CN112730330B - Carbon point waveguide-based benzoyl peroxide gas sensor - Google Patents

Abstract

The invention discloses a carbon dot waveguide-based benzoyl peroxide gas sensor, and particularly relates to a high-selectivity and ultra-sensitive sensing method for detecting the content of Benzoyl Peroxide (BPO) in food based on an optical waveguide material. The preparation process mainly comprises the following steps: 1) Synthesizing carbon dots with colorimetric response to BPO by a hydrothermal method; 2) Obtaining oil-soluble carbon dots through modification, and coating the oil-soluble carbon dots on a sensing arm of a Mach-Zehnder interferometer (MZI); 3) As BPO concentration increases, the uv absorption of the carbon dots changes significantly, and the discoloration of the carbon dots induces a refractive index change, resulting in a shift in the MZI interference fringes. The amount of shift is linear with the concentration of BPO introduced. The invention firstly proposes that the BPO content in food is detected by utilizing the optical waveguide sensing technology in an ultra-sensitive way, and compared with the traditional BPO detection method, the method has the advantages of high sensitivity, high speed and good selectivity. The requirement of batch preparation in industrial production is met, and the method is extremely easy to popularize and apply practically.

Description

A sensor for benzoyl peroxide gas based on carbon dot waveguide

technical field

The invention belongs to the field of optical waveguide sensing materials, and relates to an optical waveguide sensor for detecting benzoyl peroxide (BPO) gas, which combines sensitive materials and optical waveguide refractive index sensors to realize highly selective and ultrasensitive BPO detection. At present, it has not been reported that carbon dots are selected as optical waveguide materials. Therefore, the present invention proposes to use carbon dots as optical waveguide materials to construct waveguide sensors for the first time. The invention belongs to the application field of analysis and detection.

Background technique

Compared with traditional sensors, optical fiber/waveguide sensors based on refractive index changes have extremely high sensitivity and resolution, wide frequency band range, large dynamic range, and no interference from electromagnetic fields. It has been practically applied in scientific research departments and in the fields of scientific research such as manufacturing industry, energy industry, and medical treatment. Among the many optical fiber/waveguide sensors, the optical fiber/waveguide sensor based on the Mach-Zehnder structure has developed rapidly and has become an important branch of the research field of optical fiber/waveguide sensors. It is widely used in strain, stress, temperature, pressure, deformation, and vibration in structures. Continuous and real-time safety detection of physical quantities such as displacement and displacement, and can also be used to monitor the curing state of composite materials. It is of great significance for the safe use and integrity testing of aircraft, ships, buildings, etc. At present, various methods of using Mach-Zehnder interferometers to detect toxic gas molecules emerge in endlessly.

Benzoyl peroxide (BPO) is a highly active oxidant, which is widely used as an additive of wheat flour due to its good oxidative bleaching properties, which not only has bleaching effect, but also greatly shortens the aging cycle of flour. However, it was later discovered that adding excessive amounts of benzoyl peroxide to wheat flour would not only destroy nutrition, but also threaten human health. Studies have shown that benzoyl peroxide in wheat flour is irritating and sensitizing to human skin and upper respiratory tract. Due to the existence of many potential risks, the use of benzoyl peroxide has received more and more attention, especially by the food safety supervision department. Many countries have therefore formulated strict standards to control the maximum use of benzoyl peroxide in food. In 2009, the Codex Alimentarius Commission established a use standard, that is, the maximum amount of benzoyl peroxide in wheat flour is 75mg/kg. The European Union has banned the use of benzoyl peroxide in wheat flour since May 1, 2011. Until 2011, seven departments in our country announced the prohibition of adding benzoyl peroxide to flour. Even though benzoyl peroxide is banned in many countries, due to its good bleaching effect and low price, many unscrupulous traders still add it to food for illegal profits. Therefore, monitoring the level of benzoyl peroxide in food is of great significance to food security and public health, and developing a simple and convenient detection method for benzoyl peroxide is the only way to achieve effective monitoring. Currently on the market, many instrumental analysis methods have been developed based on the detection of benzoyl peroxide content, including chemiluminescence, amperometry, electrochemistry, spectrophotometry and high-performance liquid chromatography detection methods, and most methods require time-consuming samples Pretreatment and separation are not convenient for rapid detection results, and these traditional methods either show low sensitivity or require expensive instruments and complicated pretreatment processes, which limit their practical application.

Optical waveguide sensors based on refractive index changes have the advantages of high sensitivity, small resolution, high integration, and anti-electromagnetic interference. Materials such as silicon dioxide, silicon-on-insulator (SOI), Si ₃ N ₄ , polymers (SU-8, epoxy, Ormocore, etc.) have been used to fabricate waveguide sensors that are useful tools for the detection of various analytes. In recent years, optical waveguide sensors based on various semiconductors, polymers and other materials have been widely used in many fields such as environmental hygiene, food safety, and disease diagnosis. However, optical waveguide sensors based on novel fluorescent carbon nanomaterials have not been paid attention to and developed yet. Therefore, it is of great significance to explore the real-time, high-sensitivity and rapid detection of BPO content in wheat flour using optical waveguide sensors using fluorescent carbon dots.

Contents of the invention

A carbon dot waveguide based benzoyl peroxide gas sensor with fast response and high sensitivity. Economical, environmentally friendly, high stability, and easy-to-prepare carbon dots are used as waveguide materials. Our material system is less expensive than conjugated fluorescent polymers. Carbon dots are used as the coating, and the photolithography/development one-step method is used to make it. Our miniature waveguide sensors provide fast, sensitive BPO detection. Unlike fluorescent sensors, waveguide sensors do not undergo photobleaching. Our approach of applying functionalized carbon dots to waveguide devices can be further developed into practical additive sensors for field applications.

Carbon dot synthesis method: Add 0.2g p-phenylenediamine, 1.0g o-phenylenediamine, 2.0g dopamine and 25mL of 1M HCl into a 50mL stainless steel reactor, and synthesize carbon dots by hydrothermal method at 200°C for 16h. After centrifugation, 0.22μM membrane filtration, and then dialysis purification through a dialysis bag with a molecular weight of 1000Da. Take 10 mL of carbon dot solution, 100 μL of oleylamine, and 5 mL of ethyl acetate into a round-bottomed flask, stir and react for 24 hours, centrifuge, and rotary evaporate to obtain oil-soluble carbon dots. Apply carbon dots to the sensing arm of the Mach-Zehnder interferometer as a waveguide material that responds to BPO. Due to the adsorption of carbon dots, BPO gas can be adsorbed to cause the refractive index of carbon dots to change, and then according to the change in wavelength shift Realize the gas sensing of BPO.

The detection mechanism of the waveguide gas sensor: BPO has strong oxidative properties, which can quench the fluorescence of carbon dots, resulting in the aggregation of carbon dots, the corresponding absorption spectrum and solution color changes, and the induction of sensitive cladding refractive index changes, so that the waveguide is effective. The refractive index changes. For the MZI structure waveguide, the effective refractive index changes of the reference arm and the sensing arm are different, so that the effective refractive index difference of the two arms changes, so that the phase difference of the light transmitted in the two arms changes, and the output The two beams of light at the end are combined and interfered, resulting in the shift of the center wavelength of the interference spectrum, and the BPO gas is detected.

Description of drawings

Figure 1. Schematic diagram of the synthesis process of carbon dots.

Figure 2. Schematic diagram of the sensing mechanism of waveguide materials.

Figure 3. Schematic transmission electron microscopy of synthesized carbon dots.

Figure 4. XRD schematic diagram of synthesized carbon dots.

Fig. 5. The waveguide sensor prepared by the present invention responds to the absorption spectrum of different concentrations of BPO.

Figure 6. The color change of the carbon dot solution after adding different concentrations of BPO (left to right: blank to increasing concentration)

Figure 7. Wavelength shift graph of sensing response at different times.

Detailed ways

In order to facilitate those skilled in the art to understand the technical content of the present invention, the content of the present invention will be further explained below in conjunction with the accompanying drawings.

Take 0.2g p-phenylenediamine, 1.0g o-phenylenediamine, 2.0g dopamine and 1M 25mL HCl into a 50mL stainless steel reaction kettle, synthesize carbon dots by hydrothermal method at 200°C for 16h, centrifuge at 9000rpm for 10min, Filter with a 0.22μM filter membrane, and then go through a dialysis bag with a molecular weight of 1000Da for dialysis purification to obtain pure carbon dots.

Take 10mL of carbon dot solution, 100μL of oleylamine, 5mL of ethyl acetate and EDC/NHS into a round-bottomed flask, stir and react for 24h, centrifuge, and rotary evaporate to obtain oil-soluble carbon dots.

Figure 1 is a transmission electron microscope image of the prepared carbon dots, from which it can be obtained that the particle size is 3nm and the distribution is uniform.

Figure 2 is the XRD pattern of the prepared carbon dots, which has an obvious peak at 24.2 ⁰ , indicating that it has a very high lattice structure.

Figure 3 and Figure 4 show the changes in the absorption spectrum and the color of the corresponding solution after adding different concentrations of BPO. From the figure, it can be seen that the carbon dot has a visual detection effect on BPO.

Figure 5 shows that the oil-soluble carbon dots are coated on the sensing arm, and the BPO is detected by the interferometer, and the determination of different concentrations of BPO is realized according to the wavelength shift.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications made within this idea and method, improvements and equivalent replacements on this basis should be included in the present invention. within the scope of protection.

Claims (1)

1. A preparation method of a fluorescent carbon dot-based waveguide benzoyl peroxide gas sensor is characterized by comprising the following steps:

adding 0.2g of p-phenylenediamine, 1.0g of o-phenylenediamine, 2.0g of dopamine and 1M and 25mL of HCl into a 50mL stainless steel reaction kettle, synthesizing carbon points by a hydrothermal method at 200 ℃ for 16h, centrifuging, filtering with a 0.22 mu m filter membrane, dialyzing and purifying by a dialysis bag with the molecular weight of 1000Da, adding 10mL of carbon point solution, 100 mu L of oleylamine and 5mL of ethyl acetate into a round bottom flask, stirring for reacting for 24h, centrifuging, and performing rotary evaporation to obtain oil-soluble carbon points;

coating carbon dots on a sensing arm of the Mach-Zehnder interferometer to serve as a waveguide material responding to the BPO;

and step three, adsorbing BPO gas to cause the change of the refractive index of the carbon dots due to the adsorption effect of the carbon dots, and further realizing the gas sensing of the BPO according to the change of the wavelength displacement.

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