CN115007232B - Microfluidic chip and droplet in situ explosion method based on Janus swimming microelectrode - Google Patents

Abstract

The invention discloses a microfluidic chip and a liquid droplet in-situ blasting method, which includes a cover plate, a substrate, a PDMS channel, and an inlet and an outlet; Conductive layer; the cavity is provided with at least one Janus swimming microelectrode that can move freely in the cavity; the Janus swimming microelectrode includes a conductive part and a magnetic part combined together, by means of the The magnetic part controls the movement and attitude of the Janus swimming microelectrode in the cavity through an external magnetic field, and realizes the conductive layer between the Janus swimming microelectrode and the cover plate and the base through the conductive part. Conduction, thereby forming a local electric field, thereby blasting the droplet. The invention is applicable to biomedical fields such as targeted drug delivery, cell therapy and cultivation.

Description

Microfluidic chip and droplet in-situ explosion method based on Janus swimming microelectrode

technical field

The invention relates to the fields of cell biology such as targeted drug delivery and cell culture, and in particular to a microfluidic chip and a liquid droplet in-situ blasting method based on a Janus swimming microelectrode.

Background technique

As a new form of microfluidic control, droplet microfluidic technology can prepare monodisperse microdroplets with controllable structure and composition, and has shown great potential in flexible encapsulation and controllable release of active substances. In particular, microcapsules with double emulsion droplets or multiple emulsion droplets as templates with controllable size and internal structure can effectively avoid cross-contamination between the encapsulated substance and the external environment due to its unique "core-shell" structure. Therefore, microcapsules using droplets as templates are widely used as transport carriers for the encapsulation, transportation, and release of various functional substances including drugs, cosmetic ingredients, and cells, especially to deliver the droplets' inner wrappers to designated areas and achieve Controlled release has excellent application prospects in the fields of biomedicine and chemical detection.

At present, the release of inclusions in microdroplets is mainly accomplished through temperature control, chemical environment, mechanical stress response, and external electric field regulation. The release of substances inside microcapsules regulated by temperature changes is essentially accomplished by utilizing the melting properties of temperature-responsive materials at specific temperatures, mainly for temperature-sensitive lipids or hydrocarbon compounds (glycerin fatty acids, paraffin oil and eicosane). Material. Changes in the chemical environment can also cause the micro-droplet shell to undergo a chemical reaction and be quickly degraded, but this method also has special requirements for the structure material of the droplet shell, such as pH-sensitive materials, plastic response materials, etc., which means that it can only be used for specific samples. released, limiting its scope of application. Mechanical stress-regulated droplet release requires hard and brittle shells and complex channel structures, which correspondingly limit the droplet size and internal active material content. Electronically controlled droplet release is a droplet rupture method that does not depend on the external environment. It can flexibly adjust the droplet rupture method according to the external medium environment and the inner core material, and is highly controllable. However, if the active material in the droplet is to be controlled Direction and position release require complex electrode structure design.

To sum up, none of the above droplet release methods can realize the release of the core substance of the droplet at any position and direction on the droplet surface, that is, the in-situ rupture at any position on the droplet surface cannot be realized, and there is a lack of flexibility. . Blasting any position on the surface of the droplet can release the material inside the droplet to the designated position as required, which will facilitate the targeted delivery of drugs.

Contents of the invention

The object of the present invention is to provide a liquid droplet in situ blasting method and microfluidic chip based on the Janus swimming microelectrode, which utilizes the floating microelectrode to create a strong local electric field at any position near the droplet, through stronger local The electric field blasts the droplet shell at this position, aiming to realize the electric rupture at any position on the droplet, so that the drug in the droplet can be released in any direction, providing theoretical and technical support for targeted drug delivery and cell drug therapy .

To achieve the above object, the present invention provides the following technical solutions:

A microfluidic chip comprising a plate-shaped cover plate, a base, and a PDMS (polydimethylsiloxane) channel arranged between the cover plate and the base, the cover plate, the base and the PDMS channel A closed cavity is formed between them, and an inlet and an outlet communicating with the cavity are also included; both the inlet and the outlet are arranged on the cover plate or the base, or the inlet and the outlet are respectively arranged on the cover plate and on the base; the inner side of the cover plate and the base are all provided with a conductive layer for connecting to an external power supply; the cavity is provided with at least one Janus swimming microelectrode that can move freely in the cavity; the The Janus swimming microelectrode includes a conductive part and a magnetic part combined together, by means of the magnetic part to control the movement and posture of the Janus swimming microelectrode in the cavity through an external magnetic field, through the conductive part to realize the conduction between the Janus swimming microelectrode and the conductive layer of the cover plate and the base, thereby forming a local electric field.

Preferably, both the cover plate and the base are made of conductive glass coated with indium tin oxide.

Preferably, the distance between the cover plate and the base is 1.0 mm; the Janus swimming microelectrode is spherical with a radius of 300 μm or rod-shaped with a cross-sectional radius of 300 μm.

Preferably, the volume ratio of the conductive part and the magnetic part of the Janus swimming microelectrode is 1:1.

Preferably, the microfluidic chip is processed by the following process:

1) A channel mold with a zigzag cavity is obtained through CNC machine tools, and the channel mold is pasted on the cleaned glass surface with shadowless glue; the conductive glass with indium tin oxide coating is cut to make the cover plate and the base; the cover plate is drilled with inlets and outlets;

2) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, pour it on the smooth glass surface, and paste a PVA film on the surface after heating and curing, as a pressing plate;

3) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, in a closed processing device, pour it on the glass with the channel mold attached, so that it covers the mold Inside and outside the chamber, vacuumize the inside of the processing device to remove the air bubbles inside the uncured polydimethylsiloxane; and use the prepared pressure plate to press on the uncured polydimethylsiloxane, press firmly To the bottom; remove the channel mold to obtain an uncured zigzag-shaped PDMS channel; then put the uncured PDMS channel and pressure plate together in an oven for curing;

4) Clean the side of the cured PDMS channel opening and the side of the substrate coated with indium tin oxide coating, put it into the plasma machine chamber, evacuate it to make it in a vacuum environment, and then inject oxygen as the excitation gas And plasma treatment for 35 seconds under the action of high-frequency electric field, bonded together after taking out, to get semi-finished products;

5) Put the bonded semi-finished product into water to dissolve the PVA film on the press plate to separate the press plate from the semi-finished product;

6) The side of the cover plate coated with the indium tin oxide coating and the side of the semi-finished product separated from the press plate are subjected to plasma treatment and bonded together to obtain the microfluidic chip.

Preferably, the Janus swimming microelectrodes are processed through the following steps:

1) Preparation of raw materials: mix metal silver powder and water to make conductive raw materials; mix magnetic ferric iron tetroxide powder and light-curing adhesive powder to make magnetic raw materials;

2) forming; pumping the conductive raw material and the magnetic raw material into a preparation tool simultaneously, the preparation tool including two inlet passages for the conductive raw material and the magnetic raw material respectively and a confluence passage connecting the two inlet passages, and A cutting hole that runs through the merging channel; after the conductive material and the magnetic material are merged into the merging channel, cutting oil is regularly injected into the cutting hole to pass through the merging channel so that the Conductive raw materials and magnetic raw materials are punched and cut to form blanks;

4) Curing, irradiating the above blank with ultraviolet rays, so that the light-curing adhesive in it is cured, and Janus particles are obtained;

5) Heating, by performing a high-temperature heating treatment on the above-mentioned Janus particles to remove the moisture therein and fuse the silver powder therein to obtain a Janus swimming microelectrode.

The present invention also provides a droplet in situ blasting method based on the Janus swimming microelectrode, which includes the microfluidic chip, which comprises the following steps:

1) Hydrophilic treatment: Clean and dry the inner cavity of the microfluidic chip, put it into the plasma machine chamber, use oxygen as the excitation gas under the action of an electric field to conduct plasma treatment on the inner surface of the cavity, and introduce The -OH group of hydrophilic nature makes the inner surface of the cavity into a hydrophilic surface to prevent the Janus swimming microelectrodes from adhering to the conductive layer of the cover plate or substrate;

2) Filling with KCL solution: configure a KCL solution with a conductivity of 0.2 S/m, and fill it into the cavity of the microfluidic chip;

2) Configure water-in-oil double-emulsion droplets; configure 500 nm polystyrene particles as the active material model, use droplet microfluidic technology and wrap them into the oil shell to form water-in-oil double-emulsion droplets. The Janus swimming microelectrode and the water-in-oil double emulsion droplet are sent into the cavity of the microfluidic chip to suspend them in the KCL solution;

3) Connect the signal generator, connect the output terminal of the signal generator to the input terminal of the signal amplifier, the conductive layer of the base is used as the ground electrode, and the conductive layer of the cover plate is connected to the positive pole of the output terminal of the signal amplifier;

4) Use the electromagnet to pull the Janus swimming microelectrode to swim in the cavity of the microfluidic chip, find and approach the water-in-oil double emulsion droplet under the microscope, and make the Janus swimming microelectrode The conductive part is in contact with the water-in-oil double emulsion droplet;

5) By adjusting the signal generator so that it outputs a suitable voltage amplitude and electrical signal frequency so that a local strong electric field is generated on the conductive part of the Janus swimming microelectrode, which is used to blast the water-in-oil dual lotion drop;

6) Repeat the above steps to obtain the best voltage amplitude and electrical signal frequency.

The beneficial effects of the present invention are:

The Janus swimming microelectrode can be pulled by an external magnet to swim in the cavity and positioned to the position where the droplet needs to burst, and then the bursting of the droplet and the release of the internal substance can be controlled by adjusting the external voltage and frequency signals. Using the magnetic field to regulate and arbitrarily change the contact position of the Janus swimming microelectrode and the micro-droplet, so as to realize the blasting at any position on the droplet surface, can fill the gap in the current technology of droplet blasting. The invention is applicable to biomedical fields such as targeted drug delivery, cell therapy and cultivation.

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the present invention;

Fig. 2 is a schematic diagram of an exploded structure of the present invention;

Fig. 3 is the structure schematic diagram of Janus swimming microelectrode;

Fig. 4 is a schematic diagram of the processing technology of the microfluidic chip;

Fig. 5 is a schematic diagram of the processing technology of the Janus mobile microelectrode.

Detailed ways

The technical solution of this patent will be further described in detail below in conjunction with specific embodiments.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "inner", "outer", "upper", "lower", "horizontal" etc. is based on the orientation or positional relationship shown in the drawings , is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

As shown in Figures 1 to 5, a microfluidic chip of the present invention includes a plate-shaped cover plate 1, a substrate 6, and a PDMS channel 4 (PDMS polydimethyl silicone). A closed cavity is formed between the cover plate 1 , the substrate 6 and the PDMS channel 4 , and also includes an inlet 2 and an outlet 3 communicating with the cavity; the inlet 2 and the outlet 3 are both arranged on the cover plate 1 . Both the cover plate 1 and the base 6 are made of conductive glass with an indium tin oxide coating, and the indium tin oxide coating on the inside of the cover plate 1 and the base 6 forms a conductive layer for connecting to an external power supply.

The cavity is provided with at least one Janus swimming microelectrode 5 that can move freely in the cavity; the Janus swimming microelectrode 5 includes a combined conductive part 8 and a magnetic part 7, and the magnetic part 7 passes through the external magnetic field The movement and posture of the Janus floating microelectrodes 5 in the cavity are controlled, and the conduction between the Janus floating microelectrodes 5 and the conductive layer of the cover plate 1 and the substrate 6 is realized through the conductive part 8, thereby forming a local electric field.

Further, the distance between the cover plate 1 and the substrate 6 is 1.0 mm; the Janus swimming microelectrode 5 is spherical with a radius of 300 μm or a rod with a cross-sectional radius of 300 μm. The above-mentioned dimensional structure, matched with the conductive liquid in the cavity, can conduct electricity through the conductive part 8 of the Janus floating microelectrode 5 after the conductive layer is energized.

The volume ratio of the conductive part 8 and the magnetic part 7 of the Janus swimming microelectrode 5 is 1:1.

Microfluidic chips are processed by the following processes:

1) A channel mold (not shown) with a zigzag cavity is obtained through CNC machine tools, and the channel mold is pasted on the cleaned glass surface with shadowless glue; it is made by cutting conductive glass with indium tin oxide coating The cover plate 1 and the base 6; the entrance 2 and the exit 3 are processed on the cover plate 1 by drilling;

2) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, pour it on the smooth glass surface, heat and cure it, and paste a PVA film (not shown) on the surface as a pressure plate;

3) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, in a closed processing device (not shown), pour it on the glass with the channel mold attached to it to cover Inside and outside the mold cavity, vacuumize in the processing device to remove the air bubbles inside the uncured polydimethylsiloxane; and use the prepared pressure plate to press on the uncured polydimethylsiloxane, press firmly to the bottom, Extrusion molding; remove the channel mold to obtain an uncured zigzag-shaped PDMS channel 4; then place the uncured PDMS channel 4 and the pressure plate together in an oven for curing;

4) Clean the side of the cured PDMS channel opening and the side of the substrate coated with indium tin oxide coating, put it into the plasma machine chamber, evacuate it to make it in a vacuum environment, and then inject oxygen as the excitation gas And plasma treatment for 35 seconds under the action of high-frequency electric field, bonded together after taking out, to get semi-finished products;

5) Put the bonded semi-finished product into water to dissolve the PVA film (PVA polyvinyl alcohol) on the pressing plate to separate the pressing plate and the semi-finished product;

6) The side of the cover plate 1 coated with the indium tin oxide coating and the side of the semi-finished product separated from the pressing plate are subjected to plasma treatment and bonded together to obtain a microfluidic chip.

Janus swimming microelectrode 5 is processed by the following steps:

1) Preparation of raw materials: mixing metal silver powder and water to make conductive raw material 13; mixing magnetic ferric iron tetroxide powder and light-curing adhesive powder to make magnetic raw material 14;

2) Forming: pumping the conductive material 13 and the magnetic material 14 into the preparation tool 15 at the same time, the preparation tool 15 includes two inlet channels 16 for the conductive material 13 and the magnetic material 14 respectively and a confluence channel 17 connecting the two inlet channels 16, And the cutting hole 18 that runs through the confluence channel 17; after the conductive material 13 and the magnetic material 14 merge into the confluence channel 17, the cutting oil is regularly fed into the cutting hole 18, so as to penetrate the confluence channel 17 so that the conductive material flowing therein 13 and the magnetic raw material 14 are punched and cut to form blanks; the blanks continue to move along the converging channel 17 through the cutting oil hydrodynamic method. The above-mentioned device can obtain the required structure of the billet by adjusting the flows of the two inlet passages 16 .

4) Curing. At the end of the confluence channel 17, ultraviolet light is emitted from the ultraviolet lamp 19 to irradiate the above blank, so that the light-curing adhesive (for example, ETPTA ethoxylated trimethylolpropane triacrylate) is cured, Get Janus particles;

5) Heating, by performing high-temperature heat treatment on the above-mentioned Janus particles to remove the moisture therein and fuse the silver powder therein to obtain the Janus swimming microelectrode 5 .

The present invention also provides a droplet in-situ blasting method based on the Janus swimming microelectrode 5, which includes a microfluidic chip, which includes the following steps:

1) Hydrophilic treatment: Clean and dry the inner cavity of the microfluidic chip, put it into the plasma machine chamber, use oxygen as the excitation gas under the action of an electric field to conduct plasma treatment on the inner surface of the cavity, and introduce The -OH group of the hydrophilic property makes the inner surface of the cavity become a hydrophilic surface, to prevent the Janus swimming microelectrodes 5 from adhering to the conductive layer of the cover plate 1 or the base 6;

2) Fill KCL solution: configure KCL solution with a conductivity of 0.2 S/m, and fill it into the cavity of the microfluidic chip;

2) Configure water-in-oil double-emulsion droplets; configure 500 nm polystyrene particles as the active material model, use droplet microfluidic technology and wrap them into the oil shell to form water-in-oil double-emulsion droplets, and swim Janus The moving microelectrode 5 and the water-in-oil double emulsion are dropped into the cavity of the microfluidic chip to suspend them in the KCL solution;

3) Connect the signal generator, connect the output terminal of the signal generator to the input terminal of the signal amplifier, the conductive layer of the substrate 6 is used as the ground electrode, and the conductive layer of the cover plate 1 is connected to the positive pole of the output terminal of the signal amplifier;

4) Use the electromagnet to pull the Janus mobile microelectrode 5 to swim in the cavity of the microfluidic chip, find and approach the water-in-oil double emulsion droplet under the microscope, and make the conductive part 8 of the Janus mobile microelectrode 5 contact Water-in-oil double emulsion droplets;

5) By adjusting the signal generator, make it output the appropriate voltage amplitude and electrical signal frequency so that a local strong electric field is generated on the conductive part 8 of the Janus swimming microelectrode 5, so as to blast the water-in-oil double emulsion droplet , so that the internal active substances are released;

6) Repeat the above steps to obtain the best voltage amplitude and electrical signal frequency.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technologies fields, are all included in the scope of patent protection of the present invention in the same way.

Claims (7)

1. A microfluidic chip, characterized in that: it comprises a plate-shaped cover plate, a base, and a PDMS channel arranged between the cover plate and the base, forming A closed cavity also includes an inlet and an outlet communicating with the cavity; both the inlet and the outlet are arranged on the cover plate or the base, or the inlet and the outlet are respectively arranged on the cover plate and the base ; The inside of the cover plate and the base are all provided with a conductive layer for connecting to an external power supply; the cavity is provided with at least one Janus swimming microelectrode that can move freely in the cavity; the Janus swimming The moving microelectrode includes a conductive part and a magnetic part combined together, by means of the magnetic part to control the movement and posture of the Janus moving microelectrode in the cavity through an external magnetic field, and through the conductive part to realize The Janus floating microelectrodes are connected to the cover plate and the conductive layer of the base, thereby forming a local electric field. 2. The microfluidic chip according to claim 1, characterized in that: the cover plate and the base are both made of conductive glass coated with indium tin oxide. 3. The microfluidic chip according to claim 1, characterized in that: the distance between the cover plate and the substrate is 1.0 mm; the Janus swimming microelectrode is a spherical shape with a radius of 300 μm or a cross-sectional radius of 300 μm rod shape. 4. The microfluidic chip according to claim 3, characterized in that: the volume ratio of the conductive part and the magnetic part of the Janus swimming microelectrode is 1:1. 5. The microfluidic chip according to claim 2, wherein the microfluidic chip is processed by the following process: 1) Obtain a channel mold with a zigzag cavity through CNC machine tool processing, use shadowless glue to paste the channel mold on the cleaned glass surface; cut the conductive glass with indium tin oxide coating to make the cover plate and the base; the cover plate is drilled with inlets and outlets; 2) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, pour it on the smooth glass surface, and paste a PVA film on the surface after heating and curing, as a pressing plate; 3) After mixing polydimethylsiloxane and curing agent at a ratio of 10:1, in a closed processing device, pour it on the glass with the channel mold adhered to make it cover the mold Inside and outside the chamber, vacuumize the inside of the processing device to remove the air bubbles inside the uncured polydimethylsiloxane; and use the prepared pressure plate to press on the uncured polydimethylsiloxane, press firmly To the bottom; remove the channel mold to obtain an uncured zigzag-shaped PDMS channel; then put the uncured PDMS channel and pressure plate together in an oven for curing; 4) Clean the side of the cured PDMS channel opening and the side of the substrate coated with indium tin oxide coating, put it into the plasma machine chamber, evacuate it to make it in a vacuum environment, and then introduce oxygen as the excitation gas And plasma treatment under the action of high-frequency electric field for 35 seconds, so that a large number of free radicals are generated on the surface of the material, and bonded together after taking out, to obtain a semi-finished product; 5) putting the bonded semi-finished product into water, dissolving the PVA film on the pressing plate to separate the pressing plate and the semi-finished product; 6) The side of the cover plate coated with the indium tin oxide coating and the side of the semi-finished product separated from the press plate are subjected to plasma treatment and bonded together to obtain the microfluidic chip. 6. The microfluidic chip according to claim 4, wherein the Janus swimming microelectrodes are processed through the following steps: 1) Preparation of raw materials: mixing metal silver powder and water to make conductive raw materials; mixing magnetic iron oxide powder and light-curing adhesive powder to make magnetic raw materials; 2) Forming; pumping the conductive material and the magnetic material into a preparation tool simultaneously, the preparation tool comprising two inlet channels for the conductive material and the magnetic material to enter respectively and a confluence channel connecting the two inlet channels, and A cutting hole that runs through the merging channel; after the conductive material and the magnetic material are merged into the merging channel, cutting oil is regularly injected into the cutting hole to pass through the merging channel so that the Conductive raw materials and magnetic raw materials are punched and cut to form blanks; 4) curing, irradiating the above blank by ultraviolet rays, so that the light-curing adhesive therein is cured to obtain Janus particles; 5) Heating, by performing high-temperature heat treatment on the above-mentioned Janus particles to remove the moisture therein and fuse the silver powder therein to obtain the Janus swimming microelectrode. 7. A liquid droplet in situ blasting method based on Janus swimming microelectrode, it comprises the microfluidic chip described in one of claims 1 to 6, it is characterized in that, it comprises the following steps: 1) Hydrophilic treatment: Clean and dry the inner cavity of the microfluidic chip, put it into the plasma machine chamber, and use oxygen as the excitation gas to perform plasma treatment on the inner surface of the cavity under the action of an electric field, and introduce The -OH group of hydrophilic nature makes the inner surface of the cavity into a hydrophilic surface to prevent the Janus swimming microelectrodes from adhering to the conductive layer of the cover plate or substrate; 2) Filling with KCL solution: configure a KCL solution with a conductivity of 0.2 S/m, and fill it into the cavity of the microfluidic chip; 3) configure water-in-oil double-emulsion droplets; configure 500nm polystyrene particles as the active material model, use droplet microfluidic technology and wrap it into the inside of the oil shell to form water-in-oil double-emulsion droplets, and put the Janus Swimming microelectrodes and water-in-oil double emulsion droplets are fed into the cavity of the microfluidic chip to suspend them in the KCL solution; 4) connect the signal generator, the output end of the signal generator is connected with the input end of the signal amplifier, the conductive layer of the base is used as a ground electrode, and the conductive layer of the cover plate is connected to the positive pole of the output end of the signal amplifier; 5) Use electromagnet to pull the Janus swimming microelectrode to swim in the cavity of the microfluidic chip, find and approach the water-in-oil double emulsion droplet under the microscope, and make the Janus swimming microelectrode The conductive part is in contact with the water-in-oil double emulsion droplet; 6) By adjusting the signal generator so that it outputs a suitable voltage amplitude and electrical signal frequency so that a local strong electric field is generated on the conductive part of the Janus swimming microelectrode, which is used to blast the water-in-oil dual lotion drop; 7) Repeat the above steps to obtain the best voltage amplitude and electrical signal frequency.

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