Pliable silk medical device
An implantable, pliable silk device (e.g., in a form of a knitted mesh) for use in human soft tissue support and/or repair that provides stretch or pliable properties, e.g., multi-directional elongation properties. Such a device permits physicians or users to alter or manipulate the device dimension and/or shape at the time of device implantation, thereby permitting the device to conform to the contour of a target area or tissue more easily and providing more precise positioning of the device over the target area or tissue. In some embodiments, the implantable pliable silk device comprises a knit pattern feature that substantially prevents unraveling and preserves the stability of the mesh when cut. For example, the pliable silk device is a knitted mesh comprising at least two yarns laid in a knit direction and engaging each other to define a plurality of nodes.
1. A process for forming a pliable silk fibroin mesh, the process comprising the steps of:
knitting a first silk fibroin yarn in a first wale direction using the knit pattern 1/1-1/3-3/3-3/1;
knitting a second silk fibroin yarn in a second wale direction using the knit pattern 3/1-1/1-1/3-3/3;
knitting a third silk fibroin yarn in a first course direction using the knit pattern 1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3; and
knitting a fourth silk fibroin yarn in a second course direction using the knit pattern 3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-1/1-1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5,
thereby forming the pliable silk fibroin mesh.
2. The process of claim 1 , wherein the pliable silk fibroin mesh is characterized in that elongation at break along a direction of the pliable silk fibroin mesh formation is greater than 85% and elongation at break along a width of the pliable silk fibroin mesh is greater than 85%.
3. The process of claim 1 , wherein the pliable silk fibroin mesh comprises pores having an average pore area of greater than 1 mm 2 .
4. The process of claim 1 , wherein the silk fibroin yarn comprises silk fibroin fibers.
5. The process of claim 1 , wherein the silk fibroin yarn is sericin-depleted.
6. A pliable silk fibroin mesh formed by a process comprising:
knitting a first silk fibroin yarn in a first wale direction using the knit pattern 3/1-1/1-1/3-3/3;
knitting a second silk fibroin yarn in a second wale direction using the knit pattern 1/1-1/3-3/3-3/1;
knitting a third silk fibroin yarn in a first course direction using the knit pattern 3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-1/1-1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5; and
knitting a fourth silk fibroin yarn in a second course direction using the knit pattern 1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3.
7. The pliable silk fibroin mesh of claim 6 , wherein the pliable silk fibroin mesh is characterized in that elongation at break along a direction of the pliable silk fibroin mesh formation is greater than 85% and elongation at break along a width of the pliable silk fibroin mesh is greater than 85%.
8. The pliable silk fibroin mesh of claim 6 , wherein the pliable silk fibroin mesh comprises pores having an average pore area of greater than 1 mm 2 .
9. The pliable silk fibroin mesh of claim 6 , wherein the silk fibroin yarns are made of nine filament and twisted silk fibroin fibers.
10. The pliable silk fibroin mesh of claim 6 , wherein the silk fibroin yarn is sericin-depleted.
11. An implantable device comprising a knitted network of silk fibroin yarns, wherein the knitted network is characterized in that average elongation at break along a direction of the knitted network formation is greater than 85% and average elongation at break along a width of the knitted network is greater than 85%, and wherein the average pore size of the knitted network is greater than 1 mm 2 .
12. The implantable device of claim 11 , wherein the knitted network exhibits one or more of the following characteristics:
(a) an average burst strength of about 0.3 MPa to about 1.5 MPa, or about 0.3 MPa to about 0.6 MPa;
(b) an average maximum tensile stress along the direction of the knitted network formation of about 0.2 MPa to about 0.4 MPa, or about 0.2 MPa to about 0.3 MPa;
(c) an average maximum tensile stress along the width of the knitted network of about 0.1 MPa to about 0.3 MPa, or about 0.15 MPa to about 0.2 MPa;
(d) an average tear strength along the direction of the knitted network formation of about 100 N to about 170 N or about 110 N to about 160 N;
(e) an average tear strength along the width of the knitted network of about 50 N to about 100 N or about 60 N to about 90 N;
(f) an average density of about 0.10 mg/mm 3 to about 0.15 mg/mm 3 ;
(g) an average elongation at a force of about 16 N along the direction of the knitted network formation of about 20% to about 50% or about 25% to about 40%; and
(h) an average elongation at a force of about 16 N along the width of the knitted network formation of about 20% to about 60% or about 30% to about 50%.
13. The implantable device of claim 11 , wherein the silk fibroin yarn comprises silk fibroin fibers.
14. The implantable device of claim 11 , wherein the silk fibroin yarn is sericin-depleted.
15. The implantable device of claim 11 , wherein the silk fibroin yarn is made of 9 silk fibroin fibers.
16. The implantable device of claim 11 , wherein the knitted network is formed by a process comprising at least one of the following steps:
(i) knitting a first silk fibroin yarn in a first wale direction using a knit pattern 1/1-1/3-3/3-3/1 or a portion thereof;
(ii) knitting a second silk fibroin yarn in a second wale direction using a knit pattern 3/1-1/1-1/3-3/3 or a portion thereof;
(iii) knitting a third silk fibroin yarn in a first course direction using a knit pattern 1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3 or a portion thereof; and
(iv) knitting a fourth silk fibroin yarn in a second course direction using a knit pattern 3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-1/1-1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5 or a portion thereof.
17. The implantable device of claim 11 , wherein the knitted network is formed by a process comprising at least one of the following steps:
(i) knitting a first silk fibroin yarn in a first wale direction using a knit pattern 3/1-1/1-1/3-3/3 or a portion thereof;
(ii) knitting a second silk fibroin yarn in a second wale direction using a knit pattern 1/1-1/3-3/3-3/1 or a portion thereof;
(iii) knitting a third silk fibroin yarn in a first course direction using a knit pattern 3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-1/1-1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5 or a portion thereof; and
(iv) knitting a fourth silk fibroin yarn in a second course direction using the knit pattern 1/1-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-7/7-7/7-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3-3/3-5/5-5/5-3/3 or a portion thereof.