NL2026560A - Composite material of magnetic mycelium sphere loaded with reduced graphene oxide and preparation method thereof - Google Patents

Abstract

The disclosed is a composite material of magnetic mycelium spheres loaded with reduced graphene oxide and a preparation method thereof. The composite material is of a microsphere structure, and includes aspergl'llus flavus mycelium spheres that are formed by winding of an aspergillus flavus mycelia and are loaded with reduced graphene oxide, and magnetic nanoparticles Fe3O4 that are evenly distributed on the aspergl'llus flavus mycelium spheres and have a uniform size. The composite material of magnetic mycelium spheres loaded with reduced graphene oxide prepared by the disclosure can not only make the magnetic nanoparticles Fe3O4 evenly distributed, but also has a micrometer-scaled mycelium sphere structure, avoids the properties of easy agglomeration and difficult recovery of the nanoparticles. The composite material has a good adsorption property, and can be magnetically separated and recovered, so as to serve as a good water body purif1cation adsorbent.

Description

COMPOSITE MATERIAL OF MAGNETIC MYCELIUM SPHERE LOADED WITH

REDUCED GRAPHENE OXIDE AND PREPARATION METHOD THEREOF Field

[0001] The present disclosure relates to the field of biomaterials, and particularly relates to a composite material of magnetic mycelium spheres loaded with reduced graphene oxide and a preparation method thereof. Background

[0002] Graphene oxide is a carbon-based nanomaterial that contains multiple oxygen-containing functional groups, and has a two-dimensional structure similar to that of graphene. Reduced graphene oxide is a product obtained by a reduction reaction of graphene oxide to remove part of the oxygen-containing functional groups, and presents properties different from those of graphene oxide because of different degrees of oxidation and different quantities of the oxygen-containing functional groups. A composite material of graphene-type nanometer materials and iron-based oxides has an adsorbing-enriching property of the graphene-type nanometer materials and a magnetic response property of the magnetic materials in combination with graphene-type nanometer materials because particular iron oxides have magnetism, and has a wide application prospect in fields of chemistry analysis and pollutant removal. However, magnetic particles and the graphene-type materials have nanoscale sizes, which results in high agglomeration, and defects of the difficulty in collection and the poor performance caused by agglomeration in practical application, thus affecting their application. Fungus mycelium is a tube-shaped biomass material in a micrometer scale, and has received extensive attention in the field of nanometer material assembly in recent years, because of the advantages of easy reproduction, low cost, existence of a large quantity of functional groups and easy reaction with active materials. However, currently the general practice of the compositing of most of binary or ternary materials is to use a physical binding method of nanoparticles wound by mycelia, wherein a nanometer powder material is firstly prepared, and then mixed with mycelia to obtain a mixture, and the mixture is cultured to prepare a binary or ternary composite material. Such a method requires to prepare multiple nanometer materials in advance, and the binding between the multi-component nanometer materials and the mycelium is realized mainly by using the narrow spatial domain generated by the winding of mycelia, and has a weak acting force and poor stability.

[0003] The patent CN 201610011889.2 discloses a graphene/mycelium hydrogel loaded with nanoparticles, a preparation method thereof and use of the graphene/mycelium hydrogel in water treatment. The method comprises mixing uniformly the nanoparticles, graphene oxide and fungus mycelia, performing filtering and separation to obtain a formed composite material precursor, and performing a low-temperature hydrothermal process on the obtained precursor to obtain the graphene/mycelium hydrogel loaded with the nanoparticles, wherein a stable functional material is prepared by using a hydrothermal condition. However, in the patent, the nanoparticles are still fixed by a co-culturing mode, and the hydrothermal condition in the later stage 1s merely for stably preparing a composite material structure, and cannot guarantee the evenness of the nanoparticles loaded on the mycelia.

[0004] An object of the present disclosure is to, aiming at the deficiencies of the conventional methods, by utilizing the properties of different loaded materials, provide a composite material of magnetic mycelium spheres loaded with reduced graphene oxide having good structural stability of mycelia, good mechanical property and good performance, which is prepared by preparing a mycelium sphere loaded with even reduced graphene oxide by using a spore of toxigenic aspergillus flavus as a precursor of the mycelia through the co-culturing of a graphene-type nanometer material and a spore liquor of aspergillus flavus, and, on that basis, performing hydrothermal reaction.

Summary

[0005] An object of the present disclosure is to, aiming at the deficiencies of the conventional methods, provide a composite material of magnetic mycelium spheres loaded with reduced graphene oxide, which has good mycelium structural stability and even distribution of magnetic nanoparticles Fe30O: and a preparation method thereof.

[0006] In order to achieve the above object, the present disclosure employs the following technical solutions.

[0007] A composite material of magnetic mycelium spheres loaded with reduced graphene oxide is provided, wherein the composite material is of a microsphere structure, and comprises aspergillus flavus mycelium spheres that are formed by winding of aspergillus flavus mycelia and are loaded with reduced graphene oxide, and magnetic nanoparticles Fe3O: that are evenly distributed on the aspergillus flavus mycelium spheres and have a uniform size.

[0008] According to the above solution, particle sizes of the magnetic nanoparticles Fe3O: are 20-40 nm.

[0009] According to the above solution, a size of a microsphere is 2-3 mm.

[0010] According to the above solution, the aspergillus flavus mycelium spheres are fluffy, and are formed by mycelia inside, the mycelia are 1.5-3 um in diameter of and 20 um or above in length, and reduced graphene oxide is adhered to surfaces of the mycelia.

[0011] A preparation method of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide is provided, wherein the preparation method comprises: by using a fungal spore of filamentous toxigenic aspergillus flavus as a precursor, co-culturing the precursor with graphene oxide, to prepare aspergillus flavus mycelium spheres loaded with S reduced graphene oxide; and then performing purifying and functionalizing treatment on the aspergillus flavus mycelium spheres loaded with reduced graphene oxide, and performing hydrothermal treatment on the aspergillus flavus mycelium spheres and an iron precursor, to obtain the composite material of magnetic mycelium spheres loaded with reduced graphene oxide.

[0012] According to the above solution, the co-culturing comprises: by using a sterilized graphene oxide aqueous solution and the fungal spore of filamentous toxigenic aspergillus flavus as raw materials, and in a sterilized liquid culture medium, culturing the raw materials for a time period, to prepare the mycelium spheres loaded with reduced graphene oxide. The process may particularly comprise: preparing a graphene oxide aqueous solution, sterilizing the graphene oxide aqueous solution at 121 °C for 30 min, and cooling sterilized graphene oxide aqueous solution to a room temperature for later use; preparing a liquid culture medium having a concentration twice the normal concentration, sterilizing the liquid culture medium at 121 °C for 30 min, and cooling sterilized liquid culture medium to a room temperature for later use; and mixing the sterilized graphene oxide aqueous solution and the liquid culture medium above the normal concentration at a certain volume ratio, to obtain a liquid culture medium solution system having the normal concentration, adding a fungal spore of filamentous toxigenic aspergillus flavus, and performing co-culturing.

[0013] According to the above solution, a concentration of the graphene oxide aqueous solution is 1-2 mg/mL; and a final concentration of graphene oxide in a co-culturing system is

0.5-1 mg/mL.

[0014] According to the above solution, the graphene oxide has a transverse dimension of

0.5-5 um, and a longitudinal dimension of 0.35-1.2 nm.

[0015] According to the above solution, a final concentration of the fungal spore of the aspergillus flavus in the solution in the co-culturing system is 10°-10%/mL, and co-culturing conditions are as follows: shake cultivation is performed at 28 °C and at a rotational speed of 200-300 r/min for 4-5 d.

[0016] According to the above solution, the method comprises, after the co-culturing, filtering out black mycelium spheres in the liquid culture medium by using a nylon cloth, and washing out residual liquid culture medium with water for later use.

[0017] According to the above solution, the purifying and functionalizing treatment is hydrogen peroxide treatment, and the hydrogen peroxide treatment comprises: adding the black mycelium spheres into 20-30% hydrogen peroxide, soaking the black mycelium spheres for 5-7 d, and then performing aftertreatment to obtain mycelium spheres loaded with reduced graphene oxide. The hydrogen peroxide treatment can perform decoloring and detoxification on the mycelia to a certain extent, and meanwhile, the hydrogen peroxide treatment changes the oxidoreduction property of the surfaces of the mycelia, which facilitates the reduction reaction, and facilitates generation of the magnetic mycelium spheres in a later phase. The concentration of the mycelium spheres in a hydrogen peroxide solution is 20-100 mg/mL.

[0018] According to the above solution, the aftertreatment comprises: filtering out decolored mycelium spheres by using a nylon cloth, and washing the mycelium spheres with a large amount of water to remove residual hydrogen peroxide.

[0019] In the preparation method according to the present disclosure, the nylon cloth is 200-400 meshes.

[0020] According to the above solution, the purifying and functionalizing treatment further comprises glutaraldehyde treatment, and the glutaraldehyde treatment comprises: transferring the black mycelium spheres into a 2.5% glutaraldehyde aqueous solution, soaking the black mycelium spheres for 1d to inactivate, filtering out mycelium spheres by using a nylon cloth, washing the mycelium spheres with a large amount of water to remove residual glutaraldehyde, and performing the hydrogen peroxide treatment.

[0021] According to the above solution, the hydrothermal treatment comprises: by using ferric chloride or ferric chloride hexahydrate and sodium bicarbonate as raw materials, and ascorbic acid as a reducing agent, performing hydrothermal reaction to synthesize the composite material of the magnetic mycelium spheres Fe30: loaded with reduced graphene oxide, wherein the ferric chloride or ferric chloride hexahydrate is metered based on the ferric chloride, and a mass ratio of the mycelium spheres loaded with the reduced graphene oxide to the ferric chloride or ferric chloride hexahydrate to the ascorbic acid is (1.2-3):4.86:(0.293-0.88).

[0022] An optimum amount of the above sodium bicarbonate is based on a mass ratio of the ferric chloride to the sodium bicarbonate being 4.86:7.56, i.e, a molar ratio of the ferric chloride to the sodium bicarbonate is a theoretical molar ratio being 1:3, so that the ferric chloride hexahydrate or ferric chloride can be sufficiently converted to generate an Fe(OH); precipitate which is converted into magnetic mycelium spheres Fe:O4 under the action of the ascorbic acid.

[0023] According to the above solution, the hydrothermal reaction is as follows: a hydrothermal process is performed at 140-160 °C for 6-8 h.

[0024] According to the above solution, after the hydrothermal reaction is ended, aftertreatment is performed, and the aftertreatment comprises: filtering out reacted black mycelium spheres by using a nylon cloth, washing the reacted black mycelium spheres with a large amount of water till a filtrate is colorless and transparent, washing and soaking the black mycelium spheres by using anhydrous ethanol for 7-10 times, to remove impurities that are easily soluble in organic solvents, washing the black mycelium spheres with water for 5-10 5 times, and finally performing freeze-drying, to obtain the composite material of magnetic mycelium spheres loaded with reduced graphene oxide.

[0025] According to the above solution, in the preparation method according to the present disclosure, the liquid culture medium is a Potato Dextrose Broth, a sabouraud medium or a Czapek's medium.

[0026] Use of the above composite material of magnetic mycelium spheres loaded with reduced graphene oxide as an adsorbent in adsorption removal of heavy metals and/or aflatoxins is provided.

[0027] According to the present disclosure, by using the co-culturing between the fungal spore of the filamentous toxigenic aspergillus flavus and the graphene oxide, the mycelium I5 spheres loaded with reduced graphene oxide are obtained, and then subjected to hydrothermal reaction with an iron precursor, and the composite material of magnetic mycelium spheres loaded with reduced graphene oxide having a stable structure is obtained by the functionalized assembly of magnetic nanoparticles, the micrometer-scaled biomass (mycelium spheres) and the reduced graphene oxide. In the composite material of the mycelium spheres, the binding between the reduced graphene oxide and the mycelium spheres is stable and uniform, and the magnetic particles have a high loading capacity and cannot easily fall.

[0028] In a process of the high-temperature sterilization and/or the co-culturing between the graphene oxide and a culture solution containing the fungal spore of the filamentous toxigenic aspergillus flavus, oxygen-containing functional groups on the lamella of the graphene oxide are partially reduced into reduced graphene oxide, and simultaneously the spore grows into mycelia which grow while winding the lamella of the graphene, whereby mycelium spheres that are loaded with reduced graphene oxide evenly and have a maximum loading capacity can be prepared. Then, the mycelium spheres loaded with reduced graphene oxide are further subjected to functionalization, which facilitates the generation and adhesion of the magnetic particle crystals Fe;Os. After the hydrothermal reaction between iron precursor liquor and the mycelium spheres subjected to functionalization, the magnetic particles Fe3O4 having a uniform particle size are evenly distributed on the mycelium spheres. In an aspect, the hydrothermal reaction enables seed crystals to grow naturally, which guarantees the uniform size of the magnetic particles Fe30O, and in another aspect, the hydrothermal reaction can guarantee that Fe3O04 is bound with the mycelium spheres via chemical bonds, and cannot easily fall from the mycelium spheres, which avoids the difficulty in the recovery of materials. The composited ternary material has a good magnetic response property, and can be conveniently recovered and reused.

The binding between the reduced graphene oxide and the mycelium spheres is stable and uniform, the magnetic mycelium spheres have a stable structure, and the magnetic particles have a large loading capacity and cannot easily fall. The preparation materials are simple, requirements on equipment are low, and an environment-friendly effect is achieved.

[0029] The composite material of magnetic mycelium spheres loaded with reduced graphene oxide prepared by the present disclosure not only makes the magnetic nanoparticles FesOq to distribute evenly, but also has a micrometer-scaled mycelium sphere structure, and avoids the properties of easy agglomeration and difficult recovery of the nanoparticles. The composite material has a good adsorption property, and can be magnetically separated and recovered, so as to serve as a good water purification adsorbent. In studies on the removal of water pollutants, the composite material exhibits the capability of simultaneously enriching and removing multiple pollutants. 10 mg of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide can remove 49.22 ng of aflatoxin B1, 48.83 ng of aflatoxin B2, 50 ng of aflatoxin GI, 46.3 ng of aflatoxin G2, 151 ug of Cu?’ and 123 ug of Cd**. The composite material has a low preparation cost and is environmentally friendly, and therefore has a prospect of becoming a competitive adsorbent.

Brief Description of the Drawings

[0030] Fig. 1 is photographs of samples of mycelium spheres loaded with reduced graphene oxide and a composite material of magnetic mycelium spheres loaded with reduced graphene oxide prepared by the present disclosure, wherein Fig. l(a) is a photograph of a mycelium sphere loaded with reduced graphene oxide that is prepared by the co-culturing of graphene oxide and a spore; Figs. 1(b) and 1(c) are photographs of mycelium spheres loaded with reduced graphene oxide subjected to hydrogen peroxide treatment, from which it can be seen that sizes of the mycelium spheres are between 1.5-2 mm; and Figs. 1(d) and 1(e) are photographs of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide, from which it can be seen that sizes of the mycelium spheres are between 2-3 mm.

[0031] Fig. 2 is SEM images of mycelium spheres loaded with reduced graphene oxide and magnetic mycelium spheres loaded with reduced graphene oxide, wherein Fig.2(a) is an SEM image of one mycelium in the mycelium spheres loaded with reduced graphene oxide, from which it can be seen that the mycelium is loaded with a layer of a silk-like material, which is inferred as the reduced graphene oxide; Figs. 2(b) and 2(c) are SEM images of different magnifications of magnetic mycelium spheres loaded with reduced graphene oxide, wherein from Fig. 2(c) it can be seen that the mycelium sphere is intact, and from Fig. 2(b) it can be seen that 20-40 nm magnetic nanoparticles are evenly distributed on the mycelium in the mycelium sphere, and the particles have a uniform size; and Fig. 2(d) is an SEM image of a section of a magnetic mycelium sphere loaded with reduced graphene oxide, from which it can be seen that the mycelium sphere is fluffy, and is formed by mycelia inside.

[0032] Fig. 3 is a comparison diagram of X-ray diffractions (XRDs) of mycelium spheres loaded with reduced graphene oxide and magnetic mycelium spheres loaded with reduced graphene oxide. It can be known from the figure that the positions of diffraction peaks of the magnetic mycelium spheres are consistent with those of diffraction peaks of Fe;O4, which proves that the prepared magnetic nanoparticles are Fe;O..

[0033] Fig. 4 is a comparison diagram of infrared spectrums of mycelium spheres loaded with reduced graphene oxide and magnetic mycelium spheres loaded with reduced graphene oxide. It can be known from the figure that the magnetic mycelium spheres have one more absorption peak than the non-magnetic mycelium spheres nearby the wavelength of 500 nm, the absorption peak corresponds to an iron-oxygen vibration peak, which proves that an iron element exists in the composite material.

[0034] Fig. 5 is photographs of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide in water and ultrasound treatment for 2 h, wherein Fig. 5(a) is a photograph of the magnetic mycelium spheres loaded with reduced graphene oxide in water; and Fig. 5(b) is a photograph of the magnetic mycelium spheres loaded with reduced graphene oxide subjected to ultrasound treatment for 2h. Detailed Description of the Embodiments

[0035] Example 1

[0036] The preparation of mycelium spheres loaded with reduced graphene oxide comprises: weighing 5 g of peptone, 20 g of glucose, 2 g of yeast extract powder, | g of dipotassium phosphate and 0.24g of anhydrous magnesium sulfate, adding water to reach a constant volume of 0.5 L, performing uniform mixing to obtain a mixture, and sterilizing the mixture at 121 °C for 30 min; sterilizing a 1 mg/mL graphene-oxide aqueous solution at 121 °C for 30 min to obtain a sterilized graphene-oxide aqueous solution; adding 20 mL of the sterilized graphene-oxide aqueous solution into 20 mL of a sterilized sabouraud medium, performing uniform mixing, and adding 600 uL of a purified spore liquor of a representative strain of aspergillus flavus A.flavus 3.4408 commercially available from the China General Microbiological Culture Collection Center, to obtain mycelium spheres and guarantee that a final concentration of a final aspergillus flavus spore liquor in the 40 mL solution is 5x105/mL;

placing the mycelium spheres into a shaking table at 28 °C, culturing the mycelium spheres at a rotational speed of 200-300 r/min for 5 d, filtering out black mycelium spheres by using a 200-mesh nylon cloth, and washing out free reduced graphene oxide and the culture medium with water, to obtain black co-cultured mycelium spheres, which can be been in Fig. 1(a); transferring the black mycelium spheres into a 2.5% glutaraldehyde aqueous solution, soaking the black mycelium spheres for 1 d to inactivate, filtering out black mycelium spheres by using a 200-mesh nylon cloth, and washing the black mycelium spheres with a large amount of water to remove residual glutaraldehyde; and transferring the black mycelium spheres to 50 mL of 30% hydrogen peroxide, soaking the black mycelium spheres for 6 d, filtering out decolored mycelium spheres by using a 200-mesh nylon cloth, washing the decolored mycelium spheres with a large amount of water to remove residual hydrogen peroxide, and performing freeze-drying to obtain mycelium spheres loaded with reduced graphene oxide, which can be been in Figs. 1(b) and 1(c).

[0037] The preparation of a composite material of magnetic mycelium spheres loaded with reduced graphene oxide comprises: weighing 7.5610 g of NaHCO3, adding ultrapure water to reach a constant volume of 200 mL, and performing uniform mixing; weighing 8.109g of FeCl;*6H20, adding ultrapure water to reach a constant volume of 100 mL, and performing uniform mixing; weighing 0.44 g of ascorbic acid, dissolving by using 20 mL of distilled water, and performing uniform mixing, weighing 1.2 g of treated mycelium spheres loaded with reduced graphene oxide, placing the mycelium spheres loaded with reduced graphene oxide into a 500 mL conical flask, adding 100 mL of an FeCl; solution into the conical flask, and oscillating the conical flask for 1 d; adding slowly 200 mL of a NaHCO: solution, stirring while dropwise adding the NaHCO; solution, after the NaHCO; solution is completely added, continuing stirring for 120 min, adding slowly 20 mL of an ascorbic acid solution, stirring while dropwise adding the ascorbic acid solution , after the ascorbic acid solution completely added, continuing stirring for 30 min to obtain a mixed liquid, adding the mixed liquid in the conical flask into a reactor having a polytetrafluoroethylene container, and placing the reactor into an oven at 150 °C for reaction for 8 h; and placing a reaction product on a 200-mesh nylon cloth, washing the reaction product with a large amount of water till a filtrate is colorless and transparent, soaking and washing the reaction product with anhydrous ethanol for 7 times, performing washing with deionized water for 10 times, and performing freeze-drying, to obtain a composite material of magnetic mycelium spheres loaded with reduced graphene oxide, which can be seen in Figs. 1(d) and 1(e).

[0038] Fig. 1 is photographs of samples of mycelium spheres loaded with reduced graphene oxide and a composite material of magnetic mycelium spheres loaded with reduced graphene oxide that are prepared according to the present disclosure, wherein Fig. 1(a) is a photograph of a mycelium sphere loaded with reduced graphene oxide that is prepared by the co-culturing of graphene oxide and a spore; Figs. 1(b) and 1(c) are photographs of the mycelium spheres loaded with reduced graphene oxide subjected to hydrogen peroxide treatment, from which it can be seen that sizes of the mycelium spheres are between 1.5-2 mm; and Figs. 1(d) and 1(e) are photographs of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide, from which it can be seen that sizes of the mycelium spheres are between 2-3 mm.

[0039] Fig. 2 is SEM images of the mycelium spheres, wherein Fig. 2(a) is an SEM image of one mycelium in the mycelium spheres loaded with reduced graphene oxide, from which it can be seen that one mycelium sphere is coated with a layer of a silk-like material, which is inferred as reduced graphene oxide; from Fig. 2(c) it can be seen that the magnetic mycelium spheres are intact, and from Fig. 2(b) it can be seen that 20-40 nm magnetic nanoparticles are evenly distributed on the mycelium in the mycelium spheres, the particles have a uniform size, and a diameter of the mycelium is approximately 2 um; and Fig. 2(d) is an SEM image of a section of a magnetic mycelium sphere loaded with reduced graphene oxide, from which it can be seen that the mycelium sphere is fluffy, and is formed by the mycelium inside, and the length of the mycelium is 20 um or above.

[0040] Fig. 3 is a comparison diagram of XRDs of the mycelium spheres loaded with reduced graphene oxide and one magnetic mycelium sphere loaded with reduced graphene oxide. It can be known from the figure that the positions of diffraction peaks of the magnetic mycelium sphere is consistent with those of diffraction peaks of Fe;O4, which proves that the prepared magnetic nanoparticles are Fe; Os.

[0041] Fig. 4 is a comparison diagram of infrared spectrums of the mycelium spheres loaded with reduced graphene oxide and magnetic mycelium spheres loaded with reduced graphene oxide. It can be seen from the figure that the magnetic mycelium spheres have one more absorption peak than the non-magnetic mycelium spheres nearby a wavelength of 500 nm, the absorption peak corresponds to an iron-oxygen vibration peak, which proves that an iron element exists in the composite material.

[0042] Fig. 5(a) is a photograph of the magnetic mycelium spheres loaded with reduced graphene oxide in water, and Fig. S5(b) 1s a photograph of the magnetic mycelium spheres loaded with reduced graphene oxide subjected to ultrasound treatment for 2h. It can be seen from the figure that, after being subjected to ultrasound treatment for 2h, a solution containing the materials is still colorless and transparent, and has no obvious difference from a solution before ultrasound treatment, which proves that the magnetic microspheres loaded with reduced graphene oxide provided by the present disclosure are substantially not stripped after being subjected to ultrasound treatment for 2h, and therefore the loading stability of magnetic beads of the magnetic mycelium spheres according to the present disclosure is high.

[0043] Example 2

[0044] An experiment for removal of heavy metals and aflatoxin in a water body: 10 uL of a mixture standard solution of 4 types of aflatoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2) prepared by using a methanol solution of a concentration of 5 pg/mL, and 200 pL of a 1000 pg/mL standard solution of Cu?’ and Cd?’ were added into 100 mL of water, 10 mg of the composite material of magnetic mycelium spheres loaded with reduced graphene oxide was added, shaking was performed for 10 min, magnetic separation was performed, the contents of the aflatoxin, the Cu** and the Cd” in a supernatant solution were detected by using the national standard GB, and the content of the supernatant solution was subtracted from the added standard contents, to obtain the adsorbing contents of the materials, which were respectively

49.22 ng for the aflatoxin B1, 48.83 ng for the aflatoxin B2, 50 ng for the aflatoxin G1, 46.3 ng for the aflatoxin G2, 151 ug for the Cu?” and 123 ug for the Cd”.

Claims (9)

tl CONCLUSIONS A composite material consisting of magnetic mycelial spheres loaded with reduced graphene oxide, the composite material having a microspherical structure and containing Aspergillus flavius mycelial spheres formed by wrapping spergillus flavus mycelia and loaded with reduced graphene oxide and magnetic nanoparticles Fe;O4 which are equivalent distributed on the Aspergillus flavius mycelium spheres and which have a uniform shape. The composite material of magnetic mycelial spheres according to claim 1, wherein the particle size of the magnetic nanoparticles Fe 3 O: 20 to 40 nm and the microsphere has a size of 2 to 3 mm. The composite material of the magnetic mycelial spheres according to claim 1, wherein the aspergillus flavus mycelial spheres are airy and formed by the inner side of the mycelia, the mycelia have a diameter of 1.5 to 3 µm and a length of 20 µm or more, and reduced graphene oxide is attached to the surface of the mycelia. A method of preparing the composite material of magnetic mycelial spheres loaded with reduced graphene oxide according to claim 1, wherein by using a fungal spore of filamentous toxigenic aspergillus flavus as an initiator, said initiator being co-cultured with the graphene oxide to form the aspergillus flavus preparing mycelial spheres loaded with reduced graphene oxide and then performing the purifying and functionalizing treatment on the aspergillus flavus mycelial spheres loaded with reduced graphene oxide and performing a hydrothermal treatment on the purified and functionalized aspergillus flavus mycelial spheres with an iron initiator to arrive at the composite material of magnetic mycelial spheres loaded with reduced graphene oxide. The preparation method according to claim 4, wherein the graphene oxide has a transverse dimension of 0.5 to 5 µm and a longitudinal dimension of 0.35 to 1.2 nm. The preparation method according to claim 4 wherein the purifying and functionalizing treatment is a hydrogen peroxide treatment and the hydrogen peroxide treatment comprises: adding black mycelial spheres in 20 to 30% hydrogen peroxide, wherein the black mycelial spheres are incubated in this hydrogen peroxide solution for 5 to 7 days. submerged and a post-treatment is performed to obtain mycelial spheres loaded with reduced graphene oxide wherein the concentration of the mycelial spheres in the hydrogen peroxide solution is 20 to 100 mg per ml. The preparation method according to claim 4, wherein the co-culture comprises: using a sterilized aqueous solution containing graphene oxide and the fungal spore of toxigenic aspergillus flavus as raw material in a liquid sterilized culture medium, wherein the raw material is stored for a period of time culture is maintained to prepare the mycelial spheres loaded with reduced graphene oxide, wherein the concentration of graphene oxide in the liquid solution is 1 to 2 mg per ml, the total concentration of graphene oxide in a co-culture system is 0.5 mg per ml; the total concentration of the fungal spores of filamentous toxigenic aspergillus flavus in the co-culture liquid system is 10°-10° ml, and the liquid culture medium is a Potato Dextrose Broth, a Sabouraud's medium or a Czapek's medium and the co-culture conditions as follows are: the culture is shaken for 4 to 5 days at 28°C at a rotation speed of 200 to 300 rpm. and after the termination of the co-culture, the black mycelial spheres are filtered out from the liquid culture medium using a nylon cloth and the residual liquid culture medium is rinsed with water for later use. The preparation method according to claim 4, wherein the purifying and functionalizing treatment further comprises a glutaraldehyde treatment, said treatment comprising: transferring the black mycelial spheres into an aqueous solution containing 2.5% glutaraldehyde and immersing the black mycelial spheres for 1 day to inactivate them and then filter out mycelial spheres by using a nylon cloth, the filtered mycelial spheres are washed in a large amount of water to remove all the residues of the glutaraldehyde and then carry out the hydrogen peroxide treatment. The preparation method according to claim 4, wherein the hydrothermal treatment comprises: performing a hydrothermal reaction by using ferric chloride or ferric chloride hexahydrate and sodium bicarbonate as raw material and ascorbic acid as reducing agent around the magnetic mycelial spheres charged with reduced graphene oxide and Fe; Os where the ferric chloride or ferric chloride hexahydrate is measured based on the ferric chloride, a mass ratio of mycelial spheres charged with reduced graphene oxide over the ferric chloride or ferric chloride hexahydrate over the ascorbic acid (1.2 to 3) 4.86 ( 0.293 to 0.88) and a state of the hydrothermal reaction is as follows: a hydrothermal process which is carried out at 140 to 160°C for 6 to 8 hours. The use of the composite material of magnetic mycelial spheres loaded with reduced graphene oxide according to claim as an adsorbent for the adsorption of heavy metals and/or alphatoxins.