CN112730330B

CN112730330B - Carbon point waveguide-based benzoyl peroxide gas sensor

Info

Publication number: CN112730330B
Application number: CN202110066392.1A
Authority: CN
Inventors: 蓝敏焕; 李香草; 赵少静
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2022-11-01
Anticipated expiration: 2041-01-19
Also published as: CN112730330A

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

Carbon point waveguide-based benzoyl peroxide gas sensor

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. At present, the selection of carbon dots as optical waveguide materials has not been reported, so the invention firstly proposes the use of carbon dots as optical waveguide materials to construct waveguide sensors. The invention belongs to the field of analysis and detection application.

Background

Compared with the traditional sensor, the optical fiber/waveguide sensor based on the refractive index change has the advantages of extremely high sensitivity and resolution, wide frequency band range, large dynamic range, no electromagnetic field interference and the like, and is practically applied in the national defense and military department, scientific research departments, and the scientific research fields of manufacturing industry, energy industry, medical treatment and the like in recent years. Among a plurality of optical fiber/waveguide sensors, the optical fiber/waveguide sensor based on the Mach-Zehnder structure is developed rapidly, becomes an important branch in the research field of the optical fiber/waveguide sensor, is widely applied to continuous real-time safety detection of physical quantities such as strain, stress, temperature, pressure, deformation, vibration, displacement and the like in the structure, and can also be used for monitoring the curing state of a composite material and the like. The method has important significance for safe use and integrity detection of airplanes, ships, buildings and the like. At present, various methods for detecting toxic gas molecules by using Mach-Zehnder interferometers are developed.

Benzoyl Peroxide (BPO) is a high-activity oxidant, is widely used as an additive of wheat flour due to good oxidation bleaching performance, not only has bleaching effect, but also can greatly shorten the curing period of flour. However, later, people found that excessive benzoyl peroxide added to wheat flour not only damaged nutrition, but also threatened human health. Researches show that benzoyl peroxide in wheat flour has irritation and sensitization to human skin and upper respiratory tract. Due to the potential risks, the use of benzoyl peroxide is receiving more and more attention, especially the attention of food safety regulatory authorities. Many countries therefore set strict standards to control the maximum amount of benzoyl peroxide used in food products. In 2009, the food code committee specified a usage standard, namely that the maximum amount of benzoyl peroxide in wheat flour was 75mg/kg. The european union prohibited the use of benzoyl peroxide in wheat flour since 5/1/2011. Until 2011, seven departments in China declare that the addition of benzoyl peroxide in flour is forbidden. Even though benzoyl peroxide is banned in many countries at present, there are still many illegal vendors who add it to food-making for illegal benefits due to its good bleaching effect and low price. Therefore, the monitoring of the level of benzoyl peroxide in food is of great significance to food safety and public health, and the development of a simple and convenient benzoyl peroxide detection method is the only way to achieve effective monitoring. Currently, many instrumental analysis methods have been developed based on benzoyl peroxide content detection in the market, including chemiluminescence, amperometry, electrochemistry, spectrophotometry and high performance liquid chromatography detection methods, but most methods require time-consuming sample pretreatment and separation, are inconvenient for rapid detection results, and either exhibit low sensitivity or require expensive instruments and complicated pretreatment processes, limiting their practical applications.

The optical waveguide sensor based on the refractive index change has the advantages of high sensitivity, small resolution, high integration level, electromagnetic interference resistance and the like. Materials such as silicon dioxide, silicon-on-insulator (SOI), si₃N₄Polymers (SU-8, epoxy, ormocore, etc.) have been used to make waveguide sensors as useful tools for detecting various analytes. In recent years, optical waveguide sensors based on various semiconductor, polymer and other materials have been widely used in many fields such as environmental sanitation, food safety, disease diagnosis and the like. However, optical waveguide sensors based on new fluorescent carbon nanomaterials have not been addressed and developed. Therefore, it is of great importance to explore the optical waveguide sensor using the fluorescent carbon dots to detect the BPO content in the wheat flour quickly and in real time with high sensitivity.

Disclosure of Invention

A carbon dot waveguide-based benzoyl peroxide gas sensor has the characteristics of quick response and high sensitivity. The carbon dots which are economical, environment-friendly, high in stability and easy to prepare are used as waveguide materials. Our material system is cheaper than conjugated fluorescent polymers. The carbon dots are used as a coating, and the carbon dots are manufactured by a photoetching/developing one-step method. Our miniature waveguide sensor can provide fast, sensitive BPO detection. Unlike fluorescent sensors, waveguide sensors do not suffer from photobleaching. Our approach of applying functionalized carbon dots to waveguide devices can be further developed into practical additive sensors for field applications.

The carbon point synthesis method comprises the following steps: 0.2g of p-phenylenediamine, 1.0g of o-phenylenediamine, 2.0g of dopamine and 1M of 25mL of HCl are added into a 50mL stainless steel reaction kettle, carbon dots are synthesized by a hydrothermal method under the conditions of 200 ℃ and 16 hours, and the mixture is centrifuged, filtered by a 0.22 mu M filter membrane and dialyzed and purified by a dialysis bag with the molecular weight of 1000 Da. And (3) adding 10mL of carbon dot solution, 100 mu L of oleylamine and 5mL of ethyl acetate into a round-bottom flask, stirring for reacting for 24 hours, centrifuging, and performing rotary evaporation to obtain the oil-soluble carbon dot. The carbon dots are coated on the sensing arm of the Mach-Zehnder interferometer to be used as waveguide materials responding to the BPO, the carbon dots can adsorb BPO gas to cause the refractive index of the carbon dots to be changed due to the adsorption effect of the carbon dots, and then the gas sensing of the BPO is realized according to the change of wavelength displacement.

The detection mechanism of the waveguide gas sensor is as follows: BPO has strong oxidizing property, can quench the fluorescence of carbon dot, lead to carbon dot to take place the gathering, it changes to correspond absorption spectrum and solution color, induced sensitive cladding refractivity changes, make the effective refractive index of waveguide change, for MZI structure waveguide, the effective refractive index of reference arm and sensing arm changes differently, make the effective refractive index difference of two arms change, make the optical phase difference of transmission in two arms change, two bunches of light converge at the output end and interfere, lead to the central wavelength of interference spectrum to drift, detect BPO gas.

Drawings

FIG. 1 is a schematic diagram of a carbon dot synthesis process.

Fig. 2 is a schematic diagram of a waveguide material sensing mechanism.

FIG. 3 is a schematic transmission electron microscope of synthetic carbon dots.

Figure 4 XRD schematic of the synthesized carbon dots.

FIG. 5 shows the response of the waveguide sensor prepared according to the present invention to different concentrations of BPO absorption spectra.

FIG. 6. Color change of carbon dot solution after addition of BPO of different concentrations (left to right: blank to increase concentration)

FIG. 7 is a graph of wavelength shift change of sensing response at different times.

Detailed Description

In order to facilitate the understanding of the technical contents of the present invention by those skilled in the art, the present invention will be further explained with reference to the accompanying drawings.

0.2g of p-phenylenediamine, 1.0g of o-phenylenediamine, 2.0g of dopamine and 1M 25mL of HCl are added into a 50mL stainless steel reaction kettle, the carbon dots are synthesized by a hydrothermal method under the condition of 200 ℃ for 16h, and are filtered by a centrifugal 9000rpm,10min and 0.22 mu M filter membrane, and are dialyzed and purified by a 1000Da molecular weight dialysis bag to obtain pure carbon dots.

And adding 10mL of carbon dot solution, 100 mu L of oleylamine, 5mL of ethyl acetate and EDC/NHS into a round-bottom flask, stirring and reacting for 24 hours, centrifuging, and performing rotary evaporation to obtain the oil-soluble carbon dot.

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

FIG. 2 is an XRD pattern for the preparation of carbon dots at 24.2⁰Has obvious peak, which indicates that the crystal lattice structure is very high.

Fig. 3 and 4 show the absorption spectrum and the corresponding color change of the solution after adding different concentrations of BPO, and the effect of the carbon point on the visual detection of BPO can be obtained from the graphs.

FIG. 5 shows the measurement of BPO at different concentrations according to wavelength shift by applying oil-soluble carbon dots to a sensor arm and detecting BPO with an interferometer.

While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

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.