CN111326743A - Application of porous carbon derived from bamboo as electrode material for glucose biosensing and glucose biofuel cell - Google Patents

Abstract

The invention discloses the application of bamboo-derived porous carbon as electrode material for glucose biosensing and glucose biofuel cells. Among them, the composite material of glucose oxidase loaded on bamboo-derived porous carbon can be used to prepare grape-like biosensors and biofuel cells, and has great potential in the field of glucose detection and electrochemistry.

Description

Bamboo-derived porous carbon as electrode material for glucose biosensing and glucose biofuel cell applications

technical field

The present invention relates to the field of biomass materials, in particular, the present invention relates to the application of porous carbon derived from bamboo as an electrode material for glucose biosensing and glucose biofuel cells.

Background technique

Glucose oxidase (GOx) is an important dimeric protein composed of two identical 80-kda subunits. Two flavin adenine dinucleotide (FAD) cofactors are tightly bound and deeply embedded in the protein. GOx can specifically catalyze β-D-glucose to D-gluconolactone, so it has been widely used in the construction of glucose biosensors and enzymatic biofuel cells, as well as in the pharmaceutical and food industries. During GOx-catalyzed glucose oxidation, the cofactor FAD acts as an electron acceptor and is reduced to FADH ₂ . Then, oxygen acts as the final electron acceptor to oxidize FADH to FAD, while reducing oxygen to _hydrogen peroxide. However, it is rather difficult to show the direct electron transfer behavior between GOx and bare electrodes. This may be due to the fact that the electroactive centers of GOx are buried in the molecular cavity, resulting in a large electron transport resistance.

Fortunately, the large surface area and unique electrical properties of nanomaterials can shorten the tunneling distance of electrons, thus providing electron relay function. To date, different nanomaterials including conducting polymers, metal oxides and carbon nanomaterials have demonstrated the ability to enhance electron transport rates. Among them, carbon nanomaterials, especially those used for graphene and carbon nanotubes (CNTs), have good compatibility, high electrical conductivity, wide potential window, and chemical inertness, thus attracting interest in immobilizing enzymes and promoting Electronic transfer concerns. Although these reports demonstrate the potential of these nanomaterials in electroanalysis, there are still some drawbacks to consider. Relatively expensive and harmful chemicals, complex equipment, and complex synthetic procedures may hinder their widespread commercialization in electrochemical analysis.

SUMMARY OF THE INVENTION

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an object of the present invention is to propose the application of porous carbon derived from bamboo as electrode material for glucose biosensing and glucose biofuel cells. Glucose oxidase-loaded composites on bamboo-derived porous carbon can be used to prepare grape-like biosensors and biofuel cells, and have great potential in the field of glucose detection and electrochemistry.

In one aspect of the present invention, the present invention proposes a composite material. According to an embodiment of the present invention, the composite material includes: bamboo-derived porous carbon (B-dPC); and glucose oxidase (GO _X ), the glucose oxidase being supported on the bamboo-derived porous carbon. In this composite material, bamboo-derived porous carbon is obtained by carbonization and pyrolysis of bamboo (Phyllostachys), which is widely available, cheap and easy to obtain, and contains abundant defect sites, which can be used as an excellent immobilized enzyme carrier material for electrolysis. Chemical glucose sensors and biofuel cell (BFC) applications. GO _X immobilized on B-dPC can exhibit efficient direct electron transfer behavior, showing high sensitivity, wide linear range, and low detection limit for glucose detection; B-dPC-assembled glucose/O ₂ BFC can generate high power density and open circuit potential, and can directly harvest energy from sugar solutions.

In addition, the composite material according to the above embodiments of the present invention may also have the following additional technical features:

According to an embodiment of the present invention, the composite material shown further includes: a cross-linking agent and a stabilizer.

According to an embodiment of the present invention, the crosslinking agent is glutaraldehyde (GA).

According to an embodiment of the present invention, the stabilizer is a Nafion polymer.

In another aspect of the present invention, the present invention provides a method for preparing the composite material of the above-mentioned embodiments. According to an embodiment of the present invention, the method includes: (1) carbonizing bamboo in an inert gas atmosphere to obtain a carbonized material; after pickling the carbonized material, performing a pyrolysis treatment to obtain bamboo-derived porous carbon; (2) mixing the bamboo-derived porous carbon with a solvent to obtain a bamboo-derived porous carbon dispersion; applying the bamboo-derived porous carbon dispersion to the surface of the substrate, then removing the solvent in the bamboo-derived porous carbon dispersion, forming a porous carbon carrier layer; (3) mixing glucose oxidase with a buffer to obtain a glucose oxidase dispersion; applying the glucose oxidase dispersion to the porous carbon carrier layer to form an active component layer; (4) ) applying a cross-linking agent solution to the active component layer, and then removing the solvent in the cross-linking agent solution; (5) applying a stabilizer solution to the active component layer to obtain the composite material. The method is simple and efficient, easy to implement industrially, and the prepared composite material has great potential in the field of glucose detection and electrochemistry.

In addition, the method for preparing a composite material according to the above embodiments of the present invention may also have the following additional technical features:

According to an embodiment of the present invention, the carbonization treatment may be performed at 700-900°C. Specifically, before the bamboo is carbonized, the bamboo can be washed and cut into small strips, and dried at 40-70° C. for 10-14 hours, and then carbonized. The temperature of the carbonization treatment can be 700° C., 750° C. °C, 800 °C, 850 °C, 900 °C, etc., the heating rate can be 5 °C·min ^-1 .

According to the embodiment of the present invention, the pickling treatment can be completed by using hydrochloric acid at 70-85° C. for 10-15 hours. Specifically, the temperature can be 70°C, 75°C, 80°C, 75°C, etc., the processing time can be 10h, 12h, 14h, 15h, etc., and the concentration of hydrochloric acid can be 3M, so that inorganic impurities in the material can be effectively removed. .

According to an embodiment of the present invention, the pyrolysis treatment can be completed at 1500-1700° C. for 1-3 hours. The temperature of the pyrolysis treatment can be 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, etc., the heating rate can be 5°C·min ^-1 , and the pyrolysis time can be 1h, 2h, 3h, etc.

According to an embodiment of the present invention, the concentration of the bamboo-derived porous carbon dispersion liquid is 10-30 mg·mL ^-1 .

According to an embodiment of the present invention, the concentration of the glucose oxidase dispersion liquid is 20-40 mg·mL ^-1 .

According to an embodiment of the present invention, the volume ratio of the bamboo-derived porous carbon dispersion liquid to the glucose oxidase dispersion liquid is (2-4):1. Thereby, the loading effect of glucose oxidase on the bamboo-derived porous carbon can be further improved, thereby further improving the performance of the obtained composite material.

In another aspect of the present invention, the present invention provides a glucose biosensor. According to an embodiment of the present invention, the glucose biosensor includes: an electrode substrate; the composite material of the above-mentioned embodiments, the composite material is formed on the electrode substrate. The glucose biosensor has a high sensitivity of 42.9 μA·mM ^-1 ·cm ^-2 , a wide linear range of 0.01 to 3.86 mM, and a low detection limit of 1.2 μM, showing great glucose detection in medical glucose injections and sugar-sweetened soft drinks possibility.

In addition, the glucose biosensor according to the above embodiments of the present invention may also have the following additional technical features:

According to an embodiment of the present invention, the electrode substrate is a glassy carbon electrode (GCE).

In another aspect of the present invention, the present invention provides a biofuel cell. According to an embodiment of the present invention, the biofuel cell includes: a bioanode and a biocathode, wherein the bioanode includes a current collector and an anode active component, and the anode active component is the composite material of the above embodiment; the The biocathode includes a current collector and a cathode active component including bamboo-derived porous carbon and laccase, the laccase being supported on the bamboo-derived porous carbon. The biofuel cell can generate a high power output of 192 μW cm ^-2 and an open-circuit potential of 0.76 V, which can directly harvest energy from different sugar-sweetened soft drinks.

In addition, the glucose biosensor according to the above embodiments of the present invention may also have the following additional technical features:

According to an embodiment of the present invention, the current collector is nickel foam.

According to an embodiment of the present invention, the cathode active component further includes: a stabilizer.

According to an embodiment of the present invention, the stabilizer is a Nafion polymer.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

Figure 1 shows the characterization results of bamboo-derived porous carbon (B-dPC), wherein A is the SEM image of B-dPC; B is the TEM image of B-dPC; C is the XRD pattern of B-dPC; D is the B-dPC Raman spectrum of dPC, E is XPS spectrum of B-dPC, inset is O1s spectrum of B-dPC; F is FT-IR spectrum of B-dPC;

Figure 2 is a graph of the electrochemical activity test results of B-dPC/GCE, wherein, A is GCE (a) and B-dPC/GCE (b) in 5 mM K ₃ [Fe(CN) ₆ containing 0.1 M KCl Cyclic voltammogram (CV) of , scan rate: 10mV s-1; B is GCE(c) and B _- ^dPC /GCE( Nyquist plot at d);

Figure 3 is the direct electrochemical test result of glucose oxidase (GOx) on B-dPC/GCE electrode, where A is Nafion/GA/GCE(a), Nafion/GA/GOx/GCE(b), Nafion/ CV of GA/B-dPC/GCE (c) and Nafion/GA/GOx/B-dPC/GCE (d) in Ar-saturated 0.1 M pH 7.0 PBS at 50 mV s ^-1 ; B is Nafion/GA/GOx CV of /B-dPC/GCE in Ar-saturated 0.1M PBS (pH 7.0) with scan rates from 50mV·s ^-1 to 600mV·s ^-1 ; C is the relationship between current and scan rate; D is E The relationship between _p and Ln v; E is the CV of Nafion/GA/GOx/B-dPC/GCE in Ar-saturated 0.1 M PBS at various pH values; F is the correlation of E'0 to the pH value of the electrolyte curve;

Figure 4 is a graph of the characterization results of the glucose biosensor, where A is the CV of Nafion/GA/GOx/B-dPC/GCE in Ar(a) and air-saturated (b) 0.1M pH 7.0PBS, scan rate: 50mV s ⁻¹ ; (B) is the CV of Nafion/GA/GOx/B-dPC/GCE in 0.1 M pH 7.0 PBS in the absence (d) and in the presence (c) of 10 mM glucose; C is Current response to continuous addition of GLU at Nafion/GA/GOx/B-dPC/GCE; D is the calibration curve of GLU at Nafion/GA/GOx/B-dPC/GCE, inset: Lineweaver-Burk type plot for Electrochemical determination of apparent Michaelis-Menten constants for Nafion/GA/GOx/B-dPC/GCE; E is at Nafion/GA/GOx/B-dPC/GCE for successive additions of 1.0 mM GLU, 0.1 mM DA, 0.1 mM Amperometric responses of UA, 0.1 mM AA, 0.1 mM L-cys and 0.1 mM APAP; F is the amperometric response stability to 0.5 mM GLU on Nafion/GA/GOx/B-dPC/GCE; panels C, E and F Electrolyte in: 0.1 M pH 7.0 PBS, applied potential for panels C, E and F: -0.45 V;

Figure ₅ is the test results of electrochemical reduction of O on B-dPC-based biocathode, where A is the Nafion/Lac/B-dPC/GCE biocathode in the absence of ABTS (a) and in the presence of 0.5 mM ABTS (b) CV curves of Ar-saturated 0.04M BR solution (pH 5.0) and Nafion/Lac/B-dPC/GCE biocathode in O _- saturated 0.04MB-R solution (pH 5.0) with 0.5 mM ABTS CV curves (c); B shows the schematic diagram and working mechanism of the designed BFC; C shows the dependence of power density on cell voltage; D shows the stability of the power output of the BFC in continuous operation at +0.51V;

Figure 6 is a graph of the energy output of a B-dPC based glucose/O ₂ biofuel cell (BFC), where A is orange juice and B is Coca-Cola.

Detailed ways

Embodiments of the present invention are described in detail below. The embodiments described below are exemplary, only for explaining the present invention, and should not be construed as limiting the present invention. If no specific technique or condition is indicated in the examples, the technique or condition described in the literature in the field or the product specification is used. The reagents or instruments used without the manufacturer's indication are conventional products that can be obtained from the market.

In the present invention, bamboo (Phyllostachys) was obtained in Beijing, China. The sodas with fruit orange and Coca-Cola brands were purchased from China Coca-Cola Co., Ltd. Commercially available glucose injection was purchased from Jilin Huamu Animal Health Products Co., Ltd. (China). Glucose oxidase (GOx, EC 1.1.3.4, initial activity: 200 U·mg ⁻¹ ) was purchased from Sigma-Aldrich. Ascorbic acid (AA), N,N-dimethylformamide (DMF) and uric acid (UA) were purchased from Sinopharm Holding Chemical Reagent Co., Ltd. Nafion solution (5 wt.% in a 15-20% mixture of lower aliphatic alcohols and water), 2,2'-azidobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Glutaraldehyde (GA, 50%), acetaminophen (APAP), dopamine (DA) and cysteine (L-cys) were obtained from Aladdin. Nickel foam was purchased from the source of independence. Anhydrous α-D-(+)-glucose was purchased from Acros Organics. Nafion 117 membrane and laccase (Lac, >4.0 U·mg ⁻¹ ) were purchased from Alfa-Aesar. All reagents are of analytical reagent grade and can be used directly without further purification.

In the present invention, cyclic voltammetry (CV), amperometric and linear sweep voltammetry (LSV) were performed on a CHI 660C electrochemical workstation (Chenhua Instrument Co., Ltd., China). Electrochemical measurements were performed using a standard three-electrode configuration consisting of a glassy carbon electrode (GCE), a platinum sheet, and an Ag/AgCl (saturated KCl) electrode as auxiliary and auxiliary electrodes, respectively. Raman spectra were provided on a WITec CRM200 instrument using a 532 nm laser. X-ray photoelectron spectroscopy (XPS) data were collected using a Thermo Scientific Escalab 250 spectrometer. Diffraction data were provided by a PANalytical X'pert Pro X-ray diffractometer. SEM images were obtained using a JSM-6701 field emission scanning electron microscope (SEM). The Micromeritics ASAP2020HD analyzer provides nitrogen adsorption-desorption data. Fourier Transform Infrared (FT-IR) spectra were obtained on a Spectrum 100 FT-IR obtained from Perkin Elmer.

Example 1

Preparation of Bamboo-derived Porous Carbon (B-dPC)

First, fresh bamboo was rinsed with deionized water, cut into strips of appropriate size (about 3×1×0.5 cm ³ ), and then dried in an oven (60° C.) for 12 h. After carbonization of dried bamboo in a tube furnace at 800°C (5°C·min ^-1 ) in Ar atmosphere, the obtained product was thoroughly treated with HCl (3M) at 80°C for 12h to remove inorganic impurities. Finally, the dried samples were transferred to a tube furnace again and pyrolyzed at 1600 °C for 2 h at 5 °C min ^-1 in an Ar atmosphere. The final product is denoted B-dPC.

Example 2

Preparation of glucose biosensors

(1) Polish GCE on a polishing cloth with 0.05 μm alumina powder. After successive sonication in dilute nitric acid solution, ethanol, and deionized water, the cleaned electrodes were air-dried. A homogeneous dispersion (20 mg·mL ^-1 ) was prepared by dissolving 20 mg of B-dPC in 1 mL of DMF by sonication. Afterwards, 6 μL of the dispersion was applied onto the cleaned GCE. After evaporation of the solvent under infrared light, B-dPC/GCE was obtained.

(2) 2 μL of GOx solution (31.8 mg·mL ⁻¹ , prepared by 0.1 M pH 7.2 PBS) was modified to B-dPC/GCE (denoted as GOx/B-dPC/GCE). To crosslink GOx onto B-dPC/GCE, 3 μL of GA solution (0.5% (w/v) in deionized water) was further spread on the surface of GOx/B-dPC/GCE (denoted as GA/GOx /B-dPC/GCE). Let the product dry naturally for 2 hours. Finally, 2 μL of 0.5 wt. % Nafion solution was uniformly dispersed on the electrode surface to maintain its stability (denoted as Nafion/GA/GOx/B-dPC/GCE).

For comparison, Nafion/GA/GCE, Nafion/GA/GOx/GCE and Nafion/GA/B-dPC/GCE were prepared in a similar manner.

Example 3

Preparation of Biofuel Cells

Preparation of glucose/O BFC in _two compartments separated by Nafion 117 membrane using Nafion/GA/GOx/B-dPC/Ni foam as bioanode and Nafion/Lac/B-dPC/Ni foam as biocathode . The bioanode was immersed in 0.1 M pH 5.0 PBS containing 10 mM glucose, and a 0.04 M pH 5.0 Britton-Robinson (BR) solution saturated with _0.5 mM ABTS in O was used as the catholyte. The performance of the glucose/O ₂ BFC was evaluated by a two-electrode LSV test (2 mV s ⁻¹ ).

Nickel foam treated with acetone and 3M HCl as current collectors for the preparation of bioanode and biocathode for biofuel cells (BFCs).

To prepare the bioanode, 100 μL of the B-dPC suspension was spread on the pretreated Ni foam (denoted as B-dPC/Ni foam). After drying under infrared light, 30 μL of GOx solution was pipetted onto the surface of the B-dPC/Ni foam. Then, 50 μL of GA solution was further modified on the surface of GOx/B-dPC/Ni foam and dried in air for 2 h. Finally, 30 μL of Nafion solution was dropped on the surface and air-dried (denoted as Nafion/GA/GOx/B-dPC/Ni foam).

To prepare the biocathode, similarly, 100 μL of the B-dPC suspension was slowly spread on the surface of Ni foam and dried under infrared light irradiation (denoted as B-dPC/Ni foam). Then, 50 μL of Lac solution (20 mg·mL ⁻¹ , prepared by 0.04 M pH 5.0 BR) was spread on the surface of B-dPC/Ni foam, and the electrode was dried at room temperature for 2 h (denoted as Lac/B-dPC/Ni foam ). Finally, the electrodes were coated with 30 μL of Nafion solution and dried at room temperature (denoted as Nafion/Lac/B-dPC/Ni foam).

Test Example 1

Characterization of Bamboo-Derived Porous Carbon (B-dPC)

和

附近有两个特征峰，分别归因于石墨的(002)和(100)平面。进一步确定拉曼光谱法以获得B-dPC的结构和拓扑信息。在图1D中，B-dPC的拉曼光谱揭示了D(位于

处)和G波段(位于

处)的存在，这是由于sp²域中的晶格畸变和E_2g的振动模式分别为sp² C＝C键。此外，D波段与G波段的强度比(I_D/I_G)可以反映结构缺陷的程度。B-dPC的I_D/I_G比经计算为1.27，高于中孔碳(0.700)和碳纳米管(0.74)。这表明B-dPC含有高密度的缺陷位点，这可能会改善电化学活性。The morphological observation of B-dPC was first verified using scanning electron microscopy (SEM). In Figure 1A, B-dPC maintains the vascular bundle structure of bamboo, which may be beneficial for electrolyte transport. Pores of about 1 μm in size were found in the cross section of B-dPC and were neatly arranged (Fig. 1A inset). The pores of B-dPC were further characterized by transmission electron microscopy (TEM) measurements, as shown in Figure 1B. To reveal the structural information of B-dPC, the nanomaterials were characterized by X-ray diffraction (XRD) (Fig. 1C). exist

and

There are two characteristic peaks nearby, which are attributed to the (002) and (100) planes of graphite, respectively. Raman spectroscopy was further determined to obtain the structural and topological information of B-dPC. In Figure 1D, the Raman spectrum of B-dPC revealed that D (located at

) and G-band (located at

), which is due to the lattice distortion in the sp ² domain and the vibrational mode of E _2g for the sp ² C=C bond, respectively. In addition, the intensity ratio of _D -band to _G -band (ID /IG ) can reflect the degree of structural defects. The ID/IG ratio of _B - _dPC was calculated to be 1.27, which was higher than that of mesoporous carbon (0.700) and carbon nanotubes (0.74). This suggests that B-dPC contains a high density of defect sites, which may improve the electrochemical activity.

Test case 2

Electrochemical activity

The electrochemical activity of B-dPC-modified GCE (B-dPC/GCE) was first examined by cyclic voltammetry (using ₅ mM K3[Fe(CN) ₆ ] containing 0.1 M KCl) (Fig. 2A). The well-defined redox peaks (b) observed on B-dPC/GCE have a lower peak-to-peak spacing (ΔEp) than GCE (78 mV, a), suggesting that B-dPC/GCE has a better electron transfer compared to GCE faster. According to the Randles–Sevcik equation, B-dPC/GCE has a larger electroactive area of 0.096 cm ² compared to GCE of 0.075 cm ² . To better understand the electron transfer ability of B-dPC/GCE, electrochemical impedance spectroscopy (EIS) was used to estimate the charge transfer resistance (Rct) of different electrodes. The Rct value is equal to the diameter of the semicircular portion of the EIS curve. As shown in Figure 2B, the Rct value of B-dPC/GCE (69.2 Ω, d) is lower than that of GCE (314.3 Ω, c), which means that B-dPC promotes the electron transfer between the electrolyte and GCE.

Test case 3

Direct Electrochemistry of Glucose Oxidase (GOx) on B-dPC/GCE Electrode

The direct electrochemical behavior of GOx on Nafion/GA/GOx/B-dPC/GCE was investigated by cyclic voltammetry. Figure 3A shows Nafion/GA/GCE (a), Nafion/GA/GOx/GCE (b), Nafion/GA/B-dPC/GCE (c) and Nafion/GA/GOx/B-dPC/GCE (d ) Cyclic voltammogram (CV) in Ar-saturated 0.1 M pH 7.0 phosphate buffer solution (PBS) at a scan rate of 50 mV·s ⁻¹ . Obviously, the CVs of Nafion/GA/GCE, Nafion/GA/GOx/GCE and Nafion/GA/B-dPC/GCE are only square due to the presence of double layer capacitance. Compared with Nafion/GA/GCE and Nafion/GA/GOx/GCE, the CV background current of Nafion/GA/B-dPC/GCE is significantly larger, which suggests that the use of high surface area B-dPC can facilitate its increase. No redox peaks were observed on the three electrodes, indicating that these electrodes are electrochemically inert. In contrast, Nafion/GA/GOx/B-dPC/GCE showed a pair of prominent redox peaks with a formal potential of -0.458 V, which was in line with the previously reported redox center of FAD/FADH ₂ at pH 7.0. The data are close. The results clearly demonstrate the direct electron transfer (DET) capability of GOx on Nafion/GA/GOx/B-dPC/GCE. Furthermore, the peak-to-peak interval of Nafion/GA/GOx/B-dPC/GCE is 36 mV, and the cathodic peak current is approximately equal to the anodic current, which indicates that GOx immobilization on Nafion/GA/GOx/B-dPC/GCE undergoes a quasi-reversible Electrochemical process.

To further evaluate the DET properties of GOx on Nafion/GA/GOx/B-dPC/GCE, the effect of scan rate on the voltammetric response was investigated. As shown in Fig. 3B, Nafion/GA/GOx/B-dPC/GCE showed clear DET characteristics at scan rates from 50 to 600 mV s ^-1 . The redox peak current is linearly related to the scan rate (Fig. 3C), indicating that the electrochemical reaction of GOx is a surface-confined process. In Figure 3D, the cathodic and anodic peak potentials of Nafion/GA/GOx/B-dPC/GCE are slightly shifted in the negative and positive directions, respectively. At scan rates higher than 150 mV·s ^-1 , the peak potential was linearly related to the logarithm of the scan rate, and the slope of the potential with respect to lnν was equal to RT/(1-α)nF and -RT/αnF. Based on this, α can be calculated to be 0.49. The electron transport rate constant (ks) of GOx at Nafion/GOx/B-dPC/GCE was calculated to be 5.43 s ⁻¹ by means of the Laviron equation for the surface control process. This value is significantly larger than previously reported values for GOx immobilized on pCoTTP-SWNTs/GCE (1.01s ^-1 ), graphene/SWCNT cogel electrodes (0.23s ^-1 ), and AuNPs-MWCNTs-PVA films (2.2s ^-1 ), GCE/RGO (4.8s ^-1 ) and porous TiO ₂ electrodes (3.96s ^-1 ). This means that B-dPC can greatly facilitate the electron transfer between GOx and electrodes. The DET of GOx is a 2-proton and 2-electron transfer process, so the DET properties will be affected by the buffer pH. As follows:

Figure 3E shows the CV of Nafion/GA/GOx/B-dPC/GCE in Ar-saturated 0.1 M PBS with different pH values. As shown, the electrode displayed a pair of well-defined GOx redox peaks in each buffer. Furthermore, increasing buffer pH from 5.0 to 9.0 resulted in negative shifts in both the cathodic and anodic peaks. Furthermore, as shown in Figure 3F, the formal potential was found to be linearly related to buffer pH with a slope of -57.1 mV/pH. This slope is close to the theoretical Nernsteng value of -58.6mV/pH, indicating that the two-proton-coupled two-electron process is involved in the electrochemical process of GOx.

Test Example 4

Glucose biosensors are very important in clinical diagnostics and biotechnology applications. Nafion/GA/GOx/B-dPC/GCE can be considered as an excellent candidate for fabricating highly sensitive and selective biosensors due to the advantages of relatively negative redox potential (-0.458 V, pH 7.0) and enhanced electron transfer ability. favorable electrode. Figure 4A compares the CV of Nafion/GA/GOx/B-dPC/GCE in Ar- (curve a) and air-saturated (curve b) 0.1 M pH 7.0 PBS at 50 mV s ⁻¹ . As shown, a larger reduction peak current and a lower oxidation peak current can be found in the air-saturated solution compared to that in the Ar-saturated solution. The results may be attributed to the fact that the reductase (GOx-FADH ₂ ) on the electrode can be rapidly oxidized by oxygen in an air-saturated solution as follows:

GOx-FADH ₂ +O ₂ →GOx-FAD+H ₂ O ₂

Notably, the catalytic regeneration of GOx to the oxidized form (GOx-FAD) resulted in a loss of curve reversibility. Furthermore, the addition of 10 mM glucose to the air-saturated solution resulted in a decrease in the reduction peak current of Nafion/GA/GOx/B-dPC/GCE (Fig. 4B, where curves c and d are in the presence and absence of 10 mM glucose, respectively). Bottom, CV of Nafion/GA/GOx/B-dPC/GCE in 0.1M pH7.0 PBS). This can be explained by the occurrence of enzymatic catalysis. According to the equation, the reaction between GOx-FAD and glucose is as follows:

Glucose+GOx-FAD→Gluconolactone+GOx-FADH ₂

Based on the excellent electrochemical performance of Nafion/GA/GOx/B-dPC/GCE in the electro-oxidation of glucose, the biosensing of Nafion/GA/GOx/B-dPC/GCE for glucose was evaluated by amperometric method at -0.45 V application. Figure 4C shows the current-time curves for different glucose concentrations in magnetically stirred air-saturated 0.1 M pH 7.0 PBS under Nafion/GA/GOx/B-dPC/GCE. As shown, a clear response was found with each glucose injection. The calibration curve depicted in Figure 4D exhibited a linear range of 0.01 to 3.86 mM (R ² =0.996) with a sensitivity of 42.9 μA mM ⁻¹ cm ⁻² and a detection limit of 1.2 μM (S/N=3). The apparent Michaelis-Menten constant (Km,app) determined as an indicator of the kinetics of the enzyme substrate reaction was 1.7 mM according to the Lineweaver-Burk plot (inset of Figure 4D). The Km,app values were significantly smaller than those of GOx/SWC nanohorn (8.5mM) and GOx/Pt@MZF-1 (6.1mM). Smaller Km,app values indicate that Nafion/GA/GOx/B-dPC/GCE has a significant affinity for glucose.

Nafion/GA/GOx/B-dPC/GCE also has high selectivity for glucose detection. As shown in Figure 4E, 0.1 mM interfering agents such as uric acid (UA), ascorbic acid (AA), dopamine (DA), acetaminophen (APAP), and L-cysteine (L-cys) were injected into the electrolytes The current changes were negligible, while significant current changes were observed with the addition of 1.0 mM glucose. To evaluate its antifouling ability, the antifouling ability of Nafion/GA/GOx/B-dPC/GCE was determined by evaluating the current temporal response to 0.5 mM glucose. As shown in Fig. 4F, the current response at Nafion/GA/GOx/B-dPC/GCE still maintains 95.3% of the initial response after 10000 s, which indicates that the antifouling ability of Nafion/GA/GOx/B-dPC/GCE is very good high. Furthermore, the current response of Nafion/GA/GOx/B-dPC/GCE to 1 mM glucose after 2 weeks of storage at 4 °C was still 96.9% of its original response, indicating a long shelf life. Reproducibility was also investigated by measuring the current response to 0.5 mM glucose at five Nafion/GA/GOx/B-dPC/GCEs. The relative standard deviation was determined to be 1.8%, which indicates the excellent reproducibility of Nafion/GA/GOx/B-dPC/GCE. The high-performance glucose detection capability of Nafion/GA/GOx/B-dPC/GCE makes it have great potential for the determination of glucose content in real samples. The glucose content in commercial glucose injections and soft drinks was analyzed using Nafion/GA/GOx/B-dPC/GCE using standard addition methods, and the analysis results are listed in Table 1. The recoveries were between 95.8% and 103.1%, indicating that Nafion/GA/GOx/B-dPC/GCE has great potential for sensitive and practical glucose determination. In particular, the glucose concentrations in commercial glucose injections measured by Nafion/GA/GOx/B-dPC/GCE were in good agreement with the concentrations provided by the company, indicating that the glucose concentration in Nafion/GA/GOx/B-dPC/GCE The detection accuracy is very high.

Table 1. Detection of glucose in real samples

Test Example 5

Electrochemical reduction of O _on B-dPC-based biocathode

Considering that DET between the active center of laccase (Lac) and the electrode is difficult to achieve due to the strict enzyme orientation and relatively complex reaction mechanism, 2,2'-azidobis(3-ethylbenzothiazole) was used. Phytoline-(6-sulfonic acid) (ABTS) mediates electron transfer between Lac and the electrode. Figure 5A shows CVs recorded in Nafion/Lac/B-dPC/GCE with Ar saturation with 0.5 mM ABTS (b ) and oxygen saturation (c) 0.04 M pH 5.0 Britton-Robinson (BR) solution. For comparison, the current response of the biocathode in Ar-saturated solution in the absence of ABTS was investigated (a). As shown in Fig. show that when the electrolyte is saturated with Ar, a distinct pair of redox peaks exists only in the presence of ABTS (b), which is a representative electrocatalytic property of ABTS. In an O saturated solution containing _0.5 mM ABTS (c) , a higher reduction current can be found than the Ar-saturated solution (b). This suggests that the electron transfer between the redox site of Lac and the electrode can be mediated by ABTS.

Test Example 6

Performance of the assembled B-dPC _- based glucose/O biofuel cell (BFC)

As mentioned above, Nafion/Lac/B-dPC/GCE and Nafion/GA/GOx/B- _dPC /GCE showed excellent electrochemical activities for O reduction and glucose oxidation, respectively. These advantages make B-dPC an ideal choice for the construction of high-performance glucose/O ₂ BFCs. The BFC is composed of Nafion/GA/GOx/B-dPC/Ni foam bioanode and Nafion/Lac/B-dPC/Ni foam biocathode. Figure 5B shows a schematic diagram of a glucose/O ₂ BFC equipped with a B-dPC electrode. Figure 5C shows the power output density versus cell voltage (PV curve) of the assembled BFC. As expected, the open-circuit voltage and maximum power density of the assembled BFC at 0.51 V were 0.76 V and 193 μW·cm ⁻² , respectively. After the BFC was continuously discharged for 12 h at room temperature, it retained 73.8% of its initial power, which indicated that the assembled BFC was relatively stable (Fig. 5D). In addition, the ability of the assembled BFCs to harvest energy from commercial soft drinks was further investigated. Glucose-enriched soft drinks are considered suitable fuels for glucose/O ₂ BFC due to their green, available and low-cost properties. Figures 6A-B show power-voltage curves using a mixture of soft drink and 0.1M PBS (pH 5.0) in a ratio of 1:4 (v:v) as fuel. If orange juice or Coca-Cola are used as fuel, the OCP of BFC is almost the same, and the maximum power density of BFC is 96.2 or 113.7 μW·cm ⁻² , respectively. The excellent power output of replacing soft drinks with glucose can be explained by the relatively high glucose levels and complex composition. Therefore, BFCs equipped with B-dPC can directly generate energy from commercial soft drinks.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. a composite material, is characterized in that, comprises: Bamboo-derived porous carbon; Glucose oxidase supported on the bamboo-derived porous carbon. 2. The composite material according to claim 1, further comprising: a crosslinking agent and a stabilizer; Optionally, the crosslinking agent is glutaraldehyde; Optionally, the stabilizer is a Nafion polymer. 3. A method of preparing the composite material of claim 1 or 2, characterized in that, comprising: (1) Bamboo is carbonized in an inert gas atmosphere to obtain a carbonized material; after the carbonized material is acid-washed, a pyrolysis treatment is performed to obtain the bamboo-derived porous carbon; (2) mixing the bamboo-derived porous carbon with a solvent to obtain a bamboo-derived porous carbon dispersion; applying the bamboo-derived porous carbon dispersion to the surface of the substrate, then removing the solvent in the bamboo-derived porous carbon dispersion, forming a porous carbon support layer; (3) mixing glucose oxidase with a buffer to obtain a glucose oxidase dispersion; applying the glucose oxidase dispersion to the porous carbon carrier layer to form an active component layer; (4) applying a cross-linking agent solution to the active component layer, and then removing the solvent in the cross-linking agent solution; (5) A stabilizer solution is applied to the active component layer to obtain the composite material. 4. The method according to claim 3, wherein the carbonization treatment is carried out at 700-900°C; Optionally, the pickling treatment is performed with hydrochloric acid at 70-85° C. for 10-15 h; Optionally, the pyrolysis treatment is completed at 1500-1700° C. for 1-3 h. 5. The method according to claim 3, wherein the concentration of the bamboo-derived porous carbon dispersion liquid is 10-30 mg·mL ^-1 ; Optionally, the concentration of the glucose oxidase dispersion liquid is 20˜40 mg·mL ⁻¹ . 6 . The method according to claim 3 , wherein the volume ratio of the bamboo-derived porous carbon dispersion liquid to the glucose oxidase dispersion liquid is (2-4):1. 7 . 7. A glucose biosensor, comprising: electrode substrate; The composite material of claim 1 or 2, which is formed on the electrode substrate. 8. The glucose biosensor according to claim 1, wherein the electrode substrate is a glassy carbon electrode. 9. A biofuel cell, comprising: a bioanode and a biocathode, wherein, The biological anode comprises a current collector and an anode active component, and the anode active component is the composite material according to claim 1 or 2; The biocathode includes a current collector and a cathode active component, the cathode active component includes bamboo-derived porous carbon and laccase, the laccase is supported on the bamboo-derived porous carbon. 10. The biofuel cell according to claim 9, wherein the current collector is nickel foam; Optionally, the cathode active component further comprises: a stabilizer; Optionally, the stabilizer is a Nafion polymer.

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