NANOFIBROUS WOUND DRESSING

Abstract

The invention is related to the nanofibrous wound dressing that has been developed to be used in the treatment of various types of skin wounds including chronic and acute wounds in the biomedical sector, wherein said wound dressing comprises a bioactive agent that promotes the process of wound healing.

Claims

1. Nanofibrous wound dressing comprising black seed oil and polymer.

2. The wound dressing according to claim 1, wherein the polymer is selected from a group consisting of polyurethane polymer, polyacrylonitrile polymer, polyester polymer, polylactic acid, cellulose acetate, poly (e-caprolactone), polyethylene oxide, alginate, polyvinyl alcohol, fibroin, hyaluronic acid, and polycaprolactone.

3. A method for producing a wound dressing according to claim 1, comprising the steps of: extracting black oil from black seed, dissolving the polymer in a solvent, adding the black seed oil into the polymer solution obtained, obtaining a nanofibrous mat with a method of electrospinning from the solution containing the polymer, solvent and black seed oil.

4. The method for producing a wound dressing according to claim 3, wherein the polymer is selected from a group consisting of polyurethane polymer, polyacrylonitrile polymer, polyester polymer, polylactic acid, cellulose acetate, poly (e-caprolactone), polyethylene oxide, alginate, polyvinyl alcohol, fibroin, hyaluronic acid, and polycaprolactone.

5. Nanofibrous wound dressing according to claim 3, wherein the step of the process of extracting black seed oil from black seed comprises the use of a cold pressing method.

6. The method for producing a wound dressing according to claim 5, wherein the cold pressing method having an operating temperature of a maximum 30-40° C.

7. The method for producing a wound dressing according to claim 3, comprising the step of the process of dissolving 5%-18% polymer (w/v) by weight in a solvent.

8. The method for producing a wound dressing according to claim 3, wherein the step of the process of dissolving the polymer with the solvent comprises mixing a magnetic mixer at the temperature range of 30° C. to 45° C.

9. The method for producing a wound dressing according to claim 3, wherein the step of the process of adding black seed oil is in the range of 5%-20% by volume.

10. The method for producing a wound dressing according to claim 3, comprising the step of the process of applying electrospinning with a feeding rate in the range of 0.5 mL/hour-1.5 mL/hour.

11. The method for producing a wound dressing according to claim 3, comprising the step of the process of applying electrospinning such that the distance between the feeding unit and the collector is 8 cm to 30 cm.

12. The method for producing a wound dressing according to claim 3, comprising the step of the process of applying electrospinning at a voltage at the range of 6 kV-30 kV.

Description

DRAWINGS OF THE INVENTION

[0027] FIG. 1 shows a general perspective view of an electrospinning unit through which the wound dressing subject to the invention has been produced.

[0028] FIG. 2 illustrates the molecular structure of the thermoplastic polyurethane.

[0029] FIG. 3 shows SEM images of nanofibrous mats

[0030] FIG. 3a shows an image of Polyurethane;

[0031] FIG. 3b; shows images of the Polyurethane containing black seed oil.

DETAILED DESCRIPTION OF THE INVENTION

[0032] In this detailed description, preferred embodiments of the invention have been disclosed for a better understanding of the subject matter and without limitation.

[0033] The invention is related to nanofibrous wound dressing to be used in the biomedical sector. The nanofibrous mat that forms said wound dressing contains black seed oil and polymer. As polymer, those to be selected out of polyurethane (PU) polymer, polyacrylonitrile (PAN) polymer, polyester (PES) polymer, polylactic acid (PLA), cellulose acetate (CA), poly (ε-caprolactone) (PCL), polyethylene oxide (PEO), alginate, polyvinyl alcohol, fibroin, hyaluronic acid, polycaprolactone, and similar polymers are used. In the invention, the preferred polymer; is polyurethane (PU) polymer. Throughout the description, the term “nanofiber” refers to the fibers having a diameter of less than one micron.

[0034] The wound dressing subject to the invention contains polymer in the range of 5% -18% by weight, black seed oil in the range of 5% -20% by volume, and a solvent in the range of 75% -95% by volume. In a preferred embodiment of the invention, said wound dressing contains 10% polymer by weight, 10% black seed oil by volume, 80% solvent by volume.

[0035] Polyurethane is used as a polymer in the composition according to the invention. Said polyurethane; is a polymer that is the final product of a reaction of a polyol (alcohol containing more than two reactive hydroxyl groups per mole (—OH) with a di or poly-isocyanate (—N═C═O) that occurs in the presence of a suitable catalyzer, a chain extender, and inactive ingredients. Organic units on the polymer chain are joined to each other by the urethane bonds that repeat between themselves (—NH—CO—O—). The polyurethane structure comprises a polyether or polyester-based soft segment and an isocyanate based hard segment. The hard segment disperses in the soft segment and molecules are linked to each other through the urethane bonds. Polyurethanes can be synthesized under thermoplastic or thermoset conditions. The polyurethanes having a linear macromolecule chain structure that exhibits similar behavior with an elastomeric material are called thermoplastic polyurethanes (TPU). In FIG. 2, the molecular structure of the thermoplastic polyurethane is illustrated. With the use of thermoplastic polyurethane (TPU) polymer, suitable solvents for electrospinning can be prepared.

[0036] Black seed oil has been used as an additive in polyurethane. It is obtained from Nigella sativa (NS) species of Ranunculaceae (The Buttercup Family) and it has a long history of use as a therapeutic plant since ancient times.

[0037] The black seed plant has high nutritional values and contains a variety of active components. The primary components making up the structure of the seed are; 0.4-0.45% essential oils, 31-35.5% saturated/unsaturated fixed oils, 33-34% carbohydrates, 16-19.9% proteins, 4.5-6.5% fiber, 3.7-7% ash (calcium salts), 0.013% saponins, 5-7% moisture.

[0038] One of the vegetative resources that have been traditionally utilized in the treatment of wounds and burns is the black seed and extracts thereof. The bioactive components contained in the fixed/essential oil of the black seed oil have therapeutically and pharmacologically important features. A great number of studies have been provided to show that wound healing aspect and the other therapeutic features of black seed and its extracts including antioxidant, antihistamine, anti-inflammatory, antimicrobial, anticancer are a result of the bioactive components they contain, and particularly, of the thymoquinone which is a major bioactive component of the essential oil.

[0039] In the production method of the wound dressing subject to the invention, first of all the seed oil is extracted. Said black seed oil is extracted from the black seed (Nigella sativa) through the use of the method of cold pressing. In this step of the process, a cold pressing machine is used, and the operating temperature of said machine is preferably 40° C. After completing the step of the invention in which the black seed oil is extracted, the polymer is stirred into the solvent until it has a concentration rate in the range of 5% -18% (w/v) by weight. As polymer, those to be selected out of polyurethane (PU) polymer, polyacrylonitrile (PAN) polymer, polyester (PES) polymer, polylactic acid (PLA), cellulose acetate (CA), poly (ε-caprolactone) (PCL), polyethylene oxide (PEO), alginate, polyvinyl alcohol, fibroin, hyaluronic acid, polycaprolactone, and similar polymers are used. In the invention, the polymer is able to be dissolved in the solvent systems that have been prepared by mixing one or more than one of the solvents including dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), chloroform, dichloromethane at certain ratios.

[0040] The black seed oil in the range of 5% to 20% (v/v) (preferably 10% (v/v)) by volume of the total mixture is added into the mixture obtained after the polymer is dissolved in the solvent. In preparation of the mixture, polymer chips are added onto a certain amount of solvent contained in an inert glass vial and are continuously stirred in a magnetic mixer at the temperature range of 30° C. to 45° C. (preferably 45° C.), and hence said polymer chips are enabled to be dissolved. Subsequently, the black seed oil additive is added into this solution obtained, and the solution is completed to any desired volume by adding solvent. Said solution is preferably stirred in the magnetic mixer for 24 hours at the room temperature and hence a homogenous solution is obtained.

[0041] The next step of the process is the process of electrospinning. The method of electrospinning is more commonly preferred in the production of nanofibers due to its multifunctionality, operational compatibility with most of the polymers, and suitability for the production of proper nanofibers at low cost compared to other methods for the production of nanofibers. The basic principle of the method of electrospinning is constituted of obtaining nanofibers from a molten or dissolved polymer by the effect of electric field strengths. An electrospinning system is basically composed of; a power source, a feeding unit and a neutral collector (grounded) plate in which the nanofibers produced are accumulated. In the process of electrospinning; the dissolved or molten polymer is continuously fed to a nozzle of a syringe pump, by means of the usage of a controllable pump in the feeding unit. Surface tensions affect the polymer solution at the nozzle of the syringe pump. With the effect of the surface tensions, the polymer solution in liquid state is suspended in a droplet state at the nozzle of the syringe pump. The electrical strengths that have been formed by the voltage (V) applied by the power source act by pushing the surface tensions that act on a surface of the drop. Due to an increase in the electrical strengths acting on the drop suspended which occurs as a result of an increase in the voltage rate applied, and the viscoelasticity of the polymer, stretching occurs in the drop to an extent. When the voltage applied reaches a critical value (VC); it overcomes surface tension forces of the electrical strengths that occur on the polymer surface and afterward, the drop takes a shape called Taylor cone. When the voltage applied exceeds the critical value (V>Vc); a polymer jet extends out of an end of the Taylor cone and moves from the electrical area to the neutral collector plate. Repelling forces of the polymer jet created, has an axial component that extends said jet toward the collector. According to the flow rate measurements carried out, as it moves away from the Taylor cone, the variance of the jet rate increases as well as the jet rate. In this regard, the jet extending out of the Taylor cone steadily moves for a certain period of time while it gradually increases its speed. As a result of this case, the diameter of the jet swiftly diminishes when the jet starts to extend and the solvent starts to evaporate. As the jet tapers off, the surface load of the jet per unit area decreases while the surface load of said jet per unit mass increases. As the polymer proceeds steadily and properly, the charges that act on the jet surface mutually propel each other and they are separated from the jet, and thus whipping instability occurs. Said polymer that exhibits whipping instability separates from its jet and proceeds to the neutral collector plate after being divided into very fine fibers. During the travelling of the fibers inside the electrical area formed between the feeding unit and the collector plate, said fibers dry and harden due to the evaporation of the solvent, and ultimately the reticular nanofibers accumulate on the neutral plate. A general view of the electrospinning unit through which the wound dressing subject to the invention is produced is represented in FIG. 1.

[0042] In the method according to the invention, the solution that has been prepared in the previous step of the process and that has been stirred until it becomes homogenous is subjected to electrospinning such that the feeding rate is preferably in the range of 0.5 mL/hour-1.5 mL/hour (preferably 0.7 mL/hour), the distance between the feeding unit and the collector is preferably 8 cm to 30 cm (preferably 20 cm) and the voltage rate applied is in the range of 6 kV-30 kV (preferably 15 kV). The production of the nanofibrous mat is performed at room temperatures.

[0043] Furthermore, the nanofibrous mat can also be produced under the same conditions from the polymer solution that does not contain black seed oil. SEM images of two different surfaces obtained are represented in FIG. 3.

[0044] To comparatively examine the activity of the wound dressing according to the invention, the wound size decrement occurring on the wound surface of the wound dressings that have been prepared with the use of the method disclosed in the detailed description mentioned above are measured on day 0, 1, 3, 5, 7, 9 and 21 with the planimetric method.

[0045] This experiment that has been performed with a control group is herein presented only as an example and without limitation. To perform the comparison mentioned, a transparent acetate film is placed on the wound and the boundaries where the wound area intersects with intact tissue are pinpointed with an acetate pencil. The wound forms obtained are scanned and transferred to a computer and then they are defined as “cm.sup.2” in the ImageJ software, and the percentage of the wound size decrement is calculated through the use of the formula given below.

Wound Size Decrement(%)=100−[A.sub.wound(n)/A.sub.0]*100

[0046] Wherein; A.sub.0: The initial wound area (Day 0) and A.sub.wound(n): n. The wound area on the day of measurement.

[0047] In addition to this, the performance of the wound dressing subject to the invention in in vivo environment has been assessed by comparison with the Tegaderm® commercial wound dressing which is a product of the company 3M. The Tegaderm® is a wound dressing that is polyurethane polymer-based, elastic, self-adhesive, hypoallergenic and water-resistant. Said wound dressing has the structure of a transparent film and does not contain any wound healing active substances.

TABLE-US-00002 TABLE 2 Average and standard deviation values of the changes occurring in the wound area Sample Day 1 Day 3 Day 5 Day 7 Day 9 Day 21 Polyurethane 0 −2.4 ± 11.6 ± 37.6 ± 60.8 ± 95.5 ± nanofibrous mat 6.6 7.1 6.8 8.2 0.9 Polyurethane 33.1 ± 37.5 ± 39.9 ± 67.3 + 88.3 ± 98.4 ± nanofibrous 3.1 4.2 3.5 2.1 1.5 0.3 mat containing black seed oil Tegaderm 8.4 ± 18.8 ± 40.4 ± 56.4 ± 62.4 ± 90.6 ± Commercial 1.4 3.9 3.7 3.8 5.9 1.6 WoundDressing

[0048] In conclusion, when comparing the wound closure rates obtained on all of the control days of the experiment, the earliest wound closure has been observed on the area where the polyurethane nanofibrous mat containing black seed oil has been utilized. The area where respectively the control group and the polyurethane nanofibrous mat are utilized comes after the first area. The reason that the polyurethane nanofibrous mat containing black seed oil exhibits a better wound healing performance compared to said commercial wound dressing can be evidently associated with; the effect of the black seed oil used as an additive in the nanofibers forming the surface as well as the advantageous properties of the nanofibrous mat through the use of the electrospinning method.