阅读说明：本技术 制备基于固态纳米孔的对温度和pH双重响应的纳米流体二极管的方法 (Method for preparing nano-fluid diode based on solid-state nano-hole and having dual response to temperature and pH ) 是由 李君� 安鹏荣 谢彦博 于 2019-07-24 设计创作，主要内容包括：本发明涉及一种制备基于固态纳米孔的对温度和pH双重响应的纳米流体二极管的方法,首先将PET膜进行化学刻蚀,得到单个锥形纳米孔,此时纳米孔的内表面有很多羧基,因此在中性条件下会带有负电荷,而PLL分子上的氨基在中性条件下会质子化带有很多正电荷,因此PLL可通过静电吸附的方法修饰到纳米孔的内表,得到PLL修饰的纳米孔。而PLL分子在pH和温度的双重作用下,会呈现出α-螺旋与β-折叠两种构象,从而导致亲疏水性的变化,使PLL修饰的纳米孔呈现出对pH和温度的双重响应的ON/OFF状态。避免了用化学方法进行修饰,从而避免了PLL分子在固态纳米孔上修饰密度不够,导致无法得到固态纳米孔上pH和温度响应的纳米流体二极管的问题。(The invention relates to a method for preparing a nano fluid diode based on solid-state nano pores and having double responses to temperature and pH. And the PLL molecule can present two conformations of alpha-helix and beta-sheet under the dual action of pH and temperature, thereby leading to the change of hydrophilicity and hydrophobicity, and leading the PLL modified nanopore to present an ON/OFF state with dual response to the pH and the temperature. The problem that a nanometer fluid diode with pH and temperature response on the solid-state nanopore cannot be obtained due to insufficient modification density of PLL molecules on the solid-state nanopore is solved.)

1. A method for preparing a solid-state nanopore based nanofluidic diode with dual temperature and pH response, characterized by the steps of:

step 1: irradiating each surface of the PET film, and etching nano holes on the PET film with a clean surface by adopting a chemical etching method;

the nano-holes are single conical nano-holes, and the cone angle is 1: 6.5-1: 4.3;

step 2: soaking the PET with the etched nano holes in a polylysine solution for 3 to 5 hours; the polylysine solution is a polylysine PLL aqueous solution with the concentration of 5 to 200 mu g/mL;

and step 3: and after the water is washed clean, putting the obtained product into an oven at the temperature of 40-50 ℃ for 3-5 h, and obtaining polylysine modified solid nano-pores on the polyethylene terephthalate (PET), thus obtaining the nano-fluid diode with response to temperature.

2. The method of preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 1, wherein: the irradiation time was 1.5h per side of the PET film.

3. The method of preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 1, wherein: when the thickness of the PET film is 13 microns, the diameter of a large hole of the single conical nano hole is 2-3 microns, and the diameter of a small hole is 10-60 nm.

4. The method for preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 1 or 3, wherein: the single-cone-shaped nanometer hole is etched by adopting an asymmetric etching method.

5. The method of preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 4, wherein: the asymmetric etching method comprises the following steps: applying transmembrane voltage 1V-2V on two sides of a PET film, adding etching liquid on one side of the film, adding stopping liquid on the other side of the film, detecting the etching process by using a current measuring device, and once the ionic current is increased by 2 orders of magnitude, indicating that the nanopore is etched through to obtain the PET single-cone nanopore.

6. The method of preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 5, wherein: the etching solution is a 9mol/L NaOH solution.

7. The method of preparing a solid-state nanopore based nanofluidic diode with dual response to temperature and pH according to claim 5, wherein: the preventing solution adopts a mixed solution of 1mol/L HCOOH and KCl, and the proportion of HCOOH to KCl is 9.5mL HCOOH to 18.6g KCl.

Technical Field

The invention belongs to the technical field of nanofluid devices, and relates to a method for preparing a solid-state nanopore-based nanofluid diode with dual responses to temperature and pH, which is realized by modifying polylysine molecules to the inner surface of a solid-state nanopore.

Background

Polylysine (PLL) is widely used in tissue sections, slide bonding and in vitro cell culture. PLL as a polycation molecule can generate stronger adhesive force with the interaction of anions on tissue sections, and is suitable for slide anti-slide-falling treatment of slides used in histology, immunohistochemistry, frozen sections, cell smears, in situ hybridization and the like so as to prevent the tissues from falling in the experimental operation process. PLL can also promote cell adhesion and is therefore commonly used for in vitro cell culture. The culture dish coated by the PLL is widely used for culturing cells, and the PLL can coat containers with various shapes and materials by a physical adsorption method, so that the PLL can be surface modified in the nanopore.

The nano fluid diode has the characteristics of selectively passing ions and generating response to external environment stimulation similar to biological ion channels, and has stable physical and chemical properties and good tolerance to temperature and acid-base. The phenomenon of ion selective passage is also called rectification phenomenon, and is a physical phenomenon, which means that the forward and reverse current amplitudes are different under the same driving force. In recent years, research on nanofluid diodes has made an important progress, and certain application prospects are shown in various fields such as DNA sequencing and nanofluidic chips. Researchers have modified nanopores by various methods to obtain nanofluidic diodes that respond to external stimuli, including pH, electricity, light, specific ions, biomolecules, or pressure. At present, the preparation of the nanofluidic diode by the method of surface modification in the nanopore still has more difficulties as follows: (i) the nano-pore channel has smaller size, and the modified substance is difficult to enter, so that the density of the modified substance on the nano-pore channel is not enough; (ii) the covalent modification operation is complex, and the cost for synthesizing molecules with specific structures is high; (iii) the surface of the nano-pore is unstable after being modified, and a modifier is easy to fall off, so that the repeatability of the nano-fluid diode is poor. The method is very good

Disclosure of Invention

Technical problem to be solved

In order to avoid the defects of the prior art, the invention provides a method for preparing a nanometer fluid diode based on solid-state nanometer pores and having double responses to temperature and pH, successfully constructs the nanometer fluid diode on the solid-state nanometer pores and having double responses to pH and temperature, overcomes the difficulties, and obtains the method for modifying the nanometer pores, which has the advantages of simple operation, low cost, high modification density and good repeatability.

Technical scheme

A method for preparing a solid-state nanopore based nanofluidic diode with dual temperature and pH response, characterized by the steps of:

step 1: irradiating each surface of the PET film, and etching nano holes on the PET film with a clean surface by adopting a chemical etching method;

the nano-holes are single conical nano-holes, and the cone angle is 1: 6.5-1: 4.3;

step 2: soaking the PET with the etched nano holes in a polylysine solution for 3 to 5 hours; the polylysine solution is a polylysine PLL aqueous solution with the concentration of 5 to 200 mu g/mL;

and step 3: and after the water is washed clean, putting the obtained product into an oven at the temperature of 40-50 ℃ for 3-5 h, and obtaining polylysine modified solid nano-pores on the polyethylene terephthalate (PET), thus obtaining the nano-fluid diode with response to temperature.

The irradiation time was 1.5h per side of the PET film.

When the thickness of the PET film is 13 microns, the diameter of a large hole of the single conical nano hole is 2-3 microns, and the diameter of a small hole is 10-60 nm.

The single-cone-shaped nanometer hole is etched by adopting an asymmetric etching method.

The asymmetric etching method comprises the following steps: applying transmembrane voltage 1V-2V on two sides of a PET film, adding etching liquid on one side of the film, adding stopping liquid on the other side of the film, detecting the etching process by using a current measuring device, and once the ionic current is increased by 2 orders of magnitude, indicating that the nanopore is etched through to obtain the PET single-cone nanopore.

The etching solution is a 9mol/L NaOH solution.

The preventing solution adopts a mixed solution of 1mol/L HCOOH and KCl, and the proportion of HCOOH to KCl is 9.5mL HCOOH to 18.6g KCl.

Advantageous effects

The method for preparing the nano fluid diode based on the solid-state nano hole and having double responses to temperature and pH skillfully adopts the electrostatic adsorption method to modify the inner surface of the nano hole. Firstly, chemical etching is carried out on a PET film to obtain a single conical nanopore, and at the moment, the inner surface of the nanopore has a plurality of carboxyl groups, so the nanopore can have negative charges under a neutral condition, and amino groups on PLL molecules can be protonated and have a plurality of positive charges under the neutral condition, so PLL can be modified on the inner surface of the nanopore by an electrostatic adsorption method to obtain the PLL modified nanopore. And the PLL molecule can present two conformations of alpha-helix and beta-sheet under the dual action of pH and temperature, thereby leading to the change of hydrophilicity and hydrophobicity, and leading the PLL modified nanopore to present an ON/OFF state with dual response to the pH and the temperature. The problem that a nanometer fluid diode with pH and temperature response on the solid-state nanopore cannot be obtained due to insufficient modification density of PLL molecules on the solid-state nanopore is solved.

The invention constructs the nanometer fluid diode on the solid-state nanometer hole by a physical modification method, and provides a new method for modifying the solid-state nanometer hole to construct the nanometer fluid diode with double responses to pH and temperature.

Drawings

FIG. 1: the method of the invention is schematically shown in the figure: firstly, carrying out chemical etching on the PET film to obtain a single conical nanopore, wherein the inner surface of the nanopore is provided with carboxyl anions. And modifying the nanopore by using a soaking method to obtain the PLL-modified nanopore. And the PLL molecules respond to temperature, and the amino groups on the PLL molecules are protonated into ammonium ions which are positively charged and respond to pH, namely, the nano-fluid diode which responds to both pH and temperature is prepared.

FIG. 2: data from the I-V plot for electrochemical characterization in 0.1M KCl for a scored single-tapered nanopore. The electrochemical characterization of the unmodified single-cone nanopore is to prove that the carved-through nanopore has a rectifying effect and the inner surface of the carved-through nanopore carries carboxylate anions.

FIG. 3 is I-V plot data for electrochemical characterization of single-tapered nanopores in 0.1M KCl after PLL modification. Electrochemical characterization of the single-tapered nanopore after PLL modification demonstrated that the inner surface of the modified nanopore carries an opposite charge to that before modification, i.e., ammonium ions.

FIG. 4(a) is a schematic diagram of the pH response after modification of PLL; (b) data from I-V plots for electrochemical characterization of single-tapered nanopores after PLL modification in 0.1M KCl at different pH. Electrochemical characterization at different pH demonstrated that the modified PLL nanopore responds to pH.

FIG. 5 (a) is a schematic diagram showing the temperature response after the PLL is modified; (b) for the I-V curve diagram of electrochemical characterization of a PLL-modified single-cone nanopore in 0.1M KCl at different temperatures, the rectification effect is gradually increased in the temperature rise process from 22 ℃ to 50 ℃, which shows that when the temperature is below 70 ℃, the temperature rise can promote ions in a solution to pass through the nanopore, and the PLL on the inner surface of the nanopore is hydrophilic; when the temperature rises to 70 ℃, the rectification effect is minimum, the current is small, and the hole is close to a non-conductive state, which proves that the PLL is hydrophobic at 70 ℃; (c) the 5 cycle plots of the I-V plots of the single-tapered nanopore at 22 ℃ and 70 ℃ illustrate that the response of the single-tapered nanopore after the PLL was modified to temperature is reversible.

XPS data before and after PLL modification of the film surface are shown in fig. 6.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

the invention provides a novel method for preparing a nano fluid diode based on solid-state nano holes and having dual response to temperature and pH, which comprises the following steps of:

firstly, the surface of PET is cleaned by irradiation, the nano-pores are etched by a chemical etching method, the etched nano-pores are soaked in a polylysine solution, taken out and washed clean by secondary water, and then the obtained product is placed in a drying oven, so that the solid nano-pores modified by polylysine are obtained. The structure of the polylysine is as follows:

the polylysine molecule has a plurality of amino groups, the amino groups can be positively charged after protonation, the PLL is modified to obtain the solid-state nanopore with the inner surface having the plurality of amino groups, and the PLL molecule can present two conformations of alpha-helix and beta-sheet under the dual actions of pH and temperature, so that the hydrophilicity and hydrophobicity are changed, and the PLL modified nanopore presents an ON/OFF state with dual responses to the pH and the temperature.