A multifunctional integrated automated microfluidic chip array based on DLP 3D printing and its preparation method and application

Abstract

The present invention provides a multifunctional integrated automated microfluidic chip array based on digital light processing (DLP) 3D printing and a preparation method thereof. The spiral structure monolithic column constructed by 3D printing can effectively promote mass transfer compared with a straight channel; the microvalve control unit adopts a solution gradient channel, and uses a circular gas channel to control the gas to squeeze the gradient channel from 360° to achieve control of the channel; the monolithic column in situ polymerized in the spiral channel has a hierarchical porous structure due to the presence of an emulsion template and a covalent organic framework. The present invention combines the in situ polymerized monolithic column with a microfluidic chip array to construct a highly integrated 3D printed chip array that integrates miniaturized sample introduction technology, pre-concentration technology and automatic operation. The analytical method constructed based on the automated microfluidic chip array provided by the present invention has the advantages of high sensitivity, low detection limit, high sample throughput, strong anti-interference ability, etc., and is suitable for the analysis of trace rare earth elements (REEs) in complex samples.

Description

Technical Field

[0001] The present invention belongs to the field of separation and analysis detection technology, and specifically relates to a multifunctional integrated automated microfluidic chip array based on digital light processing (DLP) 3D printing and a preparation method thereof, and also relates to the application of the microfluidic chip array in conjunction with inductively coupled plasma mass spectrometry (ICP-MS) online to evaluate the bioaccessibility of rare earth elements (REEs) in atmospheric particulate matter samples. Background Art

[0002] With the widespread development and utilization of rare earth resources, the concentration of REEs in the environment continues to increase, and they are subsequently enriched in organisms and the human body. The impact of REEs in atmospheric particulate matter on human health cannot be ignored. Studies have shown that a daily intake of 6.00-7.00 mg of REEs in adults can cause subclinical damage to the human body, while a daily intake of up to 4.20 mg of REEs is relatively safe for adults. Given the widespread exposure of the population to atmospheric particulate matter (PM), it is worth studying the health risks of REEs exposed to PM. As one of the most sensitive instruments for metal determination, ICP-MS has the advantages of simplicity, rapidity, and simultaneous detection of multiple elements. However, when it is directly applied to the analysis of complex samples, it still suffers from insufficient detection limits, severe matrix interference, and high sample consumption. Therefore, before ICP-MS analysis, the sample needs to be pretreated to achieve matrix separation and pre-concentration.

[0003] Solid-phase microextraction (SPME) has the advantages of low sample consumption and solvent-free extraction, and has become an emerging direction for the pre-enrichment of trace analytes in miniaturized samples. However, it still suffers from the problems of cumbersome and time-consuming procedures. It is worth exploring how to combine the complex and time-consuming sample pretreatment process with the rapid ICP-MS detection process to achieve efficient analysis of multiple samples.

[0004] Microfluidics is a scientific technology primarily focused on manipulating fluids at the micrometer scale. Microarray chips are widely used due to their high throughput, miniaturization, and automation. Combining microfluidics chips with micrometer-scale channels with microarray chips to design novel miniaturized sample pretreatment devices will effectively address the aforementioned issues. Furthermore, coupling microfluidic chip arrays with ICP-MS online can effectively avoid human error and loss during offline pretreatment, enabling precise analysis of microvolume samples.

[0005] Traditional microfluidic chip arrays rely on manual layer-by-layer bonding, which is expensive, cumbersome, requires high technical expertise, and suffers from poor reproducibility. Because the channel's internal structure is not integral to the chip's inner channel walls, wall detachment is common, and the chip's pressure resistance needs to be improved, limiting the extraction flow rate and reusable life of the chip's monolithic columns. Currently, conventional soft lithography techniques are not feasible for directly fabricating monolithic columns that integrate the monolithic columns with the chip's channels. New fabrication methods are urgently needed to meet these requirements.

[0006] 3D printing technology allows for the free construction of complex 3D structures, integrated molding, diverse materials, low cost, simple fabrication, and excellent reproducibility. However, existing 3D printing techniques for the preparation of microfluidic chips suffer from insufficient resolution, limited adsorption capacity of the constructed structures for target analytes, and low sample throughput. Furthermore, manual operation can introduce errors and contamination. In some studies, researchers have attempted to create complex printed structures, using the original inner surfaces of 3D-printed fluid channels or grafting them with appropriate ligands for separation of target analytes based on size, ion exchange, or chelation. However, these efforts suffer from complex operations, low efficiency, and high costs.

[0007] Based on this, providing a multifunctional integrated automated microfluidic chip array based on DLP 3D printing and its preparation method, and combining it with in situ polymerized porous organic monolithic columns to achieve high-precision analysis and detection is an attractive research direction with application prospects, and it is also a technical problem that researchers urgently need to solve. Summary of the Invention

[0008] One of the objectives of the present invention is to provide a multifunctional integrated automated microfluidic chip array based on DLP 3D printing.

[0009] A second object of the present invention is to provide a method for preparing a multifunctional integrated automated microfluidic chip array based on DLP 3D printing.

[0010] A third object of the present invention is to provide an application of a multifunctional integrated automated microfluidic chip array based on DLP 3D printing and online coupling with ICP-MS to evaluate the bioaccessibility of REEs in atmospheric particulate matter samples.

[0011] The technical solution adopted by the present invention to achieve one of the objectives is to provide a multifunctional integrated automated microfluidic chip array based on DLP 3D printing, which includes several pre-processing systems;

[0012] The pretreatment system includes: a chip interface, a spiral structure integral column unit, and a micro gas valve control unit;

[0013] The chip interface includes a chip inlet and a chip outlet; the chip inlet includes an injection port, a desorption liquid inlet, and a cleaning liquid inlet; the chip outlet includes an ICP-MS connection port and a waste liquid outlet;

[0014] The helical structure monolithic column unit is a helical structure, and is formed by in-situ polymerization of the monolithic column polymer emulsion in the helical channel;

[0015] The micro-valve control unit includes a solution channel and an air valve; the solution channel is gradually changing, and has multiple inwardly concave diameter-changing areas distributed along the length of the solution channel; the air valve includes multiple annular microvalves, which are sleeved on the outside of the diameter-changing areas and use the gas inside the annular microvalves to squeeze the diameter-changing areas of the solution channel to achieve control of the solution channel;

[0016] The chip interface and the spiral channel of the spiral structure integral column unit are made of rigid resin, and the micro valve control unit is made of flexible resin. By replacing the resin at a specified layer during the 3D printing process, the integrated molding of the microfluidic chip array is achieved.

[0017] The overall concept of the multifunctional integrated automated microfluidic chip array based on DLP 3D printing provided by the present invention is as follows:

[0018] The present invention first uses DLP 3D printing technology to integrate and mold a multifunctional automated microfluidic chip array. In this chip array structure, the monolithic column unit adopts a spiral structure constructed by 3D printing, which effectively promotes mass transfer compared to conventional straight channels. At the same time, the present invention cleverly utilizes 3D printing technology to design multiple annular microvalves (360° microvalves) and provides a variable diameter zone on the gradient solution channel. The circular gas channel controls the gas to squeeze the gradient channel from 360°, thereby achieving channel control and automating the entire extraction process. The present invention uses integrated molding technology to combine the spiral monolithic column unit and the microvalve control unit with the microfluidic chip, which can effectively control human contamination. The spiral channel promotes mass transfer, and in-situ polymerization can increase the service life of the microarray, significantly improving sample throughput. By providing multiple pretreatment subsystems, automated and uninterrupted online analysis of multiple samples can be achieved. In addition, the monolithic column of the present invention is formed by in-situ polymerization of the polymer emulsion within the chip, overcoming the wall shedding problem of traditional microfluidic chips and significantly improving the service life of the chip array compared to traditional microfluidic chip arrays.

[0019] Furthermore, the rigid resin is selected from DLP (Digital light processing) rigid resin, and the flexible resin is a flexible resin with a breaking elongation greater than 200%, and in the present invention, F39T flexible resin is preferred.

[0020] Furthermore, the number of pretreatment systems can be calculated based on the system's sample loading time and online detection time, which is not limited here. For example, if the sample loading time is 50 minutes and the online detection time is 2 minutes (1 minute for desorption and 1 minute for rinsing), a 26-unit array can be set up based on the formula sample loading time = 25 * online detection time. This ensures that there is always one unit performing online detection and another 25 units performing sample loading, thus achieving continuous sampling.

[0021] Furthermore, the total length of the helical structure of the helical structure integral column unit is 1 to 8 cm, the length along the height direction is 1 to 2 cm, and the inner diameter is 500 to 1000 μm. Preferably, the total length of the helical structure of the helical structure integral column unit is 4 cm, the length along the height direction is 1 cm, and the inner diameter is 800 μm.

[0022] Furthermore, the plurality of inwardly concave diameter-varying regions are evenly distributed along the length direction of the solution channel.

[0023] Furthermore, the inner diameter of the solution channel varies from 200 to 1000 μm. Preferably, the maximum inner diameter of the solution channel (i.e., the widest position of the solution channel) is 500 to 1000 μm, and the minimum inner diameter of the arc-shaped recessed area (i.e., the narrowest position of the solution channel) is 200 to 300 μm.

[0024] Furthermore, the inner diameter of the annular microvalve is 500-1000 μm. Under the action of gas, the annular microvalve expands and squeezes the arc-shaped concave area of the solution channel inward, further reducing the inner diameter of the arc-shaped concave area until the inner diameter is 0, thus achieving the closure of the solution channel.

[0025] Preferably, the inner diameter of the solution channel is 800 μm, the inner diameter of the arc-shaped recessed area is 200 μm, and the inner diameter of the annular microvalve is 600 μm.

[0026] Furthermore, the monolithic column polymer emulsion includes an aqueous phase and an internal phase, and the aqueous phase includes covalent organic framework (COF) particles, monomers, a cross-linking agent, and an initiator.

[0027] In this invention, the monolithic column has a hierarchical porous structure due to the presence of the emulsion template and COF. By combining the in situ polymerized monolithic column with a microfluidic chip array, a highly integrated 3D-printed chip array is constructed to enable REEs analysis in complex samples.

[0028] The technical solution adopted by the present invention to achieve the second purpose is to provide a method for preparing a multifunctional integrated automated microfluidic chip array based on DLP 3D printing according to one of the purposes of the present invention, which comprises the following steps:

[0029] S1. Using 3D printing technology, the chip interface and the spiral channel of the spiral structure integral column unit are printed with rigid resin as the raw material, and the micro valve control unit is printed with flexible resin as the raw material. By replacing the resin at the specified layer, an integrated microfluidic chip array is produced;

[0030] S2, dissolving the monomer, crosslinking agent and initiator in water, adding COF particles and dispersing them uniformly to obtain an aqueous dispersion; adding the internal phase to the aqueous dispersion under stirring to obtain a monolithic column polymer emulsion;

[0031] S3. Injecting the monolithic column polymer emulsion into the spiral channel of the spiral structure monolithic column unit from each injection port, and performing in-situ polymerization, water washing and drying to obtain a microfluidic chip array containing in-situ polymerized monolithic columns.

[0032] In the above-mentioned preparation method, the spiral structure of the 3D-printed microfluidic chip array, compared with conventional straight channels, can effectively promote mass transfer. The raw materials for the monolithic column preparation use an emulsion template and a covalent organic framework, the presence of which gives the monolithic column a hierarchical porous structure. The present invention cleverly utilizes 3D printing technology to design a 360° microvalve, combining the in situ polymerized monolithic column with the microfluidic chip array to construct a highly integrated 3D-printed chip array that integrates miniaturized sample introduction technology, pre-concentration technology, and automatic operation. The 3D-printed microfluidic chip array is low-cost, has a long service life, and has good preparation reproducibility, saving time and labor. The analytical method constructed using the 3D-printed microfluidic chip array has the advantages of high sensitivity, low detection limit, high sample throughput, and strong anti-interference ability, making it suitable for the analysis of trace REEs in complex samples.

[0033] Preferably, the monomer is acrylamide (AAm), the cross-linking agent is N,N′-methylenebisacrylamide (MBA), and the initiator is potassium persulfate (KPS) or ammonium persulfate (APS); the in-situ polymerization temperature is 40 to 90° C., and the in-situ polymerization time is 1 to 24 hours.

[0034] Furthermore, the COF particles in the above preparation method are prepared by synthesis.

[0035] In some preferred embodiments, step S2 includes:

[0036] S201, dissolving 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 1,3,5-triformylphloroglucinol (TP) in n-butanol at a molar ratio of 1:1 to obtain an oil phase; dissolving dodecyltrimethylammonium bromide in water to obtain an aqueous phase; adding the aqueous phase dropwise to the oil phase under stirring to obtain an emulsion; adding a metal trifluoromethanesulfonate to the emulsion, heating the reaction for a certain period of time, and obtaining a first suspension;

[0037] S202, cooling and precipitating the first suspension to obtain a first solid product, adding the washed first solid product to a mixed solution of a reaction medium, water, and acetic acid to obtain a second suspension, wherein the reaction medium is a mixture of dioxane and mesitylene; heating the second suspension to react for a predetermined time to obtain a second solid product, washing the second solid product and freeze-drying it to obtain COF particles;

[0038] S203, dissolving the monomer, cross-linking agent and initiator in water to obtain a solution, dispersing the COF particles in the solution in an amount of 0.8wt.% to 4.5wt.% to obtain an aqueous dispersion; slowly adding squalane or liquid paraffin to the aqueous dispersion under stirring conditions to obtain a monolithic column polymer emulsion.

[0039] Preferably, the amount of the monomer added is 5wt.% to 50wt.% of the water in step S3; the amount of the cross-linking agent added is 2wt.% to 20wt.% of the monomer; and the amount of the initiator added is 2wt.% to 20wt.% of the monomer.

[0040] The technical solution adopted by the present invention to achieve the third purpose is to provide an application of a multifunctional integrated automated microfluidic chip array based on DLP 3D printing according to one of the purposes of the present invention, comprising:

[0041] The multifunctional integrated automated microfluidic chip array based on DLP 3D printing was combined with electrical ICP-MS to achieve online assessment of the bioaccessibility of 15 REEs in atmospheric particulate matter samples.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention provides a multifunctional integrated automated microfluidic chip array based on DLP 3D printing. The integral column unit adopts a spiral structure, which can effectively reduce the chip size compared with a straight channel while promoting mass transfer; the microvalve control unit adopts a solution gradient channel, and an internal concave structure is designed at the gas valve. The circular gas channel controls the gas to squeeze the gradient channel from 360 degrees to achieve channel control; the present invention combines the microvalve, the integral column and the microfluidic chip, and arrays the unit structure to significantly improve the sample throughput (1h -1 →22h -1 ); The integral column unit is formed by in-situ polymerization within the 3D-printed spiral channel, effectively overcoming the problem of easy wall delamination and leakage in traditional embedding methods, and the pressure resistance and service life are significantly improved (20 times → 200 times).

[0044] (2) The preparation method of the multifunctional integrated automated microfluidic chip array based on DLP 3D printing provided by the present invention, compared with the traditional soft lithography technology, can customize the chip 3D structure by using 3D printing technology, and prepare the multifunctional integrated chip array in an integrated manner, which is simple to prepare and has good reproducibility; the in-situ polymerized integral column is combined with the integrated molding technology, and the hierarchical porous structure is effectively constructed within the spiral structure of the integral column by using the emulsion in-situ polymerization method, and the C=O of COF is introduced to achieve coordination and complexation with rare earth.

[0045] (3) The multifunctional, integrated, automated microfluidic chip array provided by the present invention can be coupled with inductively coupled plasma mass spectrometry to enable online assessment of the bioaccessibility of 15 REEs (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in atmospheric particulate matter samples. This system offers advantages such as low sample consumption, low detection limits, strong interference tolerance, and high throughput. It is suitable for the analysis of trace and ultratrace REEs in trace, complex matrix samples and has significant potential for widespread application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of the multifunctional integrated microfluidic chip array prepared in Example 1 of the present invention;

[0047] Figure 2 This is a working principle diagram of the micro gas valve control unit prepared in Example 1 of the present invention;

[0048] Figure 3 1 is a scanning electron microscope (SEM) image of the monolithic column prepared in Example 1 of the present invention; wherein (a) is a cross-sectional view of the monolithic column; (b) is a partial magnified view;

[0049] Figure 4 Optimization diagram of the injection flow rate of the microfluidic chip array prepared in Example 1 according to Application Example 2 of the present invention; wherein (a) the effect of sample flow rate; (b) the comparison of straight and spiral channels;

[0050] Figure 5 3 is an optimization diagram of the desorption process of the microfluidic chip array prepared in Example 1 according to Application Example 3 of the present invention: (a) the effect of HNO3 concentration, (b) the effect of desorption volume; (c) the effect of elution flow rate;

[0051] Figure 6 This is Application Example 4 of the present invention, which shows the effect of reusing the microfluidic chip array prepared in Example 1 200 times on the target ion recovery rate. DETAILED DESCRIPTION

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0053] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0054] The present invention will be further described below with reference to specific examples, but they are not intended to limit the present invention.

[0055] Example 1

[0056] See Figure 1 and Figure 2 This embodiment provides a multifunctional integrated automated microfluidic chip array based on DLP 3D printing, which includes a total of 26 pretreatment systems; each pretreatment system includes: a chip interface, a spiral structure integral column unit, and a micro-valve control unit; wherein, the spiral channels of the chip interface and the spiral structure integral column unit are made of rigid resin, and the micro-valve control unit is made of flexible resin. By replacing the resin at a specified layer during the 3D printing process, the integrated molding of the microfluidic chip array is achieved.

[0057] The chip interface includes chip inlets (A, B, C) and chip outlets (W, O); the chip inlet includes an injection port A (using a size that directly matches a commercial syringe (outer diameter 3.9 mm)), a desorption liquid inlet B, and a cleaning liquid inlet C; the chip outlet includes an ICP-MS connection port O (for direct connection to an ICP-MS for online ICP-MS detection) and a waste liquid outlet W; switching between the outlets is achieved by a micro-valve control unit.

[0058] In this example, the helical monolithic column unit has a helical structure with a total length of 4 cm and a height of 1 cm. Its inner diameter is 800 μm. It is formed by in-situ polymerization of a monolithic column polymer emulsion within a helical channel. While enhancing mass transfer, the helical monolithic column can effectively reduce chip size compared to straight channels.

[0059] In addition, considering the limited elasticity of 3D printing resin, in this embodiment, the micro-valve control unit includes a solution channel and an air valve, and the solution channel is gradual, and the solution channel has multiple inwardly concave variable diameter areas distributed along the length direction (maximum diameter 800μm, minimum diameter 200μm); the air valve includes multiple annular microvalves (inner diameter of 600μm), which are sleeved on the outside of the variable diameter area, and use the internal gas to squeeze the variable diameter area of the solution channel. In the later stage of squeezing the variable diameter area, the internal channel diameter gradually shrinks from 200μm to 0, thereby realizing control of the solution channel.

[0060] The above-mentioned method for preparing the multifunctional integrated automated microfluidic chip array based on DLP 3D printing comprises the following steps:

[0061] Step (1) Printing of chip array: Using DLP rigid resin and F39T flexible resin as raw materials, a chip with a chip interface, a spiral structure integral column unit and a micro-valve control unit was prepared by a photocuring 3D printer (resolution of 50μm). The two resins were integrated by replacing the resin at a specified layer during the printing process. The chip interface and the spiral structure integral column unit were printed using rigid resin (267-727 layers), and the micro-valve control unit was printed using flexible resin (1-266 layers, 728-825 layers). The 3D printed spiral chip array consists of 26 pretreatment systems, each of which includes an interface unit, an integral capillary microextraction unit and a pneumatic valve unit, as shown in the figure, wherein the chip inlet A is the sample inlet, which is directly compatible with a commercial syringe (outer diameter 3.9mm), the chip inlet B is the desorption liquid inlet, the chip inlet C is the cleaning liquid inlet, the chip outlet V is used to directly connect to the ICP-MS for online ICP-MS detection, the chip outlet v is the waste liquid outlet, and the switching between the outlets is controlled by a micro-valve. The integral column unit adopts a spiral structure with a total length of 4 cm and an inner diameter of 800 μm. While promoting mass transfer, it can effectively reduce the chip size compared to a straight channel. Considering the limited elasticity of 3D printing resin, the microvalve control unit adopts a solution gradient channel (800 μm-200 μm) and designs an internal concave structure at the valve, such as Figure 2 , a circular gas channel (600μm inner diameter) is used to control the gas to squeeze the gradient channel from 360° to achieve channel control.

[0062] Step (2) Preparation of COF: The aqueous phase (200 mg / L -1 DTAB dissolved in 160 mL ultrapure water) was added dropwise to the oil phase (0.3 mmol TAPB and 0.3 mmol TP dissolved in 40 mL n-butanol), followed by the addition of 160 mL Sc(OTf)3 solution (1.0 mmol L -1) to initiate the interfacial reaction. Further growth was induced by heating at 70°C for 30 minutes. After cooling the suspension to room temperature, the solid product was washed several times with methanol, centrifuged, and then 40 mL of a 4:1 dioxane / mesitylene solution, 8 mL of ultrapure water, and 14 mL of CH3COOH were added. The suspension was heated at 70°C for 12 hours. The resulting yellow solid was further washed several times with THF and freeze-dried to yield the COF TPTAPB in approximately 79% yield.

[0063] Step (3) Preparation of in situ polymerization spiral monolithic column array: AAm (10 wt% relative to water) as monomer, MBA (5 wt% relative to monomer) as crosslinker, KPS (10 wt% relative to monomer) as initiator were dissolved in deionized water and spun at 1000 rpm min. -1 COF particles (30 mg) were dispersed in the above aqueous phase (1.0 mL) under stirring. Then, the mixture was stirred at 10 000 rpm min -1 Under constant stirring, squalane (3 mL) was slowly added to the aqueous dispersion to form an emulsion. The emulsion was then injected into the 26-channel array spiral channel from inlets A1 to A26 via a syringe and placed in a 60°C oven for 4 hours for thermally initiated free radical in situ polymerization. After three washes and freeze-drying, a yellow COF@polyHIPE spiral monolithic column chip was obtained. The cross-section of the monolithic column is shown in FIG. Figure 3 As shown, the preparation of the microfluidic chip array containing in situ polymerized monolithic columns is completed.

[0064] Example 2

[0065] The difference between this embodiment and Example 1 is that the length of the spiral structure in step (1) is replaced with 1 cm, the inner diameter is replaced with 500 μm, the solution gradient channel size of the microvalve control unit is replaced with 1 mm (maximum inner diameter)-200 μm (minimum inner diameter), the inner diameter of the annular gas channel is 500 μm, and the other steps and operations remain unchanged to prepare a microfluidic chip array containing in situ polymerized integral columns.

[0066] Example 3

[0067] The difference between this embodiment and Example 1 is that the length of the spiral structure in step (1) is replaced with 8 cm, the inner diameter is replaced with 1 mm, the solution gradient channel size of the microvalve control unit is replaced with 800 μm (maximum inner diameter)-300 μm (minimum inner diameter), the inner diameter of the annular gas channel is 700 μm, and the other steps and operations remain unchanged to prepare a microfluidic chip array containing in situ polymerized integral columns.

[0068] Example 4

[0069] The difference between this embodiment and Example 1 is that in step (3), the amount of AAm is adjusted to 5 wt% (relative to water), the amount of MBA is adjusted to 2 wt% (relative to the monomer), and the amount of KPS is adjusted to 2 wt% (relative to the monomer); the temperature of the in situ polymerization is adjusted to 90°C, and the in situ polymerization time is adjusted to 1 h. The other steps remain unchanged to prepare a microfluidic chip array containing an in situ polymerization integral column.

[0070] Example 5

[0071] The difference between this embodiment and Example 1 is that in step (3), the amount of AAm is adjusted to 50 wt% (relative to water), the amount of MBA is adjusted to 20 wt% (relative to the monomer), and the amount of KPS is adjusted to 20 wt% (relative to the monomer); the temperature of the in situ polymerization is adjusted to 40°C, and the in situ polymerization time is adjusted to 24 h. The remaining steps remain unchanged to prepare a microfluidic chip array containing an in situ polymerization integral column.

[0072] Example 6

[0073] The difference between this embodiment and embodiment 1 is that in step (3), the amount of COF particles is adjusted to 8 mg (ie, the amount added to the aqueous phase is 0.8 wt.%), and the other steps remain unchanged to prepare a microfluidic chip array containing in situ polymerized monolithic columns.

[0074] Example 7

[0075] The difference between this embodiment and embodiment 1 is that in step (3), the amount of COF particles is adjusted to 45 mg (ie, the amount added to the aqueous phase is 4.5 wt.%), and the other steps remain unchanged to prepare a microfluidic chip array containing in situ polymerized monolithic columns.

[0076] Application Example 1

[0077] The multifunctional integrated automated microfluidic chip array based on DLP 3D printing prepared in Example 1 was used for online analysis and operation. The specific steps are as follows:

[0078] A 26-channel array extraction system was used for simultaneous sample injection, followed by sequential online desorption and direct detection in conjunction with ICP-MS. The detailed operating procedures are shown in Table 1. From 0 to 50 minutes, 26 samples were introduced into inlets A1 to A26, respectively. During this process, valves V1 to V26 remained closed, while valves V1 to V26 remained open, and waste liquid flowed out through outlets W1 to W26. Then, valve V1 was closed, V1 was opened, and 0.5 mol L of desorption solution was injected from inlet B1. -1HNO3 is used to elute the REEs, and the eluent is introduced into the ICP-MS analysis through outlet O. After 60 seconds, NH4Ac buffer solution is introduced through inlet C1 to clean the channel. The analysis of the first sample is completed, and the second sample is desorbed from inlet B2 while the first channel is restarted. After the second sample is completed, the third sample is desorbed and the second sample is restarted. Repeating this process allows for uninterrupted online analysis of the chip. The sample throughput is 22 hours. -1 , the above process is controlled by Matlab program.

[0079] Table 1

[0080]

[0081]

[0082]

[0083] Application Example 2

[0084] The multifunctional integrated automated microfluidic chip array in Use Case 1 was used to optimize the adsorption conditions of 15 REEs:

[0085] The injection flow rate was optimized in the spiral channel and was between 10 and 50 μL min -1 The influence of sample flow rate was investigated in the range of Figure 4 ). The study found that in 10-25μL min -1 The flow rate can achieve quantitative adsorption of 15 kinds of REEs. As the flow rate increases, the adsorption efficiency gradually decreases. By comparing the adsorption efficiency of spiral channels and straight channels (total length 4 cm, inner diameter 800 μm) at different flow rates, it is found that Figure 4 As shown in b, the spiral channel is heated at 25 μL min -1 Quantitative adsorption can be achieved at an injection speed of 15 μL min -1 At this time, some REEs could no longer be quantitatively adsorbed, indicating that the spiral channel can effectively promote mass transfer. In order to ensure a good recovery rate, 20 μL min was finally selected. -1 injection speed.

[0086] Application Example 3

[0087] Corresponding to Use Case 1, the multifunctional integrated automated microfluidic chip array optimized the desorption conditions of 15 REEs and investigated the effects of different concentrations of nitric acid.

[0088] like Figure 5 As shown in a, the recovery rate increases with the increase of nitric acid concentration. When the nitric acid concentration increases to greater than 0.4 mol L -1, desorption reaches quantitative, select 0.5 mol L -1 HNO3 was used as desorbent.

[0089] To investigate the effect of desorption volume, 50 μL of 0.5 mol L -1 Elute the monolithic column 3 times with HNO3. Figure 5 b. The recovery rate of the first desorption was greater than 90%, and the second and third desorption rates were less than 10%, so 50 μL was selected as the desorption volume.

[0090] At 10-100 μL min -1 The influence of the suction flow rate on the recovery rate was investigated within a certain range. Figure 5 c, at 10-100 μL min -1 Quantitative recovery can be achieved within the range of 100 μL / min, indicating that the prepared monolithic column has faster desorption kinetics. Considering the impact of high flow rate on the monolithic column, low flow rate is beneficial to the service life and stability of the monolithic column. -1 Desorption is performed at a flow rate.

[0091] Application Example 4

[0092] The effect of repeated use of the multifunctional integrated automated microfluidic chip array prepared in Example 1 on the recovery rate of target ions was studied. Figure 6 shown.

[0093] Depend on Figure 6 As can be seen, compared with the relatively short service life of traditional microfluidic chip arrays (around 20 cycles), the multifunctional integrated microfluidic chip array prepared by the present invention has a service life of over 200 cycles. This demonstrates that the method of in situ polymerization of monolithic columns within the chip array adopted by the present invention effectively overcomes the wall detachment problem of traditional microfluidic chips and achieves an order of magnitude improvement in service life.

[0094] Application Example 5

[0095] The multifunctional integrated automated microfluidic chip array prepared in Example 1 was used to evaluate the bioaccessibility of 15 REEs in atmospheric particulate matter.

[0096] Atmospheric particulate matter, such as PM2.5, emitted by human activities or formed during photochemical processes, can be inhaled and penetrate deep into the lungs, posing potential health risks, including chronic and acute respiratory illnesses, cardiovascular disease, and lung cancer. It is currently recommended that bioaccessibility be considered when assessing the human health risks of atmospheric particulate matter. This application example investigated the bioaccessibility of REEs in two simulated lung fluids: Gamble solution (GS) and artificial lysosome fluid (ALF). All 15 REEs were detected in the atmospheric particulate matter samples, as shown in Table 2.

[0097] Once pollutants from pulmonary particulate matter are deposited in the lungs, they are difficult to expel from the lungs, regardless of whether they are released into the lung fluid. Pollutants are either released into the lung fluid and absorbed, or enter the body through phagocytosis. Therefore, different simulated lung fluids—Gamble solution (GS) and artificial lysosomal fluid (ALF)—are used to simulate the fluid within the lung epithelium or the intracellular fluid of phagocytes after particle deposition. Some particles are phagocytosed by macrophages within hours of deposition, and the acidic conditions within macrophages differ significantly from the neutral extracellular environment. The low pH of ALF allows for more complete dissolution of metals from particulate matter in ALF than in Gamble solution. As shown in Table 3, the bioaccessibility of 15 REEs in GS ranges from 0.31% to 17.3%, while that in ALF ranges from 0.75% to 50.1%. The higher bioaccessibility of REEs after ALF extraction compared to GS extraction may be due to differences in the physical and chemical properties of simulated lung fluid. In ALF, the coexisting cations and REEs compete for adsorption, which reduces the adsorption of REEs in PM. In GS, as pH increases, REEs decrease due to hydrolysis and precipitation, and the structure of humic acid in PM changes, all of which affect ion adsorption.

[0098] Table 2 Contents of 15 REEs in collected atmospheric particulate matter samples

[0099]

[0100]

[0101] Table 3 Bioaccessibility of 15 REEs in PM2.5

[0102]

[0103] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A multifunctional integrated automated microfluidic chip array based on digital light processing (DLP) 3D printing, characterized in that: It includes several pre-treatment systems; The pretreatment system includes: a chip interface, a spiral structure integral column unit, and a micro gas valve control unit; The chip interface includes a chip inlet and a chip outlet; the chip inlet includes an injection port, a desorption liquid inlet, and a cleaning liquid inlet; the chip outlet includes an ICP-MS connection port and a waste liquid outlet; The helical structure monolithic column unit is a helical structure, and is formed by in-situ polymerization of the monolithic column polymer emulsion in the helical channel; The micro-valve control unit includes a solution channel and an air valve; the solution channel is gradually changing, and has multiple inwardly concave diameter-changing areas distributed along the length of the solution channel; the air valve includes multiple annular microvalves, which are sleeved on the outside of the diameter-changing areas and use the gas inside the annular microvalves to squeeze the diameter-changing areas of the solution channel to achieve control of the solution channel; The chip interface and the spiral channel of the spiral structure integral column unit are made of rigid resin, and the micro valve control unit is made of flexible resin. By replacing the resin at a specified layer during the 3D printing process, the integrated molding of the microfluidic chip array is achieved.

2. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The rigid resin is selected from DLP rigid resin, and the flexible resin is selected from F39T flexible resin.

3. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The total length of the spiral structure of the spiral structure integral column unit is 1 to 8 cm, and the inner diameter thereof is 500 to 1000 μm.

4. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The plurality of inwardly concave diameter-changing regions are evenly distributed along the length direction of the solution channel.

5. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The inner diameter of the solution channel varies within a range of 200 to 1000 μm.

6. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The inner diameter of the annular microvalve is 500-1000 μm.

7. The multifunctional integrated automated microfluidic chip array according to claim 1, characterized in that: The monolithic column polymer emulsion comprises an aqueous phase and an internal phase, wherein the aqueous phase comprises COF particles, monomers, a cross-linking agent and an initiator.

8. A method for preparing a multifunctional integrated automated microfluidic chip array according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Using 3D printing technology, the chip interface and the spiral channel of the spiral structure integral column unit are printed with rigid resin as the raw material, and the micro valve control unit is printed with flexible resin as the raw material. By replacing the resin at the specified layer, an integrated microfluidic chip array is produced; S2, dissolving the monomer, crosslinking agent and initiator in water, adding COF particles and dispersing them uniformly to obtain an aqueous dispersion; adding the internal phase to the aqueous dispersion under stirring to obtain a monolithic column polymer emulsion; S3. Injecting the monolithic column polymer emulsion into the spiral channel of the spiral structure monolithic column unit from each injection port, and performing in-situ polymerization, water washing and drying to obtain a microfluidic chip array containing in-situ polymerized monolithic columns.

9. The preparation method according to claim 8, characterized in that The monomer is acrylamide AAm, the cross-linking agent is N,N′-methylenebisacrylamide MBA, and the initiator is potassium persulfate KPS or ammonium persulfate APS; the temperature of the in-situ polymerization is 40-90° C., and the time of the in-situ polymerization is 1-24 hours.

10. An application of the multifunctional integrated automated microfluidic chip array according to any one of claims 1 to 7, characterized in that: The multifunctional integrated automated microfluidic chip array was combined with inductively coupled plasma mass spectrometry to achieve online assessment of the bioaccessibility of 15 rare earth elements (REEs) in atmospheric particulate matter samples.

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