Janus particles based on chitosan and esterified starch, and preparation method and application thereof

Abstract

The application discloses Janus particles based on chitosan and esterified starch as well as a preparation method and application thereof. The preparation method of the Janus particles based on chitosan and esterified starch comprises the following steps: 1) preparing esterified starch; 2) preparing a chitosan-esterified starch compound; 3) preparing an oil-in-water emulsion; 4) performing suction filtration on the oil-in-water emulsion, washing the obtained solid with a sodium chloride-acetic acid solution, adding the solid into an organic solvent to perform ultrasonic treatment and centrifugation, and obtaining the solid obtained through centrifugation, namely, the Janus particles based on chitosan and esterified starch. The application uses natural starch as a raw material to prepare starch-based Janus particles, and has the advantages of simple operation, mild conditions, safety, environmental protection, low cost, and the like. Finally, high-quality starch-based Janus particles which can be used as emulsifiers or thickeners are prepared, and the starch-based Janus particles are suitable for large-scale industrial production and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanomaterials, and particularly relates to a Janus particle based on chitosan and esterified starch as well as a preparation method and application thereof. BACKGROUND

[0002] A Janus particle is a particle with two or more different physical and chemical structural characteristics on the surface, which has a very broad application prospect in the development of surfactants and the preparation of functional coatings. However, traditional Janus particles are generally prepared based on metal materials and synthetic polymer materials, which limits their application in biological and food fields.

[0003] Starch is a natural polymer with abundant sources, safety, biocompatibility, biodegradability, low price and wide application. Starch-based Janus particles have good application prospect in biological and food fields. At present, the research on starch-based Janus particles is less and still in the initial stage. Literature reports a method for preparing starch-based Janus particles by using Pickering emulsion template method, and the starch raw material used is starch particles with a particle size of about 1 um (Starch Janus Particles: Bulk Synthesis, Self-Assembly, Rheology, and Potential Food Applications, Arkaye Kierulf, Mojtaba Enayati, ACS Appl. Mater. Interfaces 2022, 14, 57371-57386). However, the particle size of common natural starch particles is much larger than 1 um (for example: rice starch is 3 um-8 um; corn starch is 8 um-15 um), so the natural starch particles need to be processed before they can be used in this method, which undoubtedly increases the complexity of the preparation process and leads to the increase of production cost, which is not conducive to industrial production and application.

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

[0005] The present application relates to the technical field of nanomaterials, and particularly relates to a Janus particle based on chitosan and esterified starch as well as a preparation method and application thereof.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A preparation method of a Janus particle based on chitosan and esterified starch comprises the following steps:

[0008] 1) dispersing natural starch and esterifying agent in water, and then performing esterification under the assistance of ultrasonic to obtain esterified starch;

[0009] 2) dissolving chitosan in acetic acid solution to prepare chitosan solution, dispersing esterified starch in the chitosan solution to perform electrostatic adsorption, and then performing product separation to obtain chitosan-esterified starch composite;

[0010] 3) dispersing the chitosan-esterified starch composite in water to prepare chitosan-esterified starch composite dispersion, then adding oil phase and performing homogenization to obtain oil-in-water emulsion;

[0011] 4) performing suction filtration on the oil-in-water emulsion, washing the obtained solid with sodium chloride-acetic acid solution, then adding to organic solvent to perform ultrasonic and centrifugation, and then taking the obtained solid 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-15 μm.

[0013] Further preferably, the natural starch in step 1) is at least one of rice starch (particle size 3 μm-8 μm) and corn starch (particle size 5 μm-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 food industry and have been approved by FDA. Compared with octadecenyl succinic anhydride, hexadecenyl succinic anhydride, tetradecenyl succinic anhydride and dodecenyl succinic anhydride, OSA and DCSA are safer and cheaper, and have higher reactivity with starch particles.

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

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

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

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

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

[0020] Preferably, the weight percentage of the chitosan-esterified starch complex in the chitosan-esterified starch complex dispersion solution of 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 solution of step 3) is 2% to 3%.

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

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

[0024] Preferably, the oil phase in step 3) is composed of at least one of undecylic acid (melting point 29-30°C) and paraffin wax with a melting point of 28-35°C. The melting points of undecylic acid and paraffin wax with a melting point of 28-35°C are low, and their use as the oil phase reduces energy consumption during the heating process compared to the use of lauric acid and paraffin wax (melting point about 48°C) as the oil phase in the prior art.

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

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

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

[0028] Preferably, the number of washes in step 4) is 2-5 times.

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

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

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

[0032] A chitosan-esterified starch-based Janus particle prepared by the above method.

[0033] Use of a chitosan-esterified starch-based Janus particle as described above in the preparation of an emulsifier or thickener.

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

[0035] Preferably, the thickening agent is a food thickening agent.

[0036] Principle of the present application: the present application uses natural starch (particle size of 3-15 μm) as raw material, prepares esterified starch through ultrasonic-assisted esterification reaction, then performs compounding of the esterified starch and chitosan to obtain chitosan-esterified starch particles (the starch particles are entirely wrapped with chitosan, and the stable adsorption of the particles at the oil-water interface can be realized by using the film-forming property and electrostatic adsorption of chitosan), then uses the chitosan-esterified starch particles as stabilizer of Pickering emulsion to prepare oil-in-water emulsion, uses the oil phase to fix one side of the chitosan-esterified starch particles, then washes the other side exposed by the chitosan-esterified starch particles with high-ionic-strength sodium chloride-acetic acid solution to remove the chitosan, then releases the particles, and finally obtains starch-based Janus particles.

[0037] The present application has the following advantages: the present application uses natural starch as raw material to prepare starch-based Janus particles, the preparation method is simple in operation, mild in conditions, safe and environmentally friendly, and low in cost, and finally high-quality starch-based Janus particles which can be used as emulsifier or thickening agent are prepared, and the present application is suitable for large-scale industrial production and application.

[0038] Specifically:

[0039] 1) the present application uses ultrasonic-assisted esterification reaction (esterification agent and starch are difficult to react in water phase system), which can disperse the esterification agent into smaller droplets, so as to make the esterification reaction rate faster and the distribution of esterification groups on the surface of starch more uniform;

[0040] 2) the present application mixes the esterified starch and chitosan, and uses the electrostatic interaction between the negative groups of the esterified starch and the positive groups of chitosan to obtain chitosan-esterified starch composite which is stably adsorbed at the oil-water interface;

[0041] 3) the Pickering emulsion stabilizing particles in the present application use chitosan-esterified starch composite, which is particularly stable in oil-water interface adsorption, and the oil phase cooling does not need to be carried out under low temperature conditions, but can be carried out at room temperature to realize stable solidification, thereby reducing the energy consumption in the cooling process;

[0042] 4) the present application removes the chitosan on the exposed side through ion shielding, so as to achieve the purpose of asymmetric modification, and finally prepares Janus particles based on chitosan and esterified starch;

[0043] 5) The Janus particle based on chitosan and esterified starch of the present application is wrapped by chitosan on one side, which has strong hydrophobicity, while the other side is esterified group, which has amphiphilicity, finally making the Janus particle have anisotropy, suitable for use as food emulsifier / food thickening agent. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The Fourier infrared spectrogram of esterified starch, chitosan and chitosan-esterified starch complex in Example 1.

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

[0046] Figure 3 The test result graph of nitrogen element and sodium element content of the surface of esterified starch, chitosan-esterified starch complex and Janus particle in Example 1.

[0047] Figure 4 The SEM image of Janus particle in Example 1. DETAILED DESCRIPTION

[0048] The present application is further explained and described in conjunction with specific embodiments.

[0049] Example 1:

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

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

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

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

[0054] 4) The oil-in-water emulsion was filtered, the mesh size of the filter was 120 meshes, the obtained solid was washed with a sodium chloride-acetic acid solution with an acetic acid concentration of 1.0 mg / mL and a sodium chloride concentration of 300 mmol / L and a temperature of 23°C for 3 times, then added to ethanol and heated to 30°C, then placed in an ultrasonic cleaner (KQ-250DE type) and ultrasonicated for 5 min, then centrifuged at a speed of 3500 rpm for 5 min, and the total ultrasonic- centrifugation operation was performed for 3 times to obtain chitosan and esterified starch-based Janus particles (referred to as “Janus particles”).

[0055] Performance test:

[0056] 1) The Fourier infrared spectra of the esterified starch, chitosan and chitosan-esterified starch complex in this example are shown in Figure 1 .

[0057] It can be seen from Figure 1 that the peak of chitosan at 1601 cm -1 is combined with the peak of esterified starch at 1569 cm -1 , which shows that the peak intensity of chitosan-esterified starch complex at 1644 cm -1 increases, indicating that chitosan-esterified starch complex is indeed obtained.

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

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

[0060] 3) The nitrogen and sodium element content test results of the esterified starch, chitosan-esterified starch complex and Janus particles in this example are shown in Figure 3 .

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

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

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

[0064] Example 2:

[0065] A Janus particle based on chitosan and esterified starch is prepared by the following method:

[0066] 1) Disperse 15g of corn starch (particle size 5μm~15μm) in deionized water to prepare a dispersion with a mass fraction of 30%, then add 2.25g of decenyl succinic anhydride, and then place it in an ultrasonic cleaner (KQ-250DE type) and sonicate at 35℃ for 10min with an ultrasonic power of 100W. Stir at 35℃ for 15min, centrifuge to collect the solid, and obtain esterified starch.

[0067] 2) Dissolve 4.5g of chitosan at room temperature by stirring overnight. Prepare a chitosan solution in 150mL of acetic acid solution. Add 15g of esterified starch to the chitosan solution (the weight ratio of chitosan to esterified starch is 0.30:1). Stir at 600rpm for 20min and centrifuge at 3500rpm for 15min. Take the solid obtained by centrifugation to obtain the chitosan-esterified starch complex.

[0068] 3) Disperse 0.5g of chitosan-esterified starch complex in 10g of deionized water, add 5g of paraffin (melting point 28℃; oil phase), heat to 32℃ and transfer to a high-speed dispersion homogenizer (FJ200-SH type), homogenize for 2min at 14000rpm, and then let stand naturally for 15min to obtain an oil-in-water emulsion.

[0069] 4) The oil-in-water emulsion was filtered using a 200-mesh filter. The filtered solid was washed five times with a sodium chloride-acetic acid solution containing 2.0 mg / mL acetic acid, 200 mmol / L sodium chloride, and 20°C. The solid was then added to chloroform and heated to 32°C. The mixture was then ultrasonically cleaned for 3 minutes in an ultrasonic cleaner (KQ-250DE type) and centrifuged at 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] The microstructure and properties of the chitosan and esterified starch-based Janus particles in this example are highly similar to those of the chitosan and esterified starch-based Janus particles in Example 1, as tested (the testing method is the same as that in Example 1).

[0071] Example 3:

[0072] A chitosan and esterified starch-based Janus particle is prepared as follows:

[0073] 1) 20 g of rice starch (particle size of 3-8 μm) is dispersed in deionized water to prepare a dispersion with a mass fraction of 30%, 0.2 g of octenyl succinic anhydride is added, and the mixture is subjected to ultrasonic cleaning at 35°C for 20 min at a power of 600 W, and then stirred at 35°C for 15 min, and the solid is obtained by centrifugation, thereby obtaining esterified starch;

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

[0075] 3) 0.1 g of the chitosan-esterified starch composite is dispersed in 10 g of deionized water by stirring, 0.5 g of paraffin (melting point of 35°C; oil phase) is added, the temperature is raised to 40°C, and then the mixture is transferred to a high-speed dispersion homogenizer (FJ200-SH type), and then homogenized at a speed of 6000 rpm for 2 min, and then left to stand naturally for 15 min, thereby obtaining an oil-in-water emulsion;

[0076] 4) The oil-in-water emulsion is subjected to suction filtration, the mesh size of the filter screen is 300 meshes, the obtained solid is washed twice with a sodium chloride-acetic acid solution with a concentration of acetic acid of 1.5 mg / mL and a concentration of sodium chloride of 500 mmol / L and a temperature of 25°C, and then added to toluene and heated to 40°C, and then subjected to ultrasonic cleaning in an ultrasonic cleaner (KQ-250DE type) for 5 min, and then centrifuged at a speed of 3500 rpm for 3 min, and the total ultrasonic- centrifugation operation is performed twice, thereby obtaining chitosan and esterified starch-based Janus particles.

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

[0078] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method for preparing Janus particles based on chitosan and esterified starch, characterized in that, Includes the following steps: 1) Disperse natural starch and esterifying agent in water, and then esterify them under ultrasonic assistance to obtain esterified starch; 2) Chitosan was dissolved in acetic acid solution to prepare chitosan solution, and then esterified starch was dispersed in chitosan solution for electrostatic adsorption. The products were then separated to obtain chitosan-esterified starch complex. 3) Chitosan-esterified starch complex was dispersed in water to prepare a chitosan-esterified starch complex dispersion, and then the oil phase was added and homogenized to obtain an oil-in-water emulsion. 4) Filter the oil-in-water emulsion, wash the filtered solid with sodium chloride-acetic acid solution, add it to an organic solvent for sonication and centrifugation, and take the solid obtained by centrifugation to obtain Janus particles based on chitosan and esterified starch. In step 2), the weight ratio of chitosan to esterified starch is 0.05 to 0.30:

1.

2. The preparation method according to claim 1, characterized in that: The particle size of the natural starch in step 1) is 3μm to 15μm; 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 natural starch to esterifying agent is 1:0.01 to 0.

15.

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

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

6. The preparation method according to claim 1 or 5, 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℃ to 40℃, and the homogenization time is 1 min to 2 min.

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

8. A Janus particle based on chitosan and esterified starch, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 7.

9. The use of Janus particles based on chitosan and esterified starch as described in claim 8 in the preparation of emulsifiers or thickeners.

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