CN115404534A - Porous microneedle electrode with nano-particles embedded at tips and preparation and application thereof - Google Patents

Porous microneedle electrode with nano-particles embedded at tips and preparation and application thereof Download PDF

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CN115404534A
CN115404534A CN202211053555.3A CN202211053555A CN115404534A CN 115404534 A CN115404534 A CN 115404534A CN 202211053555 A CN202211053555 A CN 202211053555A CN 115404534 A CN115404534 A CN 115404534A
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electrode
tip
microneedle
microneedle electrode
tips
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韩海涛
潘大为
于顺洋
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Yantai Institute of Coastal Zone Research of CAS
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C5/00—Electrolytic production, recovery or refining of metal powders or porous metal masses
    • C25C5/02—Electrolytic production, recovery or refining of metal powders or porous metal masses from solutions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage

Abstract

The invention relates to the field of electrochemical analysis, in particular to a porous microneedle electrode with a nanoparticle embedded at the tip, and preparation and application thereof. Preparing a micro-needle electrode body by using a nickel-chromium alloy needle; the tip part of the micro-needle electrode is electrochemically etched to form nanopores which are closely arranged at the tip of the micro-needle electrode; wherein the nanopores cover the entire electrode tip; and embedding metal particles into the obtained nanopores of the microneedle electrode with the tips closely arranged with the nanopores by a pulse electrodeposition method. The porous structure at the tip of the microneedle electrode can protect nanoparticles in a nanometer pore canal and prevent the nanoparticles from falling off in the detection process, so that the prepared electrode has good stability and longer service life, and can be widely used for high-sensitivity and high-stability detection of different pollutants in different samples.

Description

Porous microneedle electrode with nano-particles embedded at tips and preparation and application thereof
Technical Field
The invention relates to the field of electrochemical analysis, in particular to a porous microneedle electrode with a nanoparticle embedded at the tip, and preparation and application thereof.
Background
The research of chemically modified electrodes based on voltammetry is always a hot research point of electrochemical sensors. The electrochemical voltammetry analysis method has the advantages of simple instrument and equipment, simplicity and convenience in operation, high sensitivity, easiness in miniaturization and automation and the like, and is widely applied to the fields of biomedicine, food, industry, environmental analysis and the like. The core of electrochemical voltammetry is the working electrode. The traditional working electrode is a mercury electrode, but mercury is listed as a prohibited environment virulent pollutant by a plurality of countries, and has special requirements on manufacturing, storage and the like. Therefore, people pay more and more attention to the chemically modified electrode which is green and environment-friendly and can replace mercury.
In early research, people directly load the nano material with good electrochemical catalytic performance on the surface of a conventional solid electrode such as a glassy carbon electrode, a gold electrode, a platinum electrode and the like to prepare a chemically modified electrode so as to improve the detection sensitivity of the electrode. However, research shows that the electrode has larger area of the substrate solid electrode, so that the background current is larger and the sensitivity is lower. Later research shows that the mass transfer rate of the electrode can be improved, the equilibrium time can be shortened, and the detection sensitivity of the electrode can be improved by reducing the volume of the substrate solid electrode and preparing a miniaturized electrode. Therefore, chemically modified electrodes based on miniaturized solid electrodes have attracted considerable attention from researchers in the field of analysis. In the existing literature reports, gold wires, iridium wires, carbon fibers and the like have been widely used for preparing base electrode materials of chemically modified micro electrodes. However, because the micro-electrode has small volume, smooth surface, small specific surface area and few active binding sites, the modified micro-electrode prepared by the direct electrodeposition method, the physical sputtering method and the like at present can only load a small amount of nano-materials with excellent performance. In order to improve the loading capacity of the micro electrode on the nano material, at present, after a conductive layer is physically sputtered on the surface of the micro electrode, a metal alloy is electrodeposited, and then active metal in the alloy is removed to form a porous metal modification layer, so as to improve the research of the loading capacity and the reaction area; the loaded micro-electrode can improve the sensitivity of the manufactured sensor. However, the surface of the micro electrode is very smooth and lacks enough binding sites to load the nano material, and meanwhile, the smooth surface of the electrode cannot effectively protect the nano material loaded thereon, so that the modified nano material is easy to fall off from the surface of the electrode in the detection process, the detection performance is reduced, the stability is poor, and the wide application of the modified micro electrode is limited.
Therefore, based on the surface structure modification of the micro electrode body, the research of effectively improving the stability of the electrode while increasing the specific surface area opens up a new research direction for the development of chemically modified electrodes.
Disclosure of Invention
The invention aims to provide a porous microneedle electrode with a nanoparticle embedded at the tip, and preparation and application thereof.
In order to realize the purpose, the invention adopts the technical scheme that:
a preparation method of a porous microneedle electrode with a nanoparticle embedded at the tip comprises the following steps:
a. preparing a microneedle electrode body by using a nichrome needle;
b. the tip part of the micro-needle electrode is electrochemically etched to form nanopores which are closely arranged at the tip of the micro-needle electrode; wherein, the nanometer pore canal covers the whole electrode tip, and the diameter of the pore canal is between 300 and 900 nm;
c. and embedding metal particles into the obtained nanopores of the microneedle electrode with the tips closely arranged with the nanopores by a pulse electrodeposition method.
And in the step b, taking a nickel-chromium alloy micro-needle electrode as a working electrode and a graphite electrode as an auxiliary electrode, placing the two electrodes in etching solution, performing electrochemical etching by adopting a potentiostatic method, and forming the nanopores which are closely arranged at the tip of the micro-needle electrode.
The etching potential of the electrochemical etching is 1-5V, and the etching time is 30-180s;
preferably, the etching potential of the electrochemical etching is 2V, and the etching time is 120s.
The components of the etching liquid are 0.2-0.5wt% of ammonium fluoride, 2-5vol% of ethylene glycol and 95-98vol% of deionized water.
Preferably, the components of the etching solution are 0.3wt% of ammonium fluoride, 2vol% of ethylene glycol and 98vol% of deionized water.
The tip of the nickel-chromium alloy microneedle electrode body is an electrode sensing area, the top end of the nickel-chromium alloy microneedle electrode body is an electrode lead, and the rest parts of the nickel-chromium alloy microneedle electrode body are coated with insulating layers; wherein, the length of the tip part is 0.5-1mm, which accounts for 0.5-1.2% of the length of the micro-needle electrode body, and the top end is 30-50% of the length of the micro-needle electrode body.
And in the step c, the obtained microneedle electrode with the tips closely arranged with the nanometer pore canals is used as a working electrode, and the nanometer particles are deposited in the nanometer pore canals at the tips of the microneedle electrode by a pulse electrodeposition method, so that the porous microneedle electrode with the tips embedded with the nanometer particles is obtained.
Further, the microneedle electrode with the tips closely arranged with the nanometer pores is cleaned by deionized water, is used as a working electrode, is combined with a platinum electrode as an auxiliary electrode and silver/silver chloride as a reference electrode, is placed in electroplating solutions of different metal nanoparticles, is circulated by three sections of pulse potentials and time sequences, and deposits the metal nanoparticles in the nanometer pores with the tips closely arranged, wherein the size of the metal nanoparticles is between 20 and 500 nm.
The three pulse potentials and time sequences are as follows: -0.5-0.6V,4-6ms;0.1-0.15V,26-35sm;0-0.1V,900-1200ms; preferably, the three pulse potentials and time sequences are as follows: -0.5v,4ms;0.1V,26sm;0V,900ms.
The cycle times of the three sections of pulse potentials and the time sequence are 9-12 times; preferably, the cycle times of the three pulse potentials and the time sequence are 9 times.
The electroplating solution is a solution containing different metal nanoparticle precursors; wherein the ions to be detected are one or more of metal ions (copper, lead, cadmium, zinc, iron, chromium, mercury, nickel and the like), non-metal ions (arsenic, selenium, oxygen and the like), pH, nitrate, nitrite, phosphate and silicate;
the electroplating solution is obtained by dissolving different metal nanoparticle precursors by water or other organic solutions.
Then, the deposition conditions are optimized according to the deposition operation, the plating liquid concentration is determined, and the like.
Still further, the electroplating solution is at least one of chloroauric acid, silver nitrate, copper sulfate, chloroplatinic acid, sodium chloropalladate and bismuth nitrate.
According to the method, the porous microneedle electrode with the tips embedded with the nanoparticles is prepared, wherein the surface of the tip of the microneedle body is fully and closely distributed with the nanopores, and the nanoparticles are uniformly deposited in the nanopores.
The application of the porous microneedle electrode with the embedded nanoparticles at the tip end in the detection of different ions.
The invention has the advantages that:
1. according to the microneedle electrode, the densely arranged nanometer pore channels are formed at the tip end of the microneedle electrode through electrochemical etching, the specific surface area of the electrode can be obviously increased, the active binding sites of the electrode on the nanometer particles are increased, the electrode can be combined with more nanometer particles with excellent electrochemical catalytic performance, the detection response of the electrode on an object to be detected is more sensitive, and the microneedle electrode has higher sensitivity and lower detection limit.
2. According to the invention, the densely arranged nanometer pore channels are formed at the tip end of the electrode through electrochemical etching, and then the nanometer particles with excellent electrochemical catalytic performance are deposited in the nanometer pore channels at the tip end of the electrode, so that the porous microneedle electrode with the tip end embedded with the nanometer particles is obtained. Compared with a microneedle electrode which is not subjected to electrochemical etching and has a smooth surface, the nano particles can be deposited in the nano pore channel at the tip of the microneedle electrode, and the nano pore channel can effectively protect the nano particles in the nano pore channel and prevent the nano particles from falling off in the detection process, so that the microneedle electrode has better stability and longer service life. After the nanoparticles on the electrode are physically wiped, the residual quantity of the nanoparticles on the electrode is tested by cyclic voltammetry, so that the prepared porous microneedle electrode with the tips embedded in the nanoparticles has the advantages that the effect of preventing the nanoparticles from falling off is obviously higher than that of an unetched electrode, and the stability is better.
3. The porous microneedle electrode with the nano particles embedded at the tips has high sensitivity, good stability and longer service life, and can be used for high-sensitivity and high-stability detection of different pollutants in the fields of environmental monitoring, food safety, clinic and the like.
Drawings
Fig. 1 is a scanning electron microscope picture (left) of a microneedle electrode tip with closely arranged nanopores and a scanning electron microscope picture (right) of a microneedle electrode tip without etching, which are prepared by an electrochemical etching method according to an embodiment of the present invention.
Fig. 2 is a scanning electron microscope image of the porous microneedle electrode with the tip embedded with nanoparticles according to the embodiment of the present invention.
Fig. 3 shows the change of characteristic peaks of nanoparticles after physically wiping the porous microneedle electrode with the nanoparticles embedded at the tips (left) and the unetched microneedle electrode with the nanoparticles directly deposited (right) in the same manner for different times.
Fig. 4 is a dissolution voltammogram and a corresponding linear curve of the porous microneedle electrode with gold nanoparticles embedded at the tip end in a buffer solution for detection of copper ions at different concentrations (0.1, 0.3,0.5,0.7,1,3,5,7,10,50,100,300,500,700, 1000nm) according to an embodiment of the present invention.
Fig. 5 is a current response change of a porous microneedle electrode with gold nanoparticles embedded at the tips in a buffer solution for 30 times of continuous detection of copper ions according to an embodiment of the present invention.
Fig. 6 is a current response diagram and a corresponding standard working curve of the porous microneedle electrode with gold nanoparticles embedded at the tips for detecting heavy metal copper in seawater, which are provided by the embodiment of the invention.
Detailed Description
The following examples are presented to further illustrate embodiments of the present invention, and it should be understood that the embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the invention.
The porous structure at the tip of the microneedle electrode obtained by the invention can provide a large specific surface area and a large number of active binding sites, so that more nanoparticles with excellent catalytic performance can be bound, and the electrode has high sensitivity. More importantly, the porous structure at the tip of the microneedle electrode can protect nanoparticles in the nanometer pore canal and prevent the nanoparticles from falling off in the detection process, so that the prepared electrode has good stability and longer service life, and can be widely used for high-sensitivity and high-stability detection of different pollutants in different samples.
Example 1
The specific preparation steps of the porous microneedle electrode with the metal nanoparticles embedded at the tip are as follows:
(1) Preparing a nickel-chromium alloy microneedle electrode: selecting a nichrome needle with the diameter of 0.25mm and the length of 60mm, taking the length of 1mm at the tip part as an electrode sensing area, taking the length of 25mm at the top part as an electrode lead, and coating insulating layers on the rest parts of the needle body to obtain the nichrome microneedle electrode.
(2) Preparing a microneedle electrode tip nanopore: cleaning and airing a nickel-chromium alloy micro-needle electrode by using deionized water, taking the nickel-chromium alloy micro-needle electrode as a working electrode, taking a graphite electrode as an auxiliary electrode, placing the auxiliary electrode in an etching solution containing 0.3wt% of ammonium fluoride, 2vol% of ethylene glycol and 98vol% of deionized water, and carrying out electrochemical etching by adopting a constant potential technology under the conditions of 2V etching potential and 120s etching time. And after etching, washing by deionized water, and airing to obtain the microneedle electrode with the tips closely arranged with the nanopores. (see FIG. 1)
As shown in fig. 1, after the electrochemical etching, the surface of the tip of the microneedle electrode is covered with nanopores densely arranged, the whole surface is very rough, and the diameter of each pore is about 600nm; while the tip surface of the unetched microneedle electrode is very smooth.
(3) Deposition of metal nanoparticles in the nanopores at the tips of the microneedle electrodes: taking the microneedle electrode with the tips closely arranged with the nanopores obtained in the steps as a working electrode, taking a platinum electrode as an auxiliary electrode and Ag/AgCl as a reference electrode, placing the microneedle electrode in electroplating solution containing gold nanoparticle precursors under the optimal conditions of-0.5V and 4ms;0.1V,26sm; and (3) circulating for 9 times through pulse potential and time sequence of 0V and 900ms, and depositing gold nanoparticles in the nanopores with the tips arranged closely to obtain the prepared porous microneedle electrode with the tips embedded with the gold nanoparticles. (see FIG. 2)
The plating solution containing gold nanoparticle precursor used in this example was 0.5M H 2 SO 4 Prepared 1mM chloroauric acid solution.
As shown in fig. 2, after the pulse electrodeposition, the gold nanoparticles are uniformly deposited in the nanopores closely arranged at the tips of the microneedle electrodes.
In order to investigate the protection effect of nanopores with tightly arranged microneedle electrode tips on gold nanoparticles, the porous microneedle electrode with the tips embedded in the gold nanoparticles and the unetched microneedle electrode directly deposited with the gold nanoparticles are physically wiped for different times, and then the change conditions of characteristic peaks of the gold nanoparticles of the two electrodes are tested by cyclic voltammetry (see fig. 3, the left side in the figure is that the unetched microneedle electrode directly deposited with the gold nanoparticles is physically wiped for 1 time, and after 2 times, the right side is that the porous microneedle electrode with the tips embedded in the gold nanoparticles is physically wiped for 1 time, 5 times, 10 times, 15 times and 20 times).
The preparation process of the unetched microneedle electrode directly deposited with the gold nanoparticles comprises the following steps: taking the nickel-chromium alloy micro-needle electrode obtained in the step (1) as a working electrode directly, taking a platinum electrode as an auxiliary electrode, taking Ag/AgCl as a reference electrode, and placing the electrode in a position of 0.5M H 2 SO 4 In the prepared 1mM chloroauric acid electroplating solution, the temperature is controlled to be-0.5V for 4ms;0.1V,26sm; the pulse potential and time sequence of 0V and 900ms are cycled for 9 times to obtain direct depositionAn unetched microneedle electrode with gold nanoparticles.
As is apparent from fig. 3, after the unetched microneedle electrode directly deposited with the gold nanoparticles is physically wiped for 1 time, the characteristic peak of the gold nanoparticles appearing at 0.68V completely disappears, and after the porous microneedle electrode with the tip embedded in the nanoparticles is physically wiped for 20 times, the characteristic peak of the gold nanoparticles is still hardly reduced. Therefore, the porous microneedle electrode with the nano-particles embedded at the tips has excellent mechanical stability and service life due to the protection effect of the nano-pores on the gold nano-particles.
Example 2
The porous microneedle electrode with the gold nanoparticles embedded at the tips obtained in the above example was used for detecting heavy metals: take copper in seawater as an example. The determination steps are as follows:
(1) The porous microneedle electrode with the gold nanoparticles embedded at the tips is prepared according to the above embodiments and is washed and dried in the air by deionized water before use.
(2) And (2) forming a three-electrode system by the electrode cleaned in the step (1), a platinum auxiliary electrode and an Ag/AgCl reference electrode, placing the three-electrode system in an acetic acid-sodium acetate buffer solution containing a series of copper ions (0.1, 0.3,0.5,0.7,1,3,5,7,10,50,100,300,500,700 and 1000nM) with different concentrations, and measuring the dissolution peak current of the copper ions with different concentrations by an electrochemical workstation by adopting square wave anodic dissolution voltammetry, taking-0.3V as an enrichment potential and 120s as an enrichment time, and drawing a linear curve of the peak current and the corresponding ion concentration (see figure 4).
As can be seen from FIG. 4, the obtained porous microneedle electrode with the tip embedded with gold nanoparticles can be combined with more gold nanoparticles with excellent electrochemical catalytic performance due to the fact that the specific surface area and active binding sites of the electrode are remarkably increased by the nanopores, so that the copper ion detection device has high sensitivity, the linear range is 0.1-1000nM, and the detection limit is 0.03nM.
Further detecting the stability of the obtained porous microneedle electrode with the tips embedded in the gold nanoparticles for continuously detecting the copper ions:
the three electrodes are placed in acetic acid-sodium acetate buffer solution containing 50nM copper ions, and through an electrochemical workstation, square wave anodic stripping voltammetry is adopted, and continuous determination is carried out for 30 times by taking-0.3V as an enrichment potential and 120s as enrichment time. The three electrodes were kept in the above solution, and after each detection, an oxidation potential was applied for potential cleaning at a cleaning potential of 0.4V for 30s (see fig. 5).
As can be seen from fig. 5, the porous microneedle electrode with the tip embedded in the gold nanoparticle of the invention effectively prevents the gold nanoparticle from falling off in the detection process due to the protection of the nanopore to the gold nanoparticle, so that the invention has excellent stability, and the RSD of the continuous detection 30 is 1.5%.
(3) The three electrodes are placed in standard seawater containing a plurality of copper ions with different concentrations (10,30, 50,100,300 and 500nM), the dissolution peak currents of the copper ions with different concentrations are measured by an electrochemical workstation by adopting square wave anodic dissolution voltammetry, taking-0.3V as an enrichment potential and 120s as an enrichment time, and a standard working curve of the peak currents and the corresponding ion concentrations is drawn (see figure 6).
As can be seen from FIG. 6, the prepared porous microneedle electrode with the gold nanoparticles embedded at the tips can be used for detecting copper ions in seawater, can also keep higher sensitivity, reaches 7.65 muA/muM, and can be completely used for detecting heavy metal copper in seawater.
And then placing the three electrodes in seawater to be measured, measuring the dissolution peak current of copper ions, and comparing with a standard working curve of the dissolution peak current-concentration to realize the measurement of the concentration of heavy metal copper in the seawater, so as to obtain a seawater sample with the concentration of copper ions of 23.73nM.
Example 3
The specific preparation steps of the porous microneedle electrode with the silver nanoparticles embedded at the tips are as follows:
the difference from example 1 is that the metal nanoparticles embedded in the nanopores of the electrode tip are silver nanoparticles.
The preparation of the nickel-chromium alloy microneedle electrode and the preparation of the nanopore at the tip of the microneedle electrode are respectively carried out according to the steps (1) and (2) in the embodiment 1.
Deposition of silver nanoparticles in the nanopores of the tips of the microneedle electrodes: a microneedle electrode with nanopores closely arranged at the tips is used as a working electrode, a platinum electrode is used as an auxiliary electrode, ag/AgCl is used as a reference electrode, and the microneedle electrode is placed in electroplating solution containing silver nanoparticle precursors for-0.5V and 4ms;0.1V,26sm; and (3) circulating for 9 times through pulse potential and time sequence of 0V and 900ms, and depositing silver nanoparticles in the nanopores with the tips arranged closely to obtain the prepared porous microneedle electrode with the tips embedded with the silver nanoparticles.
The electroplating solution containing the silver nanoparticle precursor is a 10mM silver nitrate aqueous solution.
Example 4
The specific preparation steps of the porous microneedle electrode with the copper nanoparticles embedded at the tip are as follows:
the difference from example 1 is that the metal nanoparticles embedded in the nanopores of the electrode tip are copper nanoparticles.
The preparation of the nickel-chromium alloy microneedle electrode and the preparation of the nanopore at the tip of the microneedle electrode are respectively carried out according to the steps (1) and (2) in the embodiment 1.
Deposition of copper nanoparticles in the nanopores at the tips of the microneedle electrodes: a microneedle electrode with nanopores closely arranged at the tips is used as a working electrode, a platinum electrode is used as an auxiliary electrode, ag/AgCl is used as a reference electrode, and the microneedle electrode is placed in electroplating solution containing a copper nanoparticle precursor for-0.5V and 4ms;0.1V,26sm; and (3) circulating for 9 times through a pulse potential and time sequence of 0V and 900ms, and depositing copper nanoparticles in the nanopores with the closely-arranged tips to obtain the prepared porous microneedle electrode with the tips embedded with the copper nanoparticles.
The electroplating solution containing copper nanoparticle precursor is 0.5M CuSO 4 An aqueous solution.
Example 5
The specific preparation steps of the porous microneedle electrode with the platinum nanoparticles embedded at the tip are as follows:
the difference from example 1 is that the metal nanoparticles embedded in the nanopores of the electrode tip are platinum nanoparticles.
The preparation of the nichrome microneedle electrode and the preparation of the nanopore at the tip of the microneedle electrode are respectively carried out according to the steps (1) and (2) in the embodiment 1.
Deposition of platinum nanoparticles in the nanopore of the microneedle electrode tip: micro-needle electrodes with nanopores closely arranged at tips are used as working electrodes, platinum electrodes are used as auxiliary electrodes, ag/AgCl is used as a reference electrode, and the micro-needle electrodes are placed in electroplating solution containing platinum nanoparticle precursors for-0.5V, 4ms;0.1V,26sm; and (3) circulating for 9 times through a pulse potential and time sequence of 0V and 900ms, and depositing platinum nanoparticles in the nanopores with the closely-arranged tips to obtain the prepared porous microneedle electrode with the tips embedded with the platinum nanoparticles.
The electroplating solution containing the platinum nanoparticle precursor is a 10mM chloroplatinic acid aqueous solution.
Example 6
The porous microneedle electrode with the tip embedded with copper nanoparticles is used for detecting nutrient salts: nitrate in river water is taken as an example. The determination steps are as follows:
(1) The obtained porous microneedle electrode with the tip embedded with the copper nanoparticles is cleaned by deionized water and dried in the air before use.
(2) And (2) forming a three-electrode system by the cleaned electrode, a platinum auxiliary electrode and an Ag/AgCl reference electrode, placing the three-electrode system in sodium sulfate solution with different concentrations (0.02-6 mM) of nitrate, taking-0.3V as an initial potential and-0.8V as a termination point by an electrochemical workstation and adopting a differential pulse voltammetry method, measuring the reduction peak current of nitrate ions with different concentrations, and drawing a standard response curve of the peak current and the corresponding ion concentration. The linear range of the porous microneedle electrode with the copper nanoparticles embedded at the tip end for detecting nitrate ions is 0.02-6mM, and the detection limit is 8 mu M.
(3) And (3) placing the three electrodes in a river water sample to be detected, and measuring the reduction peak current of nitrate ions by an electrochemical workstation and adopting a differential pulse voltammetry method and taking-0.3V as an initial potential and-0.8V as a termination point. And then adding a certain amount of standard nitrate ion solution into the sample, measuring the reduction peak current of the nitrate ions, adding the standard and measuring for three times, and obtaining the concentration of nitrate in the river water sample by a standard addition method.

Claims (10)

1. A preparation method of a porous microneedle electrode with a nanoparticle embedded at the tip is characterized by comprising the following steps:
a. preparing a micro-needle electrode body by using a nickel-chromium alloy needle;
b. the tip part of the micro-needle electrode is electrochemically etched to form nanopores which are closely arranged at the tip of the micro-needle electrode; wherein, the nanometer pore canal covers the whole electrode tip, and the diameter of the pore canal is between 300 and 900 nm;
c. and embedding metal particles into the obtained nanopores of the microneedle electrode with the tips closely arranged with the nanopores by a pulse electrodeposition method.
2. The method of preparing a porous microneedle electrode with nanoparticles embedded in the tips of the microneedle electrode as claimed in claim 1, wherein: and in the step b, taking a nickel-chromium alloy micro-needle electrode as a working electrode and a graphite electrode as an auxiliary electrode, placing the two electrodes in etching solution, performing electrochemical etching by adopting a potentiostatic method, and forming the nanopores which are closely arranged at the tip of the micro-needle electrode.
3. The method of preparing a porous microneedle electrode with nanoparticles embedded in the tips of the microneedle electrode as claimed in claim 2, wherein: the etching potential of the electrochemical etching is 1-5V, and the etching time is 30-180s;
the components of the etching liquid are 0.2-0.5wt% of ammonium fluoride, 2-5vol% of ethylene glycol and 95-98vol% of deionized water.
4. The method for preparing a porous microneedle electrode with nanoparticles embedded at the tip according to claim 1 or 2, wherein: the tip of the nickel-chromium alloy microneedle electrode body is an electrode sensing area, the top end of the nickel-chromium alloy microneedle electrode body is an electrode lead, and the rest parts of the nickel-chromium alloy microneedle electrode body are coated with insulating layers; wherein, the length of the tip part is 0.5-1mm, which accounts for 0.5-1.2% of the length of the micro-needle electrode body, and the top end is 30-50% of the length of the micro-needle electrode body.
5. The method for preparing a porous microneedle electrode with nanoparticles embedded in the tip thereof according to claim 1, wherein: and in the step c, the obtained microneedle electrode with the tips closely arranged with the nanometer pore canals is used as a working electrode, and the nanometer particles are deposited in the nanometer pore canals at the tips of the microneedle electrode by a pulse electrodeposition method, so that the porous microneedle electrode with the tips embedded with the nanometer particles is obtained.
6. The method of claim 5, wherein the porous microneedle electrode comprises: and (2) cleaning the microneedle electrode with the tips closely arranged with the nanopores by using deionized water, then using the microneedle electrode as a working electrode, combining a platinum electrode as an auxiliary electrode and silver/silver chloride as a reference electrode, placing the microneedle electrode in electroplating solutions of different metal nanoparticles, circulating by three sections of pulse potentials and time sequences, and depositing the metal nanoparticles in the nanopores with the tips closely arranged, wherein the size of the metal nanoparticles is between 20 and 500 nm.
7. The method of claim 6, wherein the porous microneedle electrode comprises: the three pulse potentials and time sequences are as follows: -0.5-0.6V,4-6ms;0.1-0.15V,26-35sm;0-0.1V,900-1200ms;
the cycle times of the three sections of pulse potentials and the time sequence are 9-12 times.
8. The method of claim 6, wherein the porous microneedle electrode comprises: the electroplating solution is a solution containing different metal nanoparticle precursors; wherein, the ions to be detected are one or more of metal ions (copper, lead, cadmium, zinc, iron, chromium, mercury, nickel and the like), non-metal ions (arsenic, selenium, oxygen and the like), pH, nitrate, nitrite, phosphate and silicate.
9. A porous microneedle electrode having a nanoparticle embedded tip prepared according to claim 1, wherein: the method of claim 1 is used to prepare a porous microneedle electrode with nanopores densely distributed on the surface of the tip of the microneedle electrode body, and nanoparticles are embedded in the tips of the uniformly deposited metal nanoparticles in the nanopores.
10. Use of a porous microneedle electrode with nanoparticles embedded in its tip according to claim 1, characterized in that: the porous microneedle electrode with the nanoparticle embedded at the tip end is applied to detection of different ions.
CN202211053555.3A 2022-08-30 2022-08-30 Porous microneedle electrode with nano-particles embedded at tips and preparation and application thereof Pending CN115404534A (en)

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