Sodium hyaluronate gel for injection and preparation method thereof

Abstract

The invention provides a sodium hyaluronate gel for injection and a preparation method thereof, and belongs to the technical field of sodium hyaluronate gels, the sodium hyaluronate gel for injection comprises 1-5 parts of sodium hyaluronate, 0.01-0.1 part of a cross-linking agent, 0.1-1 part of a buffer agent, 1-3 parts of a humectant and 0.5-2 parts of an osmotic pressure modulators, the selected sodium hyaluronate and other raw materials have good biocompatibility, and the prepared sodium hyaluronate gel has good biocompatibility and can be used for injection. Obvious immune response and inflammatory response cannot be caused in vivo, the use risk is reduced, and meanwhile, the material has excellent mechanical performance.

Description

Technical Field

[0001] The invention belongs to the technical field of sodium hyaluronate gel, and particularly relates to a sodium hyaluronate gel for injection and a preparation method thereof. Background Art

[0002] As a biomedical material, sodium hyaluronate gel can be used in many medical fields such as medical cosmetology, ophthalmic surgery, orthopedic joint treatment, and tissue repair. It has excellent moisturizing, lubrication, tissue filling and repair functions, and has shown great potential in clinical applications. However, the existing sodium hyaluronate gel preparation methods and products still have many limitations. On the one hand, some preparation methods are difficult to accurately control the properties of the gel, such as the strength, elasticity, and degradation rate of the gel, which may lead to inconsistent performance in different application scenarios and affect the therapeutic effect; on the other hand, in the gel preparation process, the selection and processing of the ingredients are not fine enough, and the product often has problems such as poor biocompatibility, imprecise isotonicity control, and insufficient pH stability, which may cause adverse reactions in patients, such as inflammation, allergies, or pain at the injection site. In addition, the traditional preparation method has poor results in terms of product purity and impurity removal, which may reduce the safety and shelf life of the product, and the mechanical properties and biocompatibility are not good. In view of the above problems, the present invention provides a sodium hyaluronate gel for injection and a preparation method thereof. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a sodium hyaluronate gel for injection and a preparation method thereof. In the process of preparing the sodium hyaluronate gel, the present invention adds a suitable buffer and a moisturizer, so that the prepared gel has excellent strength, elasticity and degradation rate, effectively meets the requirements of medical use, and has broad application prospects.

[0004] To achieve this object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a sodium hyaluronate gel for injection, which comprises, in parts by mass relative to 100 parts of hyaluronic acid gel: Sodium hyaluronate 1~5 parts Cross-linking agent 0.01~0.1 parts Buffer 0.1~1 part 1~3 parts moisturizer Osmotic pressure regulator 0.5~2 parts.

[0005] Preferably, the molecular weight of the sodium hyaluronate is 1 million Da to 1.5 million Da, for example, it can be: 1 million Da, 1.05 million Da, 1.1 million Da, 1.15 million Da, 1.2 million Da, 1.3 million Da, 1.4 million Da, 1.45 million Da, 1.5 million Da, etc., but it is not limited to the listed values, and other values ​​not listed in this range are also applicable. Sodium hyaluronate in this range has both good moisturizing properties and appropriate residence time. It can form a relatively stable moisturizing environment at the injection site, and the retention time in the tissue is moderate. It is widely used in beauty fields such as facial filling. When filling wrinkles or increasing facial tissue volume, medium molecular weight sodium hyaluronate can provide a natural filling effect while maintaining the filling effect for a certain period of time, which can generally be maintained for several months to about a year, and the specific time varies depending on the product and individual differences.

[0006] Preferably, the cross-linking agent is one or more of 1,4-butanediol diglycidyl ether (BDDE), glutaraldehyde, or 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC).

[0007] 1,4-Butanediol diglycidyl ether is a compound containing two epoxy groups. The epoxy groups in its molecular structure have high reactivity, which is its key characteristic as a crosslinker. This chemical structure enables it to undergo a ring-opening reaction with polymers containing active hydrogen, such as sodium hyaluronate, thereby connecting polymer molecular chains. Due to the presence of two epoxy groups, 1,4-butanediol diglycidyl ether can form effective crosslinks between sodium hyaluronate molecules. It can react with active hydrogen groups such as hydroxyl (-OH) or amino (-NH2) on the sodium hyaluronate molecule. For example, under appropriate reaction conditions (such as appropriate temperature, pH and reaction time), the epoxy group will undergo a nucleophilic ring-opening reaction with the active hydrogen of sodium hyaluronate to form an ether bond (-O-) or other chemical bonds, quickly constructing a three-dimensional network gel structure with relatively high crosslinking efficiency.

[0008] Glutaraldehyde is a bifunctional aldehyde compound containing two aldehyde groups. It can react with the hydroxyl or amino groups on the sodium hyaluronate molecule to cross-link the sodium hyaluronate molecules by forming acetal or Schiff base (-C=N-) structures. For example, under alkaline conditions, the aldehyde group of glutaraldehyde undergoes a nucleophilic addition reaction with the hydroxyl group of sodium hyaluronate, followed by dehydration to form acetal bonds, connecting different sodium hyaluronate molecules to form a three-dimensional gel network structure. However, glutaraldehyde has certain toxicity, and its residual amount needs to be strictly controlled when preparing sodium hyaluronate gel for biomedical purposes.

[0009] EDC is a commonly used carbodiimide crosslinker. It mainly acts on the carboxyl group of sodium hyaluronate molecules, and reacts with other amino-containing molecules or the amino group of sodium hyaluronate itself by activating the carboxyl group. It is usually used in combination with N-hydroxysuccinimide (NHS), which can stabilize the intermediates during the reaction and improve the reaction efficiency. This crosslinker combination can form amide bonds (CONH-) between sodium hyaluronate molecules, making the gel have good stability and biocompatibility, and is particularly suitable for the preparation of sodium hyaluronate gel for medical purposes.

[0010] Preferably, the buffer is a phosphate buffer, and the phosphate buffer is one or more of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, and disodium hydrogen phosphate. The mass fraction of the phosphate solution is 0.1 to 5 parts, for example, it can be: 0.1 parts, 0.2 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 5 parts, etc., but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable. The phosphate solution can effectively maintain the stability of the pH of the gel and can resist a certain degree of pH change.

[0011] Preferably, the moisturizing agent is one or more of glycerol, propylene glycol, and polyethylene glycol (PEG). In moisturizing sodium hyaluronate gel, the moisturizing agent, especially glycerol, can effectively enhance the moisturizing effect and adjust the texture of the sodium hyaluronate gel.

[0012] Preferably, the osmotic pressure regulator is mannitol or sorbitol.

[0013] In a second aspect, the present invention provides a method for preparing the sodium hyaluronate gel for injection according to the first aspect, the preparation method comprising: S1: accurately weighing the pretreated hyaluronic acid, adding the hyaluronic acid into deionized water, stirring at a certain temperature, and adding sodium hydroxide solution during the stirring process to obtain a sodium hyaluronate solution; S2: adding a moisturizer, a buffer and an osmotic pressure regulator to the sodium hyaluronate solution obtained in S1, and stirring; S3: adding a cross-linking agent to the solution obtained after stirring in S2 to perform a chemical cross-linking reaction to obtain a gel; S4: degassing, degassing the gel, filtering and purifying the degassed gel to obtain sodium hyaluronate gel.

[0014] Preferably, in S1, the pretreatment of hyaluronic acid includes washing and drying to remove impurities and moisture in the hyaluronic acid and ensure the quality of the raw material; the hyaluronic acid is high-purity hyaluronic acid with a purity of ≥90% and a molecular weight of 1 million Da to 1.5 million Da.

[0015] The certain temperature is 30°C~50°C, for example, it can be: 30°C, 30.5°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 50°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0016] The stirring speed is 200 r / min~500 r / min, for example, it can be: 200 r / min, 250 r / min, 300 r / min, 350 r / minn, 400 r / min, 450 r / min, 500 r / min, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0017] The stirring time is 1 h to 3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc., but is not limited to the listed values, and other values ​​not listed in the range are also applicable. By stirring, the hyaluronic acid molecules can be evenly dispersed to avoid agglomeration.

[0018] In the process of adding sodium hydroxide, it should be added slowly, and in the process of adding sodium hydroxide, by constantly stirring, the sodium hydroxide solution and hyaluronic acid are fully dissolved to form a sodium hyaluronate solution. The concentration of the sodium hydroxide solution is 0.5mol / L~2mol / L. For example, it can be: 0.5mol / L, 0.6mol / L, 0.8mol / L, 1mol / L, 1.2mol / L, 1.4mol / L, 1.6mol / L, 1.8mol / L, 2mol / L, etc., not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0019] Preferably, in S2, during stirring, the stirring speed is 100 r / min~300 r / min, for example, it can be: 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, 300 r / min, etc., not limited to the listed values, other values ​​not listed in the range are also applicable.

[0020] The stirring time in S2 is 0.5h~2h, for example, it can be: 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc., and is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0021] Preferably, in S3, the chemical cross-linking reaction is carried out at 25°C-40°C, for example, it can be: 25°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C; the reaction time is 2h-6h, for example, it can be: 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 4h, 5h, 5.2h, 5.4h, 5.6h, 5.8h, 6h, etc., not limited to the listed values, and other unlisted values ​​within the range are equally applicable.

[0022] During the gelation process, the strength and elasticity of the gel can be precisely controlled by adjusting the amount of cross-linking agent added and the reaction conditions. In addition, real-time monitoring can be performed during the gelation process. By monitoring the structure, the stirring speed and temperature can be appropriately adjusted to ensure the uniformity of the gel structure and the consistency of performance.

[0023] In addition, the pH value of the gel can be monitored by a precision pH meter. Based on the measurement results, the pH value of the gel can be adjusted using a pH adjuster. In addition to sodium hydroxide, commonly used pH adjusters can also be hydrochloric acid, citric acid, or sodium citrate to ensure that the pH value of the final gel is within the physiologically acceptable range for the human body (pH 6.5~7.5).

[0024] Preferably, in S4, the degassing treatment uses one or a combination of vacuum degassing and ultrasonic degassing to degas the gel to eliminate bubbles in the gel and improve the uniformity and stability of the gel. The vacuum degree of vacuum degassing can be set to 0.05MPa~0.1MPa, for example, it can be: 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, 0.1MPa, etc., not limited to the listed values, and other values ​​not listed in this range are also applicable; the degassing time is 30min~60min, for example, it can be: 35min, 40min, 45min, 50min, 55min, 60min, etc., not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0025] After the gel is degassed, the gel can be filtered through a 0.22μm~0.45μm microfiltration membrane or ultrafiltration membrane to remove unreacted impurities, undissolved particles and macromolecular substances to ensure the purity and safety of the gel. At the same time, the filtration process can be carried out under a pressure range of 0.1MPa~0.5MPa.

[0026] After the gel is filtered, it can be sterilized, such as by wet heat sterilization, irradiation sterilization, etc., to obtain the final sodium hyaluronate gel for injection.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) Good biocompatibility: The sodium hyaluronate and other raw materials selected in the present invention have good biocompatibility, will not cause obvious immune response and inflammatory response in the body, and reduce the risk of use; (2) Excellent injectability: By optimizing the type and amount of the cross-linking agent, and controlling the reaction conditions, the prepared gel has a suitable viscosity and elastic modulus, is easy to inject through a syringe, and will not cause problems such as needle clogging or gel breakage during the injection process, which is convenient for clinical operation; (3) The cross-linked gel forms a stable three-dimensional network structure with high mechanical strength, can maintain a good shape and support function in the body, and improves the therapeutic effect. DETAILED DESCRIPTION

[0028] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0029] Example 1

[0030] S1: Weigh 1 part of pretreated hyaluronic acid by mass, the molecular weight of hyaluronic acid is 1 million Da, then add hyaluronic acid into sufficient deionized water, the temperature of deionized water is 30°C, stir the deionized water mixed with hyaluronic acid at a stirring speed of 200r / min, and slowly add 0.5mol / L sodium hydroxide solution into the deionized water containing hyaluronic acid, and stir for a total of 1h to obtain a sodium hyaluronate solution; S2: Add 0.1 parts by mass of potassium dihydrogen phosphate, 2 parts by mass of glycerol, and 0.5 parts by mass of mannitol to the sodium hyaluronate solution, and then start stirring at a speed of 100 r / min for 0.5 h; S3: adding 0.09 parts by mass of 1.4-butanediol diglycidyl ether to the solution obtained in S2, and then reacting at 25° C. for 6 hours to obtain sodium hyaluronate gel; S4: The hyaluronic acid gel obtained in S3 is degassed by vacuum degassing at 0.05 MPa for 35 minutes, and then the hyaluronic acid gel is filtered at 0.1 MPa by using a 0.22 μm microfiltration membrane. The filtered sodium hyaluronate gel is sterilized in steam at 122°C for 15 minutes to finally obtain the sodium hyaluronate gel for injection.

[0031] Example 2

[0032] S1: Weigh 1.5 parts by mass of pretreated hyaluronic acid, the molecular weight of which is 1.2 million Da, and then add the hyaluronic acid into sufficient deionized water, the temperature of the deionized water is 40°C, stir the deionized water mixed with the hyaluronic acid at a stirring speed of 300 r / min, and at the same time slowly add a sodium hydroxide solution with a concentration of 0.7 mol / L into the deionized water containing the hyaluronic acid, and stir for a total of 1.5 hours to obtain a sodium hyaluronate solution; S2: Add 1 part by mass of potassium dihydrogen phosphate, 2.5 parts by mass of glycerol, and 1.5 parts by mass of mannitol to the sodium hyaluronate solution, and then start stirring at a speed of 180 r / min for 0.7 h; S3: adding 0.08 parts by mass of 1.4-butanediol diglycidyl ether to the solution obtained in S2, and then reacting at 28° C. for 5.5 hours to obtain sodium hyaluronate gel; S4: The hyaluronic acid gel obtained in S3 is degassed by vacuum degassing at 0.05 MPa for 35 minutes, and then the hyaluronic acid gel is filtered at 0.1 MPa by using a 0.22 μm microfiltration membrane. The filtered sodium hyaluronate gel is sterilized in steam at 122°C for 15 minutes to finally obtain the sodium hyaluronate gel for injection.

[0033] Example 3

[0034] S1: Weigh 3 parts by mass of pretreated hyaluronic acid, the molecular weight of which is 1.5 million Da, and then add the hyaluronic acid into a sufficient amount of deionized water, the temperature of the deionized water is 30° C., stir the deionized water mixed with the hyaluronic acid at a stirring speed of 200 r / min, and at the same time slowly add a sodium hydroxide solution with a concentration of 0.5 mol / L into the deionized water containing the hyaluronic acid, and stir for a total of 1 hour to obtain a sodium hyaluronate solution; S2: Add 1 part by mass of potassium dihydrogen phosphate, 1 part by mass of glycerol, and 2 parts by mass of mannitol to the sodium hyaluronate solution, and then start stirring at a speed of 100 r / min for 0.5 h; S3: adding 0.09 parts by mass of 1.4-butanediol diglycidyl ether to the solution obtained in S2, and then reacting at 25° C. for 6 hours to obtain sodium hyaluronate gel; S4: The hyaluronic acid gel obtained in S3 is degassed by vacuum degassing at 0.05 MPa for 35 minutes, and then the hyaluronic acid gel is filtered at 0.1 MPa by using a 0.22 μm microfiltration membrane. The filtered sodium hyaluronate gel is sterilized in steam at 122°C for 15 minutes to finally obtain the sodium hyaluronate gel for injection.

[0035] Comparative Example 1 S1: Weigh 1 part of pretreated hyaluronic acid by mass, the molecular weight of hyaluronic acid is 1 million Da, then add hyaluronic acid into sufficient deionized water, the temperature of deionized water is 40°C, stir the deionized water mixed with hyaluronic acid at a stirring speed of 300r / min, and slowly add 0.7mol / L sodium hydroxide solution into the deionized water containing hyaluronic acid, and stir for a total of 1.5h to obtain a sodium hyaluronate solution; S2: Add 0.1 parts by mass of potassium dihydrogen phosphate, 2 parts by mass of glycerol, and 0.5 parts by mass of mannitol to the sodium hyaluronate solution, and then start stirring at a speed of 100 r / min for 0.5 h; S3: adding 1.5 parts by weight of 1,4-butanediol diglycidyl ether to the solution obtained in S2, and then reacting at 28° C. for 5.5 hours to obtain sodium hyaluronate gel; S4: The hyaluronic acid gel obtained in S3 is degassed by vacuum degassing at 0.05 MPa for 35 minutes, and then the hyaluronic acid gel is filtered at 0.1 MPa by using a 0.22 μm microfiltration membrane. The filtered sodium hyaluronate gel is sterilized in steam at 122°C for 15 minutes to finally obtain the sodium hyaluronate gel for injection.

[0036] Comparative Example 2 S1: Weigh 10 parts by mass of pretreated hyaluronic acid, the molecular weight of which is 3 million Da, and then add the hyaluronic acid into sufficient deionized water, the temperature of the deionized water is 30°C, stir the deionized water mixed with the hyaluronic acid at a stirring speed of 200 r / min, and slowly add a sodium hydroxide solution with a concentration of 0.5 mol / L into the deionized water containing the hyaluronic acid, and stir for a total of 1 hour to obtain a sodium hyaluronate solution; S2: Add 1 part by mass of potassium dihydrogen phosphate, 1 part by mass of glycerol, and 2 parts by mass of mannitol to the sodium hyaluronate solution, and then start stirring at a speed of 100 r / min for 0.5 h; S3: adding 0.09 parts by mass of 1.4-butanediol diglycidyl ether to the solution obtained in S2, and then reacting at 25° C. for 6 hours to obtain sodium hyaluronate gel; S4: The hyaluronic acid gel obtained in S3 is degassed by vacuum degassing at 0.05 MPa for 35 minutes, and then the hyaluronic acid gel is filtered at 0.1 MPa by using a 0.22 μm microfiltration membrane. The filtered sodium hyaluronate gel is sterilized in steam at 122°C for 15 minutes to finally obtain the sodium hyaluronate gel for injection.

[0037] It should be noted that the pre-treated hyaluronic acid mentioned above has a purity of more than 90%, and has been washed and dried to remove excess impurities and moisture.

[0038] Performance Testing ①Test standard During the elastic modulus test of sodium hyaluronate gel, the test basis and standards are: based on the requirements of the ISO 10993 series of standards for material testing in the medical device field, the elastic strength of sodium hyaluronate gel is tested under qualified conditions (temperature, humidity, etc.), and the test standard process is strictly followed.

[0039] During the viscosity test of sodium hyaluronate gel, the test was based on and followed the following standards: the general principle of using a rotational rheometer to measure the viscosity of non-Newtonian fluids (sodium hyaluronate gel belongs to this category) at different temperatures as specified in ISO 3219 was followed, and the requirements of measuring instrument calibration, sample preparation, and measurement condition preparation (such as temperature control at 23±2°C) were strictly followed.

[0040] During the pushing force test of sodium hyaluronate gel, the basis and standards of the test are: measured according to the YY / T 0962-2021 standard, and strictly implemented according to the time, instruments and procedures specified in the standard.

[0041] ②Test results Table 1: Performance of each embodiment and comparative example

[0042] As shown in Table 1, the sodium hyaluronate gel for injection prepared by Example 1, Example 2 and Example 3 has excellent mechanical properties, and elasticity and viscosity are well behaved, and the pushing force is also within the standard range, with obvious gel material advantages. Compared with Comparative Example 1, Example 1 shows that the mass fraction of the cross-linking agent used in Comparative Example 1 is significantly increased, and due to the increase of the cross-linking agent in the gel prepared in Comparative Example 1, the excessive coaching of the cross-linking agent and sodium hyaluronate is caused, the connection points between the molecular chains are too many, the structure becomes too dense or rigid, and the movement ability of the molecular chains is limited, resulting in an obvious decline in elasticity and viscosity. In addition, due to the instability of elasticity decline and viscosity, the gel is too hard or locally uneven, so that when pushing, a larger pushing force is required, that is, when the cross-linking agent exceeds a certain range, the quality of the gel will decline. Compared with Comparative Example 2, Example 3 shows that the high molecular weight hyaluronic acid used in Comparative Example 2, due to the higher molecular weight of hyaluronic acid, the longer the molecular chain, the greater the increase in the steric hindrance between molecules, the orderly arrangement and interaction between the molecular chains are disturbed, and the decline in elasticity and viscosity is caused, which also increases the pushing force.

[0043] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sodium hyaluronate gel for injection, characterized in that: Calculated relative to 100 parts by mass of hyaluronic acid gel, comprising: Sodium hyaluronate 1~5 parts Cross-linking agent 0.01~0.1 parts Buffer 0.1~1 part 1~3 parts moisturizer Osmotic pressure regulator 0.5~2 parts; The molecular weight of the sodium hyaluronate is 1 million Da to 1.5 million Da; The cross-linking agent is one or more of 1,4-butanediol diglycidyl ether (BDDE), glutaraldehyde, or 1-ethyl-(3-dimethylaminopropyl) carbodiimide (EDC); The buffer is a phosphate buffer, and the phosphate buffer is one or more of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, and disodium hydrogen phosphate; the humectant is one or more of glycerol, propylene glycol, and polyethylene glycol (PEG); and the osmotic pressure regulator is mannitol or sorbitol.

2. A method for preparing a sodium hyaluronate gel for injection as claimed in claim 1, characterized in that: The following steps are involved: S1: accurately weighing the pretreated hyaluronic acid, adding the hyaluronic acid into deionized water, stirring at a certain temperature, and adding sodium hydroxide solution during the stirring process to obtain a sodium hyaluronate solution; S2: adding a moisturizer, a buffer and an osmotic pressure regulator to the sodium hyaluronate solution obtained in S1, and stirring; S3: adding a cross-linking agent to the solution obtained after stirring in S2 to perform a chemical cross-linking reaction to obtain a gel; S4: degassing, degassing the gel, filtering and purifying the degassed gel to obtain sodium hyaluronate gel.

3. The method for preparing a sodium hyaluronate gel for injection according to claim 2, characterized in that: In S1, the pretreatment of hyaluronic acid includes washing and drying to remove impurities in the hyaluronic acid; the certain temperature is 30°C~50°C, the stirring speed is 200r / min~500r / min, the stirring time is 1h~3h, and the concentration of the sodium hydroxide solution is 0.5mol / L~2mol / L.

4. The method for preparing a sodium hyaluronate gel for injection according to claim 3, characterized in that: In S2, during stirring, the stirring speed is 100 r / min~300 r / min, and the stirring time is 0.5h~2h.

5. The method for preparing a sodium hyaluronate gel for injection according to claim 4, characterized in that: In S3, the chemical cross-linking reaction is carried out at 25°C to 40°C, and the reaction time is 2h to 6h.

Images