NONENZYMATIC BIOSENSOR BASED ON METAL-MODIFIED POROUS BORON-DOPED DIAMOND ELECTRODE, AND METHOD FOR PREPARING SAME AND USE THEREOF

Abstract

A nonenzymatic biosensor based on a metal-modified porous boron-doped diamond electrode, and a method for preparing the same and use thereof are provided. A working electrode of the nonenzymatic biosensor is a metal-modified porous boron-doped diamond electrode including a silicon wafer substrate and an electrode working layer arranged on a surface thereof, the electrode working layer is a porous boron-doped diamond layer modified with metal nanoparticles, and a pore surface of the porous boron-doped diamond layer contains an sp.sup.2 phase. In the present invention, by combining chemical vapor deposition and magnetron sputtering and by means of a tubular atmosphere annealing furnace and an electrochemical workstation, the preparation of a multi-metal-modified porous boron-doped diamond composite electrode is realized. The electrode has the characteristics of high sensitivity, stability, and resolution, and can be widely used in the fields of the construction of electrochemical biosensors, the detection of heavy metals, etc.

Claims

1. A nonenzymatic biosensor based on a metal-modified porous boron-doped diamond electrode, wherein a working electrode of the nonenzymatic biosensor is the metal-modified porous boron-doped diamond electrode comprising a silicon wafer substrate and an electrode working layer; and the electrode working layer is arranged on a surface of the silicon wafer substrate, the electrode working layer is a porous boron-doped diamond layer with a surface modified with metal nanoparticles, and a pore surface of the porous boron-doped diamond layer comprises an sp.sup.2 phase.

2. The nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 1, wherein a thickness of the porous boron-doped diamond layer is 5 μm-20 μm, a grain size is 5 μm-20 μm, and a crystal surface (111) is an exposed surface.

3. The nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 1, wherein particle sizes of the metal nanoparticles are 20 nm-30 nm; and the metal nanoparticles are selected from at least one of gold nanoparticles, platinum nanoparticles, nickel nanoparticles, and copper nanoparticles.

4. The nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 3, wherein the metal nanoparticles are selected from the gold nanoparticles and the nickel nanoparticles, and according to an atomic ratio, gold:nickel=2:8; the metal nanoparticles are selected from the gold nanoparticles and the platinum nanoparticles, and according to an atomic ratio, gold:platinum=1:1; and the metal nanoparticles are selected from the nickel nanoparticles and the copper nanoparticles, and according to an atomic ratio, nickel:copper=6:4.

5. A method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 1, comprising the following steps: step 1: first, planting seed crystals on the surface of the silicon wafer substrate, and then, performing a deposition on the surface of the silicon wafer substrate by a hot wire chemical vapor deposition to obtain a boron-doped diamond film; step 2: depositing a metal nickel layer on a surface of the boron-doped diamond film by a magnetron sputtering; step 3: performing a thermal catalytic etching on a sample covered with the metal nickel layer prepared in the step 2 to form nickel particles embedded in the boron-doped diamond film; step 4: performing an anodic polarization treatment on the sample embedded with the nickel particles prepared in the step 3 by an electrochemical workstation to remove metal nickel on a surface of the sample to form a porous structure; step 5: depositing the metal nanoparticles on the porous structure of the sample obtained in the step 4 by an electrodeposition by the electrochemical workstation to obtain the metal-modified porous boron-doped diamond electrode; and step 6: using the metal-modified porous boron-doped diamond electrode obtained in the step 5 as the working electrode to assemble the nonenzymatic biosensor.

6. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 5, wherein in the step 1, a process of planting the seed crystals is as follows: the silicon wafer substrate is immersed in a suspension containing nanodiamonds, an ultrasonic vibration is performed for 30 min or longer, and finally, cleaning and drying are performed; and in the step 1, a technology of the hot wire chemical vapor deposition is as follows: a number of turns of a hot wire is 10-20, a temperature of the hot wire is 2,000° C.-2,500° C., a mass flow ratio of gases introduced is hydrogen:methane:borane=49:1:(0.3-0.6), a growth pressure is 2.5 Kpa-5 Kpa, a growth temperature is 700° C.-900° C., and a growth time is 6 h-12 h.

7. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 5, wherein in the step 2, a technology of the magnetron sputtering is as follows: a nickel target with a purity≥99.99% is used, a distance between the silicon wafer substrate and the nickel target is 10 cm-12 cm, an argon atmosphere is used, a deposition pressure is 0.5+/−0.05 Pa, a sputtering power is 50 W-150 W, a deposition time is 60 s, and a deposition thickness of the metal nickel layer is 5 nm-50 nm; and in the step 3, a technology of the thermal catalytic etching is as follows: hydrogen is introduced for an etching, a mass flow of the hydrogen is 40 SCCM-100 SCCM, an etching temperature is 600° C.-1,000° C., an etching pressure is controlled at 10 KPa-20 KPa, and an etching time is 100 min-300 min.

8. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 5, wherein in the step 4, a process of the anodic polarization is as follows: first, the sample embedded with the nickel particles prepared in the step 3 is insulated and sealed, and then placed in a three-electrode system to connect to the electrochemical workstation, an anodic polarization voltage is +2.0+/−0.1 V, a polarization time is 150 s-180 s, and an electrolyte is a 1.0 M sodium sulfate solution; and in the step 5, a technology of the electrodeposition of the metal nanoparticles is as follows: a deposition potential is −2.0 V to −1.2 V, a deposition time of each cycle is 30 s to 50 s, and a concentration of a deposition solution is 1 mM to 10 mM.

9. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 8, wherein when the metal nanoparticles are selected from gold nanoparticles and nickel nanoparticles, a number of deposition cycles is 5 respectively; first, the gold nanoparticles are deposited, a deposition potential is −1.0 V, a deposition time of one cycle is 30 s, and a deposition solution is a 1 mM chloroauric acid solution; and then, the nickel nanoparticles are deposited, a deposition potential is −2.0 V, a deposition time of one cycle is 50 s, and a deposition solution is a 10 mM nickel nitrate solution; when the metal nanoparticles are selected from gold nanoparticles and platinum nanoparticles, a number of deposition cycles is 4 respectively; first, the gold nanoparticles are deposited, a deposition potential is −1.0 V a deposition time of one cycle is 50 s, and a deposition solution is a 1 mM chloroauric acid solution; and then, the platinum nanoparticles are deposited, a deposition potential of one cycle is −1.2 V, a deposition time of one cycle is 50 s, and a deposition solution is a 1 mM chloroplatinic acid solution; and when the metal nanoparticles are selected from nickel nanoparticles and copper nanoparticles, a number of deposition cycles is 5 respectively; first, the nickel nanoparticies are deposited, a deposition potential is −2.0 V, a deposition time of one cycle is 50 s, and a deposition solution is a 10 nM nickel nitrate solution; and during a deposition of the copper nanoparticles, a deposition potential is −1.5 V, a deposition time of one cycle is 30 s, and a deposition solution is a 10 mM copper nitrate solution.

10. A method of a use of the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 1, wherein the nonenzymatic biosensor is used for detecting dopamine or glucose.

11. The method of the use of the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 10, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, a thickness of the porous boron-doped diamond layer is 5 μm-20 μm, a grain size is 5 μm-20 μm, and a crystal surface (111) is an exposed surface.

12. The method of the use of the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 10, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, particle sizes of the metal nanoparticles are 20 nm-30 nm; and the metal nanoparticles are selected from at least one of gold nanoparticles, platinum nanoparticles, nickel nanoparticles, and copper nanoparticles.

13. The method of the use of the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 12, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, the metal nanoparticles are selected from the gold nanoparticles and the nickel nanoparticles, and according to an atomic ratio, gold:nickel=2:8; the metal nanoparticles are selected from the gold nanoparticles and the platinum nanoparticles, and according to an atomic ratio, gold:platinum=1:1; and the metal nanoparticles are selected from the nickel nanoparticles and the copper nanoparticles, and according to an atomic ratio, nickel:copper=6:4.

14. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 5, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, a thickness of the porous boron-doped diamond layer is 5 μm-20 μm, a grain size is 5 μm-20 μm, and a crystal surface (111) is an exposed surface.

15. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 5, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, particle sizes of the metal nanoparticles are 20 nm-30 nm; and the metal nanoparticles are selected from at least one of gold nanoparticles, platinum nanoparticles, nickel nanoparticles, and copper nanoparticles.

16. The method for preparing the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode according to claim 15, wherein in the nonenzymatic biosensor based on the metal-modified porous boron-doped diamond electrode, the metal nanoparticles are selected from the gold nanoparticles and the nickel nanoparticles, and according to an atomic ratio, gold:nickel=2:8; the metal nanoparticles are selected from the gold nanoparticles and the platinum nanoparticles, and according to an atomic ratio, gold:platinum=1:1; and the metal nanoparticles are selected from the nickel nanoparticles and the copper nanoparticles, and according to an atomic ratio, nickel:copper=6:4.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 shows a scanning electron microscope (SEM) diagram of a diamond film not etched in Example 1.

[0046] FIG. 2 shows an SEM diagram of a porous morphology of the diamond film etched in Example 1.

[0047] FIG. 3 shows CV detection curves of a metal-modified porous boron-doped diamond electrode modified with gold and platinum in different ratios in Comparative Example 2, where the ratio in a curve 1 is 1:9, the ratio in a curve 2 is 3:7, the ratio in a curve 4 is 1:1, and the ratio in a curve 3 is 3:2.

[0048] FIG. 4 shows an SEM diagram of a morphology of Ni nanoparticles modified with diamond not etched in Comparative Example 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] The substantive features and significant progress of the present invention are further illustrated through the following embodiments, but the present invention is by no means limited to the embodiments.

Example 1

[0050] Step 1: Preparation of a boron-doped diamond film. First, a silicon wafer substrate was placed in an acetone solution. Ultrasonic cleaning was performed for 5-20 min to remove oil stains on a surface. Then, ultrasonic cleaning was performed in deionized water for 10-20 min. The silicon wafer substrate was dried in a drying furnace and then put into a chemical vapor deposition chamber for the growth of boron-doped diamond. During the growth process, the number of turns of a hot wire was 10-20. A temperature of the hot wire was controlled at 2,000-2,500° C. A surface temperature of the substrate was 700-900° C. A gas ratio was methane:borane:hydrogen=1:49:0.3. A cavity pressure was about 2.5-5 Kpa. A grain size of the grown diamond film was 5-10 μm in diameter. A film thickness was 5-20 μm.

[0051] Step 2: Nickel layer sputtering. A method was as follows. A physical magnetron sputtering device was used. Under an atmospheric pressure of 0.5-2 Pa, a layer of nickel film was uniformly sputtered on the diamond film in step 1 by a high-purity nickel target with a purity of 99.99%. A sputtering power was 50-150 W. A thickness of the nickel layer was 5-50 nm.

[0052] Step 3: High-temperature heat treatment etching in a hydrogen environment. A method was as follows. A sheet prepared in step 2 was put into a cold-wall heat treatment furnace. 40-100 SCCM hydrogen was introduced. An etching temperature was controlled at 600-1,000° C. An etching pressure was controlled at 10-20 Kpa. An etching time was 100-300 min.

[0053] Step 4: Removal of nickel particles. A method was as follows. The sample obtained in step 3 was encapsulated and then placed in an electrochemical workstation for anodic polarization. An anodic polarization voltage was +2.0 V. A polarization time was 180 s. An electrolyte was a 1.0 M sodium sulfate solution.

[0054] Step 5: Co-modification of gold and nickel nanoparticles. Metal nanoparticles were deposited by a square wave transition potential. The number of deposition cycles was 5, During the deposition of gold nanoparticles, a deposition potential was −1.0 V. A deposition time of one cycle was 30 s. A deposition solution was a 1 mM chloroauric acid solution, During the deposition of nickel nanoparticles, a deposition potential was −2.0 V. A deposition time of one cycle was 50 s. A deposition solution was a 10 mM nickel nitrate solution. The sizes of gold-nickel composite nanoparticles obtained under this process were 20-30 nm, and a gold-nickel content ratio was about 2:8. At this time, the best catalytic performance was obtained.

[0055] Step 6: Preparation of a sensor. A method was as follows. After the electrode obtained in step 5 was encapsulated, a reference electrode and a counter electrode were used together with the encapsulated electrode to form a three-electrode detection sensor.

[0056] The three-electrode detection sensor obtained in Example 1 was used for detecting glucose concentration. The sensitivity was 1,586 μAcm.sup.−2mM.sup.−1. A linear range was 0.001-30 mM. A detection limit was 0.0005 mM. During the 30-day cycle stability test, only 7% of the response current was lost.

Example 2

[0057] Step 1: Preparation of a boron-doped diamond film. First, a silicon wafer substrate was placed in an acetone solution. Ultrasonic cleaning Was performed for 10 min to remove oil stains on a surface. Then, ultrasonic cleaning was performed in deionized water for 15 min. The silicon wafer substrate was dried in a drying furnace and then put into a chemical vapor deposition chamber for the growth of boron-doped diamond. During the growth process, the number of turns of a hot wire was 15. A temperature of the hot wire was controlled at 2,250° C. A surface temperature of the substrate was 800° C. A gas ratio was methane:borane:hydrogen=1:49:0.3. A cavity pressure was about 3.0 Kpa. A grain size of the grown diamond film was 6-8 μm in diameter. A film thickness was 10-15 μm.

[0058] Step 2: Nickel layer sputtering. A method was as follows. A physical magnetron sputtering device was used. Under an atmospheric pressure of 1 Pa, a layer of nickel film was uniformly sputtered on the diamond film in step 1 by a high-purity nickel target with a purity of 99.99%. A sputtering power was 100 W. A thickness of the nickel layer was 20-40 nm.

[0059] Step 3: High-temperature heat treatment etching in a hydrogen environment. A method was as follows. A sheet prepared in step 2 was put into a cold-wall heat treatment furnace. 60 SCCM hydrogen was introduced. An etching temperature was controlled at 800° C. An etching pressure was controlled at 15 Kpa. An etching time was 200 min.

[0060] Step 4: Removal of nickel particles. A method was as follows. The sample obtained in step 3 was encapsulated and then placed in an electrochemical workstation for anodic polarization. An anodic polarization voltage was ±2.0 V. A polarization time was 180 s. An electrolyte was a 1.0 M sodium sulfate solution.

[0061] Step 5: Co-modification of gold and platinum nanoparticles. Metal nanoparticles were deposited by a square wave transition potential. The number of deposition cycles was 4. During the deposition of gold nanoparticles, a deposition potential was −1.0 V. A deposition time was 50 s. A deposition solution was a 1 mM chloroauric acid solution. During the deposition of platinum nanoparticles, a deposition potential was −1.2 V. A deposition time of one cycle was 50 s. A deposition solution was a 1 mM chloroplatinic acid solution. The sizes of gold-platinum composite nanoparticles obtained under this process were 25-30 nm, and a gold-platinum content ratio was about 1:1. At this time, the best catalytic performance was obtained.

[0062] Step 6: Preparation of a sensor. A method was as follows. After the electrode obtained in step 5 was encapsulated, a reference electrode and a counter electrode were used together with the encapsulated electrode to form a three-electrode detection sensor for detecting dopamine concentration. The sensitivity was 208 μAcm.sup.−2mM.sup.−1. A detection limit was 0.07 μM.

Example 3

[0063] Step 1: Preparation of a boron-doped diamond film. First, a silicon wafer substrate was placed in an acetone solution. Ultrasonic cleaning was performed for 10 min to remove oil stains on a surface. Then, ultrasonic cleaning was performed in deionized water for 15 min. The silicon wafer substrate was dried in a drying furnace and then put into a chemical vapor deposition chamber for the growth of boron-doped diamond. During the growth process, the number of turns of a hot wire was 15. A temperature of the hot wire was controlled at 2,250° C. A surface temperature of the substrate was 800° C. A gas ratio was methane:borane:hydrogen=1:49:0.3. A cavity pressure was about 3.0 Kpa. A grain size of the grown diamond film was 6-8 μm is diameter. A film thickness was 10-15 μm.

[0064] Step 2: Nickel layer sputtering. A method was as follows. A physical magnetron sputtering device was used. Under an atmospheric pressure of 1 Pa, a layer of nickel film was uniformly sputtered on the diamond film in step 1 by a high-purity nickel target with a purity of 99.99%. A sputtering power was 100 W. A thickness of the nickel layer was 20-40 μm.

[0065] Step 3: High-temperature heat treatment etching in a hydrogen environment. A method was as follows. A sheet prepared in step 2 was put into a cold-wall heat treatment furnace. 60 SCCM hydrogen was introduced. An etching temperature was controlled at 800° C. An etching pressure was controlled at 15 Kpa. An etching time was 200 min.

[0066] Step 4: Removal of nickel particles. A method was as follows. The sample obtained in step 3 was encapsulated and then placed in an electrochemical workstation for anodic polarization. An anodic polarization voltage was +2.0 V. A polarization time was 180 s. An electrolyte was a 1.0 M sodium sulfate solution.

[0067] Step 5: Co-modification of nickel and copper nanoparticies. Metal nanoparticles were deposited by a square wave transition potential. The number of deposition cycles was 5. During the deposition of nickel nanoparticles, a deposition potential was −2.0 V. A deposition time was 50 s. A deposition solution was a 10 mM nickel nitrate solution. During the deposition of copper nanoparticles, a deposition potential was −1.5 V. A deposition time of one cycle was 30 s. A deposition solution was a 10 mM copper nitrate solution. The sizes of nickel-copper composite nanoparticles obtained under this process were 20-30 nm, and a nickel-copper content ratio was about 5:4. At this time, the best catalytic performance was obtained.

[0068] Step 6: Preparation of a sensor. A method was as follows, After the electrode obtained in step 5 was encapsulated, a reference electrode and a counter electrode were used together with the encapsulated electrode to form a three-electrode detection sensor.

[0069] The three-electrode detection sensor obtained in Example 3 was used for detecting glucose concentration. The sensitivity was 1,730 μAcm.sup.−2mM.sup.−1. A linear range was 0.02-8.5 mM. A detection limit was 0.005 mM. During the 30-day cycle stability test, only 5% of the response current was lost.

Comparative Example 1

[0070] Other conditions were the same as those in Example 1, except that nitric acid was used for removing nickel particles. As a result, the sp.sup.2 phase on the interface was removed, and then, a result of Comparative Example 1 for detecting glucose concentration was given.

[0071] The sensitivity of the electrode was only 566 μAcm.sup.−2mM.sup.−1. A linear range was 0.01-3.87 mM. A detection limit was 0.008 mM. During the 30-day stability test, more than 80% of the response current was lost.

Comparative Example 2

[0072] Other conditions were the same as those in Example 2, except that deposition parameters of Pt were changed by fixing deposition parameters of Au unchanged. Deposition times of one cycle were designed as 5 s, 25 s, 50 s and 75 s. Four electrodes were obtained. Through elemental analysis, Pt:Au of the four electrodes was 1:9, 3:7, 1:1 and 3:2 respectively. The electrode, Pt:Au of which was 1:1, was the electrode in Example 2.

[0073] CV detection curves of the 4 electrodes, Pt:Au of which was 1:9, 3:7, 1:1 and 3:2 respectively, in a mixed solution of 0.5 M NaOH and 1 mM glucose were shown in FIG. 3. The 4 electrodes corresponded to curves 1, 2, 4 and 3 respectively. A scanning potential range was 0.2-0.6 V, and a scanning rate was 50 mVs.sup.−1. It can be seen from the figure that when Pt:Au is 1:1 (curve 4), the catalytic activity of the obtained BDD is the highest.

Comparative Example 3

[0074] Other conditions were the same as those in Example 3, except that no etching was performed for forming a porous structure, that is, the metal nickel was repaired. Results (as shown in FIG. 4) show that the metal nickel can be successfully repaired, but the electrode was unstable due to falling off during the use.