Preparation device and application of core-shell structure material

Abstract

The invention discloses a preparation device and application of a core-shell structure material, 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 a graphene oxide-humic acid compound, and the graphene oxide-humic acid compound is composed of lignocellulose and a graphene oxide-humic acid compound. The mass ratio of the lignocellulose to the graphene oxide-humic acid is 2: 1. The method solves the problems of low adsorption efficiency and tedious pretreatment in detection of antibiotic residues in complex matrixes of aquatic products, has the advantages of high adsorption capacity, strong matrix interference resistance, 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 present invention relates to the technical field of core-shell structural materials, and in particular to a preparation device and application of core-shell structural materials. Background Art

[0002] With the intensive development of aquaculture, the widespread use of antibiotics in aquatic animal disease prevention and control has led to an increasingly serious problem of drug residues. The accumulation of antibiotics such as sulfonamides and quinolones in organisms not only threatens human health, but the induction of drug-resistant strains has become a major concern for global public health security. However, the complex nature of aquatic product matrices, such as high protein, high fat, and multiple colloids, means that traditional pretreatment methods for target separation and enrichment face technical bottlenecks such as low adsorption capacity, severe matrix interference, and cumbersome operational procedures.

[0003] Solid phase extraction technology is the core link of sample pretreatment, and its filler performance directly determines the accuracy of the test results. Traditional silica-based or polymer-based adsorption materials (such as C 18 , HLB, etc.) when dealing with complex samples such as minced meat, the selective adsorption capacity is often insufficient due to the single surface hydrophobic effect, and it is easily interfered by the nonspecific adsorption of large molecular proteins and lipid substances. 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 highly polar antibiotics even suffer from serious loss. In recent years, although nanomaterials (such as carbon nanotubes and metal-organic framework materials) have shown excellent adsorption properties, their high preparation cost, complex surface functionalization process and potential risk of secondary contamination have limited their large-scale application.

[0004] To solve the above problems, graphene oxide has a large specific surface area (2630m 2 / g) and rich oxygen-containing functional groups, showing unique advantages in the field of antibiotic adsorption. However, single graphene oxide materials are prone to stacking and agglomeration in aqueous systems, resulting in a large loss of effective adsorption sites. By introducing natural organic matter such as humic acid for surface modification, the dispersibility of the material can be significantly improved and the π-π electron donor-acceptor effect can be enhanced. At the same time, as a renewable biomass carrier, lignocellulose has a three-dimensional network structure that can effectively prevent the agglomeration of nanomaterials and provide additional hydrogen bonding sites. However, the preparation of existing composite materials mostly adopts mechanical mixing methods, which makes it difficult to achieve the precise spatial distribution of functional components, resulting in the inability to synergistically optimize the adsorption kinetics and selectivity.

[0005] In terms of material configuration design, core-shell structures have attracted much attention due to their unique spatially graded properties. Theoretical studies have shown that core-shell materials with selectively permeable shells can achieve a synergistic effect of "molecular sieving and targeted adsorption": the outer shell blocks macromolecular interferents through pore exclusion, while the inner core concentrates a high density of active sites for specific adsorption. However, existing core-shell material preparation technologies (such as emulsion polymerization and layer-by-layer self-assembly) generally suffer from complex processes, poor particle size uniformity, and difficulty in precisely controlling shell thickness. In particular, for biocompatible gel materials such as sodium alginate, traditional cross-linking methods easily lead to the collapse of the microsphere structure, seriously restricting its application effectiveness in actual sample processing.

[0006] Breakthroughs in microfluidic technology provide new ideas for solving the above problems. Coaxial microfluidic chips can achieve high-throughput preparation of monodisperse core-shell microspheres by precisely controlling the multiphase fluid dynamics parameters. Studies have 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 50-200μm and a particle size variation coefficient of less than 5% can be obtained. This precise spatiotemporal control capability has laid a technical foundation for the development of solid-phase extraction materials with customized core-shell ratios. However, existing research has mostly focused on biomedical fields such as drug delivery, and its application in environmental analysis sample pretreatment is still blank. Therefore, it is necessary to develop a preparation device and application of core-shell structured materials. Summary of the Invention

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

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

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

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

[0011] Furthermore, the sodium alginate gel forms a three-dimensional network structure with a pore size of 10-50 nm through calcium ion cross-linking.

[0012] Furthermore, the core structure is used to adsorb antibiotic molecules, and the shell structure is used to screen biological tissues and protect the core structure.

[0013] On the other hand, a device for preparing a core-shell structure material is provided, which is used to prepare the core-shell structure material, comprising a coaxial microfluidic chip, a first injection channel and a second injection channel, wherein the first injection channel is connected to the output end of a first injection pump, and the second injection channel is connected to the output end of a second injection pump, and the outlet ends of the first injection channel and the second injection channel are flush to form a concentric circle structure, and a collection device filled with 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 respectively connected to the control input end of the first injection pump and the second injection pump.

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

[0015] Furthermore, the collecting device is provided with a magnetic stirrer with a stirring speed of 200 r / min.

[0016] Furthermore, the preparation method of the preparation device includes collecting the prepared core-shell structure gel microspheres by gravity method, controlling the coefficient of variation of the microsphere particle size to be less than 5%; adjusting the mass ratio of hydrothermally synthesized cellulose to graphene oxide @ humic acid to 2:1, controlling the flow rate of the inner channel to 0.1-0.3 mL / min, and the flow rate of the outer channel to 0.3-1.5 mL / min to ensure that the flow rate fluctuation is less than ±2%, and when the core-shell structure gel microspheres come into contact with calcium chloride solution, they are rapidly cross-linked and calcified to form rigid solid gel microsphere particles; collecting the solid gel microsphere particles, washing them, and then freeze-drying them to obtain a core-shell structure material.

[0017] Furthermore, a gradient cooling strategy was adopted during the freeze-drying process, and the temperature was gradually lowered from 4°C to -20°C to -50°C.

[0018] On the other hand, a core-shell structure material is used in separation, adsorption and desorption in the detection of antibiotic residues in aquatic products.

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

[0020] The present invention is a preparation device and application of a core-shell structure material. Compared with the prior art, the present invention has the following technical effects:

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

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

[0023] Figure 2 A core filler synthesis route diagram of a core-shell structure material of the present invention and a microscopic schematic diagram of the core-shell structure material;

[0024] Wherein: 1-shell solution injection pump; 2-core filler injection pump; 3-coaxial chip; 4-core-shell structure droplet; 5-collecting device; 6-magnetic stirrer; 7-calcium chloride solution; 8-lignocellulose. DETAILED DESCRIPTION

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

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

[0027] To prepare the graphene oxide@humic acid composite adsorbent, 100 mg of graphene oxide was dispersed in 50 mL of deionized water and ultrasonicated for 30 minutes to fully disperse it. 30 mg of humic acid powder was added, and the mixture was magnetically stirred for 2 hours before being transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 180°C for 12 hours. After the reaction, the precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60°C to obtain a functionalized adsorbent with surface modifications of carboxyl (-COOH), hydroxyl (-OH), and keto (C=O) groups. To prepare the core layer slurry, the graphene oxide@humic acid and wood cellulose were mixed in a 1:2 mass ratio. Deionized water was added to prepare a homogenous suspension with a solids content of 15%. The suspension was then homogenized in a high-speed homogenizer at 8000 rpm for 10 minutes to ensure the absence of agglomerated particles. Subsequently, core-shell microspheres were prepared using a coaxial microfluidic chip: the inner needle (inner diameter 0.3mm) delivered the core slurry at a flow rate of 0.2mL / min, and the outer needle (inner diameter 1.0mm) delivered a 1-2% sodium alginate solution at a flow rate of 0.6mL / min. The two-phase fluid formed a stable laminar flow at the chip outlet, generating droplets with a core-shell ratio of approximately 40%. The droplets fell under gravity into a collection tank containing 2% CaCl2. After crosslinking for 30 seconds, rigid gel microspheres were formed with a particle size of 600±25μm (see Figure 2 Finally, the gel microspheres were washed three times with deionized water, placed in a freeze dryer, and freeze-dried according to a gradient cooling program (precooling at 4°C for 2 hours → maintaining at -20°C for 4 hours → freezing at -50°C for 24 hours) to obtain a porous core-shell structure material with a volume recovery rate of 98% after rehydration.

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

[0029] like Figure 1 As shown, the coaxial microfluidic chip device of the present invention includes a dual-channel needle assembly, a syringe pump system and a cross-linking module. During operation, the core layer slurry and the shell layer solution are respectively loaded into 20mL syringes and fixed to the dual syringe pump bracket. The inner layer flow rate is set to 0.1-0.3mL / min and the outer layer flow rate is set to 0.3-1.5mL / min through the touch screen. After startup, the pressure sensor data is monitored in real time to ensure that the flow rate fluctuation is less than ±2%. After the droplets are generated, they fall freely into a calcium chloride solution tank with a depth of 15cm. A magnetic stirrer (speed 200r / min) is provided in the tank to prevent microsphere accumulation. The cross-linked microspheres are collected through a filter and transferred to a freeze dryer for processing.

[0030] Example 3 Application Example and Effect Verification:

[0031] In a laboratory solid-phase extraction validation study, 5g of grass carp minced meat (containing enrofloxacin and sulfamethazine residues) was homogenized and extracted with 20mL of acetonitrile-water (8:2) solution. After centrifugation, the supernatant was adjusted to pH 6.8 with 0.1mol / L HCl. 500mg of the core-shell material was loaded onto a solid-phase extraction column at a flow rate of 1mL / min, using 5mL of 5% methanol as eluent and 3mL of methanol-acetic acid (9:1) as eluent. HPLC-MS / MS analysis revealed enrofloxacin recoveries of 94.2±3.1% and sulfamethazine recoveries of 91.7±2.8%, significantly higher than those of commercial HLB columns (65%-72%). For rapid on-site testing, 10 2mm-diameter core-shell particles were mixed with 5mL of surimi extract (containing 10μg / kg of ciprofloxacin). After vortexing for 5 minutes, the particles were placed on the sample area of ​​a colloidal gold test strip, and a pressure of 5N was applied to squeeze out the adsorbent. The test strip developed color within 3 minutes, with a visual detection limit of 0.5μg / kg. When used in conjunction with a portable fluorescence detector, the limit of quantification reached 0.2μg / kg.

[0032] This invention combines microfluidic molding technology with novel nanocomposites to construct a systematic preparation system for core-shell solid-phase extraction materials. Graphene oxide-humic acid composite fillers are synthesized in situ via a hydrothermal method, leveraging the biotemplating effect of lignocellulose to achieve stable loading of active ingredients. A coaxial microfluidic chip is used to precisely control the spatial configuration of the sodium alginate shell and composite core, ultimately yielding a novel extraction material that combines molecular sieving capabilities with ultra-high adsorption capacity. Experiments have demonstrated that this material has an adsorption capacity of 108.41 mg / g for typical antibiotics such as enrofloxacin, a significant improvement over commercial HLB fillers. The material can withstand seven adsorption-desorption cycles without significant degradation.

[0033] By combining core-shell structure design with microfluidic preparation technology, the present invention successfully solves the difficult problems of low adsorption efficiency and cumbersome pretreatment in the detection of antibiotic residues in complex matrices of aquatic products. Example data show that the recovery rate of this material for multiple antibiotics exceeds 90%, and it can adapt to the dual needs of laboratory precision detection and on-site rapid screening.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A core-shell structure material, comprising a core-shell structure, characterized in that: The core-shell structure includes an outer shell structure and a core structure, wherein the outer shell structure is composed of sodium alginate gel, and the core structure is composed of lignocellulose and a graphene oxide@humic acid complex, wherein the mass ratio of the lignocellulose to the graphene oxide@humic acid is 2:

1.

2. The core-shell structure material according to claim 1, characterized in that Graphene oxide@humic acid is synthesized by hydrothermal method, and humic acid is modified on the surface of single-layer graphene oxide.

3. The core-shell structure material according to claim 1, characterized in that 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.

4. The core-shell structure material according to claim 1, characterized in that The core structure is used for adsorbing antibiotic molecules, and the shell structure is used for screening biological tissues and protecting the core structure.

5. A device for preparing a core-shell structure material, for preparing the core-shell structure material according to any one of claims 1 to 4, characterized in that: The invention comprises a coaxial microfluidic chip, a first injection channel and a second injection channel, wherein the first injection channel is connected to the output end of a first injection pump, the second injection channel is connected to the output end of a second injection pump, the outlet ends of the first injection channel and the second injection channel are flush with each other to form a concentric circle structure, a collecting device filled with 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 respectively connected to the control input end of the first injection pump and the second injection pump.

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

7. The preparation device according to claim 5, characterized in that: The collecting device is provided with a magnetic stirrer with a stirring speed of 200 r / min.

8. The preparation device according to claim 5, characterized in that: The preparation method of the preparation device includes collecting prepared core-shell structure gel microspheres by gravity, controlling the coefficient of variation of the microsphere particle size to be less than 5%; adjusting the mass ratio of hydrothermally synthesized lignocellulose to 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 to ensure that the flow rate fluctuation is less than ±2%, and when the core-shell structure gel microspheres come into contact with a calcium chloride solution, they are rapidly cross-linked and calcified to form rigid solid gel microsphere particles; and collecting the solid gel microsphere particles, washing them, and then freeze-drying them to obtain a core-shell structure material.

9. The preparation device according to claim 5, characterized in that: During the freeze-drying process, a gradient cooling strategy was adopted, and the temperature was gradually lowered from 4°C to -20°C to -50°C.

10. Use of the core-shell structure material according to any one of claims 1 to 4 in separation, adsorption and desorption in the detection of antibiotic residues in aquatic products.

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