Polyethylene glycol derivative, preparation method thereof and polyethylene glycol hydrogel

Abstract

The invention provides a polyethylene glycol derivative. The polyethylene glycol derivative comprises a main chain with a structure as shown in a formula (IIa) and an end group with a structure as shown in a formula (IIb). According to the invention, hydroxyl and carboxyl of polyethylene glycol are directly subjected to esterification reaction to generate a polyethylene glycol derivative of which the end group is provided with o-phthalaldehyde, and finally the polyethylene glycol derivative and polyethylene glycol of which the end group is provided with amino form the chemical crosslinking hydrogel. Due to the introduction of ester bonds, the degradation time of the hydrogel is shortened, the gelling rate of the hydrogel is increased, and meanwhile, the hydrogel is high in adhesion performance, simple in preparation process and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the field of material technology, in particular to a polyethylene glycol derivative and a preparation method thereof and a polyethylene glycol hydrogel. Background Art

[0002] Hydrogel is a material with a three-dimensional network structure formed by a certain cross-linking effect. Hydrogel is widely used in the biomedical field because of its physicochemical properties similar to those of the extracellular matrix and good biocompatibility. Polyethylene glycol is a common raw material for preparing hydrogels, including linear polyethylene glycol and multi-arm polyethylene glycol. Due to the low reactivity of the terminal hydroxyl groups of polyethylene glycol, it is usually necessary to derivatize polyethylene glycol to produce end groups with different functions, such as carboxyl, amino, thiol, and aldehyde groups. Through the chemical reaction of the end groups, chemically cross-linked hydrogels can be easily prepared, and other molecules can also be coupled to functionalize the hydrogels.

[0003] Polyethylene glycol derivatives whose end groups are succinimide active esters are often used to prepare chemically cross-linked hydrogels (CN108525016A, KR20020089772A). The polyethylene glycol derivative aqueous solution is mixed with a polyethylene glycol aqueous solution whose end groups are amino groups, and the succinimide active ester group can react with the amino group to generate an amide bond, thereby forming a chemically cross-linked hydrogel. However, the reaction will produce a reaction byproduct of N-hydroxysuccinimide, which may cause toxicity; in addition, the succinimide active ester will gradually hydrolyze in the aqueous solution and lose its reactivity. In addition, polyethylene glycol derivatives whose end groups are benzaldehyde are also used to prepare chemically cross-linked hydrogels (WO2020029432A1). The polyethylene glycol derivative aqueous solution is mixed with a polyamino compound solution, and the benzaldehyde group can react with the amino group to generate a Schiff base bond, thereby forming a chemically cross-linked hydrogel. Since the Schiff base bond is easily hydrolyzed, the degree of cross-linking reaction is low, and the cross-linking density is low, the mechanical strength of the hydrogel is low.

[0004] Prior art 202010455951.3 prepares a polyethylene glycol derivative with an end group of o-phthalaldehyde, which is cross-linked with a polyethylene glycol derivative with an end group of amino through chemical bonds to form a hydrogel. However, its preparation process is complicated, the degradation rate is slow, and at the same concentration, the gelation rate is also relatively slow.

[0005] Therefore, it is very necessary to provide a polyethylene glycol derivative that is simple to prepare, has high synthetic efficiency, and shortens the gelation time and degradation time. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a polyethylene glycol derivative, a preparation method thereof and a polyethylene glycol hydrogel. The hydrogel prepared from the polyethylene glycol derivative provided by the present invention has a short degradation time, a fast gelation rate, high adhesion performance and a simple preparation process.

[0007] Firstly, the present invention simplifies the preparation process, reduces the synthesis steps of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid succinimide ester, and purifies the material by acid-base adjustment and extraction of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid, thereby greatly improving the synthesis efficiency; secondly, compared with the early patents, the grafting rate of o-phthalaldehyde is improved, which not only shortens the gelation time of the material, but also improves the adhesion to the skin; finally, compared with the early synthesis method, the introduction of ester bonds shortens the degradation time of the hydrogel, which is more in line with the healing rate of the human body.

[0008] The present invention provides a polyethylene glycol derivative, comprising a main chain having a structure of formula (IIa) and an end group having a structure of formula (IIb).

[0009]

[0010] According to the present invention, the polyethylene glycol derivative is any one of formula (IIc), formula (IId), formula (IIe), formula (IIf) and formula (IIg):

[0011]

[0012]

[0013] Wherein, a is the degree of polymerization, 1≤a≤1000;

[0014] b is the degree of polymerization, 1≤b≤1000

[0015] c is the degree of polymerization, 1≤c≤1000

[0016] d is the degree of polymerization, 1≤d≤1000

[0017] e is the degree of polymerization, 1≤e≤1000

[0018] The present invention also provides a method for preparing the polyethylene glycol derivative as claimed in claim 1 or 2, comprising the following steps:

[0019] A) reacting 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid with a polyethylene glycol having a hydroxyl terminal group to obtain a reaction product;

[0020] B) deprotecting the reaction product to obtain a polyethylene glycol derivative.

[0021] The reaction formula is as follows:

[0022]

[0023] The invention firstly dissolves 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid and polyethylene glycol with a terminal hydroxyl group in an organic solvent, and directly obtains the product through esterification reaction, trifluoroacetic acid deprotection, dialysis and freeze drying.

[0024] The molar equivalent of the 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid is preferably 1 to 3 times that of the hydroxyl group; preferably 2 times; the organic solvent is preferably anhydrous dichloromethane; and the selected esterification catalyst is preferably EDCI and DMAP.

[0025] The reaction time is 24 to 72 hours, preferably 48 hours; the reaction temperature is 10 to 40°C, preferably 25°C.

[0026] After obtaining the reaction product, the present invention performs deprotection, dialysis and freeze-drying on the reaction product to obtain the polyethylene glycol derivative.

[0027] The deprotection can be carried out by a technical solution well known to those skilled in the art. The present invention preferably uses a mixed solvent of trifluoroacetic acid and water; the volume of the mixed solvent is 5 to 10 times the mass of the reaction product, preferably 5 times; the deprotection time is 0.5 to 2 hours, preferably 1 hour; the deprotection temperature is 15 to 40°C, preferably 25°C.

[0028] The dialysis and freeze drying can be performed by using technical solutions well known to those skilled in the art.

[0029] According to the present invention, the 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid is prepared according to the following method:

[0030] 1) 3,4-dimethylbenzoic acid is subjected to a bromination reaction to prepare 3,4-bis(dibromomethyl)benzoic acid;

[0031] 2) hydrolyzing 3,4-bis(dibromomethyl)benzoic acid to obtain 3,4-diformylbenzoic acid;

[0032] 3) reacting 3,4-diformylbenzoic acid with methanol and a catalyst to obtain 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid.

[0033] The reaction formula is as follows:

[0034]

[0035] The preparation method of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid is as follows: firstly, 3,4-dimethylbenzoic acid is subjected to a bromination reaction to prepare 3,4-bis(dibromomethyl)benzoic acid.

[0036] The bromination reaction of the present invention can be carried out by using a technical solution well known to those skilled in the art. The present invention uses N-bromosuccinimide as a bromination reagent, benzoyl peroxide as a free radical initiator, and carbon tetrachloride as a solvent for the bromination reaction.

[0037] The molar equivalent of the N-bromosuccinimide is 3 to 5 times, preferably 4 times, that of 3,4-dimethylbenzoic acid; the molar equivalent of the benzoyl peroxide is 0.05 to 0.5 times, preferably 0.1 times, that of 3,4-dimethylbenzoic acid; the volume (mL) of the carbon tetrachloride is 10 to 50 times, preferably 20 times, the mass (g) of 3,4-dimethylbenzoic acid.

[0038] The temperature of the bromination reaction is 70-90° C., preferably 81° C.; the time of the bromination reaction is 10-20 hours, preferably 15 hours.

[0039] After the bromination reaction is completed, the reaction mixture is filtered; the filter cake is washed with ether; all the filtrates are combined and concentrated, and then vacuum-dried; the solid product is recrystallized in acetonitrile to obtain 3,4-bis(dibromomethyl)benzoic acid.

[0040] The present invention preferably uses a rotary evaporator for concentration; the preferred concentration temperature is 30° C.; and the concentration is preferably to 10% of the liquid volume.

[0041] The recrystallization may be carried out by using technical solutions well known to those skilled in the art.

[0042] The invention hydrolyzes 3,4-di(dibromomethyl)benzoic acid to obtain 3,4-diformylbenzoic acid.

[0043] The hydrolysis reaction can be carried out by using a technical solution well known to those skilled in the art. In the present invention, 3,4-bis(dibromomethyl)benzoic acid is preferably dissolved in an aqueous solution of sodium carbonate for hydrolysis reaction.

[0044] The mass-volume concentration of the sodium carbonate aqueous solution is 10%; the volume of the sodium carbonate aqueous solution is 5-20 times the mass of 3,4-bis(dibromomethyl)benzoic acid, preferably 10 times.

[0045] The temperature of the hydrolysis reaction is 60-80°C, preferably 70°C; the time of the hydrolysis reaction is 3-5h, preferably 4h.

[0046] After the hydrolysis reaction is completed, concentrated hydrochloric acid is used to adjust the pH of the reaction solution to 0-3, preferably 1; ethyl acetate is used for extraction; and 3,4-diformylbenzoic acid is obtained after concentration and vacuum drying.

[0047] The invention allows 3,4-diformylbenzoic acid to react with methanol and a catalyst to obtain 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid.

[0048] The catalyst is preferably scandium trifluoromethanesulfonate; the reaction temperature is 10-40° C., preferably 25° C.; the reaction time is 6-24 hours, preferably 12 hours.

[0049] After the reaction is completed, the crude product is purified by any of the following two methods, preferably method 2:

[0050] 1 is purified by silica gel column chromatography to obtain 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid. The mobile phase of the column chromatography is preferably n-hexane and ethyl acetate, with a volume ratio of 3:1.

[0051] 2 The crude product was dissolved with 5% sodium hydroxide solution, at which time the carboxylic acid became sodium carboxylate, and washed with ethyl acetate, retaining the aqueous phase. The aqueous phase was adjusted to pH = 5 with concentrated hydrochloric acid and extracted three times with ethyl acetate. The organic phases were combined and concentrated to dryness to obtain the purified 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid.

[0052] The preparation of the ester-bonded o-phthalaldehyde-capped polyethylene glycol can be carried out by a method well known to those skilled in the art. The organic solvent used in the esterification reaction is preferably dichloromethane, the organic acid selected for deprotection is a 50% trifluoroacetic acid aqueous solution, the preferred mass-volume ratio of the solution volume to the solid mass is 1 g / 10 mL, and the preferred reaction temperature is 25°C.

[0053] The present invention also provides a polyethylene glycol hydrogel, which is formed by chemically bonding a polyethylene glycol derivative and a polyethylene glycol having an amino group at the end. The polyethylene glycol derivative is the polyethylene glycol derivative according to claim 1 or 2.

[0054] Wherein, the polyethylene glycol containing an amino group at the terminal group comprises a main chain having a structure of formula (IVa) and a terminal group having a structure of any one of formula (IVb), formula (IVc) and formula (IVd);

[0055]

[0056] According to the present invention, the main chain of the polyethylene glycol containing amino groups at the terminal groups is any one of formula (Va), formula (Vb), formula (Vc), formula (Vd) and formula (Ve):

[0057]

[0058]

[0059] Wherein, a is the degree of polymerization, 1≤a≤1000;

[0060] b is the degree of polymerization, 1≤b≤1000

[0061] c is the degree of polymerization, 1≤c≤1000

[0062] d is the degree of polymerization, 1≤d≤1000

[0063] e is the degree of polymerization, 1≤e≤1000

[0064] R is any one of Formulae IVb, IVc and IVd.

[0065] The present invention also provides a method for preparing a polyethylene glycol hydrogel, which is prepared from polyethylene glycol derivatives, polyethylene glycol containing amino groups at the terminal groups, and a solvent.

[0066] In the present invention, the preparation process of the polyethylene glycol hydrogel comprises:

[0067] (1) preparing a solution 1 of the polyethylene glycol derivative;

[0068] (2) preparing a solution 2 of the polyethylene glycol having an amino group at the terminal group;

[0069] (3) The solution 1 and the solution 2 are mixed to obtain the polyethylene glycol hydrogel through a chemical reaction.

[0070] In the solution 1, the mass-volume concentration of the polyethylene glycol derivative is 1 to 1000 mg / mL, preferably 10 to 200 mg / mL.

[0071] In the solution 2, the mass-volume concentration of the polyethylene glycol containing an amino group at the terminal group is 1 to 1000 mg / mL, preferably 10 to 200 mg / mL.

[0072] The solvent used to prepare the solution 1 and the solution 2 is selected from water, physiological saline or a buffer solution, and the buffer solution is selected from a phosphate buffer solution.

[0073] The mass ratio of the polyethylene glycol derivative to the polyethylene glycol containing an amino group at the terminal group is 1:0.01-100, preferably 1:0.1-10.

[0074] The polyethylene glycol derivative provided by the invention has good water solubility and biocompatibility, and the o-phthalaldehyde at the end thereof can react chemically with various groups.

[0075] Due to the high reactivity of o-phthalaldehyde groups with amino groups, (acyl) hydrazide groups and amineoxy groups, chemically cross-linked hydrogels can be prepared by mixing the polyethylene glycol derivatives provided by the present invention with polyethylene glycol containing amino groups at the end groups. Compared with previous work, the present invention utilizes hydroxyl groups and carboxyl groups to directly carry out esterification reaction to increase the group grafting rate, thereby increasing the gelation rate of the hydrogel. At the same time, the introduction of ester bonds can also accelerate the degradation time of the hydrogel.

[0076] The polyethylene glycol derivative hydrogel with an end group of o-phthalaldehyde in the present invention can undergo an efficient coupling reaction with polyethylene glycol with an end group of amino, (acyl) hydrazide or amineoxy. It has a fast gelation rate and high mechanical strength. In practical applications, it can be used clinically as a tissue adhesive. An ideal tissue adhesive should have functions such as strong tissue adhesion, good biocompatibility, controllable degradation, rapid gelation and rapid hemostasis. Through process optimization, this patent improves the grafting rate of o-phthalaldehyde (the grafting rate is increased by 13%) compared with the earlier patent (application number: 202010455951.3), shortens the gelation time and degradation time of the material, and increases the bonding strength of the hydrogel. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 is the NMR spectrum of 3,4-bis(dibromomethyl)benzoic acid;

[0078] Figure 2 The NMR spectrum of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid;

[0079] Figure 3 The NMR spectrum of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid succinimide ester prepared in Comparative Example 1;

[0080] Figure 4 This is the NMR spectrum of 4aPEG-OPA containing ester bonds prepared in Example 6;

[0081] Figure 5 This is the NMR spectrum of 4aPEG-OPA with an amide bond as the terminal group in comparative example 2;

[0082] Figure 6 Comparative Example 2 contains amide bond 4aPEG-OPA and Example 11 contains ester bond 4aPEG-OPA NMR comparison spectra;

[0083] Figure 7 It is a statistical graph of the grafting rate of 4aPEG-OPA containing ester bonds and 4aPEG-OPA containing amide bonds;

[0084] Figure 8Comparison of gelation time of 4aPEG-OPA hydrogel containing ester bonds in Example 12 and 4aPEG-OPA hydrogel containing amide bonds in Comparative Example 3;

[0085] Fig. 9 Degradation curves of 4aPEG-OPA hydrogels containing ester bonds and 4aPEG-OPA hydrogels containing amide bonds in PBS solution in Example 13, Comparative Example 4 and Verification Example 4;

[0086] Fig.10 Degradation curves of 4aPEG-OPA hydrogels containing ester bonds and 4aPEG-OPA hydrogels containing amide bonds in Example 14, Comparative Example 5 and Verification Example 4 in a PBS solution containing proteinase K;

[0087] Fig.11 This is a statistical chart of the shear tensile test strength of pigskin made of different materials in Example 15, Comparative Example 6, Comparative Example 7 and Verification Example 5. DETAILED DESCRIPTION

[0088] The present invention provides a polyethylene glycol derivative and a preparation method thereof and a polyethylene glycol hydrogel. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the above. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and they all fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0089] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0090] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0091] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0092] The numerical ranges and parameters involved in the present invention have presented the relevant numerical values ​​in the specific embodiments as accurately as possible. However, any numerical value essentially inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise explicitly stated, it should be understood that all numerical ranges or specific data used in this disclosure may have certain reasonable deviations within a certain range, for example: within 1% or 0.5%.

[0093] Some cases are recorded in the embodiments and comparative examples of the present invention, wherein the embodiments show certain implementation modes of the present invention. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0094] In order to further illustrate the present invention, a polyethylene glycol derivative and a preparation method thereof and a polyethylene glycol hydrogel provided by the present invention are described in detail below in conjunction with examples.

[0095] Example 1

[0096]

[0097] Dissolve 3,4-dimethylbenzoic acid (50 g) and N-bromosuccinimide (267 g) in hot carbon tetrachloride (1200 mL), then slowly add 7.25 g of benzoyl peroxide. The mixture is refluxed at 81°C for 15 h. After filtration, the filter cake is washed with ether (300 mL×5). All filtrates are combined, concentrated by rotary evaporator, and then dried to solid by vacuum pump. The obtained solid is recrystallized in acetonitrile to obtain 3,4-bis(dibromomethyl)benzoic acid (55 g, 35%). The nuclear magnetic resonance characterization adopts 500M hydrogen spectrum, and the deuterated reagent is dimethyl sulfoxide-d6. Figure 1 This is the NMR spectrum of 3,4-bis(dibromomethyl)benzoic acid.

[0098] Example 2

[0099]

[0100] 3,4-bis(dibromomethyl)benzoic acid (55 g) prepared in Example 1 was dissolved in a sodium carbonate aqueous solution (550 mL) having a mass-volume concentration of 10%, and reacted at 70°C for 4 h. The pH of the reaction solution was adjusted to 1 with concentrated hydrochloric acid, and then extracted with ethyl acetate (4×200 mL). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and vacuum-dried to obtain 3,4-diformylbenzoic acid (13.7 g, 65%).

[0101] Example 3

[0102]

[0103] 3,4-diformylbenzoic acid (13.7 g) prepared in Example 2 was dissolved in anhydrous methanol (400 mL), and then a catalyst, scandium trifluoromethanesulfonate (2 g), was added and reacted for 12 h. The crude product of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid was obtained by vacuum drying. The crude product was purified by any of the following methods:

[0104] 1 was obtained by column chromatography, the mobile phase was V 石油醚 / V 乙酸乙酯 =5:1.

[0105] 2 Dissolve with 500 mL 5% sodium hydroxide solution, wash with 300 mL ethyl acetate × 3 and retain the aqueous phase. Adjust the aqueous phase to pH = 6 with concentrated hydrochloric acid, extract with 300 mL ethyl acetate × 3, retain the organic phase, dry with anhydrous magnesium sulfate, filter and spin dry.

[0106] The product was a white solid (15 g, 87%), characterized by 500 MHz hydrogen spectrum, and the deuterated reagent was dimethyl sulfoxide-d6. Figure 2 This is the NMR spectrum of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid.

[0107] Example 4

[0108] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15g) prepared in Example 3 was dissolved in 300mL dichloromethane, and EDCI (19g) and DMAP (2g) were added for pre-reaction for 30min. Subsequently, 600mL of dichloromethane solution of linear polyethylene glycol (number average molecular weight 2000, 33.4g) with hydroxyl end groups was added, and the reaction was performed for 48h. After the reaction was completed, the mixture was concentrated and spin-dried, dissolved in dichloromethane (1000mL), washed with water, and the organic phase was spin-dried again, and 500mL of trifluoroacetic acid aqueous solution (V ) was added. 三氟乙酸 :V 水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (31 g, 79%).

[0109] Example 5

[0110] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15g) prepared in Example 3 was dissolved in 300mL of dichloromethane, and EDCI (19g) and DMAP (2g) were added for pre-reaction for 30min. Subsequently, 600mL of a dichloromethane solution of a three-arm polyethylene glycol (number average molecular weight 10000, 111.5g) with a hydroxyl end group was added, and the reaction was performed for 48h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000mL), washed with water, and the organic phase was dried again, and 500mL of an aqueous solution of trifluoroacetic acid (V 三氟乙酸 :V水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (102 g, 87%).

[0111] Example 6

[0112]

[0113] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 was dissolved in 300 mL of dichloromethane, and EDCI (19 g) and DMAP (2 g) were added for a pre-reaction of 30 min. Subsequently, 600 mL of a dichloromethane solution of a four-arm polyethylene glycol (number average molecular weight 10000, 83.6 g) having a hydroxyl end group was added, and the reaction was continued for 48 h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000 mL), washed with water, and the organic phase was dried again, and 500 mL of an aqueous solution of trifluoroacetic acid (V ) was added. 三氟乙酸 :V 水 =1:1) for 1.5 h of reaction and deprotection. After the reaction, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (4aPEG-OPA) (81.5 g, 92%). The NMR characterization was performed using a 500M hydrogen spectrum. The deuterated reagent was D 2 Oh, Figure 4 This is the NMR spectrum of 4aPEG-OPA containing ester bonds prepared in Example 6.

[0114] Example 7

[0115] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 was dissolved in 300 mL of dichloromethane, and EDCI (19 g) and DMAP (2 g) were added for a pre-reaction of 30 min. Subsequently, 600 mL of a dichloromethane solution of a four-arm polyethylene glycol (number average molecular weight 20,000, 167.2 g) having a hydroxyl end group was added, and the reaction was continued for 48 h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000 mL), washed with water, and the organic phase was dried again, and 500 mL of an aqueous solution of trifluoroacetic acid (V ) was added. 三氟乙酸 :V 水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (164 g, 95%).

[0116] Example 8

[0117] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 was dissolved in 300 mL of dichloromethane, and EDCI (19 g) and DMAP (2 g) were added for a pre-reaction of 30 min. Subsequently, 600 mL of a dichloromethane solution of a six-arm polyethylene glycol (number average molecular weight 10000, 55.75 g) having a hydroxyl end group was added, and the reaction was continued for 48 h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000 mL), washed with water, and the organic phase was dried again, and 500 mL of an aqueous solution of trifluoroacetic acid (V ) was added. 三氟乙酸 :V 水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (54 g, 88%).

[0118] Example 9

[0119] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15g) prepared in Example 3 was dissolved in 300mL of dichloromethane, and EDCI (19g) and DMAP (2g) were added for pre-reaction for 30min. Subsequently, 600mL of dichloromethane solution of six-arm polyethylene glycol (number average molecular weight 20000, 111.5g) with hydroxyl end groups was added, and the reaction was carried out for 48h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000mL), washed with water, and the organic phase was dried again, and 500mL of trifluoroacetic acid aqueous solution (V 三氟乙酸 :V 水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (106 g, 91%).

[0120] Example 10

[0121] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 was dissolved in 300 mL of dichloromethane, and EDCI (19 g) and DMAP (2 g) were added for a pre-reaction of 30 min. Subsequently, 600 mL of a dichloromethane solution of an eight-arm polyethylene glycol (number average molecular weight 10000, 41.8 g) having a hydroxyl end group was added, and the reaction was continued for 48 h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000 mL), washed with water, and the organic phase was dried again, and 500 mL of an aqueous solution of trifluoroacetic acid (V ) was added. 三氟乙酸 :V 水 =1:1) react for 1.5h to remove the protection, and after the reaction is completed, transfer to a dialysis bag for dialysis and freeze-drying to obtain a white solid (39g, 82%).

[0122] Embodiment 11

[0123] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 was dissolved in 300 mL of dichloromethane, and EDCI (19 g) and DMAP (2 g) were added for a pre-reaction of 30 min. Subsequently, 600 mL of a dichloromethane solution of an eight-arm polyethylene glycol (number average molecular weight 20,000, 83.6 g) having a hydroxyl end group was added, and the reaction was continued for 48 h. After the reaction was completed, the mixture was concentrated and dried, dissolved in dichloromethane (1000 mL), washed with water, and the organic phase was dried again, and 500 mL of an aqueous solution of trifluoroacetic acid (V 2) was added. 三氟乙酸 :V 水 =1:1) and reacted for 1.5 h for deprotection. After the reaction was completed, the mixture was transferred to a dialysis bag for dialysis and freeze-drying to obtain a white solid (82 g, 92%). Figure 6 This is a comparative NMR spectrum of 4aPEG-OPA containing an amide bond in Comparative Example 2 and 4aPEG-OPA containing an ester bond in Example 11.

[0124] Example 12

[0125] Four-arm polyethylene glycol (number average molecular weight 10000) with amino terminal groups and four-arm polyethylene glycol (number average molecular weight 10000) with o-phthalaldehyde terminal groups containing ester bonds were dissolved in PBS solution to prepare solutions with mass fractions of 5%, 10% and 15%, respectively. At the same mass fraction, 150 μL of each was taken out, fully mixed in a centrifuge tube, and placed in a 37°C water bath to gel. The gelation time was collected. The number of collections at different mass fractions was ≥3 times and the results were statistically analyzed. The final data is as follows: Figure 8 shown. Figure 8 This is a comparison chart of the gelation time of the 4aPEG-OPA hydrogel containing ester bonds in Example 12 and the 4aPEG-OPA hydrogel containing amide bonds in Comparative Example 3.

[0126] Example 13

[0127] Four-arm polyethylene glycol with amino terminal groups (number average molecular weight 10000) and four-arm polyethylene glycol with o-phthalaldehyde terminal groups containing ester bonds (number average molecular weight 10000) were dissolved in PBS solution to prepare a solution with a mass fraction of 10%. After sufficient dissolution, 150 μL of each solution was taken out and placed in a 4 mL vial with a known weight, and 3 mL of PBS solution was added. The solution was placed in a 37°C constant temperature shaking box. All the solution was sucked away with a pipette during the interval and weighed. Then, 3 mL of fresh PBS solution was added again. The mass change pattern was statistically analyzed. The mass change pattern is as follows: Fig. 9 shown. Fig. 9 These are the degradation curves of the 4aPEG-OPA hydrogel containing ester bonds and the 4aPEG-OPA hydrogel containing amide bonds in Example 13 and Comparative Example 4 in PBS solution.

[0128] Embodiment 14

[0129] Four-arm polyethylene glycol (number average molecular weight 10000) with amino terminal groups and four-arm polyethylene glycol (number average molecular weight 10000) with o-phthalaldehyde terminal groups containing ester bonds were dissolved in PBS solution to prepare a solution with a mass fraction of 10%. After sufficient dissolution, 150 μL of each solution was taken out and placed in a 4 mL vial with a known weight, and 3 mL of PBS solution containing proteinase K (10 U) was added. The solution was placed in a 37°C constant temperature shaking box. All the solution was aspirated with a pipette and weighed every other day, and then 3 mL of fresh PBS solution containing proteinase K was added again. The mass change pattern was statistically analyzed. The mass change pattern is as follows: Fig.10 shown. Fig.10 These are the degradation curves of the 4aPEG-OPA hydrogel containing ester bonds and the 4aPEG-OPA hydrogel containing amide bonds in Example 14 and Comparative Example 5 in a PBS solution containing proteinase K.

[0130] Embodiment 15

[0131] Fresh pig skin was cut into rectangular shapes with a width of 2.5 cm and a length of 7.5 cm and pasted on a wooden board for later use. 2 Prepare 10% solution by mass and mix equal volumes. Take out 50 μL and quickly apply it on the pre-prepared pig skin. The application area is 2.5 cm × 2.5 cm. After application, quickly stick it together and place it in a constant temperature water bath at 37°C for 40 minutes. After that, use a universal testing machine to measure its tensile strength. Fig.11 This is a statistical chart of the shear tensile test strength of pigskin made of different materials in Example 15, Comparative Examples 6 and 7.

[0132] Comparative Example 1

[0133] 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid (15 g) prepared in Example 3 and N-hydroxysuccinimide (16.9 g) were dissolved in 300 mL of anhydrous acetonitrile, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (14.1 g) was added and reacted for 12 h. After the reaction was completed, the mixture was spin-dried and dissolved in dichloromethane, washed with water (300 mL × 3), the organic phase was retained and dried with magnesium sulfate, and filtered. The crude product was purified by silica gel column chromatography with the mobile phase being V 石油醚 :V 乙酸乙酯 =3:1, and a white solid 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid succinimide ester (11 g, 51%) was obtained. The nuclear magnetic resonance characterization was performed using a 500 MHz hydrogen spectrum, and the deuterated reagent was deuterated chloroform. Figure 3This is the NMR spectrum of 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid succinimide ester prepared in Comparative Example 1.

[0134] Comparative Example 2

[0135] The 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid succinimide ester (11 g) prepared in Comparative Example 1 was dissolved in 300 mL of dichloromethane, and then 600 mL of dichloromethane solution of four-arm polyethylene glycol (number average molecular weight 10000, 42.7 g) with amino terminal groups was added, and the reaction was carried out for 48 hours. After the reaction was completed, the mixture was concentrated and dried, and 500 mL of an aqueous solution of trifluoroacetic acid (V 三氟乙酸 :V 水 =1:1) for 1.5 h of reaction and deprotection. After the reaction, the mixture was transferred to a dialysis bag and dialyzed for 72 h and then freeze-dried to obtain 4aPEG-OPA white solid (43.2 g, 93%) containing an amide bond. The NMR characterization was performed using a 500M hydrogen spectrum. The deuterated reagent was D 2 Oh, Figure 5 This is the NMR spectrum of 4aPEG-OPA in comparative example 2 whose terminal group is an amide bond.

[0136] Comparative Example 3

[0137] Four-arm polyethylene glycol (number average molecular weight 10000) with amino terminal groups and four-arm polyethylene glycol (number average molecular weight 10000) with o-phthalaldehyde terminal groups containing amide bonds were dissolved in PBS solution to prepare solutions with mass fractions of 5%, 10% and 15%, respectively. At the same mass fraction, 150 μL of each was taken out, fully mixed in a centrifuge tube, and placed in a 37°C water bath to gel. The gelation time was collected. The number of collections at different mass fractions was ≥3 times and the results were statistically analyzed. The statistical results are shown in the figure. Figure 8 As shown. Figure 8 It can be seen that among the three hydrogels with different mass fractions, the gelation time of 4aPEG-OPA hydrogel containing ester bonds is significantly faster than that of 4aPEG-OPA hydrogel containing amide bonds.

[0138] Comparative Example 4

[0139] Four-arm polyethylene glycol with amino terminal groups (number average molecular weight 10000) and four-arm polyethylene glycol with o-phthalaldehyde terminal groups containing amide bonds (number average molecular weight 10000) were dissolved in PBS solution to prepare a solution with a mass fraction of 10%. After thorough mixing, 150 μL of each solution was taken out and placed in a 4 mL vial with a known weight. 3 mL of PBS solution was added and placed in a 37°C constant temperature shaking box. All the solution was aspirated with a pipette and weighed every other day, and then 3 mL of fresh PBS solution was added again. The mass change pattern was statistically analyzed. The mass change pattern is as follows: Fig. 9As shown in the figure, the 4aPEG-OPA hydrogel containing ester bonds has a higher swelling rate and faster degradation time than the 4aPEG-OPA hydrogel containing amide bonds.

[0140] Comparative Example 5

[0141] Four-arm polyethylene glycol (number average molecular weight 10000) with amino terminal groups and four-arm polyethylene glycol (number average molecular weight 10000) with o-phthalaldehyde terminal groups containing amide bonds were dissolved in PBS solution to prepare a solution with a mass fraction of 10%. After thorough mixing, 150 μL of each solution was taken out and placed in a 4 mL vial with a known weight. 3 mL of PBS solution containing proteinase K was added and placed in a 37°C constant temperature shaking box. All the solution was aspirated with a pipette and weighed every other day, and then 3 mL of fresh PBS solution containing proteinase K was added again. The mass change pattern was statistically analyzed. The mass change pattern is as follows: Fig.10 As shown in the figure, the addition of proteinase K accelerated the swelling rate and degradation rate of 4aPEG-OPA hydrogel containing ester bonds, which had a higher swelling rate and faster degradation time than 4aPEG-OPA hydrogel containing amide bonds.

[0142] Comparative Example 6

[0143] Fresh pig skin was cut into rectangular shapes with a width of 2.5 cm and a length of 7.5 cm and pasted on a wooden board for later use. 2 Prepare 10% solution by mass and mix equal volumes, take out 50 μL and quickly apply it on the pre-prepared pig skin, with the application area of ​​2.5 cm × 2.5 cm. After application, quickly stick them together and place them in a constant temperature water bath at 37°C for 40 minutes. After that, use a universal testing machine to measure the tensile strength.

[0144] Comparative Example 7

[0145] Cut fresh pigskin into rectangular shapes with a width of 2.5 cm and a length of 7.5 cm and stick them on a wooden board for later use. Quickly apply 50 μL of commercially available fibrin glue solution on the pre-prepared pigskin, with an application area of ​​2.5 cm × 2.5 cm. After application, quickly stick them together and place them in a constant temperature water bath at 37°C for 40 minutes. After completion, use a universal testing machine to measure their tensile strength. Fig.11 This is a comparison chart of skin stretching between Example 15 and Comparative Examples 6 and 7. It can be seen from the figure that the 4aPEG-OPA hydrogel containing ester bonds has higher tensile strength.

[0146] Verification Example 1

[0147] Compared with the phthalaldehyde-terminated polyethylene glycol containing amide bonds prepared in the earlier work (application number: 202010455951.3), the phthalaldehyde-terminated polyethylene glycol containing ester bonds prepared in this patent has an additional -CH 2 - vibration peak, the overall chemical shift remains basically unchanged. Figure 6 This is a comparative NMR spectrum of 4aPEG-OPA containing an amide bond in Comparative Example 2 and 4aPEG-OPA containing an ester bond in Example 11.

[0148] Verification Example 2

[0149] Through Figure 1 The grafting rate was calculated by nuclear magnetic integration, and the grafting rate of 4aPEG-OPA containing ester bonds was calculated to be 81%. The grafting rate of 4aPEG-OPA containing amide bonds prepared by o-phthalaldehyde-terminated polyethylene glycol containing amide bonds in early work (application number: 202010455951.3) was 69%. In order to further calculate the grafting rate, the two groups of samples were tested three times in parallel, and their grafting rates were calculated. The results show that the grafting rate of 4aPEG-OPA containing ester bonds is significantly higher than that of 4aPEG-OPA containing amide bonds prepared in the early patent (application number: 202010455951.3). This patent improves the grafting rate of o-phthalaldehyde by optimizing the process (the grafting rate is increased by 13%). Figure 7 Statistical graph of the grafting rate of 4aPEG-OPA containing ester bonds and 4aPEG-OPA containing amide bonds.

[0150] Verification Example 3

[0151] In the gelation experiment, the gelation time of the two hydrogels at three concentrations of 5%, 10% and 15% were compared. The results showed that the gelation rate of 4aPEG-OPA hydrogel containing ester bonds was significantly higher than that of 4aPEG-OPA hydrogel containing amide bonds. Figure 8 This is a comparison chart of the gelation time of the 4aPEG-OPA hydrogel containing ester bonds in Example 12 and the 4aPEG-OPA hydrogel containing amide bonds in Comparative Example 3.

[0152] Verification Example 4

[0153] In the in vitro degradation experiment, two gels with a mass fraction of 10% were tested in PBS buffer solution and PBS solution containing proteinase K (concentration of 10U / mL). The results showed that compared with 4aPEG-OPA hydrogels containing amide bonds, 4aPEG-OPA hydrogels containing ester bonds showed higher swelling rates and faster degradation rates in both solutions. The addition of proteinase K further accelerated the degradation of 4aPEG-OPA hydrogels containing ester bonds. Fig. 9The degradation curves of the two hydrogels of Example 13 and Comparative Example 4 in PBS buffer solution. Fig.10 The degradation curves of the two hydrogels of Example 14 and Comparative Example 5 in a PBS solution containing proteinase K are shown.

[0154] Verification Example 5

[0155] The pig skin was used as the experimental object, and the skin shear test was carried out on it with two hydrogels with a mass fraction of 10%, and fibrin glue was used as the control group. The results showed that the hydrogel containing ester bonds showed higher skin tensile strength. Fig.11 Comparative data of skin-mounted shear tests of 4aPEG-OPA hydrogel containing ester bonds in Example 15, 4aPEG-OPA hydrogel containing amide bonds in Comparative Example 6, and fibrin glue in Comparative Example 7.

[0156] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polyethylene glycol derivative, It is characterized in that It includes a main chain having a structure of formula (IIa) and an end group having a structure of formula (IIb); 2. The polyethylene glycol derivative according to claim 1, It is characterized in that The polyethylene glycol derivative is any one of formula (IIc), formula (IId), formula (IIe), formula (IIf) and formula (IIg): Wherein, a is the degree of polymerization, 1≤a≤1000; b is the degree of polymerization, 1≤b≤1000; c is the degree of polymerization, 1≤c≤1000; d is the degree of polymerization, 1≤d≤1000; e is the degree of polymerization, 1≤e≤1000.

3. A method for preparing the polyethylene glycol derivative according to claim 1 or 2, It is characterized in that The following steps are involved: A) reacting 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid with a polyethylene glycol having a hydroxyl terminal group to obtain a reaction product; B) deprotecting the reaction product to obtain a polyethylene glycol derivative.

4. The preparation method according to claim 3, It is characterized in that The 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid is prepared according to the following method: 1) 3,4-dimethylbenzoic acid is subjected to a bromination reaction to prepare 3,4-bis(dibromomethyl)benzoic acid; 2) hydrolyzing 3,4-bis(dibromomethyl)benzoic acid to obtain 3,4-diformylbenzoic acid; 3) reacting 3,4-diformylbenzoic acid with methanol and a catalyst to obtain 1,3-dimethoxy-1,3-dihydroisobenzofuran-5-carboxylic acid.

5. A polyethylene glycol hydrogel, It is characterized in that It is formed by chemically bonding a polyethylene glycol derivative and a polyethylene glycol having an amino group at the terminal. The polyethylene glycol derivative is the polyethylene glycol derivative according to claim 1 or 2.

6. The polyethylene glycol hydrogel according to claim 5, It is characterized in that The polyethylene glycol containing amino groups at the terminal groups comprises a main chain having a structure of formula (IVa) and a terminal group having a structure of any one of formulas (IVb), (IVc), (IVd) and (IVd); -NH 2 (IVb); 7. The polyethylene glycol hydrogel according to claim 5, It is characterized in that The main chain of the polyethylene glycol containing amino groups at the terminal groups is any one of formula (Va), formula (Vb), formula (Vc), formula (Vd) and formula (Ve): Wherein, a is the degree of polymerization, 1≤a≤1000; b is the degree of polymerization, 1≤b≤1000 c is the degree of polymerization, 1≤c≤1000 d is the degree of polymerization, 1≤d≤1000 e is the degree of polymerization, 1≤e≤1000 R is any one of Formulae IVb, IVc and IVd.

8. A method for preparing the polyethylene glycol hydrogel as claimed in claims 5 to 7, It is characterized in that The invention is prepared from polyethylene glycol derivatives, polyethylene glycol containing amino groups at the terminal groups and solvents.

9. The preparation method according to claim 8, It is characterized in that The solvent is water, physiological saline or buffer solution; The mass-volume concentration of the polyethylene glycol derivative is 1 to 1000 mg / mL; The mass-volume concentration of the polyethylene glycol containing amino groups at the terminal groups is 1 to 1000 mg / mL.

10. The preparation method according to claim 8, It is characterized in that The mass ratio of the polyethylene glycol derivative to the polyethylene glycol containing an amino group at the terminal is 1:0.01-100.

Images