Modified peptidoglycan with efficient adsorption effect as well as preparation method and application of modified peptidoglycan

Abstract

The invention relates to the technical field of biological adsorption materials, in particular to modified peptidoglycan with an efficient adsorption effect and a preparation method and application of the modified peptidoglycan. The preparation method comprises the steps of grafting and modifying carboxyl / hydroxyl of peptidoglycan, so that multi-site and multi-mode functional modification on the surface of the peptidoglycan is realized. The physicochemical properties of functional groups on the surface of peptidoglycan are changed through modification treatment, the density and electronegativity of carboxyl and hydroxyl functional groups on the surface of peptidoglycan are improved, the hydrogen-bond interaction and electrostatic adsorption capacity between the peptidoglycan and biotoxin are enhanced, and the adsorption efficiency is improved. In addition, the peptidoglycan is subjected to carboxyl and hydroxyl modification at the same time, and the tetrodotoxin adsorption effect of the peptidoglycan can be further improved. The technology provides a new strategy for functionalization of natural polymer materials, has good theoretical popularization value and application prospects, and is suitable for the fields of food safety, removal and purification of biotoxins and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of biological adsorption materials, and in particular to a modified peptidoglycan with high-efficiency adsorption function, a preparation method and application thereof. Background Art

[0002] Currently, adsorption is considered a relatively rapid and safe method for detoxification. Adsorbents such as activated carbon, synthetic silica gel, and biopolymers have demonstrated some effectiveness, but remain inefficient. Consequently, there is an urgent need to develop highly efficient, environmentally friendly adsorption materials to meet practical application needs.

[0003] Peptidoglycan (PG), a three-dimensional network polymer composed of alternating polysaccharides and short peptide chains, is widely found in the cell walls of Gram-positive bacteria and exhibits excellent biocompatibility and adsorption properties. Previous studies have demonstrated that peptidoglycan derived from lactic acid bacteria can remove microbial toxins (aflatoxin B1), marine biotoxins (tetrodotoxin), and carcinogenic compounds produced during food processing (benzo(a)pyrene) through adsorption. However, the adsorption capacity is relatively low, making it difficult to meet the requirements for efficient detoxification in industrial applications.

[0004] Studies have shown that lactic acid bacteria peptidoglycan can bind to biotoxins through carboxyl and hydroxyl groups. However, PG has a complex structure and poor solubility, making its adsorption efficiency difficult to meet industrial needs. To address the above problems, the present invention grafts and modifies the carboxyl and hydroxyl groups of PG to increase the activity of its surface functional groups and further enhance its adsorption capacity for biotoxins. The present invention provides a safe and efficient PG-modified biosorbent suitable for multiple application scenarios such as food safety monitoring, aquatic toxin purification, and environmental pollution remediation. It has important theoretical significance and application value in the research and development of efficient biotoxin adsorption materials. Summary of the Invention

[0005] The present invention aims to provide a modified peptidoglycan with efficient adsorption, a preparation method and application thereof. The carboxyl / hydroxyl modified peptidoglycan prepared by specific chemical grafting and modification has efficient adsorption in biological toxins, overcomes the shortcoming of low peptidoglycan adsorption rate, and has green and environmentally friendly characteristics.

[0006] To achieve the above object, the present invention provides a method for preparing a modified peptidoglycan with high-efficiency adsorption, comprising: dissolving the peptidoglycan in a solvent, adding a carboxyl grafting agent, a hydroxyl grafting agent, a carboxyl modifier or a hydroxyl modifier to react, washing, dialyzing and drying to obtain the modified peptidoglycan;

[0007] The carboxyl grafting agent is selected from polyacrylic acid (PAA) and alginic acid (Alg), the hydroxyl grafting agent is selected from polyvinyl alcohol (PVA) and polyethylene glycol (PEG), the carboxyl modifier is selected from ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and HO, and the hydroxyl modifier includes TEMPO, NaBr and NaClO.

[0008] Furthermore, after the carboxyl grafting agent or hydroxy modifier reacts, the carboxyl grafted peptidoglycan or hydroxy modified peptidoglycan is obtained by washing, dialyzing and drying, and then the hydroxy modifier or carboxyl grafting agent is added respectively, and the modified peptidoglycan is obtained by washing, dialyzing and drying again.

[0009] Furthermore, a method for preparing a modified peptidoglycan by adding a carboxyl grafting agent comprises: dissolving the peptidoglycan in a NaOH solution, adding EDC and NHS for light-protected activation, then adding the carboxyl grafting agent for reaction, washing, dialyzing, and drying to obtain the carboxyl grafted peptidoglycan. Preferably, the NaOH solution has a concentration of 0.01-5M, and the total amount of EDC and NHS added is 10-100 wt% of the peptidoglycan. Specifically, dry PG powder is dissolved in a 2M NaOH solution to obtain a deacetylated peptidoglycan solution; then, the pH value is adjusted to 5-8, a certain amount of EDC and NHS are added, and the solution is activated in the dark for a certain period of time; then, polyacrylic acid or alginic acid is dissolved in a MEST (pH 5.0) buffer solution and added to the deacetylated peptidoglycan solution, wherein the amount of polyacrylic acid or alginic acid added is 10-200wt% of the peptidoglycan. The grafting reaction is stirred at 40-80°C for 4-24 hours, and after washing, the solution is dialyzed using a 3500Da-45000Da dialysis bag for 3 days, and then freeze-dried to obtain polyacrylic acid grafted peptidoglycan (PAA-PG) or alginate grafted peptidoglycan (Ag-PG).

[0010] Furthermore, the method for preparing modified peptidoglycan by adding a hydroxyl grafting agent includes: dispersing the peptidoglycan in MEST buffer, adding EDC and NHS for light-protected activation, then adding a hydroxyl grafting agent for reaction, and obtaining hydroxyl grafted peptidoglycan through washing, dialysis, and drying.

[0011] Specifically, peptidoglycan is dispersed in MEST (pH = 6) buffer of 1 to 20 times the mass of peptidoglycan, and 1 to 5 times the volume of NHS and EDC are added, and the reaction is carried out at room temperature for 1 to 5 hours to activate the carboxyl groups on the PG surface. Accurately weigh 1 to 5 times the mass of peptidoglycan polyvinyl alcohol and dissolve it in glutaraldehyde solution to activate the hydroxyl groups of polyvinyl alcohol. Subsequently, the polyvinyl alcohol solution is added dropwise to the activated PG solution and reacted at room temperature for 1 to 10 hours. After the grafting reaction is completed, wash with deionized water 3 times, dialyze for 3 days, and then freeze-dry to obtain polyvinyl alcohol grafted peptidoglycan (polyvinyl alcohol-PG or PVA-PG).

[0012] Specifically, peptidoglycan is dispersed in MEST (pH = 6) buffer with a volume of 1 to 20 times the mass of peptidoglycan, and 1 to 5 times the volume of NHS and EDC are added for 1 to 5 hours to activate the carboxyl groups on the PG surface. Polyethylene glycol with a volume of 1 to 5 times the mass of peptidoglycan is accurately weighed and dissolved in the MEST solution. Subsequently, the polyethylene glycol solution is added dropwise to the activated PG solution and reacted at room temperature for 1 to 10 hours. After the grafting reaction is completed, it is washed with deionized water 3 times, dialyzed for 3 days, and then freeze-dried to obtain polyethylene glycol-grafted peptidoglycan (polyethylene glycol-PG or PEG-PG).

[0013] Furthermore, the method for preparing the modified peptidoglycan by adding a carboxyl modifier is selected from any one of the following methods:

[0014] (1) Azide-amino conversion-ligand coupling modification: Peptidoglycan was dispersed in DMF solution, filled with nitrogen protection, activated at 60-100°C for 10-120 min, and NaN3 was added for azidation reaction for 1-8 h. The azide group was reduced to amino group by PPh3 / CBr4 system. After washing, dialyzing, and drying, amino-functionalized peptidoglycan (PG-NH) was obtained. PG-NH was reacted with EDTA or NTA in EDC / NHS activation system under DIEPA catalysis at room temperature. After washing, dialyzing, and drying, EDTA-modified peptidoglycan (EDTA-PG) or NTA-modified peptidoglycan (NTA-PG) was obtained.

[0015] (2) Fenton oxidation modification: Peptidoglycan was dissolved in water, a Fenton reaction catalyst was added, and HO was added dropwise for oxidation reaction. After ethanol precipitation, centrifugation, and drying, H2O2-modified peptidoglycan (HO-PG) was obtained.

[0016] Specifically, the preparation method of EDTA-modified peptidoglycan includes: dispersing the peptidoglycan in a certain volume of DMF solution, purging with nitrogen, stirring in an oil bath at 60-100°C for 10-120 minutes, adding 1-5 times the weight of the peptidoglycan in NaN3, and reacting for 1-8 hours; after cooling, adding 1-10 times the weight of the peptidoglycan in triphenylphosphine (PPh3) and 1-100 times the weight of the peptidoglycan dissolved in DMF, and reacting at room temperature for 10-100 hours. The solution is washed three times with anhydrous methanol, anhydrous ethanol, and deionized water; and freeze-dried to obtain PG-N3. PG-N3 is weighed and placed in a container, DMSO is added, and the solution is stirred at 30-90°C for 1-5 hours. Then, sodium borohydride (1-10 times the weight of the PG-N3) is added, and the solution is reacted at room temperature for 1-24 hours. Excess anhydrous ethanol is added, and the solution is dialyzed using a 3500Da dialysis bag, and freeze-dried to obtain PG-NH2. PG-NH2 was added to DMSO and reacted at room temperature for 1 to 10 hours to obtain solution 1. A mixture of 1 to 5 times the mass of peptidoglycan EDTA, 1 to 5 times the mass of peptidoglycan NHS, and 1 to 5 times the mass of peptidoglycan EDC was prepared. DMSO and DIEPA were added to the mixture, and the mixture was reacted at room temperature under nitrogen for 5 to 30 hours to obtain solution 2. Solution 1 and solution 2 were mixed and reacted at room temperature under nitrogen for 10 to 50 hours. After repeated washing with deionized water and ethanol, the mixture was dialyzed in a 3500Da dialysis bag for 72 hours and freeze-dried to obtain EDTA-modified PG (EDTA-PG).

[0017] Specifically, the preparation method of NTA-modified peptidoglycan includes: preparing PG-NH2 using the same steps as above; preparing a mixture of NTA, NHS and EDC with a mass of 1 to 5 times that of PG-NH2, dissolving it in a mixture of DMSO and DIEPA, reacting it at room temperature for 10 hours under nitrogen protection, adding 1 to 10 times the volume of DMSO-dissolved PG-NH2 solution, protecting it with nitrogen, reacting it at room temperature for 10 to 50 hours, washing it, dialyzing it in a 3500Da dialysis bag, and freeze-drying it to obtain NTA-modified peptidoglycan (NTA-PG).

[0018] Specifically, the preparation method of H2O2-modified PG includes: dispersing peptidoglycan in deionized water, adding 1 to 10 times the weight of the peptidoglycan in FeSO4·7H2O solution, stirring at 10 to 50°C for 10 to 80 minutes, adding 1 to 5 times the volume of 30% H2O2 (0.1 mol / L NaHCO3 solution adjusted to pH 6.2), and continuing the reaction for 1 to 5 hours. The mixture is precipitated by adding excess ethanol solution, centrifuged, and freeze-dried to obtain H2O2-modified PG (H2O2-PG).

[0019] Furthermore, a method for preparing a modified peptidoglycan by adding a hydroxyl modifier comprises: dispersing the peptidoglycan in deionized water, adding the hydroxyl modifier to react, then adding a terminator to terminate the reaction, and obtaining the hydroxyl-modified peptidoglycan by centrifugation, washing, dialysis, and drying. For example, the terminator is anhydrous ethanol.

[0020] Specifically, dry PG powder is dissolved in deionized water, 1 / 10 to 1 / 20 of the peptidoglycan mass of TEMPO and 1 to 10 times the peptidoglycan mass of NaBr are added, and the mixture is mixed until an emulsion forms. A 1 to 20-fold volume of NaClO solution (concentration range: 0.01 to 0.2 mmol, active chlorine content: 10%) is added, the pH is adjusted to 7.0 to 10.5, and the reaction is carried out at 0 to 50°C for 10 to 120 minutes. Sodium thiosulfate is added to reduce unreacted NaClO, NaBr, and TEMPO. Subsequently, a small amount of anhydrous ethanol is added to adjust the pH to neutral, and 4 times the volume of anhydrous ethanol is added, stirred, and precipitated overnight at 4°C. The precipitate is washed three times with 70% ethanol, dissolved in deionized water, dialyzed using a 3.5K Da dialysis bag for 3 days, and freeze-dried to obtain hydroxyl-modified PG (TEMPO-PG).

[0021] According to the aforementioned method for preparing the modified peptidoglycan with high-efficiency adsorption, the drying method is preferably freeze-drying.

[0022] According to the aforementioned method for preparing modified peptidoglycan with high adsorption efficiency, the Fenton reaction catalyst is preferably ferrous ion, typically derived from FeSO4, FeCl, Fe(NO), etc.

[0023] The types of peptidoglycan include A3α, A1γ and A4α.

[0024] Typically, peptidoglycan is derived from lactic acid bacteria. Its preparation method includes: activating the lactic acid bacteria and culturing them in a culture medium (e.g., MRS broth) until the middle of the logarithmic growth phase, inactivating them with boiling water, and centrifuging them to obtain a bacterial slurry. Subsequently, teichoic acid is removed using a 5% to 20% trichloroacetic acid solution; fat is removed using a 1% to 10% SDS solution; and surface proteins are removed using a 1mg / mL to 10mg / mL trypsin solution and a pronase solution. After inactivating the trypsin and pronase, the slurry is dialyzed and lyophilized to obtain the peptidoglycan (PG).

[0025] Unless otherwise specified, the “volume times” in the present invention is based on the volume of the previously formed solution.

[0026] The present invention also provides a modified peptidoglycan with high-efficiency adsorption, which is prepared by the above preparation method.

[0027] The present invention also provides a specific application of the modified peptidoglycan with high-efficiency adsorption in the adsorption of tetrodotoxin (TTX).

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The preparation method of the present invention includes the specific grafting and modification of the carboxyl / hydroxyl groups of peptidoglycan, thereby achieving multi-site and multi-mode functional modification of its surface. The present invention changes the physicochemical properties of the functional groups on the surface of peptidoglycan through modification, increases the density and electronegativity of the carboxyl and hydroxyl functional groups on the surface of peptidoglycan, enhances the hydrogen bonding and electrostatic adsorption capacity between the peptidoglycan and biological toxins, and improves the adsorption efficiency. In addition, the present invention simultaneously modifies the carboxyl and hydroxyl groups of peptidoglycan, which can further enhance the adsorption effect of peptidoglycan on tetrodotoxin. This technology provides a new strategy for the functionalization of natural polymer materials, has good theoretical promotion value and application prospects, and is suitable for fields such as food safety and the removal and purification of biological toxins. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The infrared spectra of the modified peptidoglycan and peptidoglycan prepared in Examples and Comparative Examples are shown.

[0031] Figure 2 These are the potential diagrams of the modified peptidoglycans prepared in Examples 1, 8, 9 and 10 and the peptidoglycan prepared in Comparative Example 1.

[0032] Figure 3 The diagram shows the adsorption effect of modified peptidoglycan and peptidoglycan prepared in Examples and Comparative Examples on tetrodotoxin. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. The described embodiments are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] Dried A3α type PG powder was dissolved in a 2M NaOH solution to obtain a deacetylated peptidoglycan solution. Subsequently, the pH value was adjusted to 5, and a certain amount of EDC and NHS were added, and the solution was activated in the dark for a certain period of time. Subsequently, polyacrylic acid was dissolved in MEST (pH 5.0) buffer and added to the deacetylated peptidoglycan solution. The amount of polyacrylic acid added was 30wt% of the peptidoglycan. The grafting reaction was stirred at 50°C for 8h. After washing, the solution was dialyzed with a 45,000Da dialysis bag for 3 days and freeze-dried to obtain polyacrylic acid grafted peptidoglycan (PAA-PG).

[0036] Example 2

[0037] A3α type PG powder was dissolved in a 2M NaOH solution to obtain a deacetylated peptidoglycan solution. Subsequently, the pH was adjusted to 5, and a certain amount of EDC and NHS were added for activation in the dark for a certain period of time. Subsequently, alginate was dissolved in MEST (pH 5.0) buffer and added to the deacetylated peptidoglycan solution. The amount of alginate added was 100wt% of the peptidoglycan. The grafting reaction was stirred at 25°C for 12 hours. After washing, the solution was dialyzed using a 3500Da dialysis bag for 3 days and freeze-dried to obtain alginate-grafted peptidoglycan (Ag-PG).

[0038] Example 3

[0039] 200 mg of A3α peptidoglycan was dispersed in deionized water, and DMF was added under nitrogen atmosphere. The mixture was stirred in an oil bath at 80°C for 30 minutes. 600 mg of NaN3 was added and allowed to react for 4 hours. After cooling, 800 mg of triphenylphosphine (PPh3) and 1 g of CBr4 dissolved in DMF were added sequentially, and the mixture was allowed to react at room temperature for 40 hours. The mixture was washed three times with anhydrous methanol, anhydrous ethanol, and deionized water, and then freeze-dried to obtain PG-N3. PG-N3 was weighed and placed in a container. DMSO was added, and the mixture was stirred at 60°C for 1 hour. Then, 600 mg of sodium borohydride was added and the mixture was allowed to react at room temperature for 12 hours. Excess anhydrous ethanol was added, and the mixture was dialyzed using a 3500 Da dialysis bag. The mixture was then freeze-dried to obtain PG-NH2. PG-NH2 was added with DMSO and reacted at room temperature for 2 hours to obtain solution 1; DMSO and DIEPA with a volume ratio of 25:1 were added to EDTA, NHS and EDC with a mass ratio of 6:3:5, and the mixture was protected by nitrogen and reacted at room temperature for 10 hours to obtain solution 2; solution 1 and solution 2 were mixed, reacted at room temperature for 20 hours under nitrogen, repeatedly washed with deionized water and ethanol, dialyzed in a 3500Da dialysis bag for 72 hours, and freeze-dried to obtain EDTA-modified PG (EDTA-PG).

[0040] Example 4

[0041] PG-NH2 was prepared in the same manner as in Example 3. 50 mg of NTA, 34 mg of NHS, and 58 mg of EDC were dissolved in 1 mL of DMSO and 40 mL of DIEPA. The mixture was reacted at room temperature for 10 h under nitrogen protection. Then, PG-NH2 solution (50 mg of PG-NH2 was dissolved in 700 μL of DMSO) was added. The mixture was reacted at room temperature for 20 h under nitrogen protection. After washing, the mixture was dialyzed in a 3500 Da dialysis bag and freeze-dried to obtain NTA-modified peptidoglycan (NTA-PG).

[0042] Example 5

[0043] A3α-type peptidoglycan was dispersed in deionized water, and a FeSO4·7H2O solution was added. The mixture was stirred at 35°C for 10–80 minutes. Five volumes of 30% H2O2 (adjusted to pH 6.2 with a 0.1 mol / L NaHCO3 solution) were then added, and the reaction continued for 2 hours. The mixture was precipitated by addition of excess ethanol, centrifuged, and lyophilized to obtain H2O2-modified PG (H2O2-PG).

[0044] Example 6

[0045] A3α type peptidoglycan (100 mg) was dispersed in 10 mL of MEST (pH = 6) buffer, and 1 to 5 volumes of NHS and EDC were added. The mixture was reacted at room temperature for 2 hours to activate the carboxyl groups on the PG surface. Accurately weigh 200 mg of polyvinyl alcohol and dissolve it in 5 mL of glutaraldehyde solution to activate the hydroxyl groups of polyvinyl alcohol. Subsequently, the polyvinyl alcohol solution was added dropwise to the activated PG solution and reacted at room temperature for 6 hours. After the grafting reaction, the mixture was washed 3 times with deionized water, dialyzed for 3 days, and freeze-dried to obtain polyvinyl alcohol grafted peptidoglycan (polyvinyl alcohol-PG or PVA-PG).

[0046] Example 7

[0047] A3α type peptidoglycan (100 mg) was dispersed in 10 mL of MEST (pH = 6) buffer, and 1 to 5 volumes of NHS and EDC were added. The reaction was allowed to proceed for 2 hours to activate the carboxyl groups on the PG surface. 200 mg of polyethylene glycol was accurately weighed and dissolved in 5 mL of MEST solution. Subsequently, the polyethylene glycol solution was added dropwise to the activated PG solution and reacted at room temperature for 6 hours. After the grafting reaction was completed, the mixture was washed three times with deionized water, dialyzed for 3 days, and then freeze-dried to obtain polyethylene glycol-grafted peptidoglycan (polyethylene glycol-PG or PEG-PG).

[0048] Example 8

[0049] Dry A3α-type PG powder was dissolved in deionized water. TEMPO (1 / 15 the weight of the peptidoglycan) and NaBr (5 times the weight of the peptidoglycan) were added and mixed until an emulsion formed. A 10-fold volume of NaClO solution (concentration range: 0.05 mmol, active chlorine content: 10%) was added, the pH was adjusted to 8.5, and the reaction was carried out at 4°C for 60 minutes. Sodium thiosulfate was added to reduce unreacted NaClO, NaBr, and TEMPO. Subsequently, a small amount of anhydrous ethanol was added to adjust the pH to neutral. Four volumes of anhydrous ethanol were added, stirred, and the mixture was precipitated overnight at 4°C. The precipitate was washed three times with 70% ethanol, dissolved in deionized water, dialyzed using a 3.5K Da dialysis bag for 3 days, and freeze-dried to obtain hydroxyl-modified PG (TEMPO-PG).

[0050] Example 9

[0051] A polyacrylic acid-grafted peptidoglycan was prepared as in Example 1, and then hydroxyl-modified using the steps described in Example 8 to produce a peptidoglycan (PG-PAA-TE) that was first carboxyl-grafted and then hydroxyl-modified. In this example, three types of PG powder (A3α, A1γ, and A4α) were used for modification, and the PG-PAA-TE products are designated as PAA-TEA3α, PAA-TEA1γ, and PAA-TEA4α, respectively.

[0052] Example 10

[0053] TEMPO-PG was prepared in the same manner as in Example 8, and then grafted with polyacrylic acid using the steps described in Example 1 to produce a peptidoglycan (PG-TE-PAA) that was first modified with hydroxyl groups and then grafted with carboxyl groups. In this example, three types of PG powder (A3α, A1γ, and A4α) were used for modification. The PG-TE-PAA products are designated TEA3α-PAA, TEA1γ-PAA, and TEA4α-PAA, respectively.

[0054] The preparation method of PG powder in the examples is referred to the following Comparative Example 1.

[0055] Comparative Example 1

[0056] Lyophilized three peptidoglycans (PG: A3α, A1γ and A4α).

[0057] Comparative Example 2

[0058] A3α type peptidoglycan was dispersed in deionized water, and 20 volumes of 80% ethanol were added and mixed. Two volumes of chloroacetic acid and NaOH solution were added sequentially, and the pH was adjusted to 8. The reaction was carried out at 70°C for 3 hours. The pH was adjusted to neutral with 0.1M HCl, and the supernatant was discarded after centrifugation. The sample was repeatedly washed with deionized water and ethanol, and dried to obtain chloroacetic acid-modified peptidoglycan (chloroacetic acid-PG).

[0059] Comparative Example 3

[0060] 0.2 M diethanolamine, 0.2 M methyl acrylate, and 20 mL methanol were reacted at 40°C for 1-4 hours. Subsequently, 0.01 M trihydroxypropane and 1.0 g p-toluenesulfonic acid were added and the mixture was reacted at 120°C for 1-10 hours. The resulting light yellow viscous substance was the hydroxyl-terminated hyperbranched polymer (HBP).

[0061] A3α-type PG is dissolved in 0.6% to 2% NaIO4. The reaction is carried out at 10-100°C in the dark for 1-5 hours to achieve hydroformylation and oxidation of the PG. After oxidation, 0.1M glycerol is added and the reaction is continued for 30 minutes to remove unreacted NaIO4. The PG is then washed three times with deionized water, dialyzed, and freeze-dried to obtain the hydroformylated PG.

[0062] The hydroformylation PG was added with 1-10 volumes of cyclohexane, methanol, and 100-500 μL of hydroxyl-terminated hyperbranched polymer and reacted at 8°C for 5 h. The mixture was washed with deionized water three times, dialyzed, and freeze-dried to obtain hydroxyl-terminated hyperbranched polymer-grafted peptidoglycan (HBP-PG).

[0063] Performance measurement

[0064] The modified peptidoglycan and peptidoglycan of the embodiment and comparative example were tested for chemical structure. Figure 1 shown.

[0065] Depend on Figure 1 It can be seen that comparative example 1, 3274cm -1 -OH peak, 2925 cm -1 The CH peak at 1240 cm -1 The COC antisymmetric bond at 1500-1700 cm -1 The amide band absorption reflects the glycopeptide structural characteristics of PG. After the modification treatment of Examples 1-10 or Comparative Examples 2-3, the carboxyl vibration and hydroxyl vibration peaks of peptidoglycan were significantly shifted and changed, indicating that the modification successfully changed the structural characteristics of the peptidoglycan functional groups.

[0066] The modified peptidoglycans prepared in Examples 1, 8, 9 and 10 and the peptidoglycan prepared in Comparative Example 1 were subjected to potential measurement. The results are shown in FIG. Figure 2 As shown, this was done to verify the effect of modification on the charge of peptidoglycan.

[0067] Depend on Figure 2 It can be seen that the potential value of Comparative Example 1 is higher, at -25mV. After chemical modification, the potential value of peptidoglycan is significantly reduced, with a minimum of -62mV. This shows that the modification treatment successfully introduces new functional groups on the peptidoglycan surface, thereby changing the peptidoglycan surface charge.

[0068] Application Examples

[0069] The modified peptidoglycan and peptidoglycan prepared in the examples and comparative examples were used as adsorbents to adsorb tetrodotoxin. Figure 3 As shown, the peptidoglycan modified by the present invention improves the removal effect of tetrodotoxin, proving the application potential of the modified material in the adsorption of biological toxins.

[0070] Molecular docking simulations were performed with TTX using the modified peptidoglycans of Examples 1, 8, and 9, as well as the peptidoglycan of Comparative Example 1, to analyze their interaction types. As shown in Table 1, the peptidoglycan had the highest binding energy for TTX, while the binding energy between the modified peptidoglycan and TTX decreased, indicating that the modification enhanced the peptidoglycan's ability to bind to TTX.

[0071] Table 1

[0072]

[0073] The above descriptions are only partial embodiments of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a modified peptidoglycan with high adsorption efficiency, characterized in that: include: The peptidoglycan is dissolved in a solvent, a carboxyl grafting agent, a hydroxyl grafting agent, a carboxyl modifier or a hydroxyl modifier is added to react, and the modified peptidoglycan is obtained through washing, dialyzing and drying. The carboxyl grafting agent is selected from polyacrylic acid (PAA) and alginic acid (Alg), the hydroxyl grafting agent is selected from polyvinyl alcohol (PVA) and polyethylene glycol (PEG), the carboxyl modifier is selected from ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and H2O2, and the hydroxyl modifier includes TEMPO, NaBr and NaClO.

2. The method for preparing a modified peptidoglycan with high-efficiency adsorption according to claim 1, wherein After the carboxyl grafting agent or hydroxy modifier reacts, the carboxyl grafted peptidoglycan or hydroxy modified peptidoglycan is obtained by washing, dialyzing and drying, and then the hydroxy modifier or carboxyl grafting agent is added respectively, and the modified peptidoglycan is obtained by washing, dialyzing and drying again.

3. The method for preparing a modified peptidoglycan with high-efficiency adsorption according to claim 1 or 2, wherein: The method for preparing a modified peptidoglycan by adding a carboxyl grafting agent comprises: dissolving the peptidoglycan in a NaOH solution, adding EDC and NHS for light-protected activation, then adding the carboxyl grafting agent for reaction, washing, dialyzing, and drying to obtain the carboxyl grafted peptidoglycan. Preferably, the NaOH solution has a concentration of 0.01-5M, and the total amount of EDC and NHS added is 10-100% by weight of the peptidoglycan.

4. The method for preparing a modified peptidoglycan with high-efficiency adsorption according to claim 1 or 2, wherein: The method for preparing modified peptidoglycan by adding a hydroxyl grafting agent comprises: dispersing the peptidoglycan in a MEST buffer, adding EDC and NHS for light-protected activation, then adding the hydroxyl grafting agent for reaction, and washing, dialyzing, and drying to obtain the hydroxyl grafted peptidoglycan.

5. The method for preparing a modified peptidoglycan with high adsorption efficiency according to claim 1 or 2, wherein: The method for preparing modified peptidoglycan by adding a carboxyl modifier is selected from any of the following methods: (1) Azide-amino conversion-ligand coupling modification: Peptidoglycan was dispersed in DMF solution, filled with nitrogen protection, activated at 60-100°C for 10-120 min, and NaN3 was added for azidation reaction for 1-8 h. The azide group was reduced to amino group by PPh3 / CBr4 system. After washing, dialyzing and drying, amino-functionalized peptidoglycan (PG-NH2) was obtained. PG-NH2 was reacted with EDTA or NTA in EDC / NHS activation system under DIEPA catalysis at room temperature. After washing, dialyzing and drying, EDTA-modified peptidoglycan (EDTA-PG) or NTA-modified peptidoglycan (NTA-PG) was obtained. (2) Fenton oxidation modification: dissolve peptidoglycan in water, add Fenton reaction catalyst, add H2O2 dropwise for oxidation reaction, and obtain H2O2-modified peptidoglycan (H2O2-PG) after ethanol precipitation, centrifugation and drying.

6. The method for preparing a modified peptidoglycan with high adsorption efficiency according to claim 1 or 2, wherein: The method for preparing a modified peptidoglycan by adding a hydroxyl modifier comprises: dispersing the peptidoglycan in deionized water, adding the hydroxyl modifier to react, then adding a terminator to terminate the reaction, and obtaining the hydroxyl-modified peptidoglycan by centrifugation, washing, dialysis, and drying. For example, the terminator is anhydrous ethanol.

7. The method for preparing a modified peptidoglycan with high-efficiency adsorption according to claim 1 or 2, wherein: The drying method is freeze-drying.

8. The method for preparing a modified peptidoglycan with high-efficiency adsorption according to claim 1 or 2, wherein: The types of peptidoglycan include A3α, A1γ and A4α.

9. A modified peptidoglycan with high adsorption efficiency, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

10. Use of the modified peptidoglycan with high adsorption efficiency according to claim 8 in adsorbing tetrodotoxin.

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