CN112255293B - Preparation method and application of microneedle electrode - Google Patents
Preparation method and application of microneedle electrode Download PDFInfo
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- CN112255293B CN112255293B CN202011105662.7A CN202011105662A CN112255293B CN 112255293 B CN112255293 B CN 112255293B CN 202011105662 A CN202011105662 A CN 202011105662A CN 112255293 B CN112255293 B CN 112255293B
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Abstract
The invention discloses a preparation method and application of a microneedle electrode. The preparation method comprises the following steps: preparing a silver wire microneedle electrode and a platinum wire microneedle electrode; loading a layer of silver chloride on the surface of the silver wire microneedle electrode in a potassium chloride solution through constant potential electrodeposition to obtain a silver-silver chloride microneedle electrode; preparing a dopamine aqueous solution and an ammonia aqueous solution to prepare polydopamine beads; preparing a precious metal salt aqueous solution, and adding polydopamine pellets into the cooled precious metal salt aqueous solution to prepare a polydopamine pellet-precious metal composite material; modifying the polydopamine sphere-precious metal composite material on the platinum wire microneedle electrode, and applying the polydopamine sphere-precious metal composite material to cell and tumor tissue detection. The invention can effectively realize in-vivo detection of the electrode, the polydopamine increases the total amount of Au participating in electrode reaction, the gold nanoparticles have good electrocatalytic property, and the synergistic effect of the two can improve the detection sensitivity of the electrode.
Description
Technical Field
The invention relates to the technical field of electrode preparation, in particular to a preparation method and application of a microneedle electrode.
Background
Miniaturization is one of the trends in analytical chemistry, and is mainly reflected in the miniaturization of working electrodes in the field of electrochemical analysis. The product has the capability of realizing real-time monitoring of chemical information in vivo and improving the stability of the product. The microelectrode technology is used in the advanced field of electroanalytical chemistry, and provides powerful means for people to carry out cell level ultrasensitive detection, thereby exploring cell physiological phenomena and revealing life activity rules. When the one-dimensional size of the electrode is reduced to the micrometer or nanometer scale, the electrochemical reaction at the electrode is substantially leaped, as compared to conventional electrodes and millimeter electrodes. The electric active substance on the microelectrode has extremely high diffusion speed and can be used for measuring the rate constant of the rapid heterogeneous reaction. The density of Faraday current flowing through the electrode in the measurement process of the microelectrode is high, the charging current is attenuated quickly, the ratio of the Faraday current to the charging current is increased, the signal to noise ratio is increased, and the analysis sensitivity is improved. The particular structure of the microelectrode provides a possibility for analyzing chemical substances in cancer cells and tissue samples.
The microelectrode can meet the special requirements of an electrode system in a micrometer size range, and the special flexibility of the microelectrode can meet the requirement of easy carrying. The needle-like fiber also exhibits a series of excellent functions such as small size (diameter of 50 to 500 μm), high strength and elastic modulus, good biocompatibility, and low cost, which enables it to be used as an electrical signal conducting substrate in a minute electrode.
Nowadays, based on a platinum wire micro-needle electrode, a reasonable hierarchical structure is designed, so that the high-performance multifunctional nano hybrid modified needle microelectrode has more and better development. For example, the patent application No. 201611004612.3 discloses a microneedle electrode with a porous metal-modified surface and a preparation method thereof, and in the invention, a porous metal layer is modified on the surface of a microneedle body, the surface area of the microneedle electrode is increased through reaction holes in the porous metal layer, more attachment sites are provided for sensitive components on the premise of not increasing the volume of the microneedle electrode, the loading capacity and the reaction area of the sensitive components on the microneedle electrode are improved, and finally the sensitivity of the prepared sensor is improved. However, the volume of the micro-needle is very small, the surface area of the micro-needle electrode is increased through the reaction hole in the porous metal layer, and the effect of improving the sensitivity of the manufactured sensor is limited; meanwhile, the immobilization of active substances on the surface of a platinum wire microneedle electrode encounters a significant challenge on the limited surface area of the needle-shaped platinum wire, because the low-electrical-activity nanomaterial loaded on the needle-shaped platinum wire microelectrode limits the analytical sensitivity of the obtained electrochemical biosensor.
Disclosure of Invention
Technical problem to be solved
The invention aims to provide a preparation method and application of a microneedle electrode, which aim to solve the problem that the low-electroactive nano material loaded on a needle-shaped platinum wire microelectrode limits the analysis sensitivity of the obtained electrochemical biosensor.
(II) technical scheme
In order to realize the preparation method of the microneedle electrode and the application thereof, the invention provides the following technical scheme that the problem that the low-electroactive nano material loaded on the needle-shaped platinum wire microelectrode limits the analysis sensitivity of the obtained electrochemical biosensor is solved:
a first object of the present invention is to provide a method for preparing a microneedle electrode, comprising the steps of:
(1) Obtaining the silver wire microneedle electrode by the processes of melting, square bar pressing, wire drawing, shaping and polishing;
(2) Loading a layer of silver chloride on the surface of the silver wire microneedle electrode in a potassium chloride solution through constant potential electrodeposition to obtain a silver-silver chloride microneedle electrode as a reference electrode;
(3) Preparing a dopamine aqueous solution and an ammonia aqueous solution, uniformly mixing the dopamine aqueous solution and the ammonia aqueous solution, reacting under magnetic stirring, and then centrifuging, freezing and drying to obtain polydopamine beads;
(4) Preparing a noble metal salt aqueous solution, and cooling the noble metal salt aqueous solution; then, adding the polydopamine globules obtained in the step (3) into the cooled precious metal salt aqueous solution, stirring for reaction, and washing to obtain the polydopamine composite material with precious metal particles loaded on the surface, namely the polydopamine sphere-precious metal composite material;
(5) And (3) modifying the polydopamine sphere-precious metal composite material obtained in the step (4) on the platinum wire microneedle electrode, and applying the polydopamine sphere-precious metal composite material to cell and tumor tissue detection.
Preferably, the silver wire microneedle electrode in the step (2) is subjected to constant potential electrochemical deposition in 0.5-3 mol/L potassium chloride solution to obtain the silver-silver chloride microneedle electrode.
Preferably, the constant potential of the step (2) is-0.1V-1V, and the deposition time is 500 s-3000 s.
Preferably, the concentration of dopamine in the step (3) is 2 mg/mL-5 mg/mL, and the concentration of ammonia water is 0.1 mmol/L-0.5 mmol/L.
Preferably, in the step (3), the dopamine aqueous solution and the ammonia aqueous solution are uniformly mixed, react for 12 to 36 hours under magnetic stirring, and then are centrifuged and freeze-dried at the temperature of-10 to-60 ℃ for 24 to 72 hours.
Preferably, in the step (4), the polydopamine bead is added into the cooled precious metal salt aqueous solution, and the mixture is stirred and reacted for 10 to 30 minutes at a temperature of between-5 and 0 ℃, wherein the content of precious metal ions in the precious metal salt aqueous solution is 0.05 to 2 percent.
The invention also provides a micro-needle electrode prepared by the preparation method of the micro-needle electrode, which comprises a silver wire micro-needle electrode and a platinum wire micro-needle electrode, wherein the upper surfaces of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are cylinders, and the lower parts of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are needles.
Preferably, the diameters of the upper surfaces of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are 0.5 mm-1 mm, the lengths of the upper surfaces of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are 0.5 cm-2 cm, the diameters of the tips of the lower parts of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are 5 micrometers-500 micrometers, and the lengths of the silver wire micro-needle electrode and the platinum wire micro-needle electrode are 0.5 cm-2 cm.
The third purpose of the invention is to protect the application of the microneedle electrode prepared by the preparation method of the microneedle electrode in the detection of lactic acid in tumor tissues.
(III) advantageous effects
Compared with the prior art, the invention provides a preparation method and application of a microneedle electrode, and the preparation method has the following beneficial effects: the invention adopts the poly-dopamine ball-nano gold modified needle-shaped platinum wire microelectrode as a detection electrode and the silver wire microneedle electrode as a reference electrode, can provide a reference potential, can measure the electromotive force of the battery when being used together with a working electrode, and obtains a stable test result. The polydopamine contains a large amount of catechol, electrons can be exchanged with dielectrics on the surface of the polydopamine nano particles under the promotion of potential, so that the conversion between oxidation states and reduction states is realized, the total amount of Au participating in electrode reaction is increased, the gold nano particles have good electrocatalytic properties, and the detection sensitivity of the electrode can be improved through the synergistic effect of the gold nano particles and the dielectrics.
Drawings
FIG. 1 is a scanning electron microscope image of a platinum wire microneedle electrode prepared by the method.
Fig. 2 is a scanning electron microscope image of the poly dopamine sphere-gold nanoparticle prepared by the invention.
FIG. 3 is a differential pulse voltammetry response diagram of a poly dopamine sphere-gold nanoparticle modified platinum wire microneedle electrode prepared according to the invention to different lactic acid concentrations in a culture medium.
Fig. 4 is a lactic acid detection response diagram of the poly-dopamine sphere-gold nanoparticle modified platinum wire microneedle electrode prepared by the invention to different tumor stages.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Example 1
(1) Synthesizing a platinum wire microneedle electrode and a silver/silver chloride wire microneedle electrode:
melting platinum with the purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → polishing process to obtain the platinum wire micro-needle electrode with the lower diameter of 200 μm shown in figure 1. Similarly, melting silver with the purity of 99.999% at high temperature to obtain liquid silver, then performing square bar pressing → wire drawing → shaping → grinding process to obtain the silver wire microneedle shown in figure 1, and then depositing the silver wire microneedle in 1mol/L potassium chloride solution at constant potential for 1000s under the voltage of-0.1V to obtain the silver/silver chloride electrode as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 2 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with the ammonia water concentration of 0.25 mmol/L; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for reaction for 24 hours, centrifuging, and freeze-drying at the temperature of-10 ℃ for 24 hours to obtain polydopamine beads with uniform size;
(3) Preparation of poly-dopamine sphere-nanogold composite (i.e., poly-dopamine sphere with gold nanoparticles loaded on the surface, especially gold nanoparticles loaded on the surface of poly-dopamine):
diluting a high-concentration chloroauric acid solution with deionized water to obtain 50mL of 1% aqueous solution, adding 0.1g of polydopamine composite material after the solution is precooled in an ice bath, stirring and reacting at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying to obtain the polydopamine sphere-nanogold composite material;
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
Example 2
(1) Synthesizing a platinum wire microneedle electrode and a silver/silver chloride wire microneedle electrode:
melting platinum with the purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → polishing process to obtain the platinum wire micro-needle electrode with the diameter of 200 μm as shown in figure 1. Similarly, silver with purity of 99.999% is melted at high temperature to obtain liquid silver, then square strip pressing → wire drawing → shaping → grinding process is carried out to obtain the silver wire micro needle shown in figure 1, and then the silver wire micro needle is deposited for 1000s at constant potential in 1mol/L potassium chloride solution under the voltage of-0.1V to obtain the silver/silver chloride electrode which is used as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 3 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with 0.2mmol/L ammonia water concentration; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for 24 hours for reaction, centrifuging, and freeze-drying at-20 ℃ for 36 hours to obtain polydopamine beads with uniform size;
(3) Preparation of poly-dopamine sphere-nanogold composite (i.e., poly-dopamine sphere with gold nanoparticles loaded on the surface, especially gold nanoparticles loaded on the surface of poly-dopamine):
diluting a large-concentration chloroauric acid solution with deionized water to obtain 50mL of 1% aqueous solution, precooling the solution in an ice bath, adding 0.1g of polydopamine composite material into the solution, stirring and reacting the polydopamine composite material at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying the polydopamine sphere-nanogold composite material to obtain the polydopamine sphere-nanogold composite material.
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
Embodiment 3
(1) Synthesizing a platinum wire microneedle electrode and a silver/silver chloride wire microneedle electrode:
melting platinum with purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → grinding process to obtain the platinum wire micro-needle electrode with the diameter of 50 μm in the structure shown in figure 1. Similarly, melting silver with the purity of 99.999% at high temperature to obtain liquid silver, then performing square bar pressing → wire drawing → shaping → grinding process to obtain the silver wire microneedle shown in figure 1, and then depositing the silver wire microneedle in 1mol/L potassium chloride solution at constant potential for 1000s under the voltage of-0.1V to obtain the silver/silver chloride electrode as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 5 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with 0.2mmol/L ammonia water concentration; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for reaction for 24 hours, centrifuging, and freeze-drying at the temperature of-30 ℃ for 36 hours to obtain polydopamine pellets with uniform size;
(3) Preparation of poly-dopamine sphere-nanogold composite (i.e., poly-dopamine sphere with gold nanoparticles loaded on the surface, especially gold nanoparticles loaded on the surface of poly-dopamine):
diluting a large-concentration chloroauric acid solution with deionized water to obtain 50mL of 1% aqueous solution, precooling the solution in an ice bath, adding 0.1g of polydopamine composite material into the solution, stirring and reacting the polydopamine composite material at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying the polydopamine sphere-nanogold composite material to obtain the polydopamine sphere-nanogold composite material.
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
Example 4
(1) Synthesizing a platinum wire microneedle electrode and a silver/silver chloride wire microneedle electrode:
melting platinum with the purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → polishing process to obtain the platinum wire micro-needle electrode with the diameter of 100 μm as shown in figure 1. Similarly, melting silver with the purity of 99.999% at high temperature to obtain liquid silver, then performing square bar pressing → wire drawing → shaping → grinding process to obtain the silver wire microneedle shown in figure 1, and then depositing the silver wire microneedle in 1mol/L potassium chloride solution at constant potential for 1000s under the voltage of-0.1V to obtain the silver/silver chloride electrode as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 2 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with the ammonia water concentration of 0.15 mmol/L; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for reaction for 24 hours, centrifuging, and freeze-drying at the temperature of-40 ℃ for 48 hours to obtain polydopamine pellets with uniform size;
(3) Preparation of a polydopamine sphere-nanogold composite material (i.e., a polydopamine sphere with gold nanoparticles loaded on the surface, particularly, gold nanoparticles loaded on the surface of polydopamine):
diluting a high-concentration chloroauric acid solution with deionized water to obtain 50mL of 0.05% aqueous solution, precooling the solution in an ice bath, adding 0.1g of polydopamine composite material into the solution, stirring and reacting the polydopamine composite material at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying the polydopamine sphere-nanogold composite material to obtain the polydopamine sphere-nanogold composite material.
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
Example 5
(1) Synthesizing a platinum wire microneedle electrode and a silver/silver chloride wire microneedle electrode:
melting platinum with the purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → polishing process to obtain the platinum wire micro-needle electrode with the diameter of 150 μm as shown in figure 1. Similarly, melting silver with the purity of 99.999% at high temperature to obtain liquid silver, then performing square bar pressing → wire drawing → shaping → grinding process to obtain the silver wire microneedle shown in figure 1, and then depositing the silver wire microneedle in 1mol/L potassium chloride solution at constant potential for 1000s under the voltage of-0.1V to obtain the silver/silver chloride electrode as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 3 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with the ammonia water concentration of 0.2 mmol/L; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for reaction for 24 hours, centrifuging, and freeze-drying at the temperature of-50 ℃ for 24 hours to obtain polydopamine beads with uniform size;
(3) Preparation of poly-dopamine sphere-nanogold composite (i.e., poly-dopamine sphere with gold nanoparticles loaded on the surface, especially gold nanoparticles loaded on the surface of poly-dopamine):
diluting a high-concentration chloroauric acid solution with deionized water to obtain 50mL of 0.08% aqueous solution, precooling the solution in an ice bath, adding 0.1g of polydopamine composite material into the solution, stirring and reacting the polydopamine composite material at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying the polydopamine sphere-nanogold composite material to obtain the polydopamine sphere-nanogold composite material.
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
Example 6
(1) Synthesis of platinum wire micro-needle electrode and silver/silver chloride wire micro-needle electrode:
melting platinum with purity of 99.999% at high temperature to obtain liquid platinum, and then performing square bar pressing → wire drawing → shaping → grinding process to obtain the platinum wire micro-needle electrode with the diameter of 50 μm as shown in figure 1. Similarly, melting silver with the purity of 99.999% at high temperature to obtain liquid silver, then performing square bar pressing → wire drawing → shaping → grinding process to obtain the silver wire microneedle shown in figure 1, and then depositing the silver wire microneedle in 1mol/L potassium chloride solution at constant potential for 2000s under the voltage of-0.1V to obtain the silver/silver chloride electrode as a reference electrode.
(2) Synthesizing a polydopamine sphere-nanogold composite material:
dissolving dopamine in deionized water to prepare 40mL of aqueous solution with dopamine concentration of 2 mg/mL; then diluting 28% ammonia water with deionized water to obtain 40mL of aqueous solution with the ammonia water concentration of 0.2 mmol/L; finally, uniformly mixing dopamine and ammonia water at 25 ℃, stirring for reaction for 24 hours, centrifuging, and freeze-drying at the temperature of-60 ℃ for 72 hours to obtain polydopamine pellets with uniform size;
(3) Preparation of a polydopamine sphere-nanogold composite material (i.e., a polydopamine sphere with gold nanoparticles loaded on the surface, particularly, gold nanoparticles loaded on the surface of polydopamine):
diluting a high-concentration chloroauric acid solution with deionized water to obtain 50mL of 0.05% aqueous solution, precooling the solution in an ice bath, adding 0.1g of polydopamine composite material into the solution, stirring and reacting the polydopamine composite material at 0 ℃ for 30min, removing potassium chloroaurate attached to the surface by a rinsing method, and freeze-drying the polydopamine sphere-nanogold composite material to obtain the polydopamine sphere-nanogold composite material.
(4) The composite material can be used for detecting the lactic acid of cells and tumor tissues.
The poly-dopamine sphere-nano gold composite material is modified on a platinum wire micro-needle electrode and a silver/silver chloride wire micro-needle electrode, and is applied to cell and tumor tissue detection.
The principles of examples 1-6 are described in detail below:
in the microneedle electrode modified by the poly-dopamine sphere-nanogold composite material, the poly-dopamine contains a large amount of catechol, electrons can be exchanged with dielectrics on the surface of poly-dopamine nanoparticles under the promotion of potential, so that the poly-dopamine is converted between oxidation states and reduction states, the total amount of Au participating in electrode reaction is increased, and the gold nanoparticles have good electrocatalytic properties and can improve the detection sensitivity of the electrode. The two can improve the sensitivity of the electrode by the synergistic effect. The silver-silver chloride micro-needle electrode is used as a reference electrode, a reference potential can be provided, and the electromotive force of the battery can be measured when the silver-silver chloride micro-needle electrode is used together with the working electrode, so that a stable test result is obtained.
According to the related experiments, the performance of the microneedle electrode of the modified polydopamine sphere-nanogold composite was improved by 4.5 times as compared to the blank platinum wire microneedle electrode in the DMEM medium containing 3mM lactic acid with 10% fbs. The poly-dopamine sphere-nanogold composite material prepared by the preparation method has a good catalytic effect on lactic acid.
When the needle-shaped platinum wire microelectrode modified by the polydopamine sphere-nano gold composite material is used for sensitively detecting the content of lactic acid in supernatants with different cell volumes, the content of tumor cells can be distinguished, so that the needle-shaped platinum wire microelectrode modified by the polydopamine sphere-nano gold composite material has great application potential in pathological diagnosis of cancers. At 10 4 ～10 6 Within the range of individual cells, the peak current induced in the culture medium for colon cancer cell culture is stronger than that in the culture medium for normal colon epithelial cell culture at the same cell density, and the exact lactic acid concentration in different culture media is calculated according to a standard calibration curve.
In the real-time process of the invention, a non-enzymatic lactic acid detection system based on an electrochemical technology is also developed, and the system realizes the in-vivo recording of voltammetric signals in tumor tissues of in-vivo tumor-bearing mice. These signals exhibit a positive correlation with tumor size, indicating the potential of this sensing system to predict tumor progression in vivo. The operation process is simple, the in vivo detection of tumor-bearing mice can be realized, the in vivo detection of the lactic acid concentration of tumors can be realized within three minutes, the sample preparation is simple, and the noninvasive property is small.
FIG. 3 shows that PDAS/Au/PtMN induced peak current density is linear with lactate concentration (0.375 to 12 mM). According to the calibration curve, the sensitivity of PDAS/Au/PtMN was 11.25mA mM-1cm-2, with a detection limit as low as 0.05mM. It can be seen that in situ lactate detection, the linear range is wide and the sensitivity is high.
As shown in FIG. 4, the DPV curves recorded by PDSS/Au/PtMN for tumor-bearing mice show a distinct current peak with a voltage position consistent with the position of lactate detected in vitro. In addition, the dynamic change of the current response with tumor progression (fig. 4) was further monitored and the peak current density was positively correlated with tumor size and a significant increase in the current density in tumors detected by the electrochemical assay based on PDAS/Au/PtMN was observed with the increase in tumor growth time.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (3)
1. A preparation method of a microneedle electrode comprises a silver wire microneedle electrode and a platinum wire microneedle electrode, and is characterized by comprising the following steps:
(1) Obtaining silver wire micro-needle electrodes and platinum wire micro-needle electrodes through the processes of melting, square bar pressing, wire drawing, shaping and polishing;
(2) Loading a layer of silver chloride on the surface of the silver wire microneedle electrode in a potassium chloride solution through constant potential electrodeposition to obtain a silver-silver chloride microneedle electrode as a reference electrode, and obtaining the silver-silver chloride microneedle electrode through constant potential electrochemical deposition in the potassium chloride solution of 0.5-3 mol/L;
(3) Preparing a dopamine aqueous solution and an ammonia aqueous solution, uniformly mixing the dopamine aqueous solution and the ammonia aqueous solution, reacting under magnetic stirring, and then centrifuging, freezing and drying to obtain polydopamine beads;
(4) Preparing a noble metal salt aqueous solution, and cooling the noble metal salt aqueous solution; then, adding the polydopamine globules obtained in the step (3) into the cooled precious metal salt aqueous solution, stirring for reaction, and washing to obtain a polydopamine composite material with precious metal particles loaded on the surface, namely a polydopamine sphere-precious metal composite material;
(5) Modifying the polydopamine sphere-precious metal composite material obtained in the step (4) on the platinum wire microneedle electrode, and applying the polydopamine sphere-precious metal composite material to cell and tumor tissue detection;
the constant potential in the step (2) is-0.1V-1V, the deposition time is 500 s-3000 s, the concentration of dopamine in the step (3) is 2 mg/mL-5 mg/mL, and the concentration of ammonia water is 0.1 mmol/L-0.5 mmol/L; and (3) uniformly mixing the dopamine aqueous solution and the ammonia aqueous solution, reacting for 12-36 h under magnetic stirring, centrifuging, and freeze-drying at the temperature of-10 to-60 ℃ for 24-72 h, wherein in the step (4), the polydopamine beads are added into the cooled noble metal salt aqueous solution, and the mixture is stirred and reacted for 10-30 min at the temperature of-5-0 ℃, and the content of noble metal ions in the noble metal salt aqueous solution is 0.05-2%.
2. A microneedle electrode prepared by the method for preparing a microneedle electrode according to claim 1, comprising a silver wire microneedle electrode and a platinum wire microneedle electrode, wherein the upper surfaces of the silver wire microneedle electrode and the platinum wire microneedle electrode are cylinders, and the lower portions of the silver wire microneedle electrode and the platinum wire microneedle electrode are needles.
3. A microneedle electrode prepared by the method for preparing a microneedle electrode according to claim 1, comprising a silver wire microneedle electrode and a platinum wire microneedle electrode, wherein the diameters of the upper surfaces of the silver wire microneedle electrode and the platinum wire microneedle electrode are 0.5mm to 1mm, the lengths of the silver wire microneedle electrode and the platinum wire microneedle electrode are 0.5cm to 2cm, the diameters of the lower tip ends of the silver wire microneedle electrode and the platinum wire microneedle electrode are 5 μm to 500 μm, and the lengths of the silver wire microneedle electrode and the platinum wire microneedle electrode are 0.5cm to 2cm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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