USE OF A SHRINKABLE BIOPOLYMER FIBER AS A SENSOR

Abstract

The present invention relates to the use of a shrinkable biopolymer fiber as sensor. In a first embodiment, the sensor allows to determine the authenticity of a product. In a second embodiment, the sensor allows to determine the presence of a solvent. Further, the present invention relates to a method for determining the authenticity of a product. Furthermore, the present invention relates to a method for determining the presence of a solvent. In addition, the present invention relates to the use of a shrinkable biopolymer fiber for shaping an object. Moreover, the present invention relates to a method for shaping an object. Moreover, the present invention relates to the use of a shrinkable biopolymer fiber as suture material or wound dressing.

Claims

1. Use of a shrinkable biopolymer fiber as sensor.

2. The use of the shrinkable biopolymer fiber of claim 1, wherein said fiber has a specific shrinkage behavior which is influenceable by temperature and/or pH.

3. The use of the shrinkable biopolymer fiber of claim 1 or 2, wherein said fiber shows a shrinkage of at least 10% with regard to its total length after first contact with a solvent.

4. The use of the shrinkable biopolymer fiber of claims 1 to 3, wherein the sensor allows to determine the authenticity of a product.

5. The use of the shrinkable biopolymer fiber of claims 2 to 4, wherein the shrinkage is indicative for the authenticity of a product.

6. The use of the shrinkable biopolymer fiber of any one of claims 1 to 5, wherein the sensor allows to determine the presence of a solvent.

7. The use of the shrinkable biopolymer fiber of any one of claims 2 to 6, wherein the shrinkage is indicative for the presence of a solvent.

8. A method for determining the authenticity of a product comprising the steps of: (i) providing a shrinkable biopolymer fiber as sensor, (ii) contacting said fiber with a solvent, and (iii) observing whether a shrinkage of said fiber after contact with the solvent occurs, wherein a shrinkage of at least 10% with regard to the total length of said fiber is indicative for the authenticity of the product.

9. A method for determining the presence of a solvent comprising the steps of: (i) providing a shrinkable biopolymer fiber as sensor, and (ii) observing whether a shrinkage of said fiber occurs, wherein a shrinkage of at least 10% with regard to the total length of said fiber is indicative for the presence of a solvent in contact with said fiber.

10. The use of the shrinkable biopolymer fiber of any one of claims 3 to 7 or the method of claim 8 or 9, wherein the shrinkage starts between 3 and 200 seconds after (first) contact with the solvent/after (first) contact of the solvent with said fiber.

11. The use of the shrinkable biopolymer fiber of any one of claim 3 to 7 or 10, or the method of any one of claims 8 to 10, wherein the shrinkage is concluded to at least 80% after a time range of between 30 and 700 seconds, preferably of between 33 and 550 seconds, and more preferably of between 110 and 250 seconds.

12. The use of the shrinkable biopolymer fiber of any one of claim 3 to 7, 10 or 11, or the method of any one of claims 8 to 11, wherein the solvent is an aqueous solution, preferably water, or a solution comprising alcohol.

13. The use of the shrinkable biopolymer fiber of any one of claims 1 to 7 or 10 to 12, or the method of any one of claims 8 to 12, wherein the biopolymer is a silk polypeptide, preferably a recombinant silk polypeptide.

14. The use of the shrinkable biopolymer fiber of any one of claims 4 to 7 or 10 to 13, or the method of any one of claim 8 or 10 to 13, wherein the product is a fabric, preferably a woven fabric or knitted fabric, apparel, more preferably a garment.

15. The use of the shrinkable biopolymer fiber of any one of claims 1 to 7 or 10 to 14, or the method of any one of claims 8 or 10 to 14, wherein said fiber is part of a label or hangtag.

16. The use of the shrinkable biopolymer fiber or the method of claim 15, wherein the label or hangtag is attached to the product or is part of the product, or wherein the label or hangtag is attached to the packaging or is part of the packaging comprising the product.

17. Use of a shrinkable biopolymer fiber for shaping an object.

18. A method for shaping an object comprising the steps of: (i) providing an object comprising or consisting of a shrinkable biopolymer fiber, and (ii) contacting said object with a solvent, thereby shaping the object.

19. Use of a shrinkable biopolymer fiber as suture material.

20. Use of a shrinkable biopolymer fiber as wound dressing.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0254] The following figures and examples are merely illustrative of the present invention and should not be construed to limit the scope of the invention as indicated by the appended claims in any way.

[0255] FIG. 1: It shows the time to shrink, start of shrinkage, shrinkage duration and shrinkage conclusion of a biopolymer fiber depending on the influence of temperature and pH. The fiber was immersed in buffered aqueous solutions at three different pH values maintaining a constant salt content (pH 2.8 10 mM NaCl, pH 7.0 10 mM NaCl, pH 11.6 10 mM NaCl) at four different temperatures (8? C., 16? C., 24? C. and 35? C.). The time range between 0 and lowest value of each bar corresponds to the duration between first contact with a solvent/first contact of a solvent with said fiber and start of shrink (time to shrink). The lowest value of each bar corresponds to the starting time of shrinkage (start of shrinkage), the highest value of each bar corresponds the end of the shrinkage process (shrinkage conclusion) and the value between lowest and highest value of each bar corresponds to the time range between start of shrink and the end time/stop of the contraction of the fiber (shrinkage duration).

It could be demonstrated that the biopolymer fiber has a specific shrinkage behavior which is influenced by temperature. The shrinkage (process) started after a duration after first contact with a solvent/after first contact of a solvent with said fiber and was concluded after a time range. An increase in temperature reduced the duration between first contact of a solvent with said fiber (time to shrink) and start of the shrinkage. It could further be shown that an increase in temperature reduced the time range in which the shrinkage is concluded (shrinkage conclusion). In addition, it could be demonstrated that the biopolymer fiber has a specific shrinkage behavior which is influenced by pH: an increase in pH (towards a more basic pH) reduced the time range in which the shrinkage is concluded (shrinkage conclusion).

[0256] FIG. 2: It shows the time to shrink, start of shrinkage, shrinkage duration and shrinkage conclusion of two different biopolymer fibers of varying diameter depending on the influence of temperature and pH.

The shrinkage behavior (start of shrink and the shrinkage duration) between two different fibers of varying diameters (a first silk biopolymer multifiber with a diameter of approximately 250 ?m and a second silk biopolymer fiber with a diameter of approximately 76 ?m) were determined: Therefore the first and second biopolymer fiber were contacted with an aqueous solvent. The time range between 0 and lowest value of each bar corresponds to the duration between first contact of a solvent with said fiber and start of shrink (time to shrink). The lowest value of each bar corresponds to the starting time of shrinkage (start of shrinkage), the highest value of each bar corresponds the end of the shrinkage process (shrinkage conclusion) and the value between lowest and highest value of each bar corresponds to time range between start of shrink and end time/stop of the contraction of the fiber (shrinkage duration).

[0257] FIG. 2 A represents the shrinkage behavior of the first biopolymer fiber. FIG. 2 B represents the shrinkage behavior of the second biopolymer fiber. It could be demonstrated that the biopolymer fiber has a specific shrinkage behavior which is influenced by the diameter of the fiber. The shrinkage process started after a duration after first contact of a solvent with said fiber and was concluded after a time range. A decrease in diameter of the fiber reduced the time to shrink and the shrinkage duration in deionized water and buffered aqueous solution.

[0258] The shrinkage behavior of the biopolymer fiber in deionized water (neutral pH) compared to the shrinkage behavior of the biopolymer fiber in buffered aqueous solution (pH 12.8) shows that an increase in pH (towards a more basic pH) reduced the time to shrink and the shrinkage duration. As the lowest temperature value differs between first and second biopolymer fiber (first biopolymer fiber: 7.5? C., second biopolymer fiber 4.3? C.) the results for this lowest temperature value are not directly comparable between first and second biopolymer fiber. It should be noted that a higher temperature results in a reduction of time to shrink and shrinkage duration.

EXAMPLES

[0259] The examples given below are for illustrative purposes only and do not limit the invention described above in any way.

Example 1: Determination of the Starting Time of the Shrinkage of the Fiber after First Contact with a Solvent and the Duration Between Start of the Shrinkage Process and End of the Shrinkage Process

Definitions

[0260]

TABLE-US-00001 contact with solvent first contact with the solvent time to shrink duration between first contact with a solvent/first contact of a solvent with said fiber and start of shrink start of shrink starting time of the shrinkage/first contraction of the fiber shrinkage duration time range between first contraction of the fiber (start of shrink) and stop of the contraction of the fiber shrinkage conclusion end time/stop of the contraction of the fiber

[0261] In order to determine the starting time of the shrinkage/first contraction of the fiber after first contact with the solvent (start of shrink) and the time range (shrinkage duration) between start of shrink and end time/stop of the contraction of the fiber (shrinkage conclusion) a C.sub.32 silk biopolymer multifiber was contacted with an aqueous solvent. The time range between contact with the solvent and start of shrink and as well as the time range between start of the shrink and end of the shrinkage (shrinkage conclusion) was measured.

[0262] Therefore, three C.sub.32 silk fibers were immersed into a glass cylinder/measuring cylinder filled with the respective solvent. The fibers were fixed with one end at the top of the glass cylinder. A metal nut fixed at the other end of the fiber served as weight to fully extended the fiber. The timer was set to zero at first contact with the solvent (contact with solvent). The time range between contact with solvent and first movement of fiber contraction (start of shrink) represented the time range time to shrink. The time range between first contraction of the fiber (start of shrink) and stop of the contraction of the fiber represented the shrinkage duration.

[0263] The silk biopolymer was composed of 100% C.sub.32NR4 silk protein. The silk protein was prepared as described in WO 2006/008163. The protein was then processed into fibers as described in WO 2014/037453. The fiber used for the experiments is a multifilament consisting of 40 mono filaments. The fiber has an overall diameter of approximately 140 ?m

[0264] The experiments were carried out in triple at four different temperatures (8? C., 16? C., 24? C., 35? C.). In a first experiment, the fiber was immersed in buffered aqueous solutions at three different pH values maintaining a constant salt content (pH 2.8 10 mM NaCl, pH 7.0 10 mM NaCl, pH 11.6 10 mM NaCl). In a second experiment, the fiber was immersed in buffered aqueous solutions at different salt contents maintaining a constant pH value (50 mM NaCl pH 7.0, 100 mM NaCl pH 7.0, 200 mM NaCl pH 7.0).

[0265] The results are shown in FIG. 1. It could be demonstrated that the biopolymer fiber has a specific shrinkage behavior which is influenced by temperature. The shrinkage (process) started after a duration after first contact with a solvent/after first contact of a solvent with said fiber and was concluded after a time range. An increase in temperature reduced the duration between first contact of a solvent with said fiber (time to shrink) and start of the shrinkage. It could further be shown that an increase in temperature reduced the time range in which the shrinkage is concluded (shrinkage conclusion). In addition, it could be demonstrated that the biopolymer fiber has a specific shrinkage behavior which is influenced by pH: an increase in pH (towards a more basic pH) reduced the time range in which the shrinkage is concluded (shrinkage conclusion).

Example 2: Influence of the Thickness of the Fiber on the Shrinkage Behaviour

[0266] In order to determine the different shrinkage behavior (start of shrink and shrinkage duration) between two different fibers of varying diameters a first silk biopolymer multifiber (with a diameter of approximately 250 ?m) and a second silk biopolymer fiber (with a diameter of approximately 76 ?m) were contacted with an aqueous solvent. The time range between contact with the solvent and start of shrink and as well as shrinkage conclusion were measured.

[0267] Therefore the first and the second silk biopolymer fiber were immersed into a glass cylinder/measuring cylinder filled with the respective solvent. The biopolymer fibers were fixed with one end at the top of the glass cylinder. A metal nut fixed at the other end of the fiber served as weight to fully extended the fiber. The timer was set to zero at first contact with the solvent. The time range between contact with solvent and first movement of fiber contraction (start of shrink) represents time range time to shrink. The time range between first contraction of the fiber (start of shrink) and stop ofthe contraction ofthe fiber represents the shrinkage duration.

[0268] The first and second silk biopolymer fiber were composed of 100% C.sub.32NR4 silk protein. The silk protein was prepared as described in WO 2006/008163. The protein was then processed into fibers as described in WO 2014/037453. The first biopolymer fiber used for the experiments was a multifilament comprising three multifilaments, each multifilament consisting of 40 monofilaments. The three multifilaments were twisted into a yarn which comprises three multifilaments, each multifilament consisting of 40 monofilaments. The resulting fiber has an overall diameter of approximately 250 ?m. The second biopolymer fiber used for the experiments was a multifilament consisting of 30 monofilaments with a diameter of approximately 76 ?m.

[0269] The experiments were carried out at different temperatures (first biopolymer fiber: 7.5? C., 16.9? C., 22.3? C., 24.8? C.; second biopolymer fiber: 4.3? C., 15.7? C., 22.63? C., 25.0? C.). In a first experiment the first and second biopolymer fiber were immersed in deionized water. In a second experiment the first and second biopolymer fiber were immersed in a buffered aqueous solution (pH 12.8 100 mM NaCl).

[0270] The results are shown in FIG. 2. FIG. 2 A represents the shrinkage behavior of the first biopolymer fiber. FIG. 2 B represents the shrinkage behavior of the second biopolymer fiber. It could be demonstrated that the biopolymer fibers have a specific shrinkage behavior which is influenced by the diameter of the fiber. The shrinkage process started after a duration after first contact of a solvent with said fiber and was concluded after a time range. A decrease in diameter of the fiber reduced the time to shrink and the shrinkage duration in both experiments (deionized water and buffered aqueous solution).

[0271] The shrinkage behavior of the biopolymer fiber in deionized water (neutral pH) compared to the shrinkage behavior of the biopolymer fiber in buffered aqueous solution (pH 12.8) shows that an increase in pH (towards a more basic pH) reduced the time to shrink and the shrinkage duration. As the lowest temperature value differs between first and second biopolymer fiber (first biopolymer fiber: 7.5? C., second biopolymer fiber 4.3? C.) the results for this lowest temperature value are not directly comparable. It should be noted that a higher temperature results in a reduction of time to shrink and shrinkage duration.