A surface charge-based operating platform for material enrichment in droplets

Abstract

The present invention discloses an operating platform for enriching substances in droplets based on surface charge, including a sensing substrate and a thin sheet with hydrophobic or super-amphiphobic properties on the surface; the size of the sensing substrate is smaller than the thin sheet, the thin sheet is covered on the sensing substrate and is completely attached to the sensing substrate and completely covers the sensing substrate; the sensing substrate is a double-sided conductive film with a flat surface; the thin sheet with hydrophobic properties on the surface is made of a hydrophobic polymer dielectric material, or is obtained by fluorination treatment of a glass sheet; the thin sheet with super-amphiphobic properties on the surface is obtained by successively hydrophilic treatment and hydrophobic treatment of a glass sheet as a substrate. The sensing substrate can also be connected to an external DC high-voltage power supply. The present invention utilizes the ability of the hydrophobic or super-amphiphobic surface to stably maintain charge, and can enrich the substances inside the droplet by electrostatic force without external energy input or external voltage, and can control the substance enrichment position after applying a DC power supply, and the enrichment efficiency is higher.

Description

Technical Field

[0001] The invention relates to the technical field of chemical and biological analysis, and in particular to an operating platform for enriching substances in droplets based on surface charges. Background Art

[0002] In chemical and biological analysis, the analyte generally needs to reach the detection line to obtain the analysis result, so the concentration enrichment of substances in droplets is receiving widespread attention. The current method of enriching substances in microdroplets is mainly to prepare superhydrophilic micropores on the superhydrophobic surface, and then evaporate the droplets adhered to the superhydrophilic micropores to enrich the substances. The evaporation enrichment method requires complex equipment preparation, requires additional preparation of superhydrophilic areas, and the evaporation process is slow and takes extra time. The use of traditional microfluidics for substance enrichment and separation requires the preparation of special physical structures, such as a "Y"-shaped junction structure to separate sub-droplets, which limits the conditions of use. Therefore, there is an urgent need for a simple and fast method to enrich the substances contained in droplets. Summary of the invention

[0003] The object of the present invention is to provide a simple and rapid method for enriching substances contained in droplets, that is, an operating platform for enriching substances in droplets based on surface charge.

[0004] The structure of the operating platform for enriching substances in droplets based on surface charge provided by the present invention mainly includes a sensing substrate and a sheet with hydrophobic or super-amphiphobic properties on the surface. The sensing substrate is smaller than the sheet, and the sheet is covered on the sensing substrate and is completely attached to the sensing substrate and completely covers the sensing substrate.

[0005] The thin sheet with hydrophobic surface is made of hydrophobic polymer dielectric material, or is obtained by fluorination treatment of glass sheet. The thin sheet with super-amphiphobic surface is obtained by using glass sheet as substrate and successively undergoing hydrophilic treatment and hydrophobic treatment.

[0006] The sensing substrate is a double-sided conductive film with a flat surface. The main characteristics of the sensing substrate are that the material has high electrical conductivity and a flat surface to achieve the best possible fit with the lower surface of the sheet. For example, the sensing substrate can be preferably, but not limited to, a copper foil tape. When charging the sensing area of ​​the super-amphiphobic or hydrophobic surface, the sensing area can be charged by contact separation by using droplets to impact the sensing area, or electrodes can be connected to the sensing area and a high-voltage DC power supply can be used to provide a stable voltage.

[0007] The substance enrichment operation platform may also be provided with an external DC high voltage power supply, and the high voltage power supply is connected to the induction substrate.

[0008] Preferably, the sheet with hydrophobic surface is made of polytetrafluoroethylene or polyvinylidene fluoride.

[0009] Preferably, the thin sheet with hydrophobic surface is prepared by the following method: a glass sheet is treated with a plasma cleaner, and after treatment, the glass sheet is placed on a ceramic rack in a vacuum glass dryer, a sample bottle containing dodecyltrichlorosilane is placed at the bottom of the vacuum glass dryer, and the vacuum is evacuated to 0.1 MPa, and the chemical vapor deposition reaction time is more than 0.5 hours to obtain a hydrophobic surface.

[0010] Preferably, the thin sheet with super-amphiphobic properties on the surface is prepared by the following method: a glass sheet is used as a substrate, and the glass sheet is reciprocatedly fired on a candle flame so that the candle ash is evenly coated on one side of the glass sheet; then, chemical vapor deposition is performed in a vacuum glass dryer to generate SiO2 nanoparticles through a Stober reaction to obtain a hydrophilic treated glass sheet; then the hydrophilic treated glass sheet is treated with a plasma cleaner, and after the treatment, the glass sheet is placed on a ceramic rack in the vacuum glass dryer, a sample bottle containing dodecyltrichlorosilane is placed at the bottom of the vacuum glass dryer, and the vacuum is evacuated to 0.1MPa, and the chemical vapor deposition reaction time is more than 0.5 hours to obtain a super-amphiphobic surface.

[0011] Preferably, the sheet is rectangular with a size of 60 mm×24 mm; and the sensing substrate is a square double-sided conductive copper foil tape with a size of 1.5 mm×1.5 mm.

[0012] The working principle of the substance enrichment operation platform of the present invention is as follows:

[0013] When a droplet is released at a certain height and hits a hydrophobic / super-hydrophobic surface, the hydrophobic / super-hydrophobic surface will be positively charged and can be retained for a long time under low humidity conditions. The negative charge on the surface will produce an electrostatic force on the charged substances in the droplet. Negatively charged substances will be enriched in the upper half of the droplet, and positively charged substances will be enriched in the lower half of the droplet. Neutral particles will also move in the direction of high electric field strength under the action of dielectrophoretic force, achieving the enrichment of substances inside the droplet. This method can enrich a variety of substances in droplets on the operating platform, including biomacromolecules (such as hemoglobin) and nanomaterials (such as ZIF-8).

[0014] Compared with the prior art, the present invention is beneficial in that:

[0015] The present invention utilizes the ability of hydrophobic or super-amphiphobic surfaces to stably maintain charges, and can enrich substances inside droplets through electrostatic forces without external energy input or external voltage. After applying a DC power supply, the substance enrichment position can be controlled and the enrichment efficiency is higher.

[0016] Moreover, the enrichment platform of the present invention has good universality. The electrostatic force generated by the enrichment platform can not only perform material enrichment operations on aqueous solution droplets, but also achieve the same enrichment effect on substances in oil droplets. At the same time, due to the presence of oil in the oil system or oil-water system, the evaporation rate of the system is much slower than that of the water system, which can greatly reduce the mass loss of the solvent.

[0017] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 , a schematic diagram of the operating platform for enriching substances in droplets based on surface charge of the present invention.

[0019] Figure 2 , schematic diagram of the material enrichment operation platform composed of two hydrophobic sheets and a sensing substrate.

[0020] Figure 3 , schematic diagram of the method for hydrophilic treatment of glass slide.

[0021] Figure 4 , the relationship between surface charge and film thickness.

[0022] Figure 5 , the effect of thin film thickness and low dielectric constant on the enrichment platform.

[0023] Figure 6 , a diagram showing the working principle of the surface charge-based material enrichment operation platform of the present invention.

[0024] Figure 7 , a diagram showing the effect of using the material enrichment operation platform of the present invention for enrichment of ZIF-8 nanoparticles.

[0025] Figure 8 , a diagram showing the effect of the substance enrichment operation platform of the present invention being used for hemoglobin enrichment.

[0026] Fig. 9 , the effect of a high-voltage DC power supply applying a positive voltage on the copper foil. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] like Figure 1As shown, the surface charge-based operating platform for enriching substances in droplets provided by the present invention mainly comprises a sheet 1 having a hydrophobic or super-amphiphobic surface and a sensing substrate 2. The sensing substrate 2 is smaller in size than the sheet 1, and the sheet 1 is covered on the sensing substrate 2 and is completely attached to the sensing substrate and completely covers the sensing substrate.

[0029] The sheet 1 is preferably rectangular and has a size of 60 mm×24 mm. The sensing substrate 2 is preferably a 1.5 mm×1.5 mm square double-sided conductive copper foil tape. The main features of the sensing substrate are high material conductivity and a flat surface to achieve the best possible fit with the lower surface of the sheet.

[0030] The sheet 1 having a hydrophobic surface can be made directly from a hydrophobic polymer dielectric material, or can be made from a glass sheet after a fluorination treatment. Figure 2 As shown, the left picture is a material enrichment operation platform composed of a thin sheet with hydrophobic surface made of polytetrafluoroethylene (PTFE) and a sensing substrate. The right picture is a material enrichment operation platform composed of a hydrophobic glass sheet obtained after fluorination treatment of the glass sheet and a sensing substrate.

[0031] The thin sheet 1 with super-amphiphobic properties on the surface is obtained by using a glass sheet as a substrate and then undergoing hydrophilic treatment and hydrophobic treatment. The specific treatment method is as follows: a rectangular glass sheet with a size of 60 mm×24 mm is used as a substrate, and the glass sheet is reciprocated for 1 minute in a candle flame, so that the candle ash is evenly coated on one side of the glass sheet; then chemical vapor deposition is performed in a vacuum glass dryer to generate SiO2 nanoparticles through the Stober reaction, as follows: Figure 3 As shown, 20 mL glass sample bottles containing 2 mL ammonia water and 2 mL tetraethyl silicate are placed on both sides of the bottom of the vacuum glass dryer, and the glass piece coated with candle ash is placed on the ceramic rack of the dryer, and vacuumed until the ammonia water boils, and kept for 24 hours; after being taken out, it is placed in a muffle furnace and calcined at 600 ° C for 2 hours, and calcined until the surface is white, to obtain a hydrophilic glass piece. Then the hydrophilic glass piece is treated with a plasma cleaner for 15 minutes, and after treatment, the glass piece is placed on the ceramic rack in the vacuum glass dryer, and a 20 mL sample bottle containing 200 μL dodecyl trichlorosilane is placed at the bottom of the vacuum glass dryer, and vacuumed to 0.1 MPa. The chemical vapor deposition reaction time is 6 hours to obtain a super-amphiphobic surface.

[0032] The sheet 1 should have the characteristics of small thickness (thinness) and low dielectric constant. Figure 4 It can be seen that as the thickness of the substrate increases, the surface potential decreases sharply, the electric field strength generated by the surface charge decreases, and the force on the substances in the droplet will also weaken. Figure 5It can be seen that only substrates with low thickness or low dielectric constant can produce a surface potential large enough to make the enrichment platform effective.

[0033] The substance enrichment operation platform can also be provided with an external DC high voltage power supply, and the high voltage power supply is connected to the sensing substrate. Figure 6 As shown, when charging the sensing area of ​​the super-amphiphobic or hydrophobic surface, the sensing area can be charged by contact separation by using droplets to impact the sensing area, or electrodes can be connected to the sensing area and a high-voltage DC power supply can be used to provide a stable voltage.

[0034] Figure 7 This is a diagram showing the effect of the material enrichment operation platform of the present invention on enrichment of ZIF-8 nanoparticles. It can be seen that in the absence of an external electric field, compared with the uncharged superamphiphobic surface, the negatively charged superamphiphobic surface has a significant enrichment effect on the ZIF-8 nanoparticles under the action of electrostatic force, because the ZIF-8 nanoparticles carry positive charges, and the enrichment rate of ZIF-8 is as high as 86%.

[0035] Figure 8 This is a diagram showing the effect of the substance enrichment operation platform of the present invention on hemoglobin enrichment. The figure shows that the concentrations of the upper and lower parts of the positively charged hemoglobin solution on the negatively charged superamphiphobic surface are measured by a UV-visible spectrophotometer. It can be seen that the charged superamphiphobic surface also has a significant enrichment effect on smaller-sized hemoglobin. The power source introduced from the outside can achieve the opposite effect because the positive and negative voltages are adjustable. Fig. 9 This is the effect diagram when a high-voltage DC power supply is used to apply a positive voltage to the copper foil. It can be seen that when a high-voltage DC power supply is used to apply a positive voltage to the copper foil, the positively charged hemoglobin is enriched in the upper part of the droplet and has a more obvious enrichment effect.

[0036] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. An operating platform for enriching substances in droplets based on surface charge, characterized in that: The invention comprises a sensing substrate and a sheet with hydrophobic or super-amphiphobic properties on the surface; the sensing substrate is smaller than the sheet, and the sheet is covered on the sensing substrate and is completely attached to the sensing substrate and completely covers the sensing substrate; the sensing substrate is a double-sided conductive film with a flat surface; the sheet with hydrophobic properties on the surface is made of a hydrophobic polymer dielectric material, or is obtained by fluorination treatment of a glass sheet; the sheet with super-amphiphobic properties on the surface is obtained by using a glass sheet as a substrate and successively undergoing hydrophilic treatment and hydrophobic treatment; When a droplet is released at a certain height and hits a hydrophobic / super-hydrophobic surface, the hydrophobic / super-hydrophobic surface will have a negative charge. The negative charge on the surface will produce an electrostatic force on the charged substances in the droplet, thereby enriching the substances inside the droplet.

2. The surface charge-based operating platform for material enrichment in droplets according to claim 1, characterized in that: It also includes an external DC high-voltage power supply, which is connected to the inductive substrate.

3. The surface charge-based operating platform for material enrichment in droplets according to claim 1, characterized in that: The sheet with hydrophobic surface is made of polytetrafluoroethylene or polyvinylidene fluoride material.

4. The surface charge-based operating platform for material enrichment in droplets according to claim 1, characterized in that: A thin sheet with hydrophobic surface is prepared by the following method: a glass sheet is treated with a plasma cleaner, and the treated glass sheet is placed on a ceramic rack in a vacuum glass dryer, a sample bottle containing dodecyltrichlorosilane is placed at the bottom of the vacuum glass dryer, and the vacuum is evacuated to 0.1 MPa, and a chemical vapor deposition reaction is performed for more than 0.5 hour to obtain a hydrophobic surface.

5. The surface charge-based operating platform for material enrichment in droplets according to claim 1, characterized in that: The thin sheet with super-amphiphobic properties on the surface is prepared by the following method: A glass sheet is used as a substrate and is fired back and forth over a candle flame so that the candle ash is evenly coated on one side of the glass sheet. Then, chemical vapor deposition is carried out in a vacuum glass dryer to generate SiO2 nanoparticles through the Stober reaction to obtain a glass sheet with a special surface microstructure. The hydrophilic-treated glass sheet is then treated with a plasma cleaner and placed on a ceramic rack in a vacuum glass dryer. A sample bottle containing dodecyltrichlorosilane is placed at the bottom of the vacuum glass dryer and the vacuum is evacuated to 0.1 MPa. The chemical vapor deposition reaction time is more than 0.5 hours to obtain a super-amphiphobic surface.

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