / Cu2+ Fluorescence quenching in ACDs can be caused by dynamic or static quenching, photoinduced electron transfer, internal filtering effect (IFE), or fluorescence resonance energy transfer (FRET). Therefore, we investigated the detection of Fe by ACDs. 3+ and Cu 2+ The possible mechanisms were investigated. First, ACDs and Fe were measured and compared. 3+ / Cu 2+ Fluorescence lifetime before and after mixing. For example... Figure 8 As shown in a, in Fe 3+ and Cu 2+ With or without the presence of ACDs, the fluorescence lifetime profiles showed negligible variations, with average lifetimes of 4.25 ns, 4.38 ns, and 4.90 ns, respectively. This indicates that Fe... 3+ and Cu 2+ The fluorescent hardening of ACDs is not caused by FRET and single dynamic hardening, but by a static hardening process.

[0056] from Figure 8 b discovered Fe 3+ There is partial spectral overlap between the absorption spectrum of Fe and the excitation spectrum of ACDs, indicating that Fe 3+ Fluorescence quenching of ACDs may be caused by IFE. However, Cu... 2+ There was no absorption in the studied band, therefore Cu 2+ The fluorescence quenching of ACDs was not caused by an internal filtering effect. Next, the UV-Vis absorption spectra were analyzed to further investigate Fe. 3+ and Cu 2+ The fluorescence quenching mechanism of ACDs. For example... Figure 8 As shown in c, after Fe 3+ and Cu 2+ After treatment, no new absorption peaks were found in the UV spectrum of ACDs. Furthermore, ACDs-Fe 3+ / Cu 2+ The absorbance of the reaction mixture is not ACDs and Fe 3+ / Cu 2+ - The sum of absorbance values, rather than an enhancement based on this. This may be due to the non-fluorescent ACDs-Fe in the system. 3+ and ACDs-Cu 2+ Formation of ground-state complexes

[0057] Taking all factors into consideration, Fe 3+ The fluorescence quenching of ACDs is mainly attributed to IFE and ACDs-Fe. 3+ The formation of non-fluorescent complexes, but Cu 2 + The fluorescence quenching of ACDs is due to ACDs-Cu 2+Formation of non-fluorescent composite materials.

[0058] in conclusion

[0059] Water-soluble carbon dots (ACDs) were synthesized via a one-step hydrothermal method using AMP as the sole precursor. The obtained ACDs were uniformly sized spherical particles with an average diameter of 4.6 nm, exhibiting bright blue fluorescence under ultraviolet light. The quality of the produced ACDs was confirmed by comprehensive characterization using ultraviolet-visible spectroscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Further studies showed that the non-fluorescent complex ACDs-Fe 3+ and ACDs-Cu 2+ The formation of Fe 3+ and Cu 2+ This significantly quenched the fluorescence intensity of ACDs. The fluorescence intensity of ACDs is related to Fe. 3+ (0.9 to 80 μM) and Cu 2+ (0.8 to 90 μM) concentrations showed a good linear relationship, Fe 3+ and Cu 2+ The detection limits were 0.31 μM and 0.26 μM, respectively. Furthermore, the designed ACD fluorescent probe is suitable for determining Fe in water samples. 3+ and Cu 2+ The recoveries ranged from 98.00% to 102.40%. Notably, ACDs are highly suitable for Fe3+ and Cu in HeLa cells. 2+ The developed ACD has potential applications in cell imaging and environmental monitoring. The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. Ampicillin carbon dots in the detection of real environmental water samples and intracellular Fe 3+ and Cu 2+ In terms of applications, the preparation method of the ampicillin carbon dots includes the following steps: (1) Dissolve ampicillin sodium in water, sonicate for 30 minutes, then react the mixture at 180°C for 12 hours, and cool to obtain a yellow suspension; (2) The yellow suspension was filtered through a 0.22 μm filter membrane. The filtered solution was then placed in a dialysis bag and dialyzed for 24 hours to obtain a purified solution. (3) The purified solution was freeze-dried for 24 hours to obtain ampicillin carbon dot powder; The mass-to-volume ratio of ampicillin sodium and water in step (1) is 0.56 g: 30 mL; The reaction conditions described in step (1) are as follows: the reaction is carried out in a high-pressure reactor lined with polytetrafluoroethylene; The dialysis molecular weight cutoff in step (2) is 500 Da.

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