CN116120918A - A dual-mode nanoprobe for detecting nitrite and its preparation method and application - Google Patents

Abstract

The invention relates to the technical fields of fluorescence spectrum, ultraviolet-visible absorption spectrum and the like, in particular to a bimodal nanoprobe for detecting nitrite, a preparation method and application thereof. The invention aims to provide a bimodal nano probe for detecting nitrite substances, which has high sensitivity, good selectivity and simple operation. Based on the fluorescence internal filtering effect and the oxidation-reduction reaction, the method is simple and has good selectivity and the potential of establishing a portable sensor; simultaneously, the ultraviolet-visible absorption spectrum and fluorescence spectrum technology are utilized, and the method can be used for colorimetric method and fluorescence method detection of the object to be detected, and has the advantages of rapid and simple operation, high sensitivity, good specificity, low detection limit and good repeatability.

Description

A dual-mode nanoprobe for detecting nitrite and its preparation method and application

technical field

The invention relates to the technical fields of fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, etc., and specifically relates to a dual-mode nanoprobe for detecting nitrite, a preparation method and application thereof.

Background technique

Modern instrumental analysis mainly includes electrochemical methods, spectroscopy, chromatography and mass spectrometry. Among them, spectroscopy is an analytical method that can determine the chemical composition of substances (qualitative analysis) and determine the content of substances (quantitative analysis). According to electromagnetic radiation, it can be divided into atomic spectroscopy and molecular spectroscopy. Atomic spectroscopy mainly includes atomic absorption spectroscopy and atomic emission spectroscopy. Atomic absorption spectroscopy, also known as atomic spectrophotometry, is based on the characteristic absorption line of the ground state atomic vapor of the element to be measured, or the degree to which the line is weakened An instrumental analysis method for qualitative and quantitative analysis of elements. Atomic emission spectrometry refers to an analytical method that uses the comparison of the characteristic spectrum emitted by atoms or ions with the standard spectrum to determine the composition and content of material elements. Molecular spectroscopy mainly includes ultraviolet-visible absorption spectroscopy, infrared spectroscopy, molecular fluorescence spectroscopy, molecular phosphorescence spectroscopy, nuclear magnetic resonance and paramagnetic resonance spectroscopy, and surface-enhanced Raman scattering. Spectroscopy has been widely used in industrial analysis, food inspection, environmental protection and biosensing due to its advantages of fast analysis speed, simple operation and high sensitivity. Among them, fluorescence spectroscopy and UV-Vis absorption spectroscopy have the advantages of high sensitivity, good selectivity, wide linear range, and easy operation. Sensors that detect a variety of substances. Fluorescence sensing mechanisms include fluorescence quenching, enhancement, off-on, on-off, ratiometric, anisotropy, fluorescence resonance energy transfer, photoinduced electron transfer, and metal-enhanced fluorescence, among others. Common fluorescence quenching methods include static quenching, dynamic quenching, inner filter effect and fluorescence quenching caused by fluorescence resonance energy transfer. Among them, the inner filter effect is a kind of non-radiative energy transfer, which occurs because when the absorption spectrum of the quencher overlaps with the excitation or emission spectrum of the phosphor, the quencher absorbs the excitation or emission light of the phosphor.

Since the 1990s, nanotechnology has developed rapidly and has been widely used in the field of biosensing. Due to the unique physical and chemical properties of nanomaterials, such as surface and interface effects, small size effects, quantum size effects, macroscopic quantum tunneling effects, and dielectric confinement effects, these properties are of great significance to the development of the field of biosensing. So far, a variety of analytical methods for nitrite detection have been developed, including electrochemical methods, capillary electrophoresis, chromatography, redox titration, and chemiluminescence. However, most of these techniques require expensive instruments, time-consuming and cumbersome processes, which limit their practical application. In contrast, the fluorescence method has excellent characteristics such as low cost, fast reaction speed, low detection limit, high sensitivity and specificity. Colorimetry has the advantages of simplicity, rapidity, and high sensitivity, and has been widely used in the determination of trace components. However, most probes have poor stability, low sensitivity, complex synthesis, or can only be used in single-method assays. Therefore, it is necessary to design a low-cost and simple dual-modal nitrite detection method. Luminescent nanomaterials mainly include semiconductor quantum dots, carbon dots, metal nanoclusters and upconversion nanomaterials. Silicon is the second most abundant element on earth. Due to the high reserve and low price of silicon element, it has been widely used as a raw material for the synthesis of silicon quantum dots. Silicon quantum dots have excellent biocompatibility, strong photostability, low toxicity and good water solubility, and can be applied in the fields of bioluminescent imaging, disease treatment and nano-sensing. There are various synthesis methods of silicon quantum dots, such as microwave synthesis, electrochemical etching of silicon wafers, hydrothermal synthesis, etc., which are expected to further play an important role in the field of food analysis.

Contents of the invention

The technical problem to be solved by the present invention is to provide a dual-mode nanoprobe for detecting nitrite substances with high sensitivity, good selectivity and easy operation.

Technical scheme of the present invention is as follows:

A method for preparing a dual-mode nanoprobe for detecting nitrite, comprising the following steps:

(1) Prepare fluorescent silicon quantum dots according to existing methods;

(2) According to the fluorescence quenching efficiency of the o-phenanthrene-iron(II) complex on silicon quantum dots, a dual-mode nanoprobe was constructed;

(3) The detection of nitrite substances is realized by using fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy techniques.

Preferably, the process of step (1) is: mixing N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride to prepare a silicon quantum dot solution.

Further, the above specific process is as follows: mix and stir the aqueous solution of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the freshly prepared dopamine hydrochloride solution at room temperature for more than 1 hour, and then prepare it after purification by dialysis out of the silicon quantum dot solution.

Preferably, the process of step (2) is: according to the coordination ratio of Fe ²⁺ and phenanthroline of 1:4, different concentrations of phenanthroline are prepared with different amounts of Fe ²⁺ and phenanthroline Nitrophenanthrene-Fe ²⁺ complex; then, add the silicon quantum dot solution diluted with ultrapure water, mix well, and record the fluorescence spectrum; the ratio when the fluorescence intensity reaches the minimum stability is the silicon quantum dot/o-nitrogen Composition of phenanthrene/Fe2 ⁺ nanoprobes.

Another object of the present invention is to protect the bimodal nanoprobe prepared by the above method.

Another object of the present invention is to protect the application of the above-mentioned bimodal nanoprobe in detecting nitrite content.

Further, fluorescence method: linear range 0.1-1 mM detection limit: 15.3 μM; UV-visible absorption spectrometry: linear range 0.01-0.35 mM detection limit: 18.6 μM.

The experimental process of detecting nitrite by fluorescence method and colorimetry is as follows: mix Fe ²⁺ solution, dilute hydrochloric acid and sodium nitrite standard solution of different concentrations evenly, after the reaction stands still, add o-phenanthroline solution and silicon quantum dots respectively solution, diluted to the same volume with ultrapure water. After the reaction was left to stand, the fluorescence spectrum and the UV-Vis absorption spectrum were recorded respectively. Draw a standard curve to obtain the concentration of nitrite in the sample to be tested.

Beneficial effects of the present invention:

(1) The nanoprobe constructed by the present invention utilizes both UV-visible absorption spectrum and fluorescence spectrum technology, and can be used for colorimetric and fluorescence detection of the analyte at the same time, with fast and simple operation, high sensitivity and good specificity , low detection limit and good repeatability; the fluorescence method linear range 0.1-1 mM detection limit: 15.3 μM (S/N = 3); UV-Vis absorption spectroscopy: linear range 0.01-0.35mM detection limit : 18.6 μM.

(2) As a fluorescent material, silicon quantum dots have good luminescence stability and high fluorescence quantum yield.

(3) The construction principle of the nanoprobe is based on the fluorescence inner filter effect and redox reaction. This method is simple and selective, and has the potential to establish a portable sensor. The fluorescent method of this probe has a wide linear range and low detection limit, which is suitable for nitrite analytes with a wider concentration range, and the fluorescence detection speed is fast; the ultraviolet-visible absorption spectrometry has the performance of "colorimetry" and "visualization" , has the potential to develop portable sensing devices.

Description of drawings

Fig. 1 is the schematic diagram of detection mechanism of the present application;

Fig. 2 is the fluorescence spectrogram of fluorescence intensity to nitrite;

Fig. 3 is the working curve figure of fluorescence intensity to nitrite;

Fig. 4 is the absorption spectrogram of nitrite by ultraviolet-visible absorption intensity;

Fig. 5 is the working curve figure of ultraviolet-visible absorption intensity to nitrite;

Figure 6 is a graph of the selectivity and interference results of this probe fluorescence method;

Figure 7 shows the selectivity and interference of this probe in UV-Vis absorption spectroscopy.

Detailed ways

Embodiment 1 (determination of nitrite in aqueous solution)

A method for preparing a dual-mode nanoprobe for detecting nitrite, comprising the following steps:

(1) Preparation of fluorescent silicon quantum dots: Mix N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride at room temperature to prepare silicon quantum dots in one pot. Briefly, 4.56 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was slowly added to 4.44 mL of ultrapure water. Then 1 mL of freshly prepared 10 mM dopamine hydrochloride solution was mixed with the above solution system, stirred, and the color of the solution changed from colorless to chocolate yellow, indicating the synthesis of the silicon quantum dots. Purify with dialysis bags (1kD) for 24 hours to remove excess N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride.

(2) Construction of dual-mode nanoprobes: 5 mM ferrous ion (Fe ²⁺ ) solution and 5 mM o-phenanthroline solution were newly prepared. First, according to the coordination ratio of Fe ²⁺ and phenanthroline is 1:4, different concentrations of phenanthroline-Fe ²⁺ complexes were prepared with different amounts of Fe ²⁺ and phenanthroline solutions. Then, add 100 μL of silicon quantum dot solution and dilute the solution to 2 mL with ultrapure water, mix well, and record the fluorescence spectrum. The ratio when the fluorescence intensity reaches the lowest stability is the composition of the silicon quantum dot/o-phenanthroline/Fe ²⁺ nanoprobe. The concentrations of Fe ²⁺ and phenanthroline were 200 μM and 800 μM, respectively.

(3) Quantitative detection of nitrite: 60 μL of Fe ²⁺ solution (5 mM), 112.5 μL of dilute hydrochloric acid (100 mM) and different concentrations of sodium nitrite standard solution were reacted for 45 min, and then 240 μL of phenanthroline was added solution (5 mM) and 100 μL of silicon quantum dot solution, diluted to 1.5 mL with ultrapure water. After standing for 5 min, the fluorescence spectrum was measured at an excitation wavelength of 380 nm. The same processing steps were also used before the UV-Vis absorption spectrometry to draw a standard curve. After the sample to be tested is pretreated, the quantitative detection of nitrite in the sample to be tested is realized by fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy.

It can be determined directly with the most basic aqueous solution sample; without additional sample pretreatment process, it can be directly determined by fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy. See Table 1 for the results of the related standard addition experiments.

Table 1. Analysis results of this probe for nitrite in water samples (n=3)

Embodiment 2 (determination of nitrite in pickled vegetables)

(1) Preparation of fluorescent silicon quantum dots: Mix N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride at room temperature to prepare silicon quantum dots in one pot. Briefly, 4.56 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was slowly added to 4.44 mL of ultrapure water. Then 1 mL of freshly prepared 10 mM dopamine hydrochloride solution was mixed with the above solution system, stirred, and the color of the solution changed from colorless to chocolate yellow, indicating the synthesis of the silicon quantum dots. Purify with dialysis bags (1kD) for 24 hours to remove excess N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride.

(2) Construction of dual-mode nanoprobes: 5 mM ferrous ion (Fe ²⁺ ) solution and 5 mM o-phenanthroline solution were newly prepared. First, according to the coordination ratio of Fe ²⁺ and phenanthroline is 1:4, different concentrations of phenanthroline-Fe ²⁺ complexes were prepared with different amounts of Fe ²⁺ and phenanthroline solutions. Then, add 100 μL of silicon quantum dot solution and dilute the solution to 2 mL with ultrapure water, mix well, and record the fluorescence spectrum. The ratio when the fluorescence intensity reaches the lowest stability is the composition of the silicon quantum dot/o-phenanthroline/Fe ²⁺ nanoprobe. The concentrations of Fe ²⁺ and phenanthroline were 200 μM and 800 μM, respectively.

(3) The pretreatment of samples was carried out according to the pretreatment method of vegetables in the national standard GB5009.33-2016. Then, the nitrite content was determined by fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy. See Table 2 for the results of the related standard addition experiments.

Table 2. Analysis results of this probe for nitrite in pickled vegetable samples (n=3)

Embodiment 3 (determination of nitrite in sausage)

(1) Preparation of fluorescent silicon quantum dots: Mix N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride at room temperature to prepare silicon quantum dots in one pot. Briefly, 4.56 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was slowly added to 4.44 mL of ultrapure water. Then 1 mL of freshly prepared 10 mM dopamine hydrochloride solution was mixed with the above solution system, stirred, and the color of the solution changed from colorless to chocolate yellow, indicating the synthesis of the silicon quantum dots. Purify with dialysis bags (1kD) for 24 hours to remove excess N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride.

(2) Construction of dual-mode nanoprobes: 5 mM ferrous ion (Fe ²⁺ ) solution and 5 mM o-phenanthroline solution were newly prepared. First, according to the coordination ratio of Fe ²⁺ and phenanthroline is 1:4, different concentrations of phenanthroline-Fe ²⁺ complexes were prepared with different amounts of Fe ²⁺ and phenanthroline solutions. Then, add 100 μL of silicon quantum dot solution and dilute the solution to 2 mL with ultrapure water, mix well, and record the fluorescence spectrum. The ratio when the fluorescence intensity reaches the lowest stability is the composition of the silicon quantum dot/o-phenanthroline/Fe ²⁺ nanoprobe. The concentrations of Fe ²⁺ and phenanthroline were 200 μM and 800 μM, respectively.

(3) The pretreatment of samples is carried out according to the pretreatment method of pickled products in the national standard GB5009.33-2016. Then, the nitrite content was determined by fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy.

Example of implementation effect

Effect Example 1 Inspection of linear range and detection limit of fluorescence method detection

The experimental conditions were: 60 μL Fe ²⁺ solution (5 mM), 112.5 μL dilute hydrochloric acid (100 mM) and different concentrations of sodium nitrite standard solution reacted for 45 min, then added 240 μL o-phenanthroline solution (5 mM) and 100 µL of silicon quantum dot solution was diluted to 1.5 mL with ultrapure water. After standing for 5 min, the fluorescence spectrum was measured at an excitation wavelength of 380 nm.

The experimental results are shown in Figures 2 and 3, from which it can be seen that the fluorescence method: linear range 0.1-1 mM detection limit: 15.3 μM (S/N = 3).

Effect Example 2 Investigation of the Linear Range and Detection Limit of UV-Vis Absorption Spectroscopy

The experimental conditions were: 60 μL Fe ²⁺ solution (5 mM), 112.5 μL dilute hydrochloric acid (100 mM) and different concentrations of sodium nitrite standard solution reacted for 45 min, then added 240 μL o-phenanthroline solution (5 mM) and 100 µL of silicon quantum dot solution was diluted to 1.5 mL with ultrapure water. After standing for 5 min, the UV-vis absorption spectrum was recorded.

The experimental results are shown in Figures 4 and 5, from which it can be seen that the UV-Vis absorption spectroscopy: linear range 0.01-0.35 mM detection limit: 18.6 μM (S/N = 3).

Effect example 3 Anti-interference analysis of this probe

The experimental conditions are: 60 μL Fe ²⁺ solution (5 mM), 112.5 μL dilute hydrochloric acid (100 mM) and nitrite solution (or blank sample and different interfering ions) reacted for 45 min, then added 240 μL o-phenanthroline solution (5 mM) and 100 μL of silicon quantum dot solution, diluted to 1.5 mL with ultrapure water. After standing for 5 min, the fluorescence spectrum and UV-vis absorption spectrum were recorded respectively.

The results are shown in Figures 6 and 7, from which it can be seen that the application has strong anti-interference and good detection specificity for the detection of nitrite.

Claims (7)

1. a preparation method for detecting a dual-mode nanoprobe of nitrite, is characterized in that, comprises the following steps: (1) Prepare fluorescent silicon quantum dots according to existing methods; (2) According to the fluorescence quenching efficiency of the o-phenanthrene-iron(II) complex on silicon quantum dots, a dual-mode nanoprobe was constructed; (3) The detection of nitrite substances is realized by using fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy techniques. 2. The preparation method according to claim 1, characterized in that, the process of step (1) is: mixing N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and dopamine hydrochloride , to prepare a silicon quantum dot solution. 3. preparation method according to claim 2, is characterized in that, concrete process is: the aqueous solution of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the freshly prepared dopamine hydrochloride solution room temperature The mixture was mixed and stirred for more than 1 hour, and the silicon quantum dot solution was prepared after purification by dialysis. 4. The preparation method according to claim 1, characterized in that, the process of the step (2) is: according to the coordination ratio of Fe ²⁺ and o-phenanthroline is 1:4, different amounts of Fe ^{2 +} and phenanthroline solution to prepare different concentrations of phenanthroline-Fe ²⁺ complexes; then, add the silicon quantum dot solution diluted with ultrapure water, mix well, and record the fluorescence spectrum; the fluorescence intensity reaches the minimum stability The proportioning ratio is the composition of the silicon quantum dot/o-phenanthroline/Fe ²⁺ nanometer probe. 5. The dual-mode nanoprobe prepared by the method according to any one of claims 1-4. 6. The application of the dual-mode nanoprobe as claimed in claim 5 in detecting nitrite content. 7. The application according to claim 6, characterized in that, fluorescence method: linear range 0.1-1 mM detection limit: 15.3 μM; ultraviolet-visible absorption spectroscopy: linear range 0.01-0.35 mM detection limit: 18.6 μM.

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