CN101713735A - Oxygen-sensitive fluorescent membrane and preparation method thereof - Google Patents

Abstract

The invention relates to a fluorescent sensitive film which responds quickly to oxygen and a preparation method thereof. The invention uses the sol-gel technology to effectively embed the bipyridyl ruthenium complex, and prepares a fluorocarbon sol-gel photochemical sensing membrane with good response to oxygen. The film has good hydrophobicity and corrosive gas resistance, as well as good mechanical properties, light transmittance and flexibility. It also has long service life, wide measurement range, fast response speed, good repeatability, stable performance and easy advantages of miniaturization.

Description

A kind of oxygen fluorescence sensitive membrane and preparation method thereof

technical field

The invention relates to an oxygen sensitive film, in particular to a fast-response oxygen fluorescence sensitive film and a preparation method thereof, which is an oxygen sensitive material based on a bipyridyl ruthenium-embedded fluorocarbon sol-gel film.

Background technique

Oxygen is the reactant or product of many chemical reactions and biochemical reactions, and is the basic substance for the survival of living organisms. The traditional methods for measuring oxygen include iodometric method (ie Winkler method) and oxygen electrode (ie Clark method). The iodometric method has high measurement accuracy, but it takes a long time and the procedure is cumbersome, which cannot meet the requirements of online measurement. Oxygen electrode method can realize on-site continuous measurement, but it needs to consume oxygen, and the electrode used is easily poisoned by H ₂ S and other substances in the sample. Optical oxygen sensor is a sensing technology gradually developed in the mid-eighties. This type of sensor can work normally at normal temperature and pressure, and can also work at lower or higher temperature according to the characteristics of different luminescent materials; because it uses the principle of fluorescence quenching by oxygen to measure oxygen, it does not involve the mass consumption of oxygen , and the equilibrium time is very short. Due to the above advantages, optical oxygen sensors have been widely used in fields such as chemistry, biology, clinical medicine and environmental monitoring.

Sol-gel technology is a new film-making technology developed in recent years. It uses the mesh-like porous matrix formed by hydrolysis and polymerization of siloxane reagents as the carrier matrix to embed sensitive substances. The carrier has a variety of unique advantages, such as good chemical stability, porosity and light transmittance, etc., but the single inorganic sol-gel film is easy to break, the hydrothermal stability of the film is poor, and the long-term stability of the film Poor and other shortcomings. Organically modified sol-gel films have good mechanical flexibility, but there are few reports on fluorocarbon-modified sol-gel films. Bukowski (Anal.Chem.2005, 77:2670) and Chu (Sens.Actuators B Chem.2007, 124:376) embedded Ru(dpp) ₃ ²⁺ and Pt(II) into TFP-TriMOS/n- Propyl-TriMOS, for the determination of oxygen. However, the membrane prepared in the report has a long response time, about 5s, and is only used for the determination of gaseous oxygen concentration.

Contents of the invention

The purpose of the present invention is to provide a fast-response oxygen fluorescent sensitive membrane and its preparation method, the synthesized membrane has photosensitivity to oxygen, and the sensitive process is reversible and does not consume fluorescent substances of measured oxygen molecules; the preparation process Fluorocarbon group-modified sol-gel embeds fluorescent substances, and the sensitive membrane is used as the sensitive material of the oxygen sensor, which can be used for the determination of gaseous and dissolved oxygen in water.

In order to achieve the above object, the technical scheme adopted in the present invention is:

1. An oxygen fluorescence sensitive film, characterized in that: it is composed of a fluorocarbon sol-gel matrix embedded with a fluorescent substance, wherein the molar ratio of the fluorescent substance to the fluorocarbon sol-gel matrix is 1 to 30;

2. according to the described sensitive membrane of claim 1, it is characterized in that: described fluorescent substance is metal ruthenium complex, metal osmium complex, metal lead complex, metal platinum complex, metal palladium complex , metal rhenium complexes;

The fluorocarbon sol-gel matrix is a hydrolyzed copolymer of trifluoropropyltrimethoxysilane TFP-TriMOS and other siloxane monomers; the volume ratio of TFP-TriMOS to other siloxane monomers is 0.25- 4;

The other siloxane monomers are tetramethoxysilane TMOS, tetraethoxysilane TEOS, methyltrimethoxysilane MTMOS, methyltriethoxysilane MTEOS, propyltrimethoxysilane PTMOS, propyl Triethoxysilane PTEOS, phenyltrimethoxysilane PhTMOS, phenyltriethoxysilane PhTEOS, etc.

3. The sensitive film according to claim 1, characterized in that: the thickness of the sensitive film is 0.1-10 μm.

4. a preparation method of sensitive film according to claim 1, characterized in that:

1) Dissolving the fluorescent substance in an organic solvent to form a solution A;

2) Trifluoropropyltrimethoxysilane TFP-TriMOS and other siloxane monomers are used as precursors, hydrolyzed in an organic solvent under acidic conditions of PH = 1 to 4, and ultrasonically mixed to obtain fluorocarbon sol-gel Glue solution B;

3) Mix solution A and solution B according to the required ratio, and ultrasonically mix to obtain a reagent for preparing a sensitive film;

4) Coating the reagents for preparing the sensitive film on the glass carrier, drying in an oven to volatilize the solvent to form an oxygen fluorescent sensitive film, which can be applied to photochemical sensing of oxygen.

5. According to the preparation method of the sensitive film according to claim 4, it is characterized in that: the molar concentration of the fluorescent substance in the organic solvent is 1-15 mM, and the volume percentage of the precursor and the organic solvent is 1-4:1 .

6. according to the preparation method of the described sensitive membrane of claim 4, it is characterized in that: the volume percent of TFP-TriMOS in the precursor described in step 2) is 20～80%; The volume ratio in water and organic solvent is 1 : 1~3.

7. The method for preparing the sensitive film according to claim 4, characterized in that: the volume ratio of the solution A to the solution B is 1:2-6.

8 . The method for preparing the sensitive film according to claim 4 , characterized in that: in step 4), the film is dried in an oven at 60-100° C. for 6-12 hours.

The present invention has the following advantages:

Synthesis of an oxygen-sensitive metal complex. The complex is photosensitive to oxygen in gas and water, and the complex is embedded in a fluorocarbon sol-gel matrix to immobilize these oxygen photosensitive metal complexes and enhance the mechanical properties of the sensitive film and stable performance.

The oxygen-sensitive film is composed of fast-response and long-lived fluorescent substances and fluorinated sol-gel matrix. The complex is coated on a glass carrier, and an excitation light source of a certain wavelength is irradiated on the sensitive film, and the fluorescence emitted by the fluorescent molecules in the film is detected by a fluorescence detection device. The strength of the detection signal is related to the oxygen content in the gas or liquid.

The oxygen sensitive film of the present invention is based on the fluorescence quenching effect of oxygen on the fluorescent substance bipyridyl ruthenium. The sensitive process does not consume oxygen, so the response characteristics are relatively stable. Embedding this fluorescent reagent into a fluorocarbon sol-gel matrix can obtain a sensitive film with good mechanical properties, light transmission and flexibility. Compared with traditional oxygen-sensitive membranes, it has the advantages of long service life, wide response range, rapid response, good repeatability, stable performance, can be used in both gas and liquid media, does not consume oxygen, and does not require frequent calibration. The membrane can be used for both gaseous and dissolved oxygen detection.

Description of drawings

Fig. 1 is a schematic diagram of the prepared oxygen-sensitive membrane; wherein: 1 is oxygen molecules, 2 is embedded fluorescent probe bipyridyl ruthenium, 3 is fluorocarbon sol-gel matrix, and 4 is glass slide carrier.

Figure 2 is the spectral characteristics of the oxygen fluorescence sensitive film.

Figure 3 shows the repeatability of the oxygen-sensitive membrane prepared in response to dissolved oxygen in water, and the response time is less than 25s.

Figure 4 shows the response repeatability of the prepared oxygen sensitive film to gaseous oxygen; the data shows that the response time of the sensitive film to oxygen is <1s.

Detailed ways

Example 1

1) Dissolving the fluorescent substance in a certain solvent. In a preferred scheme, the bipyridyl ruthenium complex [Ru(bpy) ₃ ] ²⁺ is dissolved in ethanol to obtain a stock solution with a concentration of 2 mM;

2) Preparation of fluorocarbon sol-gel (Fluorinated xerogels) stock solution: using tetramethoxysilane (TMOS) and trifluoropropyltrimethoxysilane (TFP-TriMOS) as precursors, ethanol as solvent, in Hydrolysis under the catalysis of hydrochloric acid at pH=1. In the preferred scheme, the volume percentage of TFP-TriMOS in the precursor is 30%. The mixed reagent is ultrasonically mixed; .

3) Preparation of the sensitive membrane: add the ethanol solution of bipyridyl ruthenium into the fluorocarbon sol-gel solution, and mix evenly. In a preferred scheme, 2 mM [Ru(bpy) ₃ ] ²⁺ and the fluorocarbon sol-gel stock solution are ultrasonically mixed at a volume ratio of 1:3 to obtain the sensitive reagent. Coating the mixed sensing reagent on a clean glass slide by dip coating method to obtain an oxygen sensitive film;

4) The oxygen-sensitive film is aged in an oven at 80° C. for 18 hours to completely evaporate the solvent to obtain an oxygen-sensitive film with a film thickness of 1 μm.

The fluorescent substance is a bipyridyl ruthenium complex [Ru(bpy) ₃ ] ²⁺ , its excitation center wavelength is 450nm, and its fluorescence emission center wavelength is 622nm; the prepared oxygen fluorescence sensitive film is suitable for oxygen sensors. By using the prepared sensing film in combination with an optical fiber spectrometer, the oxygen content in the gaseous state and the dissolved oxygen in water can be detected continuously in real time.

Example 2

1) Dissolving the fluorescent substance in a certain solvent. In a preferred scheme, the o-phenanthroline ruthenium complex [Ru(dpp) ₃ ] ²⁺ is dissolved in ethanol to obtain a stock solution with a concentration of 5 mM;

2) Preparation of fluorocarbon sol-gel (Fluorinated xerogels) stock solution: using tetraethoxysilane (TEOS) and trifluoropropyltrimethoxysilane (TFP-TriMOS) as precursors, ethanol as solvent, in Hydrolysis under the catalysis of hydrochloric acid at pH=3. In the preferred scheme, the volume percentage of TFP-TriMOS in the precursor is 50%. The mixed reagent is ultrasonically mixed; .

3) Preparation of the sensitive membrane: add the ethanol solution of [Ru(dpp) ₃ ] ²⁺ into the fluorocarbon sol-gel solution, and mix well. In a preferred scheme, 5 mM [Ru(bpy) ₃ ] ²⁺ and fluorocarbon sol-gel stock solution are ultrasonically mixed at a volume ratio of 1:4 to obtain a sensitive reagent. Coating the mixed sensing reagent on a clean glass slide by dip coating method to obtain an oxygen sensitive film;

4) The oxygen-sensitive film is aged in an oven at 80° C. for 18 hours to completely evaporate the solvent to obtain an oxygen-sensitive film with a film thickness of 0.8 μm.

The fluorescent substance is o-phenanthroline ruthenium complex [Ru(dpp) ₃ ] ²⁺ , its excitation center wavelength is 455nm, and the fluorescence emission center wavelength is 620nm; the prepared oxygen fluorescent sensitive film is suitable for oxygen sensor superior. By using the prepared sensing film in combination with an optical fiber spectrometer, the oxygen content in the gaseous state and the dissolved oxygen in water can be detected continuously in real time.

Example 3

1) Dissolve the fluorescent substance in a certain solvent. In a preferred scheme, the platinum porphyrin complex PtOEP is dissolved in tetrahydrofuran to obtain a stock solution with a concentration of 3 mM;

2) Preparation of fluorocarbon sol-gel (Fluorinated xerogels) stock solution: using methyltrimethoxysilane (MTMOS) and trifluoropropyltrimethoxysilane (TFP-TriMOS) as precursors, ethanol as solvent, It is hydrolyzed under the catalysis of hydrochloric acid at pH=4. In the preferred scheme, the volume percentage of TFP-TriMOS in the precursor is 70%. The mixed reagent is ultrasonically mixed; .

3) Preparation of the sensitive membrane: Add the tetrahydrofuran solution of PtOEP into the fluorocarbon sol-gel solution, and mix evenly. In a preferred scheme, 3 mM PtOEP and fluorocarbon sol-gel stock solution are ultrasonically mixed at a volume ratio of 1:5 to obtain a sensitive reagent. Coating the mixed sensing reagent on a clean glass slide by dip coating method to obtain an oxygen sensitive film;

4) The oxygen-sensitive film is aged in an oven at 75°C for 15 hours to completely evaporate the solvent to obtain an oxygen-sensitive film with a film thickness of 4 μm.

The fluorescent substance is platinum porphyrin complex PtOEP, 500nm and 535nm, and the center wavelength of fluorescence emission is 646nm; the prepared oxygen fluorescence sensitive film is suitable for oxygen sensor. By using the prepared sensing film in combination with an optical fiber spectrometer, the oxygen content in the gaseous state and the dissolved oxygen in water can be detected continuously in real time.

Example 4

1) Dissolve the fluorescent substance in a certain solvent. In a preferred scheme, the platinum porphyrin complex PtTFPP is dissolved in tetrahydrofuran to obtain a stock solution with a concentration of 10 mM;

2) Preparation of fluorocarbon sol-gel (Fluorinated xerogels) stock solution: using methyltrimethoxysilane (PhTMOS) and trifluoropropyltrimethoxysilane (TFP-TriMOS) as precursors, ethanol as solvent, It is hydrolyzed under the catalysis of hydrochloric acid at pH=2. In the preferred scheme, the volume percentage of TFP-TriMOS in the precursor is 60%. The mixed reagent is ultrasonically mixed; .

3) Preparation of the sensitive membrane: adding the tetrahydrofuran solution of PtTFPP into the fluorocarbon sol-gel solution, and mixing evenly. In a preferred scheme, 10 mM PtTFPP and fluorocarbon sol-gel stock solution are ultrasonically mixed at a volume ratio of 1:5 to obtain a sensitive reagent. Coating the mixed sensing reagent on a clean glass slide by dip coating method to obtain an oxygen sensitive film;

4) The oxygen-sensitive film is aged in an oven at 85°C for 12 hours to completely evaporate the solvent to obtain an oxygen-sensitive film with a film thickness of 5 μm.

The fluorescent substance is platinum porphyrin complex PtTFPP, its excitation center wavelength is 508nm and 541nm, and the fluorescence emission center wavelength is 650nm; the prepared oxygen fluorescence sensitive film is suitable for oxygen sensor. By using the prepared sensing film in combination with an optical fiber spectrometer, the oxygen content in the gaseous state and the dissolved oxygen in water can be detected continuously in real time.

Application example

Take a piece of Example 1 with a diameter of 10mm to prepare an oxygen-sensitive membrane, which is used in a conventional optical oxygen sensor, and is fixed in the flow cell at a position corresponding to the optical fiber probe. Using a light-emitting diode with a central wavelength of 460 nm as the light source, the excitation light and emitted fluorescence were transmitted by a quartz branch fiber (BIF200-US-VIS, OceanOptics, USA). The emission fluorescence was measured at a center wavelength of 622 nm with an ocean fiber optic spectrometer (USB4000, Ocean Optics, USA). Flow the measured water through the measuring cell—the flow cell, and the measurement result is shown in Figure 3. It is also possible to pass the gas through the flow cell and measure the signals of pure _N2 and pure _O2 as shown in Figure 4.

Claims (8)

1. An oxygen fluorescence sensitive film, characterized in that it is composed of a fluorocarbon sol-gel matrix embedded with a fluorescent substance, wherein the molar ratio of the fluorescent substance to the fluorocarbon sol-gel matrix is 1-30. 2. according to the described sensitive membrane of claim 1, it is characterized in that: described fluorescent substance is metal ruthenium complex, metal osmium complex, metal lead complex, metal platinum complex, metal palladium complex , metal rhenium complexes; The fluorocarbon sol-gel matrix is a hydrolyzed copolymer of trifluoropropyltrimethoxysilane TFP-TriMOS and other siloxane monomers; the volume ratio of TFP-TriMOS to other siloxane monomers is 0.25- 4; The other siloxane monomers are tetramethoxysilane TMOS, tetraethoxysilane TEOS, methyltrimethoxysilane MTMOS, methyltriethoxysilane MTEOS, propyltrimethoxysilane PTMOS or propyl Triethoxysilane PTEOS. 3. The sensitive film according to claim 1, characterized in that: the thickness of the sensitive film is 0.1-10 μm. 4. a preparation method of sensitive film according to claim 1, characterized in that: 1) Dissolving the fluorescent substance in an organic solvent to form a solution A; 2) Trifluoropropyltrimethoxysilane TFP-TriMOS and other siloxane monomers are used as precursors, hydrolyzed in an organic solvent under acidic conditions of PH = 1 to 4, and ultrasonically mixed to obtain fluorocarbon sol-gel Glue solution B; 3) Mix solution A and solution B according to the required ratio, and ultrasonically mix to obtain a reagent for preparing a sensitive film; 4) Coating the reagents for preparing the sensitive film on the glass carrier, drying in an oven to volatilize the solvent to form an oxygen fluorescent sensitive film, which can be applied to photochemical sensing of oxygen. 5. According to the preparation method of the sensitive film according to claim 4, it is characterized in that: the molar concentration of the fluorescent substance in the organic solvent is 1-15 mM, and the volume percentage of the precursor and the organic solvent is 1-4:1 . 6. according to the preparation method of the described sensitive membrane of claim 4, it is characterized in that: the volume percent of TFP-TriMOS in the precursor described in step 2) is 20～80%; The volume ratio in water and organic solvent is 1 : 1~3. 7. The method for preparing the sensitive film according to claim 4, characterized in that: the volume ratio of the solution A to the solution B is 1:2-6. 8 . The method for preparing the sensitive film according to claim 4 , characterized in that: in step 4), the film is dried in an oven at 60-100° C. for 6-12 hours.

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