Preparation device and application of core-shell structure material

Abstract

The application discloses a preparation device and application of a core-shell structure material, wherein the core-shell structure comprises an outer shell structure and a core structure; the outer shell structure is composed of sodium alginate gel; the core structure is composed of lignocellulose and an oxidized graphene-humic acid compound; and the mass ratio of the lignocellulose to the oxidized graphene-humic acid is 2:1.The application solves the problems of low adsorption efficiency and complicated pretreatment in detection of antibiotic residues in a complex matrix of aquatic products, has the advantages of high adsorption capacity, strong anti-matrix interference capacity, flexible application mode and low preparation cost, and provides an innovative solution for efficient detection of trace antibiotic residues in aquatic products.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of core-shell structure materials, in particular to a preparation device of a core-shell structure material and application thereof. BACKGROUND

[0002] With the development of aquaculture intensification, the widespread use of antibiotics in the prevention and treatment of diseases in aquatic animals has led to increasingly serious drug residue problems. The accumulation of antibiotics such as sulfonamides and quinolones in organisms not only threatens human health, but also has become an important hidden danger to global public health safety. However, aquatic product matrices have complex characteristics such as high protein, high fat and multiple colloids, and traditional pretreatment methods face technical bottlenecks such as low adsorption capacity, serious matrix interference and complicated operation process in the separation and enrichment of target substances.

[0003] As the core link of sample pretreatment, the performance of solid-phase extraction technology directly determines the accuracy of the detection results. Traditional silica-based or polymer-based adsorbent materials (such as C 18 , HLB, etc.) often have insufficient selective adsorption capacity due to the single surface hydrophobic effect when dealing with complex meat paste samples, and are easily interfered by non-specific adsorption of macromolecular proteins and lipids. Studies have shown that the recovery rate of conventional commercial solid-phase extraction columns for antibiotics in aquatic product matrices is generally less than 60%, and some strongly polar antibiotics even have serious loss phenomena. In recent years, although nanomaterials (such as carbon nanotubes and metal-organic framework materials) have shown excellent adsorption performance, their high preparation cost, complex surface functionalization process and potential secondary pollution risk have limited their large-scale application.

[0004] In view of the above problems, graphene oxide has unique advantages in the field of antibiotic adsorption due to its ultra-large specific surface area (2630 m 2 / g) and rich oxygen-containing functional groups. However, single graphene oxide material is prone to stacking and aggregation in aqueous systems, resulting in a large loss of effective adsorption sites. By introducing humic acid and other natural organic matter for surface modification, the dispersibility of the material can be significantly improved, and the π-π electron donor-acceptor interaction can be enhanced. At the same time, lignocellulose as a renewable biomass carrier can effectively prevent the aggregation of nanomaterials and provide additional hydrogen bonding sites. However, the preparation of existing composite materials mostly uses mechanical mixing method, which is difficult to realize the precise spatial distribution of functional components, resulting in the inability to optimize the adsorption kinetics and selectivity simultaneously.

[0005] In the aspect of material configuration design, the core-shell structure is concerned due to its unique spatial hierarchical characteristics. Theoretical research shows that the core-shell material with a selective permeable shell layer can realize the synergistic effect of "molecular sieving-targeted adsorption": the outer shell layer blocks macromolecular interferents through the pore size exclusion effect, and the inner core concentrates high-density active sites for specific adsorption. However, the existing core-shell material preparation technologies (such as emulsion polymerization and layer-by-layer self-assembly) generally have problems such as complex process, poor particle size uniformity, and difficulty in accurately controlling the shell thickness. In particular, for biocompatible gel materials such as sodium alginate, the traditional cross-linking method easily leads to the collapse of the microsphere structure, which seriously restricts the application performance in actual sample processing.

[0006] The breakthrough of microfluidic technology provides a new idea for solving the above problems. The coaxial microfluidic chip can realize high-throughput preparation of monodisperse core-shell microspheres by precisely controlling the hydrodynamic parameters of multi-phase fluids. Research has shown that when the flow rate ratio of the inner phase (core layer) to the outer phase (shell layer) is controlled at 0.1-0.3, regular microspheres with a shell thickness of 50-200 μm and a particle size variation coefficient of less than 5% can be obtained. This precise spatiotemporal control capability lays a technical foundation for developing solid-phase extraction materials with customized core-shell ratios. However, existing researches mostly focus on the biomedical field such as drug delivery, and the application in environmental analysis sample pretreatment is still blank. Therefore, it is necessary to develop a preparation device and application of core-shell structure material. SUMMARY

[0007] The purpose of the present application is to provide a preparation device and application of core-shell structure material to solve the problems existing in the prior art.

[0008] To achieve the above purpose, the present application is implemented according to the following technical solutions:

[0009] On the one hand, the present application includes a core-shell structure, the core-shell structure includes an outer shell structure and a core structure, the outer shell structure is composed of sodium alginate gel, and the core structure is composed of lignocellulose and graphene oxide@humic acid complex, the mass ratio of lignocellulose to graphene oxide@humic acid is 2:1.

[0010] Further, the graphene oxide@humic acid is synthesized by a hydrothermal method, and the humic acid is modified on the surface of single-layer graphene oxide.

[0011] Further, the sodium alginate gel is cross-linked by calcium ions to form a three-dimensional network structure with a pore size of 10-50 nm.

[0012] Further, the core structure is used for adsorbing antibiotic molecules, and the outer shell structure is used for screening biological tissues and protecting the core structure.

[0013] In another aspect, a preparation device of a core-shell structure material is used to prepare the core-shell structure material, comprising a coaxial microfluidic chip, a first injection channel and a second injection channel, the first injection channel is connected with the output end of a first injection pump, the second injection channel is connected with the output end of a second injection pump, the outlet ends of the first injection channel and the second injection channel are flush to form a concentric structure, a collection device containing a calcium chloride solution is placed below the first injection channel and the second injection channel, and the control output end of the coaxial microfluidic chip is connected with the control input end of the first injection pump and the second injection pump respectively.

[0014] Further, the first injection channel is an inner layer channel, the inner diameter of the inner layer channel is 0.2-0.5 mm, and the inner layer channel is used for conveying core structure slurry; the second injection channel is an outer layer channel, the channel inner diameter is 0.8-1.2 mm, and the outer layer channel is used for conveying 1-2% sodium alginate solution.

[0015] Further, the collection device is provided with a magnetic stirrer, and the stirring speed is 200 r / min.

[0016] Further, the preparation method of the preparation device comprises collecting the prepared core-shell structure gel microspheres by using a gravity method, controlling the particle size variation coefficient of the microspheres to be less than 5%, controlling the mass ratio of the hydrothermally synthesized lignocellulose and graphene oxide@humic acid to be 2:1, controlling the flow rate of the inner layer channel to be 0.1-0.3 mL / min and the flow rate of the outer layer channel to be 0.3-1.5 mL / min to ensure that the flow rate fluctuation is less than ±2%, rapidly crosslinking and calcifying the core-shell structure gel microspheres after the core-shell structure gel microspheres are contacted with the calcium chloride solution, and preparing rigid solid gel microsphere particles; and collecting the solid gel microsphere particles, washing the solid gel microsphere particles, and then freeze-drying the solid gel microsphere particles to obtain the core-shell structure material.

[0017] Further, a gradient cooling strategy is adopted during the freeze-drying treatment, and the temperature is gradually reduced according to 4℃→-20℃→-50℃.

[0018] In another aspect, the core-shell structure material is applied to separation, adsorption and desorption in detection of antibiotic residues in aquatic products.

[0019] The beneficial effects of the present application are:

[0020] Compared with the prior art, the present application has the following technical effects:

[0021] Compared with the prior art, the core-shell structure solid-phase extraction material has high adsorption capacity, strong anti-matrix interference ability, flexible application mode and low preparation cost, and provides an innovative solution for efficient detection of trace antibiotic residues in aquatic products. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A core-shell structure material preparation device for a core-shell structure material of the application;

[0023] Figure 2 A core filler synthesis route map and a core-shell structure material micrograph for a core-shell structure material of the application;

[0024] Wherein 1 is a shell layer solution sample pump; 2 is a core filler sample pump; 3 is a coaxial chip; 4 is a core-shell structure droplet; 5 is a collection device; 6 is a magnetic stirrer; 7 is a calcium chloride solution; and 8 is a lignocellulose. DETAILED DESCRIPTION

[0025] The application will be further described below through specific examples. The illustrative examples of the application and the descriptions used to explain the application are not intended to limit the application.

[0026] Example 1: Preparation method of a core-shell structure solid-phase extraction material

[0027] Preparation of graphene oxide@humic acid composite adsorbent: 100 mg of graphene oxide was dispersed in 50 mL of deionized water, and ultrasonic treatment was performed for 30 minutes to ensure sufficient dispersion; 30 mg of humic acid powder was added, and magnetic stirring was performed for 2 hours, and then the mixture was transferred to a polytetrafluoroethylene reaction kettle, and hydrothermal reaction was performed at 180℃ for 12 hours. After the reaction was completed, the precipitate was collected by centrifugation, washed with ethanol for 3 times, and dried at 60℃ under vacuum to obtain a functional adsorbent with carboxyl (-COOH), hydroxyl (-OH), and ketone (C=O) groups on the surface. When preparing the core layer slurry, the graphene oxide@humic acid and the lignocellulose were mixed in a mass ratio of 1:2, deionized water was added to prepare a homogeneous suspension with a solid content of 15%, and the mixture was treated by a high-speed homogenizer at 8000 r / min for 10 minutes to ensure that there were no aggregated particles. Subsequently, a coaxial microfluidic chip was used to prepare the core-shell microspheres: the core layer slurry was transported by an inner needle (inner diameter 0.3 mm) at a flow rate of 0.2 mL / min, and the 1-2% sodium alginate solution was transported by an outer needle (inner diameter 1.0 mm) at a flow rate of 0.6 mL / min, and the two-phase fluid formed a stable laminar flow at the outlet of the chip to generate droplets with a core-shell ratio of about 40%. The droplets fell into a collection tank containing 2% CaCl2 under the action of gravity, and rigid gel microspheres were formed after crosslinking for 30 seconds, with a particle size of 600±25 μm (see Figure 2 ). Finally, the gel microspheres were washed with deionized water for 3 times, and were placed in a freeze-drying machine for freeze-drying treatment according to a gradient cooling program (pre-cooling at 4℃ for 2 hours→maintaining at -20℃ for 4 hours→freezing at -50℃ for 24 hours), and a porous core-shell structure material was obtained, and the volume recovery rate of the material after rehydration reached 98%.

[0028] Example 2: Operation process of the preparation device

[0029] AsFigure 1 As shown, the coaxial microfluidic chip device of the present application includes a double-channel needle assembly, a syringe pump system and a crosslinking module. In operation, the core layer slurry and the shell layer solution are respectively loaded into 20 mL syringes and fixed on the double syringe pump support. The inner layer flow rate is set to 0.1-0.3 mL / min and the outer layer flow rate is set to 0.3-1.5 mL / min through the touch screen. After starting, the pressure sensor data is monitored in real time to ensure that the flow rate fluctuation is less than ±2%. After the droplet is generated, it freely falls into a calcium chloride solution tank with a depth of 15 cm. A magnetic stirrer (speed 200 r / min) is arranged in the tank to prevent the accumulation of microspheres. The microspheres after crosslinking are collected by a filter screen and transferred to a freeze dryer for processing.

[0030] Example 3 Application Example and Effect Verification:

[0031] In the laboratory solid phase extraction verification, 5 g of grass carp surimi sample (containing enrofloxacin and sulfamethazine residues) was taken, 20 mL of acetonitrile-water (8:2) solution was added for homogenization extraction, and the supernatant was taken after centrifugation and the pH was adjusted to 6.8 with 0.1 mol / L HCl. 500 mg of core-shell material was loaded into a solid phase extraction column, the loading flow rate was 1 mL / min, the elution volume of the washing liquid (5% methanol) was 5 mL, and the elution volume of the elution liquid (methanol-acetic acid = 9:1) was 3 mL. HPLC-MS / MS detection was used, and the results showed that the recovery rate of enrofloxacin was 94.2±3.1%, and the recovery rate of sulfamethazine was 91.7±2.8%, which was significantly higher than that of the commercial HLB column (65%-72%). For the demand of on-site rapid detection, 10 core-shell particles with a particle size of 2 mm were mixed with 5 mL of surimi extract solution (containing 10 μg / kg of ciprofloxacin), and vortex oscillation was performed for 5 minutes. Then, the particles were placed in the sample addition area of the colloidal gold test strip, and a pressure of 5N was applied to squeeze the adsorbed liquid. The test strip developed color within 3 minutes, and the visual detection limit was 0.5 μg / kg. When used with a portable fluorescence detector, the quantification limit reached 0.2 μg / kg.

[0032] The present application combines microfluidic molding technology with new nano-composite materials to construct a systematic preparation system of core-shell structure solid phase extraction material. Graphene oxide-humic acid composite filler is synthesized in situ by hydrothermal method, and the active component is stably loaded by using the biological template effect of lignocellulose; the spatial configuration of sodium alginate shell and composite core layer is accurately regulated by using coaxial microfluidic chip, and finally a new type of extraction material with molecular sieving function and ultra-high adsorption capacity is obtained. Experimental results show that the adsorption capacity of the material for typical antibiotics such as enrofloxacin reaches 108.41 mg / g, which is significantly improved compared with commercial HLB filler, and can withstand 7 adsorption-desorption cycles without significant attenuation.

[0033] The application successfully solves the problems of low adsorption efficiency and complicated pretreatment in the detection of antibiotic residues in complex matrix of aquatic products by combining the core-shell structure design with the microflow control preparation process. The data of the examples show that the recovery rate of the material for various antibiotics is more than 90%, and the material can adapt to the dual needs of laboratory precision detection and on-site rapid screening.

[0034] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A core-shell structure material comprising a core-shell structure, characterized in that, The core-shell structure comprises an outer shell structure and a core structure, the outer shell structure is composed of sodium alginate gel, the core structure is composed of lignocellulose and graphene oxide @ humic acid compound, the mass ratio of lignocellulose to graphene oxide @ humic acid is 2:1, wherein the graphene oxide @ humic acid is synthesized by a hydrothermal method, and the humic acid is modified on the surface of single-layer graphene oxide.

2. The core-shell structure material of claim 1, wherein, The sodium alginate gel is cross-linked by calcium ions to form a three-dimensional network structure with a pore size of 10-50 nm.

3. The core-shell structure material of claim 1, wherein, The core structure is used for adsorbing antibiotic molecules, and the outer shell structure is used for screening biological tissues and protecting the core structure.

4. An apparatus for producing a core-shell structure material, for producing the core-shell structure material according to any one of claims 1 to 3, characterized by, The coaxial microfluidic chip comprises a first injection channel and a second injection channel, the first injection channel is connected with the output end of a first injection pump, the second injection channel is connected with the output end of a second injection pump, the outlet ends of the first injection channel and the second injection channel are flush to form a concentric circle structure, a collection device containing a calcium chloride solution is placed below the first injection channel and the second injection channel, and the control output end of the coaxial microfluidic chip is connected with the control input end of the first injection pump and the second injection pump respectively.

5. The preparation device according to claim 4, characterized in that The first injection channel is an inner channel, the inner diameter of the inner channel is 0.2-0.5 mm, and the inner channel is used for conveying core structure slurry; the second injection channel is an outer channel, the inner diameter of the outer channel is 0.8-1.2 mm, and the outer channel is used for conveying 1-2% sodium alginate solution.

6. The preparation device according to claim 4, characterized in that A magnetic stirrer is arranged in the collection device, and the stirring speed is 200 r / min.

7. The preparation device according to claim 4, characterized in that The preparation method of the preparation device comprises collecting the prepared core-shell structure gel microspheres by using a gravity method, controlling the particle size variation coefficient of the microspheres to be less than 5%, controlling the mass ratio of lignocellulose to hydrothermally synthesized graphene oxide @ humic acid to be 2:1, controlling the flow rate of the inner channel to be 0.1-0.3 mL / min and the flow rate of the outer channel to be 0.3-1.5 mL / min, ensuring that the flow rate fluctuation is less than ±2%, and when the core-shell structure gel microspheres are in contact with the calcium chloride solution, the core-shell structure gel microspheres are quickly cross-linked and calcified to form solid gel microsphere particles with rigidity; and the solid gel microsphere particles are collected, washed and then subjected to freeze-drying treatment to obtain the core-shell structure material.

8. The preparation device of claim 4, wherein, In the freeze-drying treatment, a gradient cooling strategy is adopted, and the temperature is gradually reduced according to 4℃→-20℃→-50℃.

9. The use of the core-shell structure material according to any one of claims 1-3 in separation, adsorption and desorption in the detection of antibiotic residues in aquatic products.

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