A microalgae-based carbon nanocomposite and its preparation method and application

Abstract

The present invention relates to a microalgae-based carbon nanocomposite and its preparation method and application, belonging to the technical field of nanocomposites. The preparation method described in the present invention includes the following steps: (1) culturing microalgae in a culture medium until the logarithmic growth phase, adding a metal ion solution of 1-5 mM and continuing to culture for 10-15 days, followed by centrifugation, desalting, and freeze-drying to obtain co-cultured microalgae powder; (2) carbonizing the co-cultured microalgae powder obtained in step (1) under an inert atmosphere to obtain the microalgae-based carbon nanocomposite. The microalgae-based carbon nanocomposite NC / Me of the present invention has better catalytic effects. At the same time, co-culturing also improves the distribution state of metals inside the carbon material and enhances the conductivity. NC / Me can be used as a sensing material to manufacture high-performance electrochemical biosensors, and the electrochemical sensor constructed with NC / Me is used for the detection of biomolecules such as dopamine, obtaining a relatively wide detection range.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanocomposites, and particularly relates to a microalgae-based carbon nanocomposite, a preparation method thereof, and an application thereof. Background Art

[0002] Biosensors have been widely used in aspects such as food, pharmaceuticals, biomedicine, petrochemical industry, environmental monitoring, and clinical detection. Current research mainly focuses on developing new nanocomposites to improve sensing performances such as the sensitivity and selectivity of biomolecule detection.

[0003] Biomass carbon has characteristics such as high chemical stability, high electrical conductivity, and structural stability, and has been widely used in the field of electrochemical biosensing. Generally speaking, future efforts should be dedicated to systematically defining the relationship between material structure and sensing performance, and at the same time, referring to the applications of other carbonaceous materials (such as graphene), printing with inks containing biomass carbon on different substrate materials to construct miniaturized electrochemical sensor devices, and promoting the large-scale production of portable electrochemical sensor devices based on biomass carbon materials.

[0004] Microalgae-based biomass carbon materials are a new type of low-cost and sustainable sensing application materials. Although microalgae-based biomass carbon materials (NC) have been used to construct electrochemical biosensors, their electrocatalytic activity can be further enhanced through functional modification as a sensing material, thereby improving the sensitivity for detecting target molecules. Most current material functional modifications adopt surface modification methods such as physical mixing, resulting in uneven modification of the obtained materials. For example, modified nanoparticles and the like have agglomerated, leading to weak improvement in the performance of the sensing material.

[0005] Common algae such as Chrysochromulina parva are planktonic single-celled microalgae widely distributed in the ocean, with characteristics such as fast reproduction and small size. The most prominent feature is that the cells of Chrysochromulina parva have no cell wall and have two equal-length flagella. Due to its rich lipid production, most current research focuses on using it as a raw material for producing biofuels, and rarely uses it as a precursor for biomass carbon. Therefore, how to use microalgae to prepare carbon nanocomposites with better performance is worthy of attention. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a microalgae-based carbon nanocomposite, a preparation method thereof, and an application thereof. A method of co-culturing by adding metal ions during the microalgae culture process is adopted to achieve high-efficiency and uniform internal and external metal co-doping of the microalgae-based biomass carbon material. Thus, based on the efficient utilization of the doped metal, more reactive sites and higher catalytic activity are provided for the detection of target molecules, which is of great significance for realizing the early diagnosis of diseases caused by relevant target molecules.

[0007] The first object of the present invention is to provide a method for preparing a microalgae-based carbon nanocomposite, comprising the following steps:

[0008] (1) Cultivate microalgae in a culture medium until the logarithmic growth phase, add a metal ion solution of 1-5 mM and continue to cultivate for 10-15 days, followed by centrifugation, desalting, and freeze-drying to obtain co-cultured microalgae powder;

[0009] (2) Under an inert atmosphere, carbonize the co-cultured microalgae powder obtained in step (1) to obtain the microalgae-based carbon nanocomposite.

[0010] In one embodiment of the present invention, in step (1), the culture medium is f / 2 medium.

[0011] In one embodiment of the present invention, in step (1), the inoculation amount of microalgae in the culture medium is 5-15%; this inoculation amount is just in a relatively good state suitable for growth. If the inoculation amount is too low, the microalgae state is not good and the growth is slow; if the inoculation amount is too high, the growth is too fast and it will also affect the state of the algae.

[0012] In one embodiment of the present invention, in step (1), the microalgae is one or more of Isochrysis galbana 8701, Chlorella vulgaris, IMET-1, and Navicula minima, and the nitrogen content of the microalgae is relatively high.

[0013] In one embodiment of the present invention, in step (1), the volume ratio of the metal ion solution to the culture medium is 1:50-150.

[0014] In one embodiment of the present invention, in step (1), the rotation speed of the centrifugation is 2000 rpm - 6000 rpm. The setting of the centrifugation speed can better collect the material. If the speed is too low, the centrifugation is incomplete and the material is lost; if the speed is too high, the morphology of the microalgae will be damaged.

[0015] In one embodiment of the present invention, in step (1), the metal ion is one or more of gold ion, platinum ion, iron ion, manganese ion, copper ion, and nickel ion.

[0016] In one embodiment of the present invention, in step (2), the heating rate of the carbonization is 2 °C / min; the carbonization temperature is 600 °C - 900 °C; the carbonization time is 1.5 h - 3 h. If the carbonization temperature is too low, the carbonization is incomplete; if the temperature is too high, the structure of the carbon material will collapse and affect the doping effect of N and metals.

[0017] In one embodiment of the present invention, in step (2), the inert atmosphere is nitrogen or argon.

[0018] The second object of the present invention is to provide a microalgae-based carbon nanocomposite prepared by the method described above.

[0019] The third object of the present invention is to provide an application of the microalgae-based carbon nanocomposite described above as an electrochemical biosensor.

[0020] The technical solution of the present invention has the following advantages compared with the prior art:

[0021] (1) In the preparation method described in the present invention, due to the excellent stress resistance of microalgae, which can adapt to the environment of acid-base imbalance, biocompatible metal ions such as acidic chloroauric acid are added during the cultivation of microalgae such as Isochrysis galbana 8701 for co-cultivation, and photosynthesis is utilized to achieve the purpose of reducing and utilizing metal ions. Metal doping is carried out in-situ during the growth of microalgae. After the cultivation is completed, collection and carbonization treatment are carried out to obtain a microalgae-based carbon nanocomposite (NC / Me, Me represents metal). Compared with the traditional physical mixing modification method (more of surface modification), the metal doping in the obtained material can achieve co-doping of the inside and outside of microalgae. The metal distribution is more uniform and its particles are relatively small, which can expose more reactive centers, greatly improving the sensitivity of sensing detection. In addition, this synthesis method is more environmentally friendly and can be extended to a variety of different fields, providing new ideas for expanding its application scope.

[0022] (2) The microalgae-based carbon nanocomposite NC / Me described in the present invention has better catalytic action. At the same time, co-cultivation also improves the distribution state of metal inside the carbon material and enhances the conductivity. The NC material and Me can produce a synergistic effect. The metal element provides rich reactive sites, and nitrogen doping will accelerate the electron transfer rate, thereby promoting the active center of Me to induce the rapid electron transfer of biomolecules such as dopamine on the surface of NC, realizing the efficient catalytic oxidation reaction of biomolecules such as dopamine. NC / Me can be used as a sensing material to manufacture a high-performance electrochemical biosensor, and the electrochemical sensor constructed by NC / Me is used for the detection of biomolecules such as dopamine, obtaining a relatively wide detection range. Description of the Drawings

[0023] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in conjunction with the drawings, wherein:

[0024] Figure 1 are SEM images of NC and NC / Au in different nanoscale in Test Example 1 of the present invention; among them, A, A 1 is the SEM image of NC; B, B 1 is the SEM image of NC / Au;

[0025] Figure 2It is the distribution diagram of each element in NC / Au in Test Example 1 of the present invention; wherein, A is NC / Au; B is the element distribution diagram of C; C is the element distribution diagram of N; D is the element distribution diagram of Au;

[0026] Figure 3 It is the electrochemical response test of NC and NC / Au to dopamine in Test Example 2 of the present invention; wherein, A is the DPV response of NC and NC / Au to dopamine; B is the CV response of NC / Au to dopamine with different concentrations;

[0027] Figure 4 It is the selectivity test of NC / Au to dopamine in Test Example 2 of the present invention. Detailed implementation manners

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the examples given are not intended to limit the present invention.

[0029] In the present invention, unless otherwise specified, the formula of f / 2 medium is as follows:

[0030] (1) Accurately weigh 7.5 g of NaNO 3 and 0.5 g of NaH 2 PO 4 ·H 2 O, dissolve them separately with about 90 mL of ultrapure water, and make up the volume to 100 mL after complete dissolution, and sterilize at 121 °C under high pressure for 20 min.

[0031] (2) Prepare a mixed metal salt solution:

[0032] ① Accurately weigh 0.98 g of CuSO 4 ·5H 2 O, 0.63 g of Na 2 MoO 4 ·2H 2 O, 2.2 g of ZnSO 4 ·7H 2 O, 1.0 g of CoCl 2 ·6H 2 O and 18.0 g of MnCl 2 ·4H 2 O, and make up the volume to 100 mL with ultrapure water respectively and wait for use.

[0033] ② Weigh 0.315 g of FeCl 3 ·6H 2 O and 0.436 g of Na 2 EDTA·2H 2O was dissolved in 90 mL of ultrapure water, 1 mL of each of the 5 reagents prepared in step ① was measured and added to the mixed solution, and finally the mixed solution was made up to 100 mL with ultrapure water, sterilized at 121 °C under high pressure for 20 min, and stored in the dark.

[0034] (3) Preparation of vitamin mixture:

[0035] ① Accurately weigh 0.01 g of biotin and 0.01 g of vitamin B12, and make up to 100 mL with ultrapure water respectively for later use.

[0036] ② Weigh 0.02 g of thiamine hydrochloride and dissolve it in 90 mL. Then measure 1 mL of each of the two solutions prepared in step ① and add them thereto. Make up to 100 mL with ultrapure water, filter and sterilize with a 0.22 μm sterile filter membrane, and finally store the solution in the dark in a 4 °C refrigerator.

[0037] (4) Prepare 950 mL of filtered natural seawater, sterilize it at 110 °C under high pressure for 30 min, and add 1 mL of the NaNO 3 and NaH 2 PO 4 solution prepared in step (1), 1 mL of the mixed metal solution prepared in step (2), and 0.5 mL of the vitamin mixture prepared in step (3) thereto. Finally, make up to 1 L with sterilized seawater to obtain the f / 2 medium suitable for microalgae growth.

[0038] Example 1

[0039] A microalgae-based carbon nanocomposite and its preparation method specifically include the following steps:

[0040] (1) Cultivation and collection of microalgae and metal ions: Isochrysis galbana 8701 was inoculated into 450 mL of f / 2 medium at an inoculation amount of 10%, and 2 mM chloroauric acid solution was added during the logarithmic growth phase of the microalgae. The volume ratio of the chloroauric acid solution to the f / 2 medium was 1:100. Finally, on the 12th day of growth, the algal solution was centrifuged and collected at 4000 rpm for concentration, the seawater salt was removed, and then freeze-dried to obtain the co-cultured microalgae powder.

[0041] (2) Synthesis of NC / Au: Under an argon atmosphere, the co-cultured microalgae powder was carbonized in a tube furnace at a heating rate of 2 °C / min at 600 °C for 2 h, and the obtained solid powder was ground to obtain the microalgae-based carbon nanocomposite NC / Au.

[0042] Example 2

[0043] A microalgae-based carbon nanocomposite and its preparation method specifically include the following steps:

[0044] (1) Cultivation and collection of microalgae and metal ions: Isochrysis galbana 8701 was inoculated into 450 mL of f / 2 medium at an inoculation amount of 5%, and 1 mM chloroauric acid solution was added during the logarithmic growth phase of the microalgae. The volume ratio of the chloroauric acid solution to the f / 2 medium was 1:50. Finally, on the 10th day of growth, the algal solution was centrifuged and concentrated at 3000 rpm, desalted with seawater, and freeze-dried to obtain the co-cultured microalgae powder.

[0045] (2) Synthesis of NC / Au: Under an argon atmosphere, the co-cultured microalgae powder was carbonized in a tubular furnace at a heating rate of 2 °C / min at 600 °C for 1.5 h, and the obtained solid powder was ground to obtain the microalgae-based carbon nanocomposite NC / Au.

[0046] Example 3

[0047] A microalgae-based carbon nanocomposite and its preparation method specifically include the following steps:

[0048] (1) Cultivation and collection of microalgae and metal ions: Isochrysis galbana 8701 was inoculated into 450 mL of f / 2 medium at an inoculation amount of 15%, and 5 mM chloroauric acid solution was added during the logarithmic growth phase of the microalgae. The volume ratio of the chloroauric acid solution to the f / 2 medium was 1:150. Finally, on the 15th day of growth, the algal solution was centrifuged and concentrated at 6000 rpm, desalted with seawater, and freeze-dried to obtain the co-cultured microalgae powder.

[0049] (2) Synthesis of NC / Au: Under an argon atmosphere, the co-cultured microalgae powder was carbonized in a tubular furnace at a heating rate of 2 °C / min at 900 °C for 3 h, and the obtained solid powder was ground to obtain the microalgae-based carbon nanocomposite NC / Au.

[0050] Comparative Example 1

[0051] (1) Cultivation and collection of microalgae and metal ions: Isochrysis galbana 8701 was inoculated into 450 mL of f / 2 medium at an inoculation amount of 10%, and the algal solution was centrifuged and concentrated at 4000 rpm during the logarithmic growth phase of the microalgae, desalted with seawater, and freeze-dried to obtain the co-cultured microalgae powder.

[0052] (2) Synthesis of NC / Au: Under an argon atmosphere, the co-cultured microalgae powder was carbonized in a tubular furnace at a heating rate of 2 °C / min at 600 °C for 2 h, and the obtained solid powder was ground to obtain the microalgae-based carbon nanocomposite NC / Au.

[0053] Test Example 1

[0054] Based on Example 1 and Comparative Example 1, the morphologies of the carbon materials of directly carbonized Isochrysis galbana 8701 without doped chloroauric acid (NC) and NC / Au obtained by carbonization after co-cultivation with chloroauric acid were characterized by SEM, and the results are as Figure 1-2 shown. It can be seen from Figure 1 A that NC presented an irregular porous structure after direct carbonization without maintaining the normal spherical structure of algal cells. It can be seen from Figure 1 A 1 that the surface of NC had rich convex structures under high magnification, increasing the specific surface area of the material. It can be seen from Figure 1 B that NC / Au showed a uniformly arranged honeycomb-like pore structure, and at the same time each pore had a convex structure similar to that of NC ( Figure 1 B 1 ). It can be seen that the doping of Au element changed the microstructure of Isochrysis galbana 8701 cells, forming a uniformly arranged pore structure. It can be seen from the scanning results in Figure 2 that the distributions of C, N, and Au elements in NC / Au were very uniform, especially the distribution of Au was significantly better than that of traditional metal doping methods.

[0055] Test Example 2

[0056] Based on Example 1 and Comparative Example 1, the electrochemical properties of dopamine sensors constructed with NC and NC / Au were analyzed. NC and NC / Au were respectively used to modify the materials (5 μL 2 mg / mL) on a glassy carbon electrode through a standard three-electrode system for the test of dopamine. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to test and analyze the redox reactions occurring at the electrode interface, and the results are as Figure 3-4 shown.

[0057] It can be seen from Figure 3 that by comparing the electrochemical responses of dopamine of NC and NC / Au alone, compared with NC, NC / Au had a higher oxidation current response to dopamine ( Figure 3 A), and by testing different concentrations of dopamine, it was proved that NC / Au obtained by co-cultivation with Au had a relatively wide detection range of 5 - 800 μM for the sensing response of dopamine ( Figure 3 B).

[0058] It can be seen from Figure 4It can be seen that by testing different interferents to analyze the selectivity of NC / Au for dopamine, the detection results show that the oxidation current response to 200 μM dopamine (DA) is the highest, and there is almost no response to other interfering substances with the same concentration, such as glucose (Glu), ascorbic acid (AA), and uric acid (UA), indicating that the NC / Au material has excellent anti-interference ability.

[0059] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. Application of a microalgae-based carbon nanocomposite as an electrochemical biosensor in dopamine detection, Characterized in that, The preparation method of the microalgae-based carbon nanocomposite comprises the following steps, (1) Culturing microalgae in a medium until the logarithmic growth phase, adding a metal ion solution of 1-5 mM and continuing to culture for 10-15 days, followed by centrifugation, desalting, and freeze-drying to obtain co-cultured microalgae powder; the microalgae is one or more of Isochrysis galbana 8701, Chlorella vulgaris, IMET-1, and Navicula minima; the metal ion is one or more of gold ion, platinum ion, iron ion, manganese ion, copper ion, and nickel ion; (2) Under an inert atmosphere, carbonizing the co-cultured microalgae powder obtained in step (1) to obtain the microalgae-based carbon nanocomposite.

2. The application according to claim 1, Characterized in that, In step (1), the medium is f / 2 medium.

3. The application according to claim 1, Characterized in that, In step (1), the inoculation amount of microalgae in the medium is 5-15%.

4. The application according to claim 1, Characterized in that, In step (1), the volume ratio of the metal ion solution to the medium is 1:50-150.

5. The application according to claim 1, Characterized in that, In step (1), the rotation speed of the centrifugation is 2000 rpm - 6000 rpm.

6. The application according to claim 1, Characterized in that, In step (2), the heating rate of the carbonization is 2 °C / min; the temperature of the carbonization is 600 °C - 900 °C; the time of the carbonization is 1.5 h - 3 h.

7. The application according to claim 1, Characterized in that, In step (2), the inert atmosphere is nitrogen or argon.

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