Method for preparing food-grade Janus nanoparticles by ultrasonic-assisted induction of Maillard reaction

Abstract

The invention discloses a method for preparing food-grade Janus nano-particles through ultrasonic-assisted induction of a Maillard reaction, and belongs to the technical field of nano-materials. According to the preparation method, zein with free amino and ethyl cellulose containing residual carbonyl are taken as raw materials, an ultrasonic-assisted and Maillard reaction synergistic preparation method is adopted, and the exposure of reactive active sites of amino and carbonyl and the collision efficiency among molecules are accelerated by utilizing an ultrasonic cavitation effect; by accurately regulating and controlling the glycosylation reaction process and the interface phase separation behavior of the nano-particles, the two biomacromolecules form an asymmetric dumbbell-shaped structure, and finally the food-grade Janus nano-particles which are uniform in size, good in dispersity and high in stability are prepared. The preparation method of the food-grade Janus nanoparticles provided by the invention is mild and controllable in reaction conditions, simple and efficient in operation steps, free of introduction of toxic chemical reagents, capable of guaranteeing the safety of the nanoparticles from the source and wide in application prospect.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically to a method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction. Background Technology

[0002] Janus nanoparticles refer to composite materials with two or more different chemical compositions integrated into a single structural system. Due to their unique asymmetric structure, Janus nanoparticles exhibit excellent performance in drug delivery, interfacial stability, and environmental responsiveness, making them a superior material for active ingredient carriers and interfacial regulation in the food industry. However, current methods for preparing Janus nanoparticles largely rely on synthetic polymers and organic chemical reagents, whose biosafety fails to meet food-grade requirements, significantly limiting their application in the food sector. Furthermore, existing preparation methods, such as microfluidic methods, seed emulsion polymerization, and Pickering emulsion template methods, are not only lengthy and dependent on sophisticated equipment but also require organic solvents, resulting in high costs, significant pollution risks, and difficulties in large-scale production, conflicting with the food industry's requirements for "green, efficient, and safe" processes. Zein and ethyl cellulose, as natural biopolymers, are abundant, biocompatible, and edible, making them ideal raw materials for constructing food-grade Janus nanoparticles. The Maillard reaction, a common reaction in food processing, requires no toxic reagents and achieves stable binding of components through intermolecular covalent cross-linking. Ultrasonic-assisted technology can not only promote material dispersion but also accelerate the reaction process and simplify the operation. Therefore, it is necessary to develop a simple, low-requirement, and scalable method for preparing food-grade Janus nanoparticles by utilizing ultrasonic-assisted technology and the Maillard reaction principle.

[0003] Patent document CN 119856775 A discloses a method for preparing Janus droplets using microfluidics. This method uses immiscible zein and sodium alginate solutions as dispersed phases, and dissolves an emulsifier in an oil phase as the continuous phase. By controlling the laminar flow behavior of the three phases in a microfluidic chip, food-grade Janus droplets are prepared under the shearing action of the continuous phase. However, the particle size of Janus droplets is typically in the micrometer range, and this large size limits their application in small-size carrier scenarios. The Janus nanoparticles prepared in this invention can reach the nanometer scale, offering a wider range of applications.

[0004] Patent document CN 119909021 A discloses a technique for preparing Janus microspheres using Janus droplet templates. This method involves mixing tea polyphenol-magnesium nanoparticles and melanin nanoparticles with methacryloyl collagen as the mobile phase, using vegetable oil as the dispersion phase, and forming Janus droplets through flow shearing in a coaxial co-flow microfluidic device. After UV curing, Janus microspheres co-loaded with melanin / tea polyphenol-magnesium are obtained. However, this method requires multiple nanoparticle preparation steps, making it cumbersome and potentially increasing the difficulty of large-scale production. Furthermore, this method is highly dependent on microfluidic equipment, and its production efficiency is limited by the channels of the microfluidic chip, resulting in low efficiency and hindering the large-scale preparation of Janus particles.

[0005] Patent document CN 118237079 A discloses a method for preparing Janus particles via seed emulsion polymerization. This method first prepares polystyrene particles using emulsion polymerization, then obtains core-shell structured chlorinated polystyrene particles via seed emulsion polymerization, subsequently forming dumbbell-shaped Janus particles through seed swelling polymerization, and finally amination to obtain dumbbell-shaped Janus particles. However, this method is cumbersome and requires stringent process conditions, making it unsuitable for large-scale industrial production. Furthermore, the preparation process requires a large amount of organic solvent, posing a potential risk of solvent residue and thus preventing its application in food.

[0006] The article "Amphiphilic Janus nanoparticles with controlled composition and wettability for pickering emulsion with controllable movement and release" discloses a method for synthesizing Janus nanoparticles via seed emulsion polymerization. This method first prepares Fe3O4 nanoparticles using a co-precipitation method, then obtains PS / Fe3O4 seed particles through emulsion polymerization, and subsequently coats one side of the seed particles with SiO2 to obtain Janus nanoparticles. However, this method requires multiple reaction steps, is complex, and is difficult to scale up for continuous production. Furthermore, Janus nanoparticles are made of polystyrene, iron(III) oxide, and silicon dioxide, which have a certain degree of toxicity, potentially limiting their application in the food industry.

[0007] As mentioned above, although there has been some research on this topic in the existing technology, there is still a lack of a simple, equipment-independent, and scalable method for preparing food-grade Janus nanoparticles. Furthermore, a method for constructing food-grade Janus nanoparticles using proteins and polysaccharides as raw materials via ultrasound-assisted Maillard reaction has not yet been reported. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the primary technical problem to be solved by the present invention is to provide food-grade Janus nanoparticles constructed by ultrasound-assisted Maillard reaction.

[0009] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned food-grade Janus nanoparticles.

[0010] The technical principle of this invention is the synergistic effect of ultrasonic field enhancement and Maillard reaction. By controlling ultrasonic parameters and Maillard reaction conditions, the asymmetric assembly of intermolecular interfaces is driven, achieving the controllable construction of zein-ethyl cellulose Janus nanoparticles. First, zein containing free amino groups and ethyl cellulose containing free carbonyl groups are dispersed in an ethanol-water mixture. The ultrasonic cavitation effect promotes the exposure of the reactive sites of amino and carbonyl groups and improves the collision efficiency between molecules, promoting uniform dispersion of the two raw materials. Subsequently, the zein-ethyl cellulose mixture is injected into water and heated to the suitable temperature for the Maillard reaction, initiating the condensation reaction of amino and carbonyl groups to generate a glycosylated complex intermediate containing both polymer segments. Simultaneously, by controlling parameters such as ultrasonic power, system pH, reaction temperature, and reaction time, the Maillard reaction process and the difference in interfacial affinity between the two polymers are precisely controlled. When two polymer segments form enriched regions with significant energy differences on the surface of the intermediate, the composite intermediate is asymmetrically oriented along the energy gradient, eventually forming food-grade Janus nanoparticles with uniform particle size and well-defined functional zones.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: 1) Dissolve zein in an ethanol-water solution, adjust the pH of the solution, and stir at 300 rpm for 2 h to completely dissolve it, thus obtaining a zein solution; 2) Dissolve ethyl cellulose in an ethanol-water solution, adjust the pH of the solution, and stir at 300 rpm for 2 h to completely dissolve it, thus obtaining an ethyl cellulose solution; 3) Mix the zein solution from step 1) with the ethyl cellulose solution from step 2) in equal volumes to obtain a zein-ethyl cellulose mixed solution; 4) The zein-ethyl cellulose mixture solution obtained in step 3) is subjected to ultrasonic treatment to obtain an ultrasonicated zein-ethyl cellulose mixture solution. 5) Heat the ultrasonicated zein-ethyl cellulose mixture obtained in step 4) to a constant temperature in a constant temperature water bath; 6) Adjust the ultrapure water to a certain pH value and heat it to a constant temperature in a constant temperature water bath; 7) Take 1 mL of the zein-ethyl cellulose mixed solution from step 5), inject it into 10 mL of the ultrapure water from step 6) while stirring at 400 rpm, heat it for a period of time, and then cool it naturally to obtain a zein-ethyl cellulose Janus nanoparticle dispersion. 8) Place the zein-ethyl cellulose Janus nanoparticle dispersion obtained in step 7) into a vacuum freeze dryer and freeze dry for 36 h to obtain zein-ethyl cellulose Janus nanoparticle powder.

[0012] Preferably, the ethanol-water solution in step 1) has an ethanol concentration of 90% (v / v), a solution pH of 5.0, and a zein concentration of 2.0% (w / v).

[0013] Preferably, in step 2), the ethanol-water solution has an ethanol concentration of 90% (v / v), a solution pH of 5.0, and an ethyl cellulose concentration of 2.0% (w / v).

[0014] Preferably, in step 4), the ultrasonic power is 300 W and the ultrasonic time is 5 min.

[0015] Preferably, the heating temperature in step 5) is 60°C.

[0016] Preferably, the ultrapure water in step 6) has a pH of 5.0 and a heating temperature of 60°C.

[0017] Preferably, the injection rate in step 7) is 10 mL / min, and the heating time is 10 min. Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The zein selected in this invention is a natural plant protein derived from corn endosperm. It is widely available and low in cost, has good edible safety and self-assembly ability, and can synergistically construct structurally stable nanoparticles with other components. It has high affinity and good loading capacity for lipophilic active ingredients. Ethyl cellulose is a hydrophobic cellulose derivative prepared by etherification of natural cellulose. It has unique swelling and sustained release properties and excellent stability in the gastrointestinal environment (pH 3-11). It can be used as a wall material for delivery carriers of lipophilic functional factors.

[0018] (2) This invention is the first to prepare food-grade dumbbell-shaped Janus nanoparticles made from proteins and polysaccharides. The two hemispheres are composed of proteins and polysaccharides respectively, combining the core advantages of two biomacromolecules, namely the biocompatibility, nutritional characteristics and high load capacity of proteins and the intestinal stability and targeted delivery characteristics of polysaccharides.

[0019] (3) This invention is the first to construct food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction. The preparation method is simple to operate, has low equipment dependence, and can be used for large-scale industrial production.

[0020] (4) The present invention employs ultrasonic treatment technology in the preparation process, which can accelerate the molecular movement of zein and ethyl cellulose through ultrasonic cavitation effect, promote the exposure and interaction of active sites, enhance the binding efficiency of the intermolecular interface, and facilitate the precise control of subsequent asymmetric structures.

[0021] (5) The Maillard reaction occurred during the preparation process of this invention. The amino group of zein covalently crosslinks with the carbonyl group of ethyl cellulose. A stable bichat structure can be formed without the need for additional chemical crosslinking agents, which not only improves the stability of nanoparticles but also avoids the risk of chemical reagent residues.

[0022] (6) The Janus nanoparticles prepared by this invention have uniform particle size, good dispersibility, and excellent stability, and can be used for the co-delivery of hydrophobic functional factors in food. This invention provides a new approach for constructing co-delivery systems of active substances with multiple functional properties, and also provides a new method for the development of food-grade Janus nanoparticles. Attached Figure Description

[0023] Figure 1 Scanning electron microscope images of food-grade Janus nanoparticles prepared for Examples 1(a) and 2(b).

[0024] Figure 2 Laser confocal microscopy images of food-grade Janus nanoparticles prepared for Examples 1(a) and 2(b).

[0025] Figure 3 The particle size and PDI of the nanoparticles prepared in Examples 1-4, Comparative Example 1, and Comparative Example 2 are shown.

[0026] Figure 4 The turbidity of the nanoparticles prepared in Examples 1, 2, 1, and 2 is given.

[0027] Figure 5 The free amino content of the nanoparticles prepared in Example 1, Example 2, and Comparative Example 1.

[0028] Figure 6 The grafting degree of the food-grade Janus nanoparticles prepared in Examples 1 and 2.

[0029] Figure 7 The absorbance at 284 nm is the absorbance of the nanoparticles prepared in Example 1, Example 2, and Comparative Example 1.

[0030] Figure 8 The absorbance at 304 nm is the absorbance of the nanoparticles prepared in Example 1, Example 2, and Comparative Example 1.

[0031] Figure 9 The absorbance at 420 nm is the absorbance of the nanoparticles prepared in Example 1, Example 2, and Comparative Example 1.

[0032] Figure 10 Fourier transform infrared spectra of the nanoparticles prepared in Examples 1, 2, 1, and 2.

[0033] Figure 11 X-ray diffraction patterns of the nanoparticles prepared in Examples 1, 2, 1, and 2.

[0034] Figure 12 Thermogravimetric curves of the nanoparticles prepared in Examples 1, 2, 1, and 2 are shown.

[0035] Figure 13 Differential thermogravimetric curves of the nanoparticles prepared in Examples 1, 2, 1, and 2.

[0036] Figure 14 Differential scanning calorimetry curves of the nanoparticles prepared in Examples 1, 2, 1, and 2.

[0037] Figure 15 Particle size, PDI (a), and Zeta potential (b) of the food-grade Janus nanoparticles prepared in Example 1 after 21 days of storage.

[0038] Figure 16 Particle size, PDI (a), and Zeta potential (b) of the food-grade Janus nanoparticles prepared in Example 2 after 21 days of storage.

[0039] Figure 17 The particle size, PDI (a), and Zeta potential (b) of the nanoparticles prepared for Comparative Example 1 after 21 days of storage.

[0040] Figure 18 The particle size, PDI (a), and Zeta potential (b) of the nanoparticles prepared for Comparative Example 2 after 21 days of storage.

[0041] Figure 19 The TSI images are of the nanoparticles prepared in Examples 1, 2, 1, and 2. Detailed Implementation

[0042] The present invention will be further described below with reference to embodiments. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0043] Unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the materials and reagents used, unless otherwise specified, are commercially available.

[0044] Example 1 Zeadin and ethyl cellulose were dissolved separately in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain a 2.0% (w / v) zeadin solution and an ethyl cellulose solution. Equal volumes of the two solutions were mixed and sonicated at 300 W for 5 min to obtain a sonicated zeadin-ethyl cellulose mixed solution. The mixed solution was heated to 60℃, and 1 mL was injected at a rate of 10 mL / min into 10 mL of 60℃ ultrapure water (pH 5.0). Heating was continued for 10 min, followed by natural cooling to obtain a zeadin-ethyl cellulose Janus nanoparticle dispersion. The dispersion was freeze-dried for 36 h to obtain zeadin-ethyl cellulose Janus nanoparticle powder.

[0045] Example 2 The difference between the technical solution in this embodiment and Embodiment 1 above lies in the heating temperature and heating time. The specific method is as follows: Zeadin and ethyl cellulose were dissolved separately in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain a 2.0% (w / v) zeadin solution and an ethyl cellulose solution. Equal volumes of the two solutions were mixed and sonicated at 300 W for 5 min to obtain a sonicated zeadin-ethyl cellulose mixed solution. The mixed solution was heated to 80℃, and 1 mL was injected at a rate of 10 mL / min into 10 mL of 80℃ ultrapure water (pH 5.0). Heating was continued for 30 min, followed by natural cooling to obtain a zeadin-ethyl cellulose Janus nanoparticle dispersion. The dispersion was freeze-dried for 36 h to obtain zeadin-ethyl cellulose Janus nanoparticle powder.

[0046] Example 3 The difference between the technical solution in this embodiment and that in Embodiment 1 above is the different concentrations of zein and ethyl cellulose. The specific method is as follows: Zeadin and ethyl cellulose were dissolved separately in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain a 1.5% (w / v) zeadin solution and an ethyl cellulose solution. Equal volumes of the two solutions were mixed and sonicated at 300 W for 5 min to obtain a sonicated zeadin-ethyl cellulose mixed solution. The mixed solution was heated to 60℃, and 1 mL was injected at a rate of 10 mL / min into 10 mL of 60℃ ultrapure water (pH 5.0). Heating was continued for 10 min, followed by natural cooling to obtain a zeadin-ethyl cellulose Janus nanoparticle dispersion. The dispersion was freeze-dried for 36 h to obtain zeadin-ethyl cellulose Janus nanoparticle powder.

[0047] Example 4 The difference between the technical solution in this embodiment and Embodiment 1 above is the injection speed. The specific method is as follows: Zeadin and ethyl cellulose were dissolved separately in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain 2.0% (w / v) zeadin and ethyl cellulose solutions. Equal volumes of the two solutions were mixed and sonicated at 300 W for 5 min to obtain a sonicated zeadin-ethyl cellulose mixed solution. The mixed solution was heated to 60℃, and 1 mL was injected at a rate of 5 mL / min into 10 mL of 60℃ ultrapure water (pH 5.0). Heating was continued for 10 min, followed by natural cooling to obtain a zeadin-ethyl cellulose Janus nanoparticle dispersion. The dispersion was freeze-dried for 36 h to obtain zeadin-ethyl cellulose Janus nanoparticle powder.

[0048] Comparative Example 1 This comparative example prepared zein nanoparticles, and the specific method is as follows: Zeatin was dissolved in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain a 2.0% (w / v) zeatin solution. The zeatin solution was sonicated at 300 W for 5 min to obtain an ultrasonicated zeatin solution. The above solution was heated to 60℃, and 1 mL was injected into 10 mL of 60℃ ultrapure water (pH 5.0) at a rate of 10 mL / min. Heating was continued for 10 min, followed by natural cooling to obtain a zeatin nanoparticle dispersion. The dispersion was freeze-dried for 36 h to obtain zeatin nanoparticle powder.

[0049] Comparative Example 2 This comparative example prepared ethyl cellulose nanoparticles, and the specific method is as follows: Ethyl cellulose was dissolved in 90% (v / v) ethanol solution, and the pH of the solution was adjusted to 5.0 to obtain an ethyl cellulose solution with a mass concentration of 2.0% (w / v). The ethyl cellulose solution was sonicated at 300 W for 5 min to obtain a sonicated ethyl cellulose solution. The above solution was heated to 60 °C, and 1 mL was injected into 10 mL of 60 °C ultrapure water (pH 5.0) at a rate of 10 mL / min. Heating was continued for 10 min, followed by natural cooling to obtain an ethyl cellulose nanoparticle dispersion. The above dispersion was freeze-dried for 36 h to obtain ethyl cellulose nanoparticle powder.

[0050] Experiment Example 1: Observation using a scanning electron microscope Using the food-grade Janus nanoparticle dispersions prepared in Examples 1 and 2 as experimental samples, 10 μL of the sample was dropped onto the surface of a silicon wafer. After drying, the silicon wafer was attached to a conductive adhesive. After sputtering a gold layer onto the sample surface, the microstructure of the sample was observed using a scanning electron microscope with an accelerating voltage of 5 kV.

[0051] according to Figure 1 The experimental results show that the zein-ethyl cellulose nanoparticles consist of two identical hemispheres with a dumbbell-like morphology, indicating the successful preparation of food-grade Janus nanoparticles. The nanoparticles prepared in Example 1 have a major diameter of approximately 220 nm and a minor diameter of approximately 110 nm; the nanoparticles prepared in Example 2 have a major diameter of approximately 250 nm and a minor diameter of approximately 125 nm. This phenomenon indicates that the size of the Janus nanoparticles tends to increase with increasing heating temperature and time. This may be because higher temperatures and longer heating times promote the movement and aggregation of raw material molecules, allowing the nanoparticles to form larger structural units during self-assembly. However, the Janus nanoparticles prepared in Example 2 exhibited aggregation, indicating that excessively high heat treatment temperatures and prolonged times may damage the dispersibility of the nanoparticles.

[0052] Experiment Example 2: Observation using a laser confocal microscope Using the food-grade Janus nanoparticle dispersions prepared in Examples 1 and 2 as experimental samples, zein and ethyl cellulose were labeled with Rhodamine B and Calcoflur fluorescent whitening agents, respectively, and observed under a 100x objective lens using a laser confocal microscope at excitation wavelengths of 561 nm and 405 nm.

[0053] according to Figure 2The experimental results show that the two hemispheres of Janus nanoparticles exhibit different colors: the zein hemisphere emits red fluorescence, while the ethyl cellulose hemisphere emits blue fluorescence. This indicates that the two hemispheres are composed of two different materials, rather than being uniformly distributed, further proving the successful preparation of Janus nanoparticles.

[0054] Experimental Example 3: Particle Size Distribution Measurement The nanoparticle dispersions prepared in Examples 1-4, Comparative Example 1, and Comparative Example 2 were used as experimental samples, and their average particle size and polydispersity index (PDI) were determined using a nanoparticle size analyzer.

[0055] according to Figure 3 The experimental results show that the particle sizes of the four Janus nanoparticles are all within the nanoscale range and are uniformly distributed. The particle size of the Janus nanoparticles prepared in Example 1 is 140.23 ± 1.27 nm, and the particle size of the Janus nanoparticles prepared in Example 2 is 162.07 ± 0.82 nm, consistent with the results observed by scanning electron microscopy. The particle size of the zein nanoparticles is 139.77 ± 1.65 nm, and the particle size of the ethyl cellulose nanoparticles is 107.9 ± 1.04 nm. The particle size of the Janus nanoparticles is significantly smaller than the sum of the two. This result indicates that the two hemispheres of the Janus nanoparticles do not maintain independent particle morphologies, but rather couple at the interface through intermolecular interactions, forming a more compact overall structure.

[0056] Experiment Example 4: Turbidity Measurement The nanoparticle dispersions prepared in Examples 1, 2, 1, and 2 were used as experimental samples. The turbidity of the samples was measured at 600 nm using a UV-Vis spectrophotometer. The transmittance (T) was calibrated to 100% with distilled water, and the turbidity was expressed as 100-T%.

[0057] according to Figure 4 The experimental results show that the turbidity of the zein-ethyl cellulose Janus nanoparticles prepared in Example 1 is significantly lower than that of zein nanoparticles, which may be related to the special structure of Janus nanoparticles. Due to their asymmetric dumbbell-shaped structure, light scattering is more biased to the sides, thereby reducing the attenuation of forward transmitted light. Therefore, compared with spherical nanoparticles, Janus nanoparticles have better light transmittance. In addition, the zein-ethyl cellulose Janus nanoparticles prepared in Example 2 are significantly higher than those in Example 1, which is attributed to the larger particle size of the formed Janus nanoparticles, thus significantly increasing the turbidity of the system.

[0058] Experimental Example 5: Determination of Free Amino Content and Grafting Degree The nanoparticle dispersions prepared in Examples 1, 2, and Comparative Example 1 were used as experimental samples. The free amino content and grafting degree of the samples were determined using the o-phthalaldehyde (OPA) method. 4 mL of OPA reagent was mixed with 0.2 mL of sample and incubated at 35°C for 2 min. The absorbance at 340 nm was measured using a UV-Vis spectrophotometer, with ultrapure water as a blank. The free amino content was calculated using an L-leucine (0 ~ 0.03 mg / mL) standard curve. The grafting degree (DG) was calculated as follows: DG = (A0 - A t ) / A0×100%, where A0 is the absorbance of the zein nanoparticles prepared in Comparative Example 1, and A t The absorbance is the light absorption of the zein-ethyl cellulose Janus nanoparticles prepared in Examples 1 and 2.

[0059] according to Figure 5 and Figure 6 The experimental results show that the free amino content decreased significantly after the Maillard reaction, and the zein-ethyl cellulose Janus nanoparticles exhibited a high grafting degree, indicating that a Maillard reaction occurred between zein and ethyl cellulose. However, there was no significant difference in the free amino content and grafting degree of the Janus nanoparticles prepared in Examples 1 and 2, indicating that heating temperature and heating time did not significantly affect the extent of the Maillard reaction between zein and ethyl cellulose. This phenomenon may be attributed to the fact that the functional groups involved in the Maillard reaction had already reacted sufficiently at the interface, and subsequent changes in heating temperature and heating time had limited effect on regulating the functional group reaction.

[0060] Experimental Example 6: Determination of Maillard Reaction Products The food-grade Janus nanoparticle dispersions prepared in Examples 1 and 2 were used as experimental samples, and the Maillard reaction products of the samples were determined using a UV-Vis spectrophotometer. The early, intermediate, and late Maillard reaction products were determined by measuring the absorbance of the samples at 284 nm, 304 nm, and 420 nm, respectively.

[0061] according to Figure 7 , Figure 8 and Figure 9The experimental results show that the absorbance of zein-ethyl cellulose Janus nanoparticles at 304 nm and 420 nm is higher than that of zein nanoparticles alone, indicating that a Maillard reaction occurred between zein and ethyl cellulose. The contents of early, middle, and late Maillard reaction products in the Janus nanoparticles prepared in Example 2 were significantly higher than those in Example 1, indicating that appropriately increasing the reaction temperature and extending the reaction time is more conducive to the Maillard reaction.

[0062] Experiment Example 7: Fourier Transform Infrared Spectroscopy Analysis The nanoparticle powders prepared in Examples 1, 2, 1, and 2 were used as experimental samples. Fourier transform infrared spectroscopy was used to analyze the chemical structure of the samples and the interactions between the raw materials. The samples were mixed with dry KBr powder at a ratio of 1:100 (w / w) and pressed into sheets. Wavenumbers were recorded from 400 to 4000 cm⁻¹. -1 The spectral signal was scanned 64 times, with a resolution of 4 cm. -1 .

[0063] according to Figure 10 The experimental results show that zein at 3346 cm⁻¹ -1 2926 cm -1 1659 cm -1 1532 cm -1 and 1455 cm -1 The characteristic peaks at 3481 cm⁻¹ correspond to the OH stretching vibration, CH stretching vibration, amide I band, amide II band, and amide III band, respectively. Ethyl cellulose shows a characteristic peak at 3481 cm⁻¹. -1 The characteristic broadband corresponds to the stretching vibration of the OH group; at 2977 and 2876 cm⁻¹ -1 The characteristic peak at 1378 cm⁻¹ belongs to the stretching vibration of the C–H group; -1 and 1111 cm -1 The characteristic peaks at these locations correspond to the bending vibration of the CH group and the stretching vibration of the COC cyclic ether, respectively. In the zein-ethyl cellulose Janus nanoparticles prepared in Example 1, the characteristic peak corresponding to the OH group red-shifted to 3467 cm⁻¹. -1 This indicates that hydrogen bonds have formed between zein and ethyl cellulose. After the binding of zein and ethyl cellulose, the absorption peak of zein in amide II shifts blue to 1541 cm⁻¹. -1 The absorption peak at amide III red-shifted to 1446 cm⁻¹. -1 This indicates that hydrophobic and electrostatic interactions are involved in the formation of zein-ethyl cellulose Janus nanoparticles.

[0064] Experimental Example 8: X-ray Diffraction Analysis The nanoparticle powders prepared in Examples 1, 2, 1, and 2 were used as experimental samples, and the molecular arrangement of the samples was determined using an X-ray diffractometer. 20 mg of sample was placed in the test chamber, with a working voltage of 40 kV, a working current of 40 mA, an θ-angle scanning range from 5° to 50°, and a scanning rate of 2° / min.

[0065] according to Figure 11 The experimental results show that zein exhibits two amorphous peaks at 9.39° and 19.58°, confirming its amorphous structural properties; while weak diffraction peaks exist at 31.84° and 45.40°, attributed to residual NaCl crystals in the system. Ethyl cellulose exhibits two broad amorphous peaks at 7.86° and 20.38°, indicating that ethyl cellulose exists in an amorphous state. The Janus nanoparticles prepared in Example 1 show camel-hump-like signals at 8.75° and 13.28°, with broadened peak shapes and decreased intensity, indicating that when zein and ethyl cellulose form a Janus structure, the interaction between the two components interferes with the ordered arrangement of molecular chains, leading to a decrease in the crystallinity of the system and a more disordered overall structure. Compared with Example 1, the amorphous peaks of the Janus nanoparticles prepared in Example 2 are broader and have lower intensity. This phenomenon indicates that as the Maillard reaction progresses, the orderliness of the molecular arrangement of the two amorphous components is further reduced during assembly, ultimately forming a composite structure with a higher degree of disorder. Structures with a higher degree of disorder typically possess higher oral bioavailability, a characteristic that lays a favorable foundation for the application of Janus nanoparticles in the field of functional factor delivery.

[0066] Experimental Example 9 Thermogravimetric Analysis The nanoparticle powders prepared in Examples 1, 2, 1, and 2 were used as experimental samples. The thermal properties of the samples were determined using a thermogravimetric analyzer under a nitrogen atmosphere at a flow rate of 20 mL / min. The samples were placed in a sealed crucible and heated from 40°C to 550°C at a constant rate of 10°C / min, and the weight loss of the samples was recorded.

[0067] according to Figure 12The experimental results show that the thermal decomposition of the sample mainly occurs in three stages. The first stage occurs below 100℃, where the sample exhibits varying degrees of mass loss, which can be attributed to moisture evaporation. As the temperature increases, the sample shows significant weight loss in the range of 280℃ to 380℃, attributed to the thermal decomposition of zein and ethyl cellulose. The final carbonization stage occurs in the temperature range of 380℃ to 550℃. Furthermore, the residual mass ratio of Janus nanoparticles at 550℃ is higher than that of ethyl cellulose, indicating that the interaction between zein and ethyl cellulose enhances the thermal stability of the nanoparticles.

[0068] according to Figure 13 The experimental results show that the temperatures at which zein and ethyl cellulose have the highest mass loss rates are 331.8℃ and 353.2℃, respectively, while the temperatures at which zein-ethyl cellulose Janus nanoparticles have the highest mass loss rates are 348.4℃ and 345.3℃. This further indicates that the combination of zein and ethyl cellulose effectively improves the thermal stability of the nanoparticles.

[0069] Experimental Example 10: Differential Scanning Calorimetry The nanoparticle powders prepared in Examples 1, 2, 1, and 2 were used as experimental samples. The thermal stability of the samples was analyzed using a differential scanning calorimeter under a nitrogen atmosphere at a rate of 20 mL / min. The samples were placed in a sealed crucible and heated from 40 °C to 220 °C at a constant rate of 10 °C / min, and the glass transition temperature (Tg) of the samples was recorded.

[0070] according to Figure 14 The experimental results show that the samples all exhibit endothermic peaks below 100℃, attributed to the endothermic evaporation process of bound water. The Tg values ​​of zein and ethyl cellulose are 166.2℃ and 197.2℃, respectively. After binding, the Tg shifts to 187.7℃ and 179.6℃, indicating intermolecular interactions between the two, which mutually constrain molecular chain motion and jointly regulate the glass transition behavior. Therefore, zein-ethyl cellulose Janus nanoparticles exhibit superior thermal stability at high temperatures.

[0071] Experimental Example 11 Storage Stability Analysis The nanoparticle dispersions prepared in Example 1, Comparative Example 1, and Comparative Example 2 were used as experimental samples. The average particle size, PDI, and Zeta potential were measured using a nanoparticle size analyzer during storage at 4°C for 21 days.

[0072] according to Figure 15 and Figure 16The experimental results show that after 21 days of storage, the particle size and PDI of Janus nanoparticles (zein-ethyl cellulose) did not change significantly, and the absolute value of the Zeta potential remained greater than 20 mV, indicating that Janus nanoparticles have good dispersibility and storage stability. Figure 17 and Figure 18 The experimental results show that the particle size and PDI of zein nanoparticles and ethyl cellulose nanoparticles increased significantly after 21 days of storage, while the absolute value of the Zeta potential decreased significantly, indicating that the dispersibility and storage stability of individual zein and ethyl cellulose nanoparticles in water are poor. These results suggest that the interfacial coupling of the two components in Janus nanoparticles forms a more stable spatial configuration and charge distribution, significantly improving their dispersibility and storage stability in water.

[0073] Experimental Example 12: Turbiscan Stability Analysis The nanoparticle dispersions prepared in Examples 1, 2, 1, and 2 were used as experimental samples, and their stability was analyzed using Turbiscan LAB. 20 mL of sample was transferred to a sample vial, and the sample was scanned every 30 seconds for 1 hour, recording the Turbiscan stability index (TSI).

[0074] according to Figure 19 The experimental results show that the TSI value of zein-ethyl cellulose Janus nanoparticles is lower than that of single zein nanoparticles and ethyl cellulose nanoparticles, indicating that Janus nanoparticles have better physical stability.

Claims

1. Application of zein and ethyl cellulose in the co-preparation of food-grade Janus nanoparticles.

2. A food-grade Janus nanoparticle, characterized in that, It contains zein and ethyl cellulose.

3. The food-grade Janus nanoparticles according to claim 2, characterized in that, It was constructed by ultrasound-assisted induction of the Maillard reaction.

4. A method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction, characterized in that, Using zein containing free amino groups and ethyl cellulose containing carbonyl groups as raw materials, a method combining ultrasound-assisted Maillard reaction was adopted. The ultrasonic cavitation effect was used to enhance intermolecular collisions. By adjusting parameters such as ultrasonic power, system pH, reaction temperature, and reaction time, the Maillard reaction process and the interfacial assembly behavior between the two phases were dynamically controlled to obtain zein-ethyl cellulose Janus nanoparticles.

5. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 4, characterized in that, Specifically, the following steps are included: 1) Dissolve zein in an ethanol-water solution, adjust the pH of the solution, and stir at 300 rpm for 2 h to completely dissolve it, thus obtaining a zein solution; 2) Dissolve ethyl cellulose in an ethanol-water solution, adjust the pH of the solution, and stir at 300 rpm for 2 h to completely dissolve it, thus obtaining an ethyl cellulose solution; 3) Mix the zein solution from step 1) with the ethyl cellulose solution from step 2) in equal volumes to obtain a zein-ethyl cellulose mixed solution; 4) The zein-ethyl cellulose mixture solution obtained in step 3) is subjected to ultrasonic treatment to obtain an ultrasonicated zein-ethyl cellulose mixture solution. 5) Heat the ultrasonicated zein-ethyl cellulose mixture obtained in step 4) to a constant temperature in a constant temperature water bath; 6) Adjust the ultrapure water to a certain pH value and heat it to a constant temperature in a constant temperature water bath; 7) Take 1 mL of the zein-ethyl cellulose mixed solution from step 5), inject it into 10 mL of the ultrapure water from step 6) while stirring at 400 rpm, heat it for a period of time, and then cool it naturally to obtain a zein-ethyl cellulose Janus nanoparticle dispersion. 8) Place the zein-ethyl cellulose Janus nanoparticle dispersion obtained in step 7) into a vacuum freeze dryer and freeze dry for 36 h to obtain zein-ethyl cellulose Janus nanoparticle powder.

6. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 5, characterized in that, The ethanol-water solution mentioned in step 1) is a 70%-95% (v / v) ethanol solution with a pH of 3.5-5.5 and a zein concentration of 0.5%-5% (w / v).

7. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 5, characterized in that, In step 2), the ethanol-water solution has an ethanol concentration of 70%-95% (v / v), a solution pH of 3.5-5.5, and an ethyl cellulose solution concentration of 0.5%-5% (w / v).

8. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 5, characterized in that, In step 4), the ultrasonic power is 150-450 W and the ultrasonic time is 2-15 min.

9. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 5, characterized in that, The heating temperature mentioned in step 5) is 50-90℃.

10. The method for preparing food-grade Janus nanoparticles by ultrasound-assisted Maillard reaction according to claim 5, characterized in that, The ultrapure water described in step 6) has a pH of 3.5-5.5 and a heating temperature of 50-90℃.

Images