Janus particle based on chitosan and esterified starch as well as preparation method and application of Janus particle

Abstract

The invention discloses a Janus particle based on chitosan and esterified starch as well as a preparation method and application of the Janus particle. The preparation method of the Janus particles based on the chitosan and the esterified starch comprises the following steps: 1) preparing the esterified starch; (2) preparing a chitosan-esterified starch compound; 3) preparing an oil-in-water emulsion; and 4) carrying out suction filtration on the oil-in-water emulsion, washing the filtered solid with a sodium chloride-acetic acid solution, adding the solid into an organic solvent, carrying out ultrasonic treatment and centrifugation, and taking the centrifuged solid, thereby obtaining the Janus particles based on the chitosan and the esterified starch. The starch-based Janus particle is prepared by taking natural starch as a raw material, the preparation method is simple to operate, mild in condition, safe, environment-friendly and low in cost, the high-quality starch-based Janus particle which can be used as an emulsifier or a thickener is finally prepared, and the starch-based Janus particle is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to a Janus particle based on chitosan and esterified starch, and a preparation method and application thereof. Background Art

[0002] Janus particles are particles that have two or more different physical and chemical structural properties, and they have shown very broad application prospects in the development of surfactants, the preparation of functional coatings, etc. However, traditional Janus particles are generally prepared based on metal materials and synthetic polymer materials, which limits their application in the fields of biology and food.

[0003] Starch is a natural polymer that is abundant, safe, biocompatible, biodegradable, cheap, and widely used. Starch-based Janus particles have good application prospects in the fields of biology and food. At present, research on starch-based Janus particles is relatively small and is still in its infancy. The literature reports a method for preparing starch-based Janus particles using a Pickering emulsion template method. The starch raw material used is starch particles with a particle size of about 1 μm (Starch Janus Particles: Bulk Synthesis, Self-Assembly, Rheology, and Potential Food Applications, Arkaye Kierulf, Mojtaba Enayati, ACS Appl. Mater. Interfaces 2022, 14, 57371-57386), while the particle size of common natural starch particles is much larger than 1 μm (for example: rice starch is 3 μm to 8 μm; corn starch is 8 μm to 15 μm). Therefore, the natural starch particles need to be processed before they can be used in this method, which will undoubtedly increase the complexity of the preparation process and lead to an increase in production costs, which is not conducive to industrial production and application.

[0004] Therefore, it is of great significance to develop a method for directly using natural starch granules to prepare starch-based Janus particles and to prepare high-quality starch-based Janus particles. Summary of the invention

[0005] The purpose of the present invention is to provide a Janus particle based on chitosan and esterified starch, and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing Janus particles based on chitosan and esterified starch comprises the following steps:

[0008] 1) dispersing natural starch and an esterifying agent in water, and then esterifying them under the assistance of ultrasound to obtain esterified starch;

[0009] 2) dissolving chitosan in an acetic acid solution to prepare a chitosan solution, dispersing the esterified starch in the chitosan solution for electrostatic adsorption, and then separating the products to obtain a chitosan-esterified starch complex;

[0010] 3) dispersing the chitosan-esterified starch complex in water to prepare a chitosan-esterified starch complex dispersion, and then adding an oil phase and homogenizing to obtain an oil-in-water emulsion;

[0011] 4) The oil-in-water emulsion is filtered, and the filtered solid is washed with a sodium chloride-acetic acid solution, and then added to an organic solvent for ultrasonication and centrifugation. The solid obtained by centrifugation is obtained to obtain Janus particles based on chitosan and esterified starch.

[0012] Preferably, the particle size of the natural starch in step 1) is 3 μm to 15 μm.

[0013] Further preferably, the natural starch in step 1) is at least one of rice starch (particle size is 3 μm to 8 μm) and corn starch (particle size is 5 μm to 15 μm).

[0014] Preferably, the esterifying agent in step 1) is at least one of octenyl succinic anhydride (OSA) and decenyl succinic anhydride (DCSA). OSA and DCSA have been widely used in the food industry and have been approved by the FDA for addition. They are safer and cheaper than esterifying agents such as octadecenyl succinic anhydride, hexadecenyl succinic anhydride, tetradecenyl succinic anhydride, and dodecenyl succinic anhydride, and have higher reactivity with starch granules.

[0015] Preferably, in step 1), the weight ratio of starch to esterifying agent is 1:0.01-0.15.

[0016] Further preferably, in step 1), the weight ratio of starch to esterifying agent is 1:0.03-0.05.

[0017] Preferably, the power of the ultrasound in step 1) is 100W to 600W.

[0018] Further preferably, the power of the ultrasound in step 1) is 200W to 300W.

[0019] Preferably, in step 2), the weight ratio of chitosan to esterified starch is 0.05-0.30:1.

[0020] Preferably, the weight percentage of the chitosan-esterified starch complex in the chitosan-esterified starch complex dispersion in step 3) is 1% to 5%.

[0021] Further preferably, the weight percentage of the chitosan-esterified starch complex in the chitosan-esterified starch complex dispersion in step 3) is 2% to 3%.

[0022] Preferably, in step 3), the volume ratio of the chitosan-esterified starch complex dispersion to the oil phase is 2 to 20:1.

[0023] Further preferably, in step 3), the volume ratio of the chitosan-esterified starch complex dispersion to the oil phase is 5 to 15:1.

[0024] Preferably, the oil phase in step 3) is composed of at least one of undecanoic acid (melting point of 29°C to 30°C) and paraffin with a melting point of 28°C to 35°C. Undecanoic acid and paraffin with a melting point of 28°C to 35°C have low melting points. Using them as the oil phase reduces energy consumption during the heating process compared to the prior art using lauric acid and paraffin (melting point of about 48°C) as the oil phase.

[0025] Preferably, the homogenization in step 3) is carried out at a homogenizer speed of 6000 rpm to 14000 rpm and a temperature of 30° C. to 40° C., and the homogenization time is 1 min to 2 min.

[0026] Preferably, the concentration of sodium chloride in the sodium chloride-acetic acid solution in step 4) is 200 mmol / L to 500 mmol / L.

[0027] Preferably, the temperature of the sodium chloride-acetic acid solution in step 4) is 20°C to 25°C.

[0028] Preferably, the washing in step 4) is performed 2 to 5 times.

[0029] Preferably, the organic solvent in step 4) is at least one of ethanol, ether, chloroform and toluene.

[0030] Preferably, the ultrasonication in step 4) is carried out at a temperature of 30°C to 40°C.

[0031] Preferably, the number of times of ultrasound and centrifugation in step 4) is 2 to 5 times.

[0032] A Janus particle based on chitosan and esterified starch is prepared by the preparation method.

[0033] A use of the chitosan and esterified starch-based Janus particles as described above in the preparation of an emulsifier or a thickener.

[0034] Preferably, the emulsifier is a food emulsifier.

[0035] Preferably, the thickener is a food thickener.

[0036] The principle of the present invention is as follows: the present invention uses natural starch (with a particle size of 3 μm to 15 μm) as a raw material, prepares esterified starch through an ultrasound-assisted esterification reaction, and then compounds the esterified starch with chitosan to obtain chitosan-esterified starch particles (the starch particles are completely wrapped with chitosan, and the film-forming property and electrostatic adsorption of chitosan can be used to achieve stable adsorption of the particles at the oil-water interface), and then uses the chitosan-esterified starch particles as a stabilizer for the Pickering emulsion to prepare an oil-in-water emulsion, uses an oil phase to fix one side of the chitosan-esterified starch particles, and then uses a high ionic strength sodium chloride-acetic acid solution to wash the exposed side of the chitosan-esterified starch particles to remove the chitosan, and then releases the particles to finally obtain starch-based Janus particles.

[0037] The beneficial effects of the present invention are as follows: the present invention uses natural starch as a raw material to prepare starch-based Janus particles, the preparation method is simple to operate, the conditions are mild, it is safe and environmentally friendly, and the cost is low, and finally high-quality starch-based Janus particles that can be used as an emulsifier or thickener are prepared, which is suitable for large-scale industrial production and application.

[0038] Specifically:

[0039] 1) The present invention adopts ultrasound to assist the esterification reaction (it is difficult for the esterification agent and starch to react in an aqueous phase system), which can disperse the esterification agent into droplets of smaller volume, thereby making the esterification reaction rate faster and making the distribution of the esterification groups on the starch surface more uniform;

[0040] 2) The present invention obtains a chitosan-esterified starch composite that is stably adsorbed at an oil-water interface by mixing esterified starch with chitosan and utilizing the electrostatic interaction between the negatively charged groups of the esterified starch and the positively charged groups of the chitosan;

[0041] 3) The Pickering emulsion stabilizing particles of the present invention use a chitosan-esterified starch complex, which has particularly stable adsorption at the oil-water interface, and the oil phase cooling does not need to be performed under low temperature conditions, and stable solidification can be achieved at room temperature, thereby reducing energy consumption during the cooling process;

[0042] 4) The present invention removes the chitosan on the exposed side by ion shielding, thereby achieving the purpose of asymmetric modification, and finally preparing Janus particles based on chitosan and esterified starch;

[0043] 5) One side of the Janus particles based on chitosan and esterified starch of the present invention is coated by chitosan and has strong hydrophobicity, while the other side is an esterified group and has amphiphilicity, which ultimately makes the Janus particles anisotropic and suitable for use as food emulsifiers / food thickeners. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The Fourier transform infrared spectra of the esterified starch, chitosan and chitosan-esterified starch composite in Example 1 are shown.

[0045] Figure 2 This is the SEM image of the oil-in-water emulsion in Example 1.

[0046] Figure 3 This is a graph showing the test results of the nitrogen and sodium content on the surface of the esterified starch, chitosan-esterified starch composite and Janus particles in Example 1.

[0047] Figure 4 This is the SEM image of the Janus particles in Example 1. DETAILED DESCRIPTION

[0048] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0049] Embodiment 1:

[0050] A Janus particle based on chitosan and esterified starch, the preparation method of which is as follows:

[0051] 1) 10 g of rice starch (particle size of 3 μm to 8 μm) was dispersed in deionized water to prepare a dispersion with a mass fraction of 30%, and then 0.5 g of octenyl succinic anhydride was added, and then placed in an ultrasonic cleaner (KQ-250DE model) at 35° C. for 15 min, the ultrasonic power was 200 W, and then stirred at 35° C. for 15 min, and the solid was centrifuged to obtain esterified starch;

[0052] 2) 1.5 g of chitosan was fully stirred and dissolved at room temperature (stirred overnight) in 100 mL of acetic acid solution to prepare a chitosan solution, and then 10 g of esterified starch was added to the chitosan solution (the weight ratio of chitosan to esterified starch was 0.15:1), and then stirred for 30 min at a stirrer speed of 400 rpm, and then centrifuged for 15 min at a centrifuge speed of 3500 rpm, and the solid obtained by centrifugation was taken to obtain a chitosan-esterified starch complex;

[0053] 3) 0.25 g of chitosan-esterified starch complex was stirred and dispersed in 10 g of deionized water, and 1.5 g of undecanoic acid (oil phase) was added, and then the mixture was heated to 30° C. and transferred to a high-speed dispersing homogenizer (FJ200-SH model), and then homogenized at a speed of 9000 rpm for 1 min, and then taken out and naturally allowed to stand for 30 min to obtain an oil-in-water emulsion;

[0054] 4) The oil-in-water emulsion was filtered with a filter screen having a mesh size of 120 meshes. The filtered solid was washed three times with a sodium chloride-acetic acid solution having an acetic acid concentration of 1.0 mg / mL, a sodium chloride concentration of 300 mmol / L, and a temperature of 23° C. The solid was then added to ethanol and heated to 30° C., and then placed in an ultrasonic cleaner (KQ-250DE model) for 5 min of ultrasonication. The solid was then centrifuged at a centrifuge speed of 3500 rpm for 5 min. A total of three ultrasonic-centrifugation operations were performed to obtain Janus particles based on chitosan and esterified starch (referred to as “Janus particles”).

[0055] Performance Test:

[0056] 1) The Fourier transform infrared spectra of the esterified starch, chitosan and chitosan-esterified starch composite in this embodiment are as follows: Figure 1 shown.

[0057] Depend on Figure 1 It can be seen that chitosan is at 1601cm -1 The peak at 1569 cm -1 The peaks at 1644 cm-1 were merged, showing that the chitosan-esterified starch complex -1 The peak intensity increased, indicating that the chitosan-esterified starch complex was indeed obtained.

[0058] 2) The scanning electron microscope (SEM) image of the oil-in-water emulsion in this embodiment is as follows: Figure 2 shown.

[0059] Depend on Figure 2 It can be seen that the chitosan-esterified starch complex is embedded on the surface of undecanoic acid.

[0060] 3) The test results of nitrogen and sodium content on the surface of esterified starch, chitosan-esterified starch composite and Janus particles in this example are as follows: Figure 3 shown.

[0061] Depend on Figure 3 It can be seen that the nitrogen content of Janus particles is lower than that of chitosan-esterified starch composites, indicating that the chitosan on the exposed side is successfully removed.

[0062] 4) The SEM image of the Janus particles in this embodiment is as follows Figure 4 shown.

[0063] Depend on Figure 4 It can be seen that one side of the particles marked by the red solid line and the dotted line has a slight bulge, indicating that the chitosan film is adsorbed on the surface of the esterified starch (the same situation could not be observed for the other particles due to orientation problems).

[0064] Embodiment 2:

[0065] A Janus particle based on chitosan and esterified starch, the preparation method of which is as follows:

[0066] 1) 15 g corn starch (particle size of 5 μm to 15 μm) was dispersed in deionized water to prepare a dispersion with a mass fraction of 30%, and then 2.25 g decenyl succinic anhydride was added, and then placed in an ultrasonic cleaner (KQ-250DE model) at 35° C. for 10 min, the ultrasonic power was 100 W, and then stirred at 35° C. for 15 min, and the solid was centrifuged to obtain esterified starch;

[0067] 2) 4.5 g of chitosan was fully stirred and dissolved at room temperature (stirred overnight) in 150 mL of acetic acid solution to prepare a chitosan solution, and then 15 g of esterified starch was added to the chitosan solution (the weight ratio of chitosan to esterified starch was 0.30:1), and then stirred for 20 min at a stirrer speed of 600 rpm, and then centrifuged for 15 min at a centrifuge speed of 3500 rpm, and the solid obtained by centrifugation was taken to obtain a chitosan-esterified starch composite;

[0068] 3) 0.5 g of chitosan-esterified starch complex was stirred and dispersed in 10 g of deionized water, and then 5 g of paraffin (melting point 28° C.; oil phase) was added, and then the mixture was heated to 32° C. and transferred to a high-speed dispersing homogenizer (FJ200-SH model), and then homogenized for 2 min at a homogenizer speed of 14000 rpm, and then taken out and naturally allowed to stand for 15 min to obtain an oil-in-water emulsion;

[0069] 4) The oil-in-water emulsion was filtered with a filter screen having a mesh size of 200 meshes, and the filtered solid was washed five times with a sodium chloride-acetic acid solution having an acetic acid concentration of 2.0 mg / mL, a sodium chloride concentration of 200 mmol / L, and a temperature of 20° C., then added to chloroform and heated to 32° C., and then placed in an ultrasonic cleaner (KQ-250DE model) for 3 minutes of ultrasonication, and then centrifuged at a centrifuge speed of 3500 rpm for 5 minutes. A total of five ultrasonic-centrifugation operations were performed to obtain Janus particles based on chitosan and esterified starch.

[0070] After testing (the testing method is the same as that in Example 1), the microstructure and performance of the Janus particles based on chitosan and esterified starch in this example are highly similar to those of the Janus particles based on chitosan and esterified starch in Example 1.

[0071] Embodiment 3:

[0072] A Janus particle based on chitosan and esterified starch, the preparation method of which is as follows:

[0073] 1) 20 g of rice starch (particle size of 3 μm to 8 μm) was dispersed in deionized water to prepare a dispersion with a mass fraction of 30%, and then 0.2 g of octenyl succinic anhydride was added, and then placed in an ultrasonic cleaner (KQ-250DE model) at 35° C. for 20 min, with an ultrasonic power of 600 W, and then stirred at 35° C. for 15 min, and the solid was centrifuged to obtain esterified starch;

[0074] 2) 1.0 g of chitosan was fully stirred and dissolved at room temperature (stirred overnight) in 200 mL of acetic acid solution to prepare a chitosan solution, and then 20 g of esterified starch was added to the chitosan solution (the weight ratio of chitosan to esterified starch was 0.05:1), and then stirred for 25 min at a stirrer speed of 500 rpm, and then centrifuged for 15 min at a centrifuge speed of 3500 rpm, and the solid obtained by centrifugation was taken to obtain a chitosan-esterified starch composite;

[0075] 3) 0.1 g of chitosan-esterified starch complex was stirred and dispersed in 10 g of deionized water, and then 0.5 g of paraffin (melting point 35° C.; oil phase) was added, and then the mixture was heated to 40° C. and transferred to a high-speed dispersing homogenizer (FJ200-SH model), and then homogenized for 2 min at a homogenizer speed of 6000 rpm, and then taken out and naturally allowed to stand for 15 min to obtain an oil-in-water emulsion;

[0076] 4) The oil-in-water emulsion was filtered with a filter screen having a mesh size of 300 meshes, and the filtered solid was washed twice with a sodium chloride-acetic acid solution having an acetic acid concentration of 1.5 mg / mL, a sodium chloride concentration of 500 mmol / L, and a temperature of 25° C., then added to toluene and heated to 40° C., and then placed in an ultrasonic cleaner (KQ-250DE model) for 5 minutes of ultrasonication, and then centrifuged at a centrifuge speed of 3500 rpm for 3 minutes. A total of 2 ultrasonic-centrifugation operations were performed to obtain Janus particles based on chitosan and esterified starch.

[0077] After testing (the testing method is the same as that in Example 1), the microstructure and performance of the Janus particles based on chitosan and esterified starch in this example are highly similar to those of the Janus particles based on chitosan and esterified starch in Example 1.

[0078] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing Janus particles based on chitosan and esterified starch, characterized in that: The following steps are involved: 1) dispersing natural starch and an esterifying agent in water, and then esterifying them under the assistance of ultrasound to obtain esterified starch; 2) dissolving chitosan in an acetic acid solution to prepare a chitosan solution, dispersing the esterified starch in the chitosan solution for electrostatic adsorption, and then separating the products to obtain a chitosan-esterified starch complex; 3) dispersing the chitosan-esterified starch complex in water to prepare a chitosan-esterified starch complex dispersion, and then adding an oil phase and homogenizing to obtain an oil-in-water emulsion; 4) The oil-in-water emulsion is filtered, and the filtered solid is washed with a sodium chloride-acetic acid solution, and then added to an organic solvent for ultrasonication and centrifugation. The solid obtained by centrifugation is obtained to obtain Janus particles based on chitosan and esterified starch.

2. The preparation method according to claim 1, characterized in that: The particle size of the natural starch in step 1) is 3 μm to 15 μm; the esterifying agent in step 1) is at least one of octenyl succinic anhydride and decenyl succinic anhydride.

3. The preparation method according to claim 1 or 2, characterized in that: In step 1), the weight ratio of the natural starch to the esterifying agent is 1:0.01-0.

15.

4. The preparation method according to claim 1 or 2, characterized in that: The power of the ultrasound in step 1) is 100W to 600W.

5. The preparation method according to claim 1, characterized in that: Step 2) The weight ratio of chitosan to esterified starch is 0.05-0.30:

1.

6. The preparation method according to claim 1, characterized in that: The weight percentage of the chitosan-esterified starch complex in the chitosan-esterified starch complex dispersion in step 3) is 1% to 5%; the volume ratio of the chitosan-esterified starch complex dispersion in step 3) to the oil phase is 2 to 20:1; the composition of the oil phase in step 3) is at least one of undecanoic acid and paraffin with a melting point of 28°C to 35°C.

7. The preparation method according to claim 1 or 6, characterized in that: Step 3) The homogenization is carried out at a homogenizer speed of 6000 rpm to 14000 rpm and a temperature of 30° C. to 40° C., and the homogenization time is 1 min to 2 min.

8. The preparation method according to claim 1, characterized in that: The concentration of sodium chloride in the sodium chloride-acetic acid solution of step 4) is 200 mmol / L to 500 mmol / L; the organic solvent of step 4) is at least one of ethanol, ether, chloroform and toluene.

9. A Janus particle based on chitosan and esterified starch, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the Janus particles based on chitosan and esterified starch as claimed in claim 9 in the preparation of an emulsifier or a thickener.

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