A method for preparing high-strength and fine-denier silk using nitrogen-rich hyperbranched molecules

Abstract

The present invention belongs to the technical field of silk materials, and specifically relates to a method for preparing high-strength and fine-denier silk using nitrogen-rich hyperbranched molecules. The present invention adopts aromatic amine and acid to prepare nitrogen-rich hyperbranched molecules through a one-step hydrothermal method through polymerization reaction. The nitrogen-rich hyperbranched molecules prepared by the present invention will not cause harm to the growth and development of silkworms and the environment during the feeding and silkworm rearing process. The present invention continuously feeds silkworms with artificial feed containing nitrogen-rich hyperbranched molecules from the end of the fourth instar to the beginning of the fifth instar when silk protein is synthesized. Through the absorption of nitrogen-rich hyperbranched molecules by the silkworms, a large amount of nitrogen-rich hyperbranched molecules are present in the silkworms' bodies. During the synthesis of silk protein, the nitrogen-rich hyperbranched molecules are directly embedded in the silk protein, thereby achieving the purpose of preparing high-strength and fine-denier silk containing nitrogen-rich hyperbranched molecules.

Description

Technical Field

[0001] The invention belongs to the technical field of silk materials, and particularly relates to a method for preparing high-strength and fine-denier silk by utilizing nitrogen-rich hyperbranched molecules. Background Art

[0002] Silk protein is a natural polymer material with excellent biocompatibility and bioactivity. In the biomedical field, silk protein is widely used in tissue engineering, drug delivery, biosensors, and other fields. Currently, the most pressing issue in silk protein applications is the modification of silk by increasing its strength to broaden its application areas and scope.

[0003] Recent research has shown that nanoparticle feeding can be used to directly produce high-strength silk by adding nanoparticles such as graphene, nano-zinc oxide, carbon nanotubes, and nano-carbon dots to silkworm feed. Using the silkworm's bioreactor, the nanoparticles enter the silk glands, interact with and bind to fibroin, and ultimately form cocoons. This simple and easy method has therefore become a new research method for modifying high-strength silk.

[0004] Related art discloses a method for preparing mulberry silk containing nano-TiO2, using a solution concentration of 100-150 mg / L. This patent assesses the nano-TiO2 content in silk by measuring the Ti content per unit mass of silk, using inductively coupled plasma spectroscopy. The silk obtained after feeding showed a difference in quality compared to the unfed group, but further mechanical properties were not characterized.

[0005] Related technologies also disclose a method for raising silkworms by feeding them with graphene oxide for the preparation of high-strength silk and its products. This patent mixes graphene oxide into silkworm feed to obtain a high-strength silk with a single-filament breaking strength of 450-580 MPa, an elongation at break of 14-17%, and a breaking energy of 33-60 J / g. This method has a certain improvement in the breaking strength of silk, but no further discussion or research has been conducted on the fineness of the silk. Considering the further expansion of the demand for the application of silk in medical tissue engineering, there are higher requirements for performance improvement. Therefore, further exploration of low-cost and easy-to-prepare natural stable high-strength fine-denier silk in the modification of silk protein is still needed. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing high-strength and fine-denier silk using nitrogen-rich hyperbranched molecules. The nitrogen-rich hyperbranched molecules prepared by the preparation method provided by the present invention can be used as feed additives to further prepare high-strength and fine-denier silk.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing nitrogen-rich hyperbranched molecules, comprising the following steps:

[0009] Aromatic amine, acid and polar organic solvent are mixed and polymerized to obtain the nitrogen-rich hyperbranched molecule.

[0010] Preferably, the aromatic amine includes one or more of aniline, o-phenylenediamine, p-phenylenediamine and methylaniline;

[0011] The acid includes one or more of boric acid, acetic acid, folic acid, malic acid, citric acid, benzenesulfonic acid, tartaric acid and terephthalic acid.

[0012] Preferably, the polymerization reaction temperature is 160-260° C., and the time is 0.5-18 h.

[0013] The present invention also provides nitrogen-rich hyperbranched molecules prepared by the preparation method described in the above technical solution. The size of the nitrogen-rich hyperbranched molecules is 1 to 10 nm and the nitrogen content is 10 to 30 wt%.

[0014] Preferably, the nitrogen-containing functional groups of the nitrogen-rich hyperbranched molecules include amino groups, imino groups and amide bonds.

[0015] The present invention also provides the use of the nitrogen-rich hyperbranched molecules described in the above technical solution as a feed additive in feeding silkworms.

[0016] The present invention also provides a nitrogen-rich hyperbranched molecule feed, comprising the following components in percentage by weight: 35% to 45% of mulberry leaf powder, 20% to 30% of defatted soybean powder, 15% to 25% of starch, 5% to 10% of sucrose, 5% to 10% of agar powder, 0.05% to 2% of nitrogen-rich hyperbranched molecule dispersion, 1% to 2.5% of vitamins, and 0.5% to 1.5% of inorganic salts;

[0017] The nitrogen-rich hyperbranched molecule dispersion comprises nitrogen-rich hyperbranched molecules and an aqueous solution; the nitrogen-rich hyperbranched molecules are the nitrogen-rich hyperbranched molecules described in the above technical solution;

[0018] The mass fraction of the nitrogen-rich hyperbranched molecules in the nitrogen-rich hyperbranched molecule dispersion is 0.01 to 0.5%.

[0019] Preferably, the pH value of the aqueous solution is 7.0 to 8.5.

[0020] The present invention also provides a method for preparing high-strength and fine-denier silk, comprising the following steps:

[0021] Providing nitrogen-rich hyperbranched molecular feed;

[0022] Feeding the silkworms with the nitrogen-rich hyperbranched molecule feed from the end of the fourth instar to the beginning of the fifth instar;

[0023] After the silkworms have laid cocoons on the cocoon nest, the high-strength and fine-denier silk is obtained through reeling.

[0024] The nitrogen-rich hyperbranched molecular feed is the nitrogen-rich hyperbranched molecular feed described in the above technical solution.

[0025] The present invention also provides high-strength and fine-denier silk prepared by the preparation method described in the above technical solution, wherein the single-filament linear density of the high-strength and fine-denier silk is 2.4 to 3.0 dtex.

[0026] The present invention provides a method for preparing nitrogen-rich hyperbranched molecules, comprising the steps of mixing an aromatic amine, an acid, and a polar organic solvent, and conducting a polymerization reaction to obtain the nitrogen-rich hyperbranched molecules. The method utilizes an aromatic amine and an acid to produce the nitrogen-rich hyperbranched molecules through a one-step hydrothermal polymerization reaction. The nitrogen-rich hyperbranched molecules produced by the present invention do not harm the growth and development of silkworms or the environment during feeding and rearing.

[0027] The present invention also provides a method for preparing high-strength and fine-denier silk, comprising the following steps: providing a nitrogen-rich hyperbranched molecular feed; feeding the silkworms with the nitrogen-rich hyperbranched molecular feed at the end of the fourth instar to the beginning of the fifth instar; after the silkworms have formed cocoons on cocoons, reeling the silkworms to obtain the high-strength and fine-denier silk; the nitrogen-rich hyperbranched molecular feed is the nitrogen-rich hyperbranched molecular feed described in the above technical solution. The present invention continuously feeds the silkworms with an artificial feed containing nitrogen-rich hyperbranched molecules from the end of the fourth instar to the beginning of the fifth instar when silk protein is synthesized. Through the absorption of the nitrogen-rich hyperbranched molecules by the silkworms, a large amount of nitrogen-rich hyperbranched molecules are present in the silkworms' bodies. During the synthesis of silk protein, the nitrogen-rich hyperbranched molecules are directly embedded in the silk protein, thereby achieving the purpose of preparing a high-strength and fine-denier silk material containing nitrogen-rich hyperbranched molecules. The synthetic components of the nitrogen-rich hyperbranched molecules provided by the present invention are small in dosage, widely available, and low in cost. This method is simple and easy to implement, does not require complex processes and expensive equipment investment, and has no special requirements or changes to the original sericulture technology. Sericulture farmers can feed silkworms artificial feed and have them make cocoons on the cocooning basis based on the sericulture technology. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing nitrogen-rich hyperbranched molecules, comprising the following steps:

[0029] Aromatic amine, acid and polar organic solvent are mixed and polymerized to obtain the nitrogen-rich hyperbranched molecule.

[0030] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0031] In the present invention, the aromatic amine preferably includes one or more of aniline, o-phenylenediamine, p-phenylenediamine and methylaniline, and more preferably o-phenylenediamine or methylaniline.

[0032] In the present invention, the acid preferably includes one or more of boric acid, acetic acid, folic acid, malic acid, citric acid, benzenesulfonic acid, tartaric acid and terephthalic acid, and more preferably folic acid, benzenesulfonic acid, tartaric acid or terephthalic acid.

[0033] In the present invention, the polar organic solvent is preferably ethanol, and the mass concentration of the ethanol is preferably 95%.

[0034] In the present invention, the mixing preferably includes: first mixing the aromatic amine and half of the polar organic solvent to obtain a first solution; second mixing the acid and the remaining polar organic solvent to obtain a second solution; mixing the first solution and the second solution in equal volumes; the first mixing and the second mixing are preferably independently carried out by ultrasonic dispersion, the frequency of the ultrasonic dispersion is preferably 60 kHz, and the time is preferably 20 minutes.

[0035] In the present invention, the mass ratio of the aromatic amine to the acid is preferably 0-5:2-10, and is not 0; the mass ratio of the aromatic amine to the polar organic solvent is preferably 0-5:200, and is not 0.

[0036] In the present invention, the polymerization reaction temperature is preferably 160 to 260° C., more preferably 160 to 180° C.; the polymerization reaction time is preferably 0.5 to 18 hours, more preferably 2.5 to 4 hours.

[0037] In the present invention, the polymerization reaction is preferably carried out in a stainless steel autoclave lined with polytetrafluoroethylene.

[0038] In the present invention, after the polymerization reaction, the dark brown polymerization reaction solution is preferably centrifugally washed and dried. The centrifugal washing is preferably performed alternately using deionized water and anhydrous ethanol. The number of alternating washings using deionized water and anhydrous ethanol is preferably three. The present invention does not particularly limit the drying process, and methods well known to those skilled in the art can be used.

[0039] The present invention also provides nitrogen-rich hyperbranched molecules prepared by the preparation method described in the above technical solution. In the present invention, the size of the nitrogen-rich hyperbranched molecules can be 1 to 10 nm; in specific embodiments, the size can be 2 to 6 nm, 1 to 5 nm, or 3 to 8 nm.

[0040] In the present invention, the nitrogen content of the nitrogen-rich hyperbranched molecules is 10 to 30 wt%, more preferably 20 to 25 wt%. In the present invention, the nitrogen-containing functional groups of the nitrogen-rich hyperbranched molecules preferably include amino groups, imino groups, and amide bonds; and the total content of the amino groups, imino groups, and amide bonds is preferably 10 to 30 wt%, more preferably 20 to 25 wt%.

[0041] The present invention also provides the use of the nitrogen-rich hyperbranched molecules described in the above technical solution as a feed additive in feeding silkworms.

[0042] The present invention also provides a nitrogen-rich hyperbranched molecule feed, comprising the following components in percentage by weight: 35% to 45% of mulberry leaf powder, 20% to 30% of defatted soybean powder, 15% to 25% of starch, 5% to 10% of sucrose, 5% to 10% of agar powder, 0.05% to 2% of nitrogen-rich hyperbranched molecule dispersion, 1% to 2.5% of vitamins, and 0.5% to 1.5% of inorganic salts;

[0043] The nitrogen-rich hyperbranched molecule dispersion comprises nitrogen-rich hyperbranched molecules and an aqueous solution; the nitrogen-rich hyperbranched molecules are the nitrogen-rich hyperbranched molecules described in the above technical solution.

[0044] The present invention has no particular limitation on the types of the vitamins and inorganic salts, and the vitamins and inorganic salts in conventional silkworm feeds in the art can be used.

[0045] In the present invention, the pH value of the aqueous solution is preferably 7.0 to 8.5, and the mass fraction of the nitrogen-rich hyperbranched molecules in the nitrogen-rich hyperbranched molecule dispersion is 0.01 to 0.5%.

[0046] The present invention also provides a method for preparing high-strength and fine-denier silk, comprising the following steps:

[0047] Providing nitrogen-rich hyperbranched molecular feed;

[0048] Feeding the silkworms with the nitrogen-rich hyperbranched molecule feed from the end of the fourth instar to the beginning of the fifth instar;

[0049] After the silkworms have laid cocoons on the cocoon nest, the high-strength and fine-denier silk is obtained through reeling.

[0050] The nitrogen-rich hyperbranched molecular feed is the nitrogen-rich hyperbranched molecular feed described in the above technical solution.

[0051] In the present invention, the silkworms are preferably fed a feed without nitrogen-rich hyperbranched molecules from the first to fourth instars, i.e., the nitrogen-rich hyperbranched molecule dispersion is removed from the nitrogen-rich hyperbranched molecule feed. In the present invention, the nitrogen-rich hyperbranched molecule feed is preferably fed every 8 hours until the silkworms cocoon.

[0052] In the present invention, the silkworms are preferably raised in an artificial climate box, the temperature of the artificial breeding box is preferably 24° C.±0.3° C., and the humidity is preferably 65%±2%.

[0053] The present invention also provides high-strength and fine-denier silk prepared by the preparation method described in the above technical solution, wherein the single-filament linear density of the high-strength and fine-denier silk is 2.4 to 3.0 dtex.

[0054] In the present invention, the breaking strength of the high-strength fine-denier silk is preferably 3.3-4.5 cN / dtex; the breaking elongation is preferably 25-35%, which is 10-30% higher than that of ordinary monofilament.

[0055] To further illustrate the present invention, a method for preparing high-strength and fine-denier silk using nitrogen-rich hyperbranched molecules provided by the present invention is described in detail below in conjunction with examples, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] By weight, 2.5 parts of o-phenylenediamine were ultrasonically dispersed in 100 parts of 95% ethanol at a frequency of 60 kHz for 20 minutes to prepare an o-phenylenediamine solution, and 2 parts of terephthalic acid were ultrasonically dispersed in 100 parts of 95% ethanol at a frequency of 60 kHz for 20 minutes to prepare a terephthalic acid solution. The o-phenylenediamine solution and the terephthalic acid solution were mixed in a polytetrafluoroethylene liner, and the polytetrafluoroethylene liner was placed in a stainless steel autoclave. The reaction was carried out at 160° C. for 3 hours to obtain a dark brown solution. The obtained product was centrifugally washed three times with deionized water and anhydrous ethanol, and finally dried to obtain nitrogen-rich hyperbranched molecules.

[0058] Nitrogen-rich hyperbranched molecules with a size of 3 to 8 nm and a nitrogen-containing group content of 20 wt% such as amino, imino and amide bonds are dissolved in a solution with a pH of 7.2 to prepare a dispersion with a mass fraction of 0.01%, and ultrasonically vibrated for 20 minutes. The formula of the nitrogen-rich hyperbranched molecule feed is: 40% mulberry leaf powder, 25% defatted soybean powder, 16% starch, 10% sucrose, 7.4% agar powder, 0.1% dispersion of the nitrogen-rich hyperbranched molecules, 1% vitamins, and 0.5% inorganic salts.

[0059] Fifty silkworms were randomly selected for the experiment. From the first to fourth instars, they were fed a diet without nitrogen-enriched hyperbranched molecules. Starting on the first day of the fifth instar, they were fed a compound artificial diet containing nitrogen-enriched hyperbranched molecules. The diet was fed every eight hours until the silkworms emerged from the cocoon. The silkworms were reared in an artificial climate chamber set at 24°C ± 0.3°C and 65% ± 2% humidity.

[0060] Before the silkworms were placed on the cocoons, five silkworms were randomly selected for dissection to obtain their silk glands for subsequent performance testing. After the silkworms formed cocoons on the cocoons, the cocoons were reeled and collected for later use.

[0061] Example 2

[0062] By weight, 4.5 parts of p-phenylenediamine were ultrasonically dispersed in 100 parts of 95% ethanol at a frequency of 60 kHz for 20 minutes to prepare a p-phenylenediamine solution, and 2 parts of tartaric acid were ultrasonically dispersed in 100 parts of 95% ethanol at a frequency of 60 kHz for 20 minutes to prepare a tartaric acid solution. The p-phenylenediamine solution and the tartaric acid solution were mixed in a polytetrafluoroethylene liner, which was then placed in a stainless steel autoclave and reacted at 160° C. for 3 hours to obtain a dark brown solution. The obtained product was centrifugally washed three times with deionized water and anhydrous ethanol, and finally dried to obtain a nitrogen-rich hyperbranched molecule.

[0063] Nitrogen-rich hyperbranched molecules with a size of 1 to 5 nm and a nitrogen-containing group content of 22 wt% such as amino, imino and amide bonds were dissolved in a solution with a pH of 7.5 to prepare a dispersion with a mass fraction of 0.05%, and ultrasonically vibrated for 20 minutes. The formula of the nitrogen-rich hyperbranched molecule feed used in the experiment was: 35% mulberry leaf powder, 25% defatted soybean meal, 20% starch, 8% sucrose, 9% agar powder, 0.5% dispersion of nitrogen-rich hyperbranched molecules, 1.5% vitamins, and 1% inorganic salts.

[0064] Fifty silkworms were randomly selected for the experiment. From the first to fourth instars, they were fed a diet without the nitrogen-enriched hyperbranched molecule. Starting on the first day of the fifth instar, they were fed a diet containing the nitrogen-enriched hyperbranched molecule every eight hours until they emerged from the cocoon. The silkworms were reared in an artificial climate chamber set at 25°C ± 0.2°C and 65% ± 2% humidity.

[0065] Before the silkworms were placed on the cocoons, five silkworms were randomly selected for dissection to obtain their silk glands for subsequent performance testing. After the silkworms formed cocoons on the cocoons, the cocoons were reeled and collected for later use.

[0066] Example 3

[0067] A methylaniline solution was prepared by ultrasonically dispersing 2 parts by mass of methylaniline in 100 parts of 95% ethanol at 60 kHz for 20 minutes. A folic acid solution was prepared by ultrasonically dispersing 4 parts of folic acid in 100 parts of 95% ethanol at 60 kHz for 20 minutes. The methylaniline and folic acid solutions were mixed in a polytetrafluoroethylene-lined container, which was then placed in a stainless steel autoclave and reacted at 160°C for 3 hours to obtain a dark brown solution. The resulting product was then washed three times by centrifugation with deionized water and anhydrous ethanol and finally dried to obtain nitrogen-rich hyperbranched molecules.

[0068] Nitrogen-rich hyperbranched molecules with a size of 2 to 6 nm and a nitrogen-containing functional group content of 25 wt% such as amino, imino and amide bonds were dissolved in a solution with a pH of 7.5 to prepare a dispersion with a mass fraction of 0.1%, and ultrasonically vibrated for 20 minutes. The formula of the artificial feed used in the experiment was: 45% mulberry leaf powder, 25% defatted soy flour, 15% starch, 5% sucrose, 7.5% agar powder, 0.5% dispersion of nitrogen-rich hyperbranched molecules, 1% vitamins, and 1% inorganic salts.

[0069] Fifty silkworms were randomly selected for the experiment. From the first to fourth instars, they were fed a diet without the nitrogen-enriched hyperbranched molecule. Starting on the first day of the fifth instar, they were fed a diet containing the nitrogen-enriched hyperbranched molecule every eight hours until they emerged from the cocoon. The silkworms were reared in an artificial climate chamber set at 25°C ± 0.2°C and 65% ± 2% humidity.

[0070] Before the silkworms were placed on the cocoons, five silkworms were randomly selected for dissection to obtain their silk glands for subsequent performance testing. After the silkworms formed cocoons on the cocoons, the cocoons were reeled and collected for later use.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the artificial feed was different. In this comparative example, the nitrogen-rich hyperbranched molecule dispersion was not added to the compound artificial feed fed starting on the first day of the fifth year of age, and the other experimental parameters were the same as in Example 1.

[0073] Comparative Example 2

[0074] The difference from Example 2 is the artificial feed. In this comparative example, the nitrogen-rich hyperbranched molecule dispersion added to the compound artificial feed fed starting from the first day of the fifth year of age was replaced with an equal amount of purified water. Other experimental parameters were the same as in Example 2.

[0075] Comparative Example 3

[0076] The difference from Example 3 is the artificial feed. In this comparative example, the nitrogen-rich hyperbranched molecule dispersion added to the compound artificial feed fed starting from the first day of the fifth year of age was replaced with an equal amount of inorganic salt solution. Other experimental parameters were the same as in Example 3.

[0077] Performance Testing

[0078] The linear density and mechanical properties of silk were measured by using an XQ-1A fiber strength and elongation tester connected to an XD-1 fineness tester. The stretching speed was 10 mm / min and the clamping distance was 20 mm. The results are shown in Table 1.

[0079] Table 1 Linear density and mechanical property test results of Examples 1 to 3 and Comparative Examples 1 to 3

[0080] Single yarn density / dtex Breaking strength (cN / dtex) Elongation at break / % Change rate of breaking strength / % Example 1 2.63±0.23 3.37 28.51 +15.68 Example 2 2.68±0.21 4.07 32.95 +28.78 Example 3 2.61±0.19 3.81 29.58 +20.80 Comparative Example 1 2.82±0.52 2.91 26.15 — Comparative Example 2 3.06±0.22 3.16 26.45 — Comparative Example 3 2.93±0.28 3.15 25.87 —

[0081] As can be seen from Table 1, compared with the comparative example, the nitrogen-rich hyperbranched molecules prepared by the present invention and added to the artificial feed of silkworms to feed silkworms improve the mechanical properties such as the breaking strength of silkworm silk, and have no toxic effect on the growth and development of silkworms, thereby obtaining a high-strength and fine-denier silk material.

[0082] It can be seen from the above embodiments that the present invention provides a high-strength and fine-denier silk and a preparation method thereof. The method of the present invention can significantly improve the breaking strength of silk, and provides a new technical method for silkworm feeding and the preparation of high-strength and fine-denier silk.

[0083] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A nitrogen-rich hyperbranched molecular feed, characterized in that: The invention comprises the following components in percentage by weight: 35% to 45% of mulberry leaf powder, 20% to 30% of defatted soybean powder, 15% to 25% of starch, 5% to 10% of sucrose, 5% to 10% of agar powder, 0.05% to 2% of nitrogen-rich hyperbranched molecular dispersion, 1% to 2.5% of vitamins and 0.5% to 1.5% of inorganic salts; The nitrogen-rich hyperbranched molecule dispersion comprises nitrogen-rich hyperbranched molecules and an aqueous solution; The preparation method of the nitrogen-rich hyperbranched molecule comprises the following steps: Mixing aromatic amine, acid and polar organic solvent to carry out polymerization reaction to obtain the nitrogen-rich hyperbranched molecule; the polymerization reaction is carried out in a stainless steel autoclave with a polytetrafluoroethylene liner; The aromatic amine is one or more of aniline, o-phenylenediamine, p-phenylenediamine and methylaniline; The acid is one or more of boric acid, acetic acid, folic acid, malic acid, citric acid, benzenesulfonic acid, tartaric acid and terephthalic acid; The polymerization reaction temperature is 160-260° C. and the reaction time is 0.5-18 hours; The nitrogen-rich hyperbranched molecules have a size of 1 to 10 nm and a nitrogen content of 10 to 30 wt %; The nitrogen-containing functional groups of the nitrogen-rich hyperbranched molecules include amino groups, imino groups and amide bonds; The mass fraction of the nitrogen-rich hyperbranched molecules in the nitrogen-rich hyperbranched molecule dispersion is 0.01 to 0.5%.

2. The nitrogen-rich hyperbranched molecular feed according to claim 1, characterized in that The pH value of the aqueous solution is 7.0-8.

5.

3. A method for preparing high-strength and fine-denier silk, characterized in that: The following steps are involved: Providing nitrogen-rich hyperbranched molecular feed; Feeding the silkworms with the nitrogen-rich hyperbranched molecule feed from the end of the fourth instar to the beginning of the fifth instar; After the silkworms have laid cocoons on the cocoon nest, the high-strength and fine-denier silk is obtained through reeling. The nitrogen-rich hyperbranched molecular feed is the nitrogen-rich hyperbranched molecular feed according to claim 1 or 2.

4. The high-strength and fine-denier silk prepared by the preparation method according to claim 3, characterized in that: The single-filament linear density of the high-strength and fine-denier silk is 2.4 to 3.0 dtex.