Transparent hydrogel membrane including hyaluronic acid, and contact lens including same

Abstract

The present invention provides a method for preparing a transparent hydrogel membrane, the method including: (a) preparing 6 to 10 wt % of a hyaluronic acid solution based on a total weight of a mixture by dissolving a hyaluronic acid in a basic aqueous solution; (b) mixing, with the hyaluronic acid solution, 0.01 to 0.05 wt % of a crosslinking agent based on the total weight of the mixture; and (c) shaping the transparent hydrogel membrane by pouring the mixture into a mold.

Claims

1. A method for preparing a transparent hydrogel membrane, the method comprising: (a) preparing 6 to 10 wt % of a hyaluronic acid solution based on a total weight of a mixture by dissolving a hyaluronic acid in a basic aqueous solution; (b) mixing, with the hyaluronic acid solution, 0.01 to 0.05 wt % of a crosslinking agent based on the total weight of the mixture; and (c) shaping the transparent hydrogel membrane by pouring the mixture into a mold, wherein the hyaluronic acid has a molecular weight of from 800,000 to 1,200,000 Dalton units, and wherein the crosslinking agent is butanediol diglycidyl ether (BDDE).

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1A illustrates a mold preparing a transparent contact lens formed by copolymerizing the hyaluronic acid according to the present invention.

(2) FIGS. 1B and 1C illustrate transparent contact lenses formed through the mold according to the present invention.

(3) FIG. 2 illustrates the degree of swelling of the transparent contact lens according to the present invention over the swelling time.

(4) FIG. 3 illustrates the visible light transmittance of the transparent contact lens according to the present invention.

(5) FIG. 4 illustrates the results of cytotoxicity evaluation over the treatment time of the eluate of the transparent contact lens according to the present invention.

MODES OF THE INVENTION

(6) An aspect of the present invention provides a transparent hydrogel membrane formed by copolymerizing by a hyaluronic acid and a crosslinking agent.

(7) As used herein, the term “hyaluronic acid” is present in the ocular vitreous body or umbilical cord, and the like in the human body, is highly viscous, and plays an important role in preventing the invasion of bacteria and the penetration of toxic substances. In the present invention, the hyaluronic acid may be preferably a low molecular weight hyaluronic acid, more preferably an 800,000 to 1,200,000 dalton hyaluronic acid. The hyaluronic acid may be included in an amount of 6 to 10 wt %, for example, 8 wt % based on the weight of the entire hydrogel membrane.

(8) As used herein, the term “crosslinking agent” serves to link and copolymerize hyaluronic acid monomers, and an internal structure of the transparent hydrogel membrane may form a network structure by the copolymerization. The crosslinking agent may be generally different types of bi- or multi-functional crosslinking agents, and may be, for example, selected from the group consisting of divinyl sulfone, bi- or multi-functional epoxides, carbodiimides, and formaldehydes, but is not limited thereto. The crosslinking agent may be preferably an agent selected from the group consisting of bi- or multi-functional epoxides, more preferably 1,4-butanediol diglycidyl ether (BDDE), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), diepoxyoctane, 1,2-bis-(2,3-epoxypropyl)-2,3-ethylene, or a combination thereof, and even more preferably 1,4-butanediol diglycidyl ether or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The 1,4-butanediol diglycidyl ether has a molecular weight of 202.25, and compensates for a disadvantage of rapid degradation by crosslinking hyaluronic acid which has a short half-life to form a hydrogel. The crosslinking agent may be included in an amount of 0.01 to 0.05 wt % based on the weight of the entire hydrogel membrane. When the content of the crosslinking agent is less than 0.01 wt %, the formation of a membrane, which maintains the curvature of the lens, may not be achieved, and when the content is more than 0.05 wt %, the blending of the membrane formation may be performed well, but the lens may not be transparent, and the water content may be excessively high.

(9) The transparent hydrogel membrane may further include, for example, a drug selected from the group consisting of an antiphlogistic agent, an analgesic agent, an epithelial regeneration promoter, an anesthetic agent, a hemostatic agent, an antimicrobial agent, an antibacterial agent, an antiviral agent, an antifungal agent, an antiinflammatory agent, an antioxidant, an antiseptic agent, an antihistamine agent, an antipruritic agent, an antipyretic agent, an immunostimulator, a dermatological preparation, an anticancer agent, and a combination thereof, but the drug is not limited thereto. The drug further included in the transparent hydrogel membrane may assist wound healing or enhance an effect of wound healing.

(10) The transparent hydrogel membrane may be used for preventing or treating an opthalmic condition, for example, various ocular conditions such as xerophthalmia, keratitis, glaucoma, uveitis, ocular inflammation, allergies, ocular infections, carcinoma, corneal neovascularization, retinal edema, macular edema, diabetic retinopathy, retinopathy of prematurity, retinal degenerative diseases (macular degeneration, retinal dystrophy), and retinal diseases associated with glial proliferation, but the ophthalmic condition is not limited thereto.

(11) An aspect of the present invention provides a contact lens for preventing or treating an opthalmic disease, which includes the transparent hydrogel membrane, preferably prepared by the transparent hydrogel membrane.

(12) An aspect of the present invention provides a method for preparing a transparent hydrogel membrane, the method including: (a) preparing a hyaluronic acid solution by dissolving hyaluronic acid in a basic aqueous solution with a pH of 8; (b) mixing a crosslinking agent with the mixed solution; and (c) gelling the mixture and shaping the transparent hydrogel membrane by pouring the mixture into a mold. In this case, the hyaluronic acid may be contained in an amount of 6 to 10 wt %, for example, 8 wt % based on the weight of the mixture, and the crosslinking agent may be contained in an amount of 0.01 to 0.05 wt % based on the weight of the mixture.

(13) As used herein, the term “basic aqueous solution” may be an aqueous solution of a hydroxide of an alkali metal or a hydroxide of an alkaline earth metal, for example, an aqueous solution of lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, beryllium hydroxide, calcium hydroxide, or a combination thereof, but is not limited thereto. An aqueous solution of sodium hydroxide may be easy in terms of pH control and concentration control.

(14) Hereinafter, the present invention will be described in more detail through one or more Examples. However, these Examples are provided only for exemplarily explaining the present invention, and the scope of the present invention is not limited by these Examples.

Preparation Example 1. Manufacture of Mold

(15) In order to prepare a hyaluronic acid contact lens according to the present invention, a mold was manufactured using a polycarbonate (PC) made of a transparent material such that a process of forming the lens could be confirmed (FIG. 1).

(16) The mold consisted of an upper jig front cover and a lower jig rear base, and in order to observe the diversity according to the size which varied depending on use, when the upper front cover was assembled with the lower rear base, the mold was processed using a machining center (MCT) to divide the interval into five types such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, and 2.5 mm.

(17) The following Examples were designed for the purpose of testing the diversity when hyaluronic acid contact lenses having different thicknesses are manufactured according to the interval between the upper and lower jigs, in the molding of contact lenses. In order to secure a precise-dimensional interval during the assembly of the mold, the contact surface of a fixing SUS PIN press-fitted to both ends of the jig was used. Fastening was performed using M4 bolts on the center tab of the SUS PIN.

(18) The mold has a structure in which during the preparation of a contact lens, an excess mixture flows to a lower portion of the mold when the capacity exceeds an allowable capacity at an interval between upper and lower jigs.

Examples 1: Preparation of Hyaluronic Acid Contact Lens

(19) A uniform hyaluronic acid mixture was prepared by dissolving non-crosslinked hyaluronic acid in an amount of 8 wt % in an aqueous sodium hydroxide solution with a pH of 8 and adding 0.01 wt % of BDDE thereto. The hyaluronic acid mixture was poured into a polycarbonate mold prepared in Preparation Example 1 and dried in an oven at 40° C. for 30 hours. Hyaluronic acid contact lenses of a predetermined size prepared by drying the hyaluronic acid mixture were washed three times in total with distilled water every 24 hours, and after a washing process of 72 hours was performed, a hyaluronic acid hydrogel film was obtained. The hyaluronic acid hydrogel membrane had a diameter of 9 mm and a thickness of 20 μm in size.

Examples 2 to 7: Preparation of Hyaluronic Acid Contact Lens

(20) Hyaluronic acid hydrogel membranes were prepared in the same manner as described in Example 1, except that the amount of BDDE used was changed as shown in the following Table 1.

(21) TABLE-US-00001 TABLE 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Hyaluronic 8 8 8 6 10 10 acid (wt %) BDDE (wt %) 0.02 0.03 0.05 0.03 0.01 0.03 Aqueous NaOH Remainder Remainder Remainder Remainder Remainder Remainder solution Total 100 100 100 100 100 100

Comparative Examples 1 to 5. Preparation of Hyaluronic Acid Contact Lens

(22) Hyaluronic acid hydrogel membranes were prepared in the same manner as described in Example 1, except that the amount of BDDE used was changed as shown in the following Table 2.

(23) TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Hyaluronic acid 8 8 8 6 10 (wt %) BDDE (wt %) 0.005 0.07 0.1 0.07 0.07 Aqueous NaOH Remainder Remainder Remainder Remainder Remainder solution Total 100 100 100 100 100

Experimental Example 1. Evaluation of Water Content of Hyaluronic Acid Contact Lens

(24) In order to evaluate the water content of the hyaluronic acid contact lens prepared in Example 1, the contact lens was immersed in PBS at 37° C. for 24 hours, and then a change in the ratio of the sample mass after immersion compared to the initial sample mass was observed.

(25) As a result of the experiment, it was confirmed that the weight of the contact lens after immersion increased 4.5-fold compared to the initial weight (that is, the water content was 350%) (FIG. 2).

Experimental Example 2. Evaluation of Oxygen Permeability of Hyaluronic Acid Contact Lens

(26) The oxygen permeability of the hyaluronic acid contact lens prepared in Example 1 was evaluated. The test method was performed in accordance with the ASTM D3985 standard, and the temperature condition and the measurement range were set to 23±2° C. and 0.05 to 10,000 cm.sup.3/m.sup.2.Math.24 hr.Math.atm, respectively.

(27) As a result of the experiment, it was confirmed that the hyaluronic acid contact lens prepared in Example 1 had an excellent oxygen permeability of 10,000 cm/m.sup.2.Math.24 hr.Math.atm or more on average.

Experimental Example 3. Evaluation of Visible Light Transmittance of Hyaluronic Acid Contact Lens

(28) In order to evaluate the visible light transmittance of the hyaluronic acid contact lens prepared in Example 1, the visible light transmittance of the contact lens was measured in a wavelength range of 200 to 1,100 nm under a transmission mode air condition of a UV-VIS spectrophotometer.

(29) As a result of the experiment, it was confirmed that the hyaluronic acid contact lens prepared in Example 1 had an excellent visible light transmittance of 92% on average (FIG. 3).

Experimental Example 4. Evaluation of Toxicity of Hyaluronic Acid Hydrogel

(30) 4.1. Cell Culture

(31) HeLa cells (CCL-2) purchased from the American Type Culture Collection (ATCC, Manassas, Va., USA) were re-suspended in a HeLa cell basal medium in a proliferation kit provided by the ATCC. After cells were inoculated into a 75 cm.sup.2 tissue culture flask, air was maintained at 37° C., 5% CO.sub.2 and 95% humidity. The culture medium was changed every three days, treat the cells with 0.05% trypsin-EDTA (Gibco BRL, CA, USA), and the cells with a subculture number of 5 or less were used in the present experimental example.

(32) 4.2. Hydrogel Treatment and Cell Viability Analysis

(33) In order to evaluate the toxicity of the hyaluronic acid contact lens prepared in Example 1, an MTT analysis was performed.

(34) In short, HeLa cells were cultured in 96-well plates at a concentration of 1×10.sup.4 cells/well 24 hours prior to treatment with a contact lens eluate. After the contact lens prepared in Example 1 was swollen in a cell medium for 24 hours, 1 mL of the eluate was added to each well in which 1 mL of the culture medium was distributed (as a control, 2 mL of a culture medium was used without adding the eluate), and then cultured at 37° C. for 1 hour, 2 hours, 6 hours, and 24 hours, respectively. Thereafter, 10 μl of an MTT tetrazolium reagent was added to each well, and the absorbance at 450 nm was measured 2 hours after the culture with the MTT tetrazolium reagent.

(35) As a result of the experiment, it was confirmed that the viability of cells was gradually increased in proportion to the eluate treatment time (see FIG. 4), and through this, it was confirmed that the eluate of the contact lens was not toxic to cells.

(36) Table 3 below shows the experimental results of the Examples and Comparative Examples including Example 1.

(37) TABLE-US-00003 TABLE 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Water content (% ) 350 363 380 405 400 300 Oxygen 10,000 10,000 10,000 10,000 10,000 10,000 permeability or more or more or more or more or more or more (cm.sup.3/m.sup.2 .Math. 24 hr .Math. atm) Apparent Transparent Transparent Transparent Transparent Transparent Transparent transparency Visible light  92  92  90  88  90  93 Transmittance (%) Toxicity Good Good Good Good Good Good evaluation Comparative Comparative Comparative Comparative Comparative Example 7 Example 1 Example 2 Example 3 Example 4 Example 5 Water content (%) 360 — 500 750 720 460 Oxygen 10,000 Cannot be 10,000 10,000 10,000 10,000 permeability or more measured or more or more or more or more (cm.sup.3/m.sup.2 .Math. 24 hr .Math. atm) Apparent Transparent Membrane Semi- Semi- Semi- Semi- transparency formation X transparent transparent transparent transparent Visible light  91 Cannot be  80  73  70  82 Transmittance (%) measured Toxicity Good Cannot be Good Good Good Good assessment measured

(38) From the foregoing, the present invention has been reviewed mainly based on the preferred examples thereof. A person with ordinary skill in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed examples should be considered not from a restrictive viewpoint, but from an explanatory viewpoint. The scope of the present invention is represented by the claims to be described below rather than the foregoing detailed description, and it should be interpreted that the meaning and scope of the claims and all the changes or modified forms derived from the equivalent concepts thereto fall within the scope of the present invention.