阅读说明：本技术 一种基于多巴胺的高强度自主自愈性水凝胶及其制备方法 (High-strength self-healing hydrogel based on dopamine and preparation method thereof ) 是由 张伟 黄金鑫 吴承伟 于 2020-04-28 设计创作，主要内容包括：一种基于多巴胺的高强度自主自愈性水凝胶及其制备方法,属于生物材料领域。高强度自主自愈性水凝胶质量以100wt％计,各组分及其质量百分比为：聚多巴胺含量为0.15wt％～0.88wt％、丙烯酰胺含量为17.56wt％～18.18wt％,其余为去离子水。由多巴胺溶解在碱性水溶液中,调节pH为8-14,充分搅拌,使多巴胺预聚形成聚多巴胺,得到聚多巴胺溶液。室温下,将丙烯酰胺、N,N’-亚甲基双丙烯酰胺和过硫酸铵与聚多巴胺溶液混合,充分搅拌混合均匀后,再加入助剂四甲基乙二胺,使丙烯酰胺聚合形成聚多巴胺-聚丙烯酰胺水凝胶。本发明采用简单的两步法成功制备了的聚多巴胺-聚丙烯酰胺水凝胶,高强度水凝胶具有良好的自愈合性能,水凝胶在受损断裂后在无外界刺激的条件下快速恢复其力学性能。(A high-strength self-healing hydrogel based on dopamine and a preparation method thereof belong to the field of biological materials. The high-strength self-healing hydrogel comprises the following components in percentage by mass, wherein the weight of the high-strength self-healing hydrogel is 100 percent by mass: 0.15-0.88 wt% of polydopamine, 17.56-18.18 wt% of acrylamide and the balance of deionized water. Dissolving dopamine in an alkaline aqueous solution, adjusting the pH value to 8-14, and fully stirring to ensure that dopamine is pre-polymerized to form polydopamine so as to obtain polydopamine solution. Mixing acrylamide, N' -methylene bisacrylamide, ammonium persulfate and polydopamine solution at room temperature, fully stirring and uniformly mixing, and then adding auxiliary agent tetramethyl ethylenediamine to polymerize the acrylamide to form polydopamine-polyacrylamide hydrogel. The polydopamine-polyacrylamide hydrogel is successfully prepared by adopting a simple two-step method, the high-strength hydrogel has good self-healing performance, and the mechanical properties of the hydrogel can be quickly recovered under the condition of no external stimulation after the hydrogel is damaged and broken.)

1. The high-strength self-healing hydrogel is characterized in that the high-strength self-healing hydrogel is polydopamine-polyacrylamide hydrogel and consists of polydopamine, polyacrylamide and deionized water; the polydopamine-polyacrylamide hydrogel comprises the following components in percentage by mass, based on 100 wt%: 0.15-0.88 wt% of polydopamine, 17.56-18.18 wt% of acrylamide and the balance of deionized water; wherein, acrylamide monomer forms a polymer network through a cross-linking agent N, N' -methylene bisacrylamide; the polydopamine chain is connected to the polyacrylamide amino network through a reversible non-covalent bond between a free catechol group and a polyacrylamide amino group; reversible non-covalent bonds are formed between the catechol groups of the polydopamine chains.

2. The high-strength self-healing hydrogel according to claim 1, wherein said polydopamine-polyacrylamide hydrogel has a high tensile strength of 9.4-16.2 kPa; the tensile breaking productivity is 1280% -1610%; after self-healing for 2 hours without external stimulation, the tensile strength can be recovered to 70-96%, and the composite material has good biocompatibility and high stretchability.

3. A method for preparing the dopamine-based high-strength self-healing hydrogel according to claim 1 or 2, comprising the steps of:

firstly, dissolving dopamine powder in an alkaline aqueous solution at room temperature, wherein the concentration of dopamine is 0.15-0.88 wt%; after stirring, adding ammonium persulfate, adjusting the pH value to 8-14, and fully stirring for more than 2 hours to ensure that dopamine is prepolymerized to form polydopamine to obtain polydopamine solution;

secondly, mixing acrylamide, N' -methylene bisacrylamide and ammonium persulfate with the polydopamine solution in the first step at room temperature; fully stirring and uniformly mixing, and then adding auxiliary agent tetramethyl ethylenediamine to polymerize acrylamide to form polydopamine-polyacrylamide hydrogel;

the high-strength self-healing hydrogel comprises the following components in percentage by weight 100 percent: in the first step, the content of ammonium persulfate is 0-3.51 wt%, and the content of deionized water is 77.27-79.98 wt%; in the second step, the acrylamide content is 17.56 wt% -18.18 wt%, the tetramethylethylenediamine content is 0.05 wt% -0.15 wt%, the N, N' -methylenebisacrylamide content is 0.008 wt% -0.029 wt%, and the ammonium persulfate content is 0.7 wt% -1.45 wt%.

4. The method according to claim 3, wherein the aqueous alkaline solution is a sodium hydroxide solution.

Technical Field

The invention belongs to the field of biological materials, and relates to a dopamine-based hydrogel with high mechanical strength and self-healing property and a preparation method thereof.

Background

The functional hydrogel based on dopamine has the performances of good biocompatibility, strong cell adhesion, good self-healing property, strong tissue adhesion property and the like, so that the functional hydrogel based on dopamine has wide application in many fields such as biological materials, tissue engineering and the like, and becomes one of research hotspots in the field of hydrogel functional materials.

In order to prepare a hydrogel with good biocompatibility and self-healing performance (without any external stimulation), researchers have reconstructed the hydrogel network by utilizing reversible interactions between phenolic hydroxyl groups on the polydopamine and amino groups on the polyacrylamide, between hydrogen bonds and pi-pi stacking between the polydopamine, have developed a polydopamine-polyacrylamide hydrogel with good self-healing ability while avoiding the potential toxicity brought by metal chelation, the polydopamine-polyacrylamide hydrogel with a tensile strength of 8kPa has been broken without requiring external stimulation for an internal strength of 2h (cited document: Han, L. et al. npg Asia Mater 2017,9(4), e 372-e.). with a lower tensile strength, which does not satisfy 98% restoration of tensile strength in the tissue engineering and the tissue engineering field after breaking (cited document: Han, L. et al. npg Asia 2017,9, e 372-e.). the original tensile strength of the hydrogel is generally reduced by external stimulation (the intrinsic tensile strength of the polydopamine-polyacrylamide hydrogel) or by metal chelation, such as the natural-healing hydrogel after implantation in a biological hydrogel, has been implanted into a living organism, has been developed into a hydrogel with a high self-healing strength, such as a high mechanical strength of a hydrogel, such as a hydrogel, a high as a hydrogel, a hydrogel with a high self-26 kPa, 26-7-26 kPa, generally, a self-26-160-7-160-7-4-7-60-7-60-4-2-60-2-4-7-4-2-4.

An effective method for improving the polydopamine content in the hydrogel and providing sufficient reversible interaction for self-healing of the hydrogel. However, the polydopamine self-healing hydrogel of polydopamine-polyacrylamide reported in the prior literature has a low polydopamine content (the mass ratio of dopamine to acrylamide is less than 0.8%, which is equivalent to 0.15 wt%) (cited literature: Suneetha M.et al. ACS Omega,2019, vol.4, No.7, pp. 12647-12656. ZHao Z.et al. SciRep,2017, vol.7, No.1, pp.1-10.) because dopamine cannot be polymerized simply by increasing the oxidant content in the current research, and H is generated during dopamine oxidative polymerization⁺The pH of the solution environment is reduced even to be acidic, the polymerization reaction can be inhibited even though an oxidant dopamine is used, unpolymerized dopamine can block the polymerization of acrylamide, so that the gelation of the polydopamine-polyacrylamide hydrogel fails, and the polydopamine-polyacrylamide hydrogel with low polydopamine content is difficult to realize high self-healing efficiency and cannot meet the application requirements. Therefore, the search for a method for preparing a polydopamine-polyacrylamide hydrogel with high dopamine content is a problem to be solved urgently.

Disclosure of Invention

In view of the problems in the prior art described above, the present invention is directed to: the polydopamine-polyacrylamide hydrogel with high dopamine content, high strength, high autonomous self-healing efficiency and good biocompatibility is prepared by a simple process, and is expected to be applied to the field of biomedical materials.

Aiming at the problems in the prior art, the invention can provide the polydopamine-polyacrylamide hydrogel and the preparation method thereof.

The technical scheme of the invention is as follows:

the high-strength self-healing hydrogel is poly-dopamine-polyacrylamide hydrogel and consists of poly-dopamine, polyacrylamide and deionized water. The polydopamine-polyacrylamide hydrogel comprises the following components in percentage by mass, based on 100 wt%: 0.15-0.88 wt% of polydopamine, 17.56-18.18 wt% of acrylamide and the balance of deionized water. Wherein the acrylamide monomer forms a polymer network through a cross-linking agent N, N' -methylene bisacrylamide. The polydopamine chains are linked to the polyacrylamide amino network by reversible non-covalent bonds between free catechol groups and polyacrylamide amino groups. Reversible non-covalent bonds are formed between the catechol groups of the polydopamine chains, including pi-pi stacking and hydrogen bonding.

The polydopamine-polyacrylamide hydrogel has high tensile strength (9.4-16.2kPa), tensile breaking productivity of 1280-1610%, and tensile strength recovery to 70-96% after self-healing for 2h without external stimulation, and has good biocompatibility and high stretchability.

A preparation method of a high-strength self-healing hydrogel based on dopamine comprises the following steps:

firstly, dissolving dopamine powder in an alkaline aqueous solution at room temperature, wherein the concentration of dopamine is 0.15-0.88 wt%. And after stirring, adding ammonium persulfate, adjusting the pH value, keeping the pH value at 8-14, and fully stirring for more than 2 hours to ensure that dopamine polymerization reaches reaction balance under an alkaline environment, so that dopamine is prepolymerized to form polydopamine to obtain a polydopamine solution.

The alkaline aqueous solution is sodium hydroxide solution.

And secondly, mixing acrylamide, N' -methylene bisacrylamide and ammonium persulfate with the polydopamine solution in the first step at room temperature. Fully stirring and uniformly mixing, and then adding auxiliary agent tetramethyl ethylenediamine to polymerize acrylamide to form polydopamine-polyacrylamide hydrogel.

The high-strength self-healing hydrogel comprises the following components in percentage by weight 100 percent: in the first step, the content of the ammonium persulfate is 0-3.51 wt%, the content of the deionized water is 77.27-79.98 wt%, when the content of the dopamine is low, the ammonium persulfate is not added in the first step, and the excessive ammonium persulfate is added in the second part to promote the oxidative polymerization of the residual dopamine. In the second step, the acrylamide content is 17.56 wt% -18.18 wt%, the tetramethylethylenediamine content is 0.05 wt% -0.15 wt%, the N, N' -methylenebisacrylamide content is 0.008 wt% -0.029 wt%, and the ammonium persulfate content is 0.7 wt% -1.45 wt%.

When the dopamine content in the first step is low and ammonium persulfate is not added, the ammonium persulfate, tetramethylethylenediamine and N, N' -methylenebisacrylamide added in the second step are relatively high in content. This is because, if dopamine is not oxidatively polymerized with ammonium persulfate in the first step, there may be remaining unpolymerized dopamine inhibiting acrylamide hydrogel polymerization, so that oxidative polymerization with an excess of ammonium persulfate is added to ensure successful dopamine polymerization, and the auxiliaries tetramethylethylenediamine and N, N' -methylenebisacrylamide are also added relatively more to accelerate acrylamide gelation.

The first step is to promote the rapid polymerization of dopamine, ammonium persulfate is added as an oxidant to ensure that dopamine can be polymerized in an alkaline and weakly acidic environment, and meanwhile, the pH value is adjusted to be 8-14 to accelerate the polymerization reaction of dopamine so as to avoid that unpolymerized dopamine hinders the smooth polymerization of acrylamide. A large amount of polydopamine prepolymer is formed by an alkaline oxidation polymerization method, various non-covalent bond effects are introduced into a polyacrylamide network, and the hydrogel has good self-healing property and high mechanical property; and the phenolic hydroxyl groups remained in the polydopamine endows the hydrogel with good cell affinity. Even though the molecular chain mobility of the high strength polydopamine-polyacrylamide hydrogel is low, more reversible bonds give the hydrogel rapid and effective self-healing properties.

The second step is to compound the polydopamine prepolymer in situ in an elastic network formed by polyacrylamide to form polydopamine-polyacrylamide hydrogel. The preparation process is simple, the process quality is easy to control, and the residual unpolymerized reductive dopamine molecules are not necessary to worry about inhibiting the ammonium persulfate/tetramethylethylenediamine system from generating oxygen free radicals to hinder the acrylamide polymerization.

According to the preparation method of the polydopamine-polyacrylamide hydrogel, the defects that the conventional polydopamine-polyacrylamide hydrogel with high polydopamine content fails to gel and the self-healing efficiency of the high-strength hydrogel is low can be overcome.

Compared with the prior art, the invention has the following beneficial effects:

(1) the polydopamine-polyacrylamide hydrogel is successfully prepared by adopting a simple two-step method. The first step is to utilize an oxidant to oxidize dopamine for polymerization in an alkaline environment, so that polydopamine is successfully, efficiently and quickly synthesized, and smooth polymerization of hydrogel in the second step is ensured.

(2) The preparation method of the invention provides high-content polydopamine for the hydrogel system, phenolic hydroxyl groups on the molecular chain of the polydopamine and active groups in a hydrogel network form more dynamic non-covalent bonds, and the high-strength hydrogel has good self-healing performance, so that the hydrogel can quickly recover the mechanical properties under the condition of no external stimulation after being damaged and broken.

Drawings

FIG. 1 is a stress-strain curve of a hydrogel tensile fracture after healing for 2 hours after the polydopamine-polyacrylamide hydrogel is fractured by pulling.

FIG. 2 is an infrared spectrum of dopamine and polydopamine.

Fig. 3(a) shows the storage modulus and loss modulus dissipation modulus of the polydopamine-polyacrylamide hydrogel during strain scanning, (f ═ 1Hz, 25 ℃).

FIG. 3(b) is the relationship between storage modulus and dissipation modulus during self-healing and time (frequency: 1.0 Hz; strain: 1.0%).

FIG. 4 is a stress-strain curve of the tensile failure of the hydrogel after 0.5, 1 and 2 hours of healing after the poly-dopamine-polyacrylamide hydrogel is pulled off.

Fig. 5 is a graph of the cytotoxicity of polydopamine-polyacrylamide hydrogels at different concentrations. Data presented are mean ± standard deviation of 4 experiments.

Detailed Description

The present invention is described in detail below according to specific embodiments with reference to the attached drawings. It should be appreciated that the description is not intended to limit the invention to the following embodiments. On the contrary, the invention is intended to cover not only these embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.