A method and device for detecting nanoparticle dual-pulse impedance based on a biomimetic ion diode nanochannel system

Abstract

This invention provides a method and apparatus for detecting nanoparticles using a biomimetic ion diode nanochannel system with dual-pulse impedance. The detection method comprises the following steps: an electrolyte solution is applied to a detection channel in the detection system, causing cations and anions to accumulate in the channel; as charged particles flow through the detection channel under the influence of electrophoretic and electric forces, the resistance value in the detection channel changes. A signal acquisition system generates a dual-pulse signal based on the changing resistance and conductivity peaks. The number of pulses in the dual-pulse signal reflects the number of detected particles, and the pulse size reflects the shape and charge of the particles. This invention utilizes the asymmetric charge distribution design at both ends of the biomimetic ion diode nanochannel to enrich the ion concentration of the electrolyte solution in the detection channel, enhancing the RPS signal sensitivity in the detection region, improving the detection effect of nanoscale particles, and enabling accurate identification of particle shape and charge.

Description

Technical Field

[0001] This invention relates to the field of impedance detection of nanoscale particles, and more particularly to a method and apparatus for dual-pulse impedance detection of nanoparticles based on a biomimetic ion diode nanochannel system. Background Technology

[0002] Driven by the development of micro and nano manufacturing technology, micro-nano particle resistance pulse sensing (RPS) technology has attracted increasing attention due to its advantages such as simple structure, strong versatility and high sensitivity, and has been widely used in the detection of nanoparticles, DNA, proteins and viruses as well as single molecules.

[0003] Traditional nanoscale impedance analysis (RPS) techniques primarily utilize the displacement of a certain volume of liquid by particles passing through a detection channel, causing a change in the channel's resistance and generating an impedance pulse signal for particle counting and detection. However, the pulse value is highly sensitive to external environmental conditions such as temperature, pH, electric field, and ion concentration, making the detection system relatively unstable and less sensitive to extremely small particles, easily leading to false detections. Furthermore, with the deepening of research and technological advancements in the micro-nano field, the requirements for RPS detection systems are becoming more diversified and multi-indicator-oriented, with particle shape and charge becoming new demands in RPS detection.

[0004] Biomimetic intelligent nanomaterials, as an important component of nanomaterial applications, have seen significant development in recent years. Among them, biological channels, as mediators for material transport and information exchange between cells and the external environment, can respond to various external stimuli, such as changes in light, ions, pH, and temperature. They play a crucial role not only in maintaining intracellular homeostasis but also in regulating nerve signal transduction, thus attracting considerable attention. Inspired by the characteristics of biological channels, researchers have focused on constructing biomimetic nanochannels to mimic their structure and function. Biomimetic ion diode channels designed based on biomembrane systems can form complex membrane potentials similar to those on cell membranes, enabling selective ion passage and providing new solutions for physicochemical analysis, especially for the detection of microscale mesoscopic particles. This paper utilizes this biomimetic structure to optimize the traditional RPS detection system.

[0005] Previously, the invention patent application number 202210605356.2 disclosed a design that uses carbon nanotube ion channels as molecular detection channels. The carbon nanotube single-molecule impedance detection device has advantages such as high mechanical strength, stable chemical properties, low processing cost, and good repeatability. However, in the actual detection of nanoscale particles, the inventors found that the system is more suitable for the detection of molecular-level targets. The detection effect is not ideal for slightly larger particulate targets, and it can only detect the number of particles, but cannot comprehensively analyze various parameters such as the charge of the particles.

[0006] In summary, existing RPS detection systems cannot meet the requirements for efficient and accurate detection of diverse and multi-indicator nanoparticles. The continuous development of the micro-nano detection field necessitates the development of newer RPS detection systems. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method and device for detecting nanoparticle dual-pulse impedance based on a biomimetic ion diode nanochannel system. This overcomes the shortcomings of existing technologies, such as susceptibility to external environmental influences and susceptibility to false detections, while simultaneously enabling the counting and detection of diverse and multi-parameter nanoparticles. The technical means employed in this invention are as follows:

[0008] A method for detecting nanoparticle dual-pulse impedance based on a biomimetic ion diode nanochannel system includes the following steps:

[0009] When an electrolyte solution is applied to a detection channel in the detection system, cations and anions are enriched in the detection channel, which is specifically a biomimetic ion diode nanochannel.

[0010] When charged particles flow through the detection channel under the influence of electrophoretic force and electric field force, the resistance value in the detection channel changes. The signal acquisition system generates a double pulse signal based on the changing resistance peak and conductivity peak. The number of pulses in the double pulse signal reflects the number of detected particles, and the pulse size reflects the shape and charge status of the particles.

[0011] Furthermore, the biomimetic ion diode nanochannel is composed of a straight channel with an inner diameter of <100nm, and the two ends of the channel are respectively carrying equal amounts of opposite charges. The two ends of the biomimetic ion diode nanochannel are respectively connected to the first main channel and the second main channel. During detection and analysis, the particle sample to be detected is dispersed in an electrolyte solution, and the microfluidic chip is ensured to be filled with electrolyte solution, and the concentration of electrolyte solution satisfies the double layer overlap and ion selective passage characteristics of the biomimetic ion diode nanochannel.

[0012] The present invention also discloses an apparatus based on the above method, including a microfluidic chip, a signal acquisition system, and a DC voltage driving device. The microfluidic chip includes a microfluidic channel, a biomimetic ion diode nanochannel, and a reservoir. The microfluidic channel includes a main channel and a corresponding detection channel. The main channel includes a first main channel located upstream of the biomimetic ion diode nanochannel and a second main channel located downstream of the biomimetic ion diode nanochannel. One end of the first main channel and the second main channel are connected through the biomimetic ion diode nanochannel, and the other end is connected to the DC voltage driving device through their respective reservoirs. The detection channels of the first main channel and the second main channel are connected to the signal acquisition system through their respective reservoirs.

[0013] Furthermore, the signal acquisition system includes a signal amplification unit, a signal acquisition unit, and a signal processing and display unit connected in sequence. The signal amplification unit is a differential amplification unit, and its two signal input terminals are connected to the liquid storage tanks of the first main channel detection channel and the second main channel detection channel, respectively, through reference electrodes. The DC voltage driving device is used to provide a stable voltage output, and its positive and negative terminals are connected to the liquid storage tanks of the first main channel and the second main channel, respectively, through inert electrodes.

[0014] Furthermore, the signal processing and display unit is used to receive and process the data acquired by the signal acquisition unit in a timely manner, and can analyze the amplitude, width, half-width, and frequency information of the pulse signal.

[0015] Furthermore, the detection method of the above-mentioned device specifically includes:

[0016] S1. Fabricate and process the microfluidic chip, and connect the signal acquisition system and DC voltage drive device to the microfluidic chip;

[0017] S2. Use a pipette to add a buffer solution containing a substance that is beneficial to the wetting of the channel wall into the reservoir of the first main channel of the microfluidic chip, let it stand for a period of time, and allow the channel wall to be completely wetted by capillary action;

[0018] S3. Discharge the solutions in the first main channel and the second main channel, and inject the dispersion sample containing the nanoparticles to be tested into the first main channel through the reservoir of the first main channel, and inject the detection buffer into the second main channel from the reservoir of the second main channel;

[0019] S4. Insert the signal detection electrodes into the liquid storage tanks of the first main channel and the second main channel respectively, and insert the DC electric field drive module electrodes into the liquid storage tanks of the first main channel and the second main channel respectively.

[0020] S5. Start the data acquisition system, monitor the impedance signals at both ends of the biomimetic ion diode nanochannel until a clear double pulse signal appears, then acquire the signal and perform subsequent analysis.

[0021] Furthermore, in step S1, the surface of the microchannel is treated with oxygen plasma to make it hydrophilic; when the driving voltage supplies power to the biomimetic ion diode nanochannel system, the Coulomb force causes ions in the electrolyte solution to accumulate in the biomimetic ion diode nanochannel, increasing the mobile charge density in the biomimetic ion diode nanochannel.

[0022] Furthermore, when charged particles flow through the detection channels of the first main channel and the second main channel, the resistance value in the biomimetic ion diode nanochannel changes. At the same time, the modulation effect of the biomimetic ion diode on the ion concentration causes the current in the channel to change abruptly twice, forming a resistance pulse peak and a conductance pulse peak.

[0023] The present invention has the following advantages:

[0024] 1. This device can detect and analyze the charge status and shape and size of particles, expanding the scope of traditional RPS detection, enriching the detection parameters, and achieving diversified detection parameters.

[0025] 2. This device relies on a biomimetic ion diode nanochannel system to achieve RPS detection of particles. The enrichment effect of the biomimetic ion diode nanochannel on particles makes the detection system stable and less affected by external environmental factors such as temperature, ion concentration, and pH.

[0026] 3. This device can generate bidirectional pulse detection signals during the detection process, which greatly improves the detection accuracy and effectively solves the problem of false detection in traditional RPS detection systems.

[0027] For the reasons stated above, this invention can be widely applied in fields such as mesoscopic particle detection and analysis. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the nanoparticle dual-pulse impedance detection method and device based on a biomimetic ion diode nanochannel system according to the present invention.

[0030] Figure 2This is a schematic diagram of the PDMS microfluidic chip in this invention.

[0031] Figure 3 This is a schematic diagram showing the distribution of ion concentration in the biomimetic ion diode nanochannel during the nanoparticle detection process in this invention.

[0032] Figure 4 This is a schematic diagram of the dual-pulse impedance pulse of the biomimetic ion diode nanochannel in the nanoparticle detection process of this invention.

[0033] In the diagram: M, microfluidic chip; 1, DC voltage drive device; 2, signal amplification unit; 3, signal processing and display unit; 4, signal acquisition unit; 5, inert platinum electrode; 6, liquid reservoir of the first main channel; 7, liquid reservoir of the second main channel; 8, liquid reservoir of the detection channel of the first main channel; 9, liquid reservoir of the detection channel of the second main channel; 10, first main channel; 11, second main channel; 12, detection channel of the first main channel; 13, detection channel of the second main channel; 15, biomimetic ion diode nanochannel; 16, negatively charged end of the nanochannel; 17, positively charged end of the nanochannel; 18, detection particle. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] A method for detecting nanoparticle dual-pulse impedance based on a biomimetic ion diode nanochannel system includes the following steps:

[0036] When an electrolyte solution is applied to a detection channel in the detection system, cations and anions are enriched in the detection channel, which is specifically a biomimetic ion diode nanochannel.

[0037] When charged particles flow through the detection channel under the influence of electrophoretic force and electric field force, the resistance value in the detection channel changes. The signal acquisition system generates a double pulse signal based on the changing resistance peak and conductivity peak. The number of pulses in the double pulse signal reflects the number of detected particles, and the pulse size reflects the shape and charge status of the particles.

[0038] The biomimetic ion diode nanochannel is composed of a straight channel with an inner diameter of <100nm. In this embodiment of the invention, the two ends of the channel are modified with different solutions to make the two ends of the channel carry equal amounts of opposite charges. The two ends of the nanochannel are connected to the first main channel and the second main channel, respectively. During detection and analysis, the particle sample to be detected is dispersed in an electrolyte solution, and the microfluidic chip is ensured to be filled with the electrolyte solution. The concentration of the electrolyte solution meets the requirements of double layer overlap and ion selective passage in the biomimetic ion diode nanochannel, such as <100mM NaCl solution, thereby meeting the conditions for normal operation of the biomimetic ion diode. The biomimetic ion diode nanochannel is obtained by, but is not limited to, semiconductor micro-nano fabrication technology.

[0039] The present invention also discloses an apparatus based on the above method, such as... Figure 1 , Figure 2 As shown, the device includes a microfluidic chip M, a signal acquisition system, and a DC voltage driving device 1. The microfluidic chip includes a microfluidic channel, a biomimetic ion diode nanochannel 15, and a reservoir. The microfluidic channel includes a main channel and a corresponding detection channel. The main channel includes a first main channel 10 located upstream of the biomimetic ion diode nanochannel and a second main channel 11 located downstream of the biomimetic ion diode nanochannel. The first and second main channels are connected at their proximal ends through the biomimetic ion diode nanochannel, and their other ends are connected to the DC voltage driving device through the reservoirs 6 and 7 of the first and second main channels, respectively. The detection channels 12 and 13 of the first and second main channels are connected to the signal acquisition system through their corresponding reservoirs.

[0040] The signal acquisition system includes a signal amplification unit 2, a signal acquisition unit 4, and a signal processing and display unit 3 connected in sequence. The signal amplification unit is a differential amplification unit. The two signal input terminals of the differential amplification unit are connected to the liquid storage tank 8 of the first main channel detection channel and the liquid storage tank 9 of the second main channel detection channel through reference electrodes, respectively. The DC voltage driving device is used to provide a stable voltage output. The positive and negative terminals of the power supply are connected to the liquid storage tanks of the first main channel and the second main channel through inert electrodes, respectively.

[0041] The signal processing and display unit is used to receive and process the data acquired by the signal acquisition unit in a timely manner, and can analyze the amplitude, width, half-width, and frequency information of the pulse signal.

[0042] The detection method for the above-mentioned device specifically includes:

[0043] S1. Fabricate and process the microfluidic chip, and connect the signal acquisition system and DC voltage drive device to the microfluidic chip;

[0044] S2. Use a pipette to add a buffer solution containing a substance that is beneficial to the wetting of the channel wall into the reservoir of the first main channel of the microfluidic chip, let it stand for a period of time, and allow the channel wall to be completely wetted by capillary action;

[0045] S3. Discharge the solutions in the first main channel and the second main channel, and inject the dispersion sample containing the nanoparticles to be tested into the first main channel through the reservoir of the first main channel, and inject the detection buffer into the second main channel from the reservoir of the second main channel;

[0046] S4. Insert the signal detection electrodes into the liquid storage tanks of the first main channel and the second main channel respectively, and insert the DC electric field drive module electrodes into the liquid storage tanks of the first main channel and the second main channel respectively.

[0047] S5. Start the data acquisition system, monitor the impedance signals at both ends of the biomimetic ion diode nanochannel until a clear double pulse signal appears, then acquire the signal and perform subsequent analysis.

[0048] In step S1, the surface of the microchannel is treated with oxygen plasma to make it hydrophilic; when the driving voltage supplies power to the biomimetic ion diode nanochannel system, the Coulomb force causes ions in the electrolyte solution to accumulate in the biomimetic ion diode nanochannel, increasing the mobile charge density in the biomimetic ion diode nanochannel.

[0049] When charged particles flow through the detection channels of the first and second main channels, they cause a change in the resistance value of the biomimetic ion diode nanochannel. At the same time, the modulation effect of the biomimetic ion diode on the ion concentration causes two sudden changes in the current in the biomimetic ion diode nanochannel, forming a resistance pulse peak and a conductance pulse peak.

[0050] Under the action of electric field force and electrophoretic force, the detection particle 18 will generate a certain resistance when it enters the biomimetic ion diode nanochannel. At this time, the characteristics of the particles in the sample can be deduced by detecting the change in the potential difference between the two ends of the biomimetic ion diode nanochannel 15 between the liquid storage pool 6 of the first main channel and the liquid storage pool 7 of the second main channel. Platinum electrodes 5 are inserted into the liquid storage tank 6 of the first main channel, the liquid storage tank 7 of the second main channel, the liquid storage tank 8 of the first main channel detection channel, and the liquid storage tank 9 of the second main channel detection channel. One end of the platinum electrode of the main channel is connected to the DC electric field driving device 1, and one end of the detection channel is connected to the input end of the differential amplifier unit. The sample particle 18 to be tested enters the second main channel 11 from the first main channel 10 through the biomimetic ion diode nanochannel 15. During the process of the particle passing through the biomimetic ion diode nanochannel 15, the potential difference between the two ends of the channel detector changes. This potential difference change is transmitted to the input end of the differential amplifier through the platinum electrodes in the liquid storage holes at both ends of the detection channel. The output end of the differential amplifier is connected to the signal acquisition and signal processing unit to realize the differential amplification, acquisition, display and storage of the detection signal. Finally, the particle detection and counting are realized through signal analysis.

[0051] like Figure 3 The diagram shown is a schematic representation of the ion concentration distribution in the nanochannel of the biomimetic ion diode of this invention during the nanoparticle detection process.

[0052] Figure 3 The inlet and outlet of the biomimetic ion diode nanochannel are respectively charged with different charges 16 and 17. Due to electrostatic interaction, the inner wall of the channel will adsorb opposite charges and repel like charges. When the biomimetic ion diode nanochannel is energized, the ions in the electrolyte solution will move directionally under the action of the electric field. When passing through the biomimetic ion diode nanochannel with charged walls, the opposite-charged ions are attracted and can quickly enter the biomimetic ion diode nanochannel due to electrostatic interaction, while the like-charged ions are repelled and cannot enter the biomimetic ion diode nanochannel, thus achieving selective ion passage. When the ions that have entered the biomimetic ion diode nanochannel move to the outlet under the continuous drive of the electric field, they cannot pass through because the biomimetic ion diode nanochannel wall at the outlet carries the same charge and repels it. Therefore, a large number of anions and cations enter the biomimetic ion diode nanochannel under the action of the biomimetic ion diode nanochannel and cannot leave, thus achieving ion enrichment in the biomimetic ion diode nanochannel.

[0053] When charged particles flow through the detection channel under the influence of electrophoretic force and electric field force, when the charged particles move to the nanochannel wall with the same charge, electrostatic repulsion reduces the movement speed of the ions, increasing the system resistance. However, when they move to the nanochannel wall of the biomimetic ion diode with the opposite charge, electrostatic adsorption promotes the movement speed of the ions, thus achieving conductivity. This causes a change in the resistance value of the biomimetic ion diode nanochannel. At the same time, the modulation effect of the biomimetic ion diode on the ion concentration causes two sudden changes in the current in the channel, forming a resistance peak and a conductivity peak.

[0054] Based on the above device and method, the current change is analyzed by the signal acquisition system to form a dual-pulse signal; the number of pulses can effectively reflect the number of detected particles, while the pulse size can reflect the shape and charge status of the particles, and the pulse morphology can reflect the shape of the particles. This method enables efficient and accurate counting and analysis of nanoscale particles. Figure 4 As shown, this invention utilizes the asymmetric charge distribution design at both ends of the nanopores of a biomimetic ion diode to enrich the ion concentration of the electrolyte solution in the detection channel, thereby enhancing the sensitivity of the RPS signal in the detection area, improving the detection effect of nanoscale particles, and enabling accurate identification of the shape and charge of the particles. In contrast, traditional RPS detection systems are easily affected by external environmental factors such as solution concentration, pH, and electric field strength due to their small pulse amplitude, which can lead to false detections or missed detections.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nanoparticle dual-pulse impedance detection method based on a biomimetic ion diode nanochannel system, characterized in that, Includes the following steps: When an electrolyte solution is applied to a detection channel in the detection system, cations and anions are enriched in the detection channel, which is specifically a biomimetic ion diode nanochannel. When charged particles flow through the detection channel under the influence of electrophoretic force and electric field force, the resistance value in the detection channel changes. The signal acquisition system generates a double pulse signal based on the changing resistance peak and conductivity peak. The number of pulses in the double pulse signal reflects the number of detected particles, and the pulse size reflects the shape and charge status of the particles.

2. The nanoparticle dual-pulse impedance detection method based on a biomimetic ion diode nanochannel system according to claim 1, characterized in that, The biomimetic ion diode nanochannel is composed of straight channels with an inner diameter of <100nm. The two ends of the channel are respectively charged with equal amounts of different surface charges. The two ends of the nanochannel are connected to the first main channel and the second main channel, respectively. During detection and analysis, the particle sample to be detected is dispersed in an electrolyte solution, and the microfluidic chip is ensured to be filled with electrolyte solution. The concentration of electrolyte solution meets the requirements of double layer overlap and ion selective passage characteristics in the biomimetic ion diode nanochannel.

3. An apparatus for implementing the method of claim 1 or 2, characterized in that, The device includes a microfluidic chip, a signal acquisition system, and a DC voltage driving device. The microfluidic chip includes a microfluidic channel, a biomimetic ion diode nanochannel, and a reservoir. The microfluidic channel includes a main channel and a corresponding detection channel. The main channel includes a first main channel located upstream of the biomimetic ion diode nanochannel and a second main channel located downstream of the biomimetic ion diode nanochannel. One end of the first main channel and the second main channel are connected through the biomimetic ion diode nanochannel, and the other end is connected to the DC voltage driving device through their respective reservoirs. The detection channels of the first main channel and the second main channel are connected to the signal acquisition system through their respective reservoirs.

4. The apparatus according to claim 3, characterized in that, The signal acquisition system includes a signal amplification unit, a signal acquisition unit, and a signal processing and display unit connected in sequence. The signal amplification unit is a differential amplification unit, and its two signal input terminals are connected to the liquid storage tanks of the first main channel detection channel and the second main channel detection channel, respectively, through reference electrodes. The DC voltage driving device is used to provide a stable voltage output, and its positive and negative terminals are connected to the liquid storage tanks of the first main channel and the second main channel, respectively, through inert electrodes.

5. The apparatus according to claim 4, characterized in that, The signal processing and display unit is used to receive and process the data acquired by the signal acquisition unit in a timely manner, and can analyze the amplitude, width, half-width, and frequency information of the pulse signal.

6. The apparatus according to claim 3, characterized in that, The detection method based on this device specifically includes: S1. Fabricate and process the microfluidic chip, and connect the signal acquisition system and DC voltage drive device to the microfluidic chip; S2. Use a pipette to add a buffer solution containing a substance that is beneficial to the wetting of the channel wall into the reservoir of the first main channel of the microfluidic chip, let it stand for a period of time, and allow the channel wall to be completely wetted by capillary action; S3. Discharge the solutions in the first main channel and the second main channel, and inject the dispersion sample containing the nanoparticles to be tested into the first main channel through the reservoir of the first main channel, and inject the detection buffer into the second main channel from the reservoir of the second main channel; S4. Insert the signal detection electrodes into the liquid storage tanks of the first main channel and the second main channel respectively, and insert the DC electric field drive module electrodes into the liquid storage tanks of the first main channel and the second main channel respectively. S5. Start the data acquisition and display system, monitor the impedance signals at both ends of the biomimetic ion diode nanochannel until a clear double pulse signal appears, then acquire the signal and perform subsequent analysis.

7. The apparatus according to claim 6, characterized in that, In step S1, the surface of the microchannel is treated with oxygen plasma to make it hydrophilic; when the driving voltage supplies power to the biomimetic ion diode nanochannel system, the Coulomb force causes ions in the electrolyte solution to accumulate in the biomimetic ion diode nanochannel, increasing the mobile charge density in the nanochannel.

8. The apparatus according to claim 3, characterized in that, When charged particles flow through the detection channels of the first and second main channels, they cause a change in the resistance value of the biomimetic ion diode nanochannel. At the same time, the modulation effect of the biomimetic ion diode on the ion concentration causes the current in the biomimetic ion diode nanochannel to undergo two sudden changes, forming a resistance pulse peak and a conductance pulse peak.

Images