Temperature-sensitive hydrogel microspheres as well as preparation method and application thereof

Abstract

The invention discloses temperature-sensitive hydrogel microspheres as well as a preparation method and application thereof, and belongs to the technical field of biological materials. The temperature-sensitive hydrogel microspheres are prepared by the following steps: dissolving a sodium sulfate solution in a composite solution of methyl cellulose and sodium alginate to obtain a dispersed phase solution; uniformly mixing isopropyl palmitate oil and a surfactant to obtain a continuous phase solution; and respectively injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding to obtain the temperature-sensitive hydrogel microspheres. The invention also discloses the temperature-sensitive hydrogel microspheres prepared by the preparation method and application of the temperature-sensitive hydrogel microspheres in cosmetic component packaging. The temperature-sensitive hydrogel microspheres prepared by the invention can realize a sol-gel phase transition process at 36-37 DEG C; meanwhile, the temperature-sensitive hydrogel microspheres are controllable and uniform in size, simple in component and good in biocompatibility, and the requirements of cosmetic component packaging protection and controllable release can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of biomaterials, and in particular relates to a thermosensitive hydrogel microsphere and a preparation method and application thereof. Background Art

[0002] In the cosmetics industry, due to the differences in added raw materials, interactions may occur between the raw materials during their mixing, causing their structures to change and lose their activity. At the same time, for raw materials such as proteins, enzymes and vitamins that are easily affected by the external environment and become inactivated, how to protect the activity of the raw materials to the greatest extent and exert their efficacy is one of the issues that urgently need to be solved.

[0003] Hydrogels have good biocompatibility and biodegradability and have been widely used in the medical field. Using hydrogel microsphere encapsulation technology, active ingredients are encapsulated in hydrogel microspheres as independent units to isolate external factors. Traditional hydrogels have the disadvantages of slow carrier drug release response rate and uncontrollable drug release. Compared with traditional hydrogels, smart hydrogels can release drugs in a controllable manner; smart hydrogels are divided into thermal responsive hydrogels, pH responsive hydrogels, and light responsive hydrogels. Among them, thermosensitive hydrogels refer to hydrogels that respond to temperature and can achieve sol-gel phase transition. However, the existing thermosensitive hydrogels have complex components and poor biocompatibility. When they are used for encapsulation of multiple active ingredients, they are prone to instability, unevenness, and limited release rate. In the preparation process of hydrogels, traditional preparation methods (such as spray drying, emulsification, and dripping methods) lack control over particle size and particle size distribution, and the size distribution of the resulting hydrogels is very likely to be uneven; these problems result in the existing thermosensitive hydrogels being unable to be well used for encapsulation protection and controlled release of active ingredients. Summary of the invention

[0004] The object of the present invention is to provide a thermosensitive hydrogel microsphere and a preparation method and application thereof. The thermosensitive hydrogel microsphere has uniform size distribution, simple composition and good biocompatibility, and meets the requirements of encapsulation protection and controllable release of cosmetic ingredients.

[0005] The technical solution adopted to achieve the above object is to provide a method for preparing thermosensitive hydrogel microspheres, comprising the following steps:

[0006] S1, dissolving the sodium sulfate solution in the composite solution of methyl cellulose and sodium alginate to obtain a dispersed phase solution;

[0007] S2, mixing isopropyl palmitate oil and a surfactant uniformly to obtain a continuous phase solution;

[0008] S3. The dispersed phase solution and the continuous phase solution are respectively injected into a microfluidic embedding instrument for embedding to obtain thermosensitive hydrogel microspheres.

[0009] The beneficial effects of the above technical scheme adopted in the present invention are as follows: methylcellulose and sodium alginate in the composite solution of the present invention directly form intermolecular hydrogen bonds, and sodium sulfate solution with greater solubility is added thereto, and the sodium sulfate interacts with the methylcellulose and sodium alginate in the composite solution, causing significant changes in the overall properties of the solution (such as viscosity, fluidity, etc.), and this change is easily affected by temperature changes, and the critical temperature of the dispersed phase solution is changed by changing the concentration of sodium sulfate. At the same time, the use of a microfluidic embedding instrument to prepare thermosensitive hydrogel microspheres has the advantages of accuracy and controllability. Microfluidic technology allows the flow and mixing of fluids to be accurately controlled at the micrometer scale, so that microspheres with uniform size and controllable morphology can be prepared; in addition, the microfluidic embedding instrument can also realize a continuous and efficient preparation process, thereby improving production efficiency. The thermosensitive hydrogel microspheres prepared by the present invention are controllable and uniform in size, simple in composition and good in biocompatibility, and can meet the requirements of encapsulation protection and controlled release of cosmetic ingredients.

[0010] Preferably, the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.4-0.6wt%; the molar concentration of the sodium sulfate solution is 0.4-0.5mol / L; and the volume ratio of the sodium sulfate solution to the composite solution is 1:7-9.

[0011] More preferably, the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.5wt%; the molar concentration of the sodium sulfate solution is 0.47mol / L; and the volume ratio of the sodium sulfate solution to the composite solution is 1:8.

[0012] Preferably, the volume ratio of isopropyl palmitate oil to surfactant is 40-60:1.

[0013] More preferably, the volume ratio of isopropyl palmitate oil to surfactant is 50:1.

[0014] More preferably, the surfactant is a nonionic surfactant.

[0015] More preferably, the surfactant is span80.

[0016] Preferably, the microfluidic embedding instrument includes an injection pump power device, a droplet production device and a collection device; the injection pump power device is connected to the droplet production device and the collection device in sequence; the injection pump power device includes an injection pump, a continuous phase syringe and a dispersed phase syringe.

[0017] The beneficial effects of the technical solution adopted in the present invention are as follows: the present invention adopts microfluidic technology to realize the preparation and collection of thermosensitive hydrogel microspheres, and the particle size and distribution of the thermosensitive hydrogel microspheres prepared by the microfluidic embedding equipment are uniform, and when they are used for component encapsulation, uniform and stable encapsulation and release effects can be achieved.

[0018] More preferably, the total flow rate of the injection pump is 6 to 12 μL / min, and the injection flow rate ratio of the continuous phase syringe and the dispersed phase syringe is 5 to 10:1.

[0019] The beneficial effect of the technical scheme adopted in the present invention is as follows: in the process of forming the thermosensitive hydrogel microspheres of the present invention, the size of the microspheres depends on the total flow rate of the injection pump and the injection flow rate ratio of the two-phase syringe. Under the above total flow rate and injection flow rate ratio, the particle size of the thermosensitive hydrogel microspheres prepared by the present invention is 60 to 500 μm, which can be used as an independent reaction unit for the controllable release of the encapsulated contents.

[0020] More preferably, the droplet production device is a flow focusing chip; the flow focusing chip includes a first inlet, a second inlet, a droplet outlet, a continuous phase separation tube and a dispersed phase tube; the first inlet is connected to the continuous phase separation tube and the dispersed phase tube outlet in sequence; the second inlet is connected to the dispersed phase tube and the droplet outlet in sequence; the continuous phase separation tube, the dispersed phase tube and the droplet outlet are cross-connected; the first inlet and the continuous phase separation tube are T-shaped cross-connected.

[0021] More preferably, the channel corresponding to the first inlet of the chip is connected to the continuous phase injector through a hose, the channel corresponding to the second inlet of the chip is connected to the dispersed phase injector through a hose, and the channel corresponding to the droplet outlet of the chip is connected to the collection device through a hose.

[0022] The present invention also provides temperature-sensitive hydrogel microspheres prepared by the preparation method.

[0023] The invention also provides application of the thermosensitive hydrogel microspheres in encapsulating cosmetic ingredients.

[0024] The present invention has the following beneficial effects:

[0025] (1) The thermosensitive hydrogel microspheres prepared by the present invention can realize the sol-gel phase transition process between 36 and 37°C; at the same time, the thermosensitive hydrogel microspheres have controllable and uniform size, simple composition and good biocompatibility, which can meet the requirements of encapsulation protection and controlled release of cosmetic ingredients.

[0026] (2) During the preparation process of the thermosensitive hydrogel microspheres of the present invention, the raw materials can form microdroplets in the microscale channel by utilizing the fluid shear force. The reaction is precise and controllable, the cost is low, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the microfluidic embedding instrument;

[0028] Figure 2 It is a schematic diagram of the structure of the droplet production device in the microfluidic embedding instrument;

[0029] Figure 3Schematic diagram of the formation process of thermosensitive hydrogel microspheres;

[0030] Figure 4 The diagram shows the influence of different concentrations of sodium sulfate solution on the critical temperature of the composite solution of methyl cellulose and sodium alginate; wherein, (a) is the critical temperature diagram when no sodium sulfate solution is added; (b) is the critical temperature diagram when 0.1 mol / L sodium sulfate solution is added; (c) is the critical temperature diagram when 0.3 mol / L sodium sulfate solution is added; (d) is the critical temperature diagram when 0.45 mol / L sodium sulfate solution is added; (e) is the critical temperature diagram when 0.47 mol / L sodium sulfate solution is added; (f) is the critical temperature diagram when 0.5 mol / L sodium sulfate solution is added;

[0031] Figure 5 This is the effect of adding 0.47 mol / L sodium chloride solution on the critical temperature of the composite solution of methyl cellulose and sodium alginate;

[0032] Figure 6 The infrared spectrum of the thermosensitive hydrogel microspheres prepared from methylcellulose and sodium alginate;

[0033] Figure 7 is a particle size distribution diagram of the thermosensitive hydrogel microspheres of Example 1 encapsulating ascorbic acid;

[0034] Figure 8 The graphs of ascorbic acid release from the thermosensitive hydrogel microspheres of Example 1 encapsulating ascorbic acid; wherein (a) is a graph of the standard curve of ascorbic acid; (b) is a graph of the UV-visible spectroscopic release of ascorbic acid; (c) is a graph of the wavelength-absorbance curve of ascorbic acid release after standing for 1 hour; (d) is a graph of the wavelength-absorbance curve of ascorbic acid release after standing for 2 hours;

[0035] Fig. 9 This is a particle size distribution diagram of the thermosensitive hydrogel microspheres of Example 2 encapsulating blue copper peptide;

[0036] Fig.10 The diagram shows the release of blue copper peptide from the thermosensitive hydrogel microspheres of Example 2 encapsulating blue copper peptide; wherein (a) is a standard curve diagram of blue copper peptide; and (b) is a liquid chromatography release diagram of blue copper peptide;

[0037] Among them, 1. first inlet; 2. first continuous phase separation tube; 3. second continuous phase separation tube; 4. second inlet; 5. dispersed phase tube; 6. droplet outlet; 7. dispersed phase syringe; 8. continuous phase syringe; 9. collecting device; 10. first injection pump; 11. second injection pump. DETAILED DESCRIPTION

[0038] The features and performance of the present invention are further described in detail below in conjunction with embodiments.

[0039] Example 1

[0040] A method for preparing thermosensitive hydrogel microspheres comprises the following steps:

[0041] S1. Weigh 0.5 g of methyl cellulose and 0.5 g of sodium alginate, mix and dissolve in 100 mL of deionized water to obtain a composite solution; the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.5 wt %;

[0042] S2, dissolving 12.5 mL of a sodium sulfate solution having a molar concentration of 0.47 mol / L in 100 mL of the composite solution to obtain a dispersed phase solution;

[0043] S3, 500 mL of isopropyl palmitate oil and 10 mL of surfactant span80 were mixed evenly to obtain a continuous phase solution;

[0044] S4, injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding, thereby obtaining thermosensitive hydrogel microspheres;

[0045] Among them, the microfluidic embedding instrument structure is as follows Figure 1 As shown, the microfluidic embedding instrument includes a syringe pump power device, a droplet production device and a collection device; the syringe pump power device is connected to the droplet production device and the collection device in sequence; the syringe pump power device includes a syringe pump, a continuous phase syringe 8 and a dispersed phase syringe 7; the syringe pump includes a first syringe pump 10 and a second syringe pump 11, the first syringe pump 10 is connected to the dispersed phase syringe 7, and the second syringe pump 11 is connected to the continuous phase syringe pump 8; in the preparation process of this embodiment, the total flow rate of the two syringe pumps is 9μL / min, the injection flow rate of the continuous phase syringe is 8μL / min, and the injection flow rate of the dispersed phase syringe is 1μL / min;

[0046] The droplet production device is a flow focusing chip, and its structure is as follows Figure 2 As shown; the flow focusing chip includes a first inlet 1, a second inlet 4, a droplet outlet 6, a continuous phase separation tube and a dispersed phase tube 5; the continuous phase separation tube includes a first continuous phase separation tube 2 and a second continuous phase separation tube 3; the first inlet 1 is connected to the first continuous phase separation tube 2 and the second continuous phase separation tube 3 for flow diversion, and then merged and connected to the right side of the dispersed phase tube 5; the second inlet 4 is connected to the dispersed phase tube 5 and the droplet outlet 6 in sequence; the first continuous phase separation tube 2, the second continuous phase separation tube 3, the dispersed phase tube 5 and the droplet outlet 6 are cross-connected; the first inlet 1 and the continuous phase separation tube are T-cross-connected; the channel of the chip corresponding to the first inlet 1 is connected to the continuous phase injector 8 through a hose, the channel of the chip corresponding to the second inlet 4 is connected to the dispersed phase injector 7 through a hose, and the channel of the chip corresponding to the droplet outlet 6 is connected to the collection device 9 through a hose.

[0047] Example 2

[0048] A method for preparing thermosensitive hydrogel microspheres comprises the following steps:

[0049] S1. Weigh 0.5 g of methyl cellulose and 0.5 g of sodium alginate, mix and dissolve in 100 mL of deionized water to obtain a composite solution; the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.5 wt %;

[0050] S2, dissolving 12.5 mL of a sodium sulfate solution having a molar concentration of 0.47 mol / L in 100 mL of the composite solution to obtain a dispersed phase solution;

[0051] S3, 500 mL of isopropyl palmitate oil and 10 mL of surfactant span80 were mixed evenly to obtain a continuous phase solution;

[0052] S4, respectively injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding, wherein the structure of the microfluidic embedding instrument is as follows: Figure 1 As shown, the microfluidic embedding instrument includes a syringe pump power device, a droplet production device and a collection device; the syringe pump power device is connected to the droplet production device and the collection device in sequence; the syringe pump power device includes a syringe pump, a continuous phase syringe 8 and a dispersed phase syringe 7; the syringe pump includes a first syringe pump 10 and a second syringe pump 11, the first syringe pump 10 is connected to the dispersed phase syringe 7, and the second syringe pump 11 is connected to the continuous phase syringe pump 8; in the preparation process of this embodiment, the total flow rate of the two syringe pumps is 8μL / min, the injection flow rate of the continuous phase syringe is 7μL / min, and the injection flow rate of the dispersed phase syringe is 1μL / min;

[0053] The droplet production device is a flow focusing chip, and its structure is as follows Figure 2 As shown; the flow focusing chip includes a first inlet 1, a second inlet 4, a droplet outlet 6, a continuous phase separation tube and a dispersed phase tube 5; the continuous phase separation tube includes a first continuous phase separation tube 2 and a second continuous phase separation tube 3; the first inlet 1 is connected to the first continuous phase separation tube 2 and the second continuous phase separation tube 3 for flow diversion, and then merged and connected to the right side of the dispersed phase tube 5; the second inlet 4 is connected to the dispersed phase tube 5 and the droplet outlet 6 in sequence; the first continuous phase separation tube 2, the second continuous phase separation tube 3, the dispersed phase tube 5 and the droplet outlet 6 are cross-connected; the first inlet 1 and the continuous phase separation tube are T-cross-connected; the channel of the chip corresponding to the first inlet 1 is connected to the continuous phase injector 8 through a hose, the channel of the chip corresponding to the second inlet 4 is connected to the dispersed phase injector 7 through a hose, and the channel of the chip corresponding to the droplet outlet 6 is connected to the collection device 9 through a hose.

[0054] Example 3

[0055] A method for preparing thermosensitive hydrogel microspheres comprises the following steps:

[0056] S1. Weigh 0.4 g of methyl cellulose and 0.4 g of sodium alginate, mix and dissolve in 100 mL of deionized water to obtain a composite solution; the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.4 wt %;

[0057] S2, dissolving 14.2 mL of a sodium sulfate solution having a molar concentration of 0.45 mol / L in 100 mL of the composite solution to obtain a dispersed phase solution;

[0058] S3, 500 mL of isopropyl palmitate oil and 10 mL of surfactant span80 were mixed evenly to obtain a continuous phase solution;

[0059] S4, injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding, thereby obtaining thermosensitive hydrogel microspheres;

[0060] Among them, the microfluidic embedding instrument structure is as follows Figure 1 As shown, the microfluidic embedding instrument includes a syringe pump power device, a droplet production device and a collection device; the syringe pump power device is connected to the droplet production device and the collection device in sequence; the syringe pump power device includes a syringe pump, a continuous phase syringe 8 and a dispersed phase syringe 7; the syringe pump includes a first syringe pump 10 and a second syringe pump 11, the first syringe pump 10 is connected to the dispersed phase syringe 7, and the second syringe pump 11 is connected to the continuous phase syringe pump 8; in the preparation process of this embodiment, the total flow rate of the two syringe pumps is 9μL / min, the injection flow rate of the continuous phase syringe is 8μL / min, and the injection flow rate of the dispersed phase syringe is 1μL / min;

[0061] The droplet production device is a flow focusing chip, and its structure is as follows Figure 2 As shown; the flow focusing chip includes a first inlet 1, a second inlet 4, a droplet outlet 6, a continuous phase separation tube and a dispersed phase tube 5; the continuous phase separation tube includes a first continuous phase separation tube 2 and a second continuous phase separation tube 3; the first inlet 1 is connected to the first continuous phase separation tube 2 and the second continuous phase separation tube 3 for flow diversion, and then merged and connected to the right side of the dispersed phase tube 5; the second inlet 4 is connected to the dispersed phase tube 5 and the droplet outlet 6 in sequence; the first continuous phase separation tube 2, the second continuous phase separation tube 3, the dispersed phase tube 5 and the droplet outlet 6 are cross-connected; the first inlet 1 and the continuous phase separation tube are T-cross-connected; the channel of the chip corresponding to the first inlet 1 is connected to the continuous phase injector 8 through a hose, the channel of the chip corresponding to the second inlet 4 is connected to the dispersed phase injector 7 through a hose, and the channel of the chip corresponding to the droplet outlet 6 is connected to the collection device 9 through a hose.

[0062] Example 4

[0063] A method for preparing thermosensitive hydrogel microspheres comprises the following steps:

[0064] S1. Weigh 0.6 g of methyl cellulose and 0.6 g of sodium alginate, mix and dissolve in 100 mL of deionized water to obtain a composite solution; the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.6 wt %;

[0065] S2, dissolving 11.2 mL of a sodium sulfate solution having a molar concentration of 0.45 mol / L in 100 mL of the composite solution to obtain a dispersed phase solution;

[0066] S3, 500 mL of isopropyl palmitate oil and 10 mL of surfactant span80 were mixed evenly to obtain a continuous phase solution;

[0067] S4, injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding, thereby obtaining thermosensitive hydrogel microspheres;

[0068] Among them, the microfluidic embedding instrument structure is as follows Figure 1 As shown, the microfluidic embedding instrument includes a syringe pump power device, a droplet production device and a collection device; the syringe pump power device is connected to the droplet production device and the collection device in sequence; the syringe pump power device includes a syringe pump, a continuous phase syringe 8 and a dispersed phase syringe 7; the syringe pump includes a first syringe pump 10 and a second syringe pump 11, the first syringe pump 10 is connected to the dispersed phase syringe 7, and the second syringe pump 11 is connected to the continuous phase syringe pump 8; in the preparation process of this embodiment, the total flow rate of the two syringe pumps is 9μL / min, the injection flow rate of the continuous phase syringe is 8μL / min, and the injection flow rate of the dispersed phase syringe is 1μL / min;

[0069] The droplet production device is a flow focusing chip, and its structure is as follows Figure 2 As shown; the flow focusing chip includes a first inlet 1, a second inlet 4, a droplet outlet 6, a continuous phase separation tube and a dispersed phase tube 5; the continuous phase separation tube includes a first continuous phase separation tube 2 and a second continuous phase separation tube 3; the first inlet 1 is connected to the first continuous phase separation tube 2 and the second continuous phase separation tube 3 for flow diversion, and then merged and connected to the right side of the dispersed phase tube 5; the second inlet 4 is connected to the dispersed phase tube 5 and the droplet outlet 6 in sequence; the first continuous phase separation tube 2, the second continuous phase separation tube 3, the dispersed phase tube 5 and the droplet outlet 6 are cross-connected; the first inlet 1 and the continuous phase separation tube are T-cross-connected; the channel of the chip corresponding to the first inlet 1 is connected to the continuous phase injector 8 through a hose, the channel of the chip corresponding to the second inlet 4 is connected to the dispersed phase injector 7 through a hose, and the channel of the chip corresponding to the droplet outlet 6 is connected to the collection device 9 through a hose.

[0070] Comparative Example 1

[0071] A method for preparing thermosensitive hydrogel microspheres comprises the following steps:

[0072] S1. Weigh 0.5 g of methyl cellulose and 0.5 g of sodium alginate, mix and dissolve in 100 mL of deionized water to obtain a composite solution; the mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.5 wt %;

[0073] S2, dissolving 12.5 mL of a sodium chloride solution having a molar concentration of 0.47 mol / L in 100 mL of the composite solution to obtain a dispersed phase solution;

[0074] S3, 500 mL of isopropyl palmitate oil and 10 mL of surfactant span80 were mixed evenly to obtain a continuous phase solution;

[0075] S4, injecting the dispersed phase solution and the continuous phase solution into a microfluidic embedding instrument for embedding, thereby obtaining thermosensitive hydrogel microspheres;

[0076] Among them, the microfluidic embedding instrument structure is as follows Figure 1 As shown, the microfluidic embedding instrument includes a syringe pump power device, a droplet production device and a collection device; the syringe pump power device is connected to the droplet production device and the collection device in sequence; the syringe pump power device includes a syringe pump, a continuous phase syringe 8 and a dispersed phase syringe 7; the syringe pump includes a first syringe pump 10 and a second syringe pump 11, the first syringe pump 10 is connected to the dispersed phase syringe 7, and the second syringe pump 11 is connected to the continuous phase syringe pump 8; in the preparation process of this embodiment, the total flow rate of the two syringe pumps is 9μL / min, the injection flow rate of the continuous phase syringe is 8μL / min, and the injection flow rate of the dispersed phase syringe is 1μL / min;

[0077] The droplet production device is a flow focusing chip, and its structure is as follows Figure 2 As shown; the flow focusing chip includes a first inlet 1, a second inlet 4, a droplet outlet 6, a continuous phase separation tube and a dispersed phase tube 5; the continuous phase separation tube includes a first continuous phase separation tube 2 and a second continuous phase separation tube 3; the first inlet 1 is connected to the first continuous phase separation tube 2 and the second continuous phase separation tube 3 for flow diversion, and then merged and connected to the right side of the dispersed phase tube 5; the second inlet 4 is connected to the dispersed phase tube 5 and the droplet outlet 6 in sequence; the first continuous phase separation tube 2, the second continuous phase separation tube 3, the dispersed phase tube 5 and the droplet outlet 6 are cross-connected; the first inlet 1 and the continuous phase separation tube are T-cross-connected; the channel of the chip corresponding to the first inlet 1 is connected to the continuous phase injector 8 through a hose, the channel of the chip corresponding to the second inlet 4 is connected to the dispersed phase injector 7 through a hose, and the channel of the chip corresponding to the droplet outlet 6 is connected to the collection device 9 through a hose.

[0078] Experimental example

[0079] 1. Characterization of the structure and properties of thermosensitive hydrogel microspheres

[0080] 1.1 Determination of the gelling ability of dispersed phase solution

[0081] The present invention utilizes methyl cellulose (MC) and sodium alginate (NaAlg) for cross-linking, and adjusts the critical temperature by sodium sulfate (Na2SO4). The cross-linking process is as follows: Figure 3 As shown; The gelling ability of the dispersed phase solution of the present invention is characterized by rheology, and the results are as shown Figure 4 As shown; by measuring the intersection of the loss modulus (G") and the storage modulus (G'), it is the sol-to-gel transition-critical temperature (LCST). Figures 3-4 It can be seen that when no Na2SO4 solution is added, the critical temperature of the composite solution (MC / NaAIg) formed by methyl cellulose and sodium alginate is 55.8°C. As the amount of Na2SO4 increases, the critical temperature of the composite solution gradually decreases. When the molar concentration of Na2SO4 is adjusted to 0.47 mol / L, the critical temperature of MC / NaAIg is 36.29°C, which is close to human body temperature. This is because Na2SO4 has a large solubility in water and can precipitate a large number of ions. + and SO4 2- It will affect the hydrophobicity in the composite solution. As the temperature rises, the hydrogen bonds begin to break, and the hydrophobic domains form a dense cross-linked network, causing the composite solution to transform from a sol to a gel state; this structural change can reduce the energy required for the solution to reach the critical state, thereby changing the critical temperature; at the same time, the addition of Na2SO4 can promote the phase separation or phase change process in the MC / NaAlg composite solution, causing the solution to reach the critical state at a lower temperature.

[0082] The 0.47 mol / L sodium sulfate solution was replaced with a sodium chloride (NaCl) solution of the same molar concentration and its gelling ability was tested. The results are as follows Figure 5 As shown in the results, it was found that under the same molar concentration of sodium chloride, the composite solution (MC / NaAIg) formed by methyl cellulose and sodium alginate did not have a sol-gel transition critical point, and the storage modulus (G”) was greater than the loss modulus (G’). At this time, the hydrogel was in a semi-solid state, and the prepared gel could not release the encapsulated contents at human body temperature (36-38°C), and could not meet the requirements of encapsulation protection and controlled release of cosmetic ingredients.

[0083] 1.2 Structural characterization of thermosensitive hydrogel microspheres

[0084] The structure of thermosensitive hydrogel microspheres was characterized by infrared spectroscopy (FTIR). Figure 6 shown. Figure 6 Medium 3600~3200cm -1 The spectral peak is the stretching vibration peak of OH, 1900~1600cm -1The spectral peak of is the stretching vibration peak of C=O. The above groups participate in the formation of hydrogen bonds, which play an important role in the sol-gel transition. After the groups form hydrogen bonds, the absorption peak moves to the low wave number direction; the OH absorption peaks of NaAIg and MC are 3392.4cm -1 and 3462.2cm -1 , the OH absorption peak of MC / NaAIg shifted to 3431.4 cm -1 , the absorption peak becomes broad; the C=O absorption peak of NaAIg is 1610.9cm -1 , the C=O absorption peak of MC / NaAIg shifted to 1606.8 cm -1 , the absorption peak moves toward the low wavenumber direction; the results show that the cross-linking process of sodium alginate and methyl cellulose is not a simple mixture, but forms intermolecular hydrogen bonds between them.

[0085] 2. Application of thermosensitive hydrogel microspheres in encapsulation of cosmetic ingredients

[0086] 2.1 Verification of the effect of thermosensitive hydrogel microspheres encapsulating ascorbic acid

[0087] Ascorbic acid (AA) was encapsulated using the thermosensitive hydrogel microspheres prepared in Example 1. Specifically, in the preparation process of the thermosensitive hydrogel microspheres in Example 1, step S2 specifically comprises: dissolving 0.1 g of ascorbic acid and 2 mL of a sodium sulfate solution having a molar concentration of 0.47 mol / L in 16 mL of a composite solution to obtain a dispersed phase solution, and the remaining steps are the same as in Example 1. The particle size distribution of the thermosensitive hydrogel microspheres encapsulating ascorbic acid is finally obtained. Figure 7 As shown, the average particle size is 76.67 μm; the collected thermosensitive hydrogel microspheres encapsulating ascorbic acid were dispersed in deionized water, and allowed to stand for 1 h and 2 h at 8 ° C and 37 ° C, respectively. The clear liquid was filtered and collected, and the ascorbic acid release was measured by ultraviolet spectrophotometry. The results are shown in Figure 8 As shown. Figure 8 It can be seen that after the thermosensitive hydrogel microspheres prepared by the present invention encapsulate ascorbic acid, long-term stable release can be achieved at 37°C, indicating that after the critical temperature of the thermosensitive hydrogel microspheres reaches 36.29°C, the thermosensitive hydrogel microspheres achieve a sol-gel phase transition, promoting the stable release of the ascorbic acid encapsulated therein; indicating that the thermosensitive hydrogel microspheres prepared by the present invention can be used for the encapsulation of unstable cosmetic active ingredients, to achieve stable preservation and long-term release of the active ingredients.

[0088] 2.2 Verification of the effect of thermosensitive hydrogel microspheres encapsulating blue copper peptide

[0089] The thermosensitive hydrogel microspheres prepared in Example 2 were used to encapsulate the blue copper peptide (GHK-Cu), specifically: in the preparation process of the thermosensitive hydrogel microspheres in Example 2, step S2 was specifically: 0.1 g of blue copper peptide and 2 mL of sodium sulfate solution with a molar concentration of 0.47 mol / L were dissolved in 16 mL of the composite solution to obtain a dispersed phase solution, and the remaining steps were the same as in Example 2. Finally, the thermosensitive hydrogel microspheres encapsulating the blue copper peptide were obtained, and the particle size distribution was as follows: Fig. 9 As shown, the average particle size is 182.4 μm; the collected thermosensitive hydrogel microspheres encapsulating blue copper peptide were subjected to release study, and 100 μL of thermosensitive hydrogel microspheres encapsulating blue copper peptide were respectively dispersed by adding 3 mL of mobile phase solution (acetonitrile solution containing 0.1% trifluoroacetic acid: aqueous solution containing 0.1% trifluoroacetic acid = 65%: 35%), and then placed at 25°C and 37°C for 2 hours, filtered and collected the clear liquid; the release amount of blue copper peptide was measured by high performance liquid chromatography, and the results are as follows Fig.10 As shown. Fig.10 It can be seen that after standing for 2h at 25°C and 37°C, the thermosensitive hydrogel microspheres prepared in Example 2 of the present invention have a large difference in the release amount of blue copper peptide. When the actual temperature is greater than the critical temperature, the thermosensitive hydrogel microspheres will achieve a certain contraction and form a dense cross-linked structure. The blue copper peptide wrapped therein will be squeezed and separated from the cross-linked structure, achieving stable release of the blue copper peptide. This shows that the thermosensitive hydrogel microspheres prepared by the present invention can achieve stable storage of blue copper peptide at room temperature, and when used on the skin surface, the release of blue copper peptide can be achieved.

[0090] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the scope of the present invention.

Claims

1. A method for preparing thermosensitive hydrogel microspheres, characterized in that: The following steps are involved: S1, dissolving the sodium sulfate solution in the composite solution of methyl cellulose and sodium alginate to obtain a dispersed phase solution; S2, mixing isopropyl palmitate oil and a surfactant uniformly to obtain a continuous phase solution; S3. The dispersed phase solution and the continuous phase solution are respectively injected into a microfluidic embedding instrument for embedding to obtain thermosensitive hydrogel microspheres.

2. The method for preparing thermosensitive hydrogel microspheres according to claim 1, characterized in that: The mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.4-0.6wt%; the molar concentration of the sodium sulfate solution is 0.4-0.5mol / L; and the volume ratio of the sodium sulfate solution to the composite solution is 1:7-9.

3. The method for preparing thermosensitive hydrogel microspheres according to claim 2, characterized in that: The mass concentrations of methyl cellulose and sodium alginate in the composite solution are both 0.5wt%; the molar concentration of the sodium sulfate solution is 0.47mol / L; and the volume ratio of the sodium sulfate solution to the composite solution is 1:

8.

4. The method for preparing thermosensitive hydrogel microspheres according to claim 1, characterized in that: The volume ratio of the isopropyl palmitate oil to the surfactant is 40-60:

1.

5. The method for preparing thermosensitive hydrogel microspheres according to claim 1, characterized in that: The microfluidic embedding instrument comprises an injection pump power device, a droplet production device and a collection device; the injection pump power device is connected to the droplet production device and the collection device in sequence; the injection pump power device comprises an injection pump, a continuous phase injector (8) and a dispersed phase injector (7).

6. The method for preparing the thermosensitive hydrogel microspheres according to claim 5, characterized in that: The total flow rate of the injection pump is 6 to 12 μL / min, and the injection flow rate ratio of the continuous phase injector (8) to the dispersed phase injector (7) is 5 to 10:

1.

7. The method for preparing the thermosensitive hydrogel microspheres according to claim 5, characterized in that: The droplet production device is a flow focusing chip; the flow focusing chip comprises a first inlet (1), a second inlet (4), a droplet outlet (6), a continuous phase separation tube and a dispersed phase tube (5); the first inlet (1) is connected to the continuous phase separation tube and the dispersed phase tube (5) outlets in sequence; the second inlet (4) is connected to the dispersed phase tube (5) and the droplet outlet (6) in sequence; the continuous phase separation tube, the dispersed phase tube (5) and the droplet outlet (6) are cross-connected; the first inlet (1) and the continuous phase separation tube are cross-connected in a T-shape.

8. The method for preparing the thermosensitive hydrogel microspheres according to claim 5 or 7, characterized in that: The channel corresponding to the first inlet (1) of the chip is connected to the continuous phase injector (8) through a hose, the channel corresponding to the second inlet (4) of the chip is connected to the dispersed phase injector (7) through a hose, and the channel corresponding to the droplet outlet (6) of the chip is connected to the collection device (9) through a hose.

9. Thermosensitive hydrogel microspheres prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the thermosensitive hydrogel microspheres according to claim 9 in encapsulating cosmetic ingredients.

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