Composite materials

a technology of composite materials and materials, applied in the field of composite materials, can solve the problem of high biocompatibility of materials

Inactive Publication Date: 2012-02-02
OXFORD BIOMATERIALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005] These and other objects of the invention are solved by providing a composite material having one or more silk elements in an acrylic or cross-linked protein matrix. This material is highly biocompatible. Preferably the silk elements are made from wild silkworm silk, domestic silkworm silk spider-dragline silk, and filaments spun from recombinant silk protein or protein analogues or mixtures of these. A protein matrix is preferred because this means that both the protein matrix and the silk elements are resorbable.
[0009] The composite material can be formed into a substantially cylindrical form with the silk elements wound at an angle in excess of 40 degrees to the long axis of the substantially cylindrical form or circumferentially to the long axis. On a luminal surface of the form, the silk elements can be wound parallel to the long axis of the substantially cylindrical form. This latter construction has the advantage that it should stimulate longitudinal movement of nerve processes in a sleeve and therefore promote nerve regeneration.
[0010] Mineralisation of the composite material is advantageous as this allows the composite material to be used as a bone substitute and stimulates regrowth of the bone material.
[0011] The principal silk protein used in the silk elements contains at least eight repeats of the triplet RGD. The eight repeats of the triplet RGD are located immediately adjacent to turns or predicted turns of a structure of the principal silk protein. This is advantageous as this sequence when next to a turn specifically recognises and holds the fibronectin binding site of integrin molecules anchored to the surface of most metazoan cell types. In turn this leads to excellent cell adhesion and advantageous changes in cell physiology including polarisation of function, cell differentiation and changes in the cell cycle.

Problems solved by technology

This material is highly biocompatible.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of Composite Materials from Carded Antheraea Pernyii Silk Filaments.

[0039] Antheraea pernyii silk filaments prepared from degummed silk cocoons were obtained from a commercial supplier. The carded silk from the sepin was smoothed into flat sheets and gently tensioned to pull the silk filaments parallel. Keeping the silk tensioned they were wound on to cylindrical formers 0.25 mm to 30 mm in diameter. The largest cylinders were made of glass and had a substantially smooth surface. The Smallest cylinders 0.25 mm were prepared by coating a thin stiff wire in low melting point wax. Cylindrical formers with intermediate diameters were made from low melting point wax. The silk filaments were generally laid circumferentially on the largest formers but were laid in a helical fashion on the smaller cylindrical formers.

[0040] Care was taken to ensure a uniform dense lay of filaments was achieved on the cylindrical formers. The silk filaments at the ends of the thin cylindrical ...

example 2

Demonstration of RGD Putative Integrin Binding Sites on Antheraea spp Heavy Chain Fibroins and their Location Adjacent to Turns.

[0043] The published sequences of silk proteins were searched on the TrBMBL and SwissPROT data bases for the well established cell binding sequence RGD and the putative cell binding sites PPSRN and KNEED. The sequence triplet RGD is of considerable interest as it forms part of the mechanism used in multicellular organisms to stick many types of cells to the connective tissue framework of the body. The RGD triplet on the silk-like connective tissue protein fibronectin binds specifically to integrins. Integrins are a class of cell adhesion molecules. They are found intercalated into the lipid bilayer of the cell membrane with the fibronectin binding (RGD recognition) site protruding into the extracellular space. Thus the RGD recognition site of integrins is available-to bind cells to the connective tissue-framework via RGD triplets on fibronectin molecules....

example 3

[0050] Tensile Data on Antheraea Pernyi Cyanoacrylate Composite

TABLE 1Tensile test data (n = 6) for wet strips of composite material containinga high density of well-oriented Antheraea pernyii filaments set in acyanoacrylate matrix. The strips (50 mm gauge length, average width10.5 mm and thickness 0.4 mm) were strainedparallel to the filament orientationUTS(Mpa)Strain to failureEnergy / kg (JKg)Modulus (Mpa)Average:310.15019001000SD8.0800.016590227

[0051] For comparison, the ultimate tensile stress of a typical-low alloy steel is in the region of 830 Mpa and a modulus of 200 Mpa but steel has a density of approximately 6 times that of the silk composite thus weight for weight this steel is less than 4 times as strong as the silk composite. The tensile data for the silk composite are comparable with that of that of two synthetic implantable materials (table 2).

TABLE 2Tensile data for wild silk cyanoacrylate composite comparedwith two synthetic implantable materials.Poly εA. pernyi ...

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Abstract

This application discloses a composite material comprising one or more silk elements in an acrylic or cross-linked protein matrix. The silk elements are made from the group of silk elements consisting of domestic silkworm silk, wild silkworm silk, spider dragline silk, and filaments spun from recombinant silk protein or protein analogues. The composite material is particularly useful for use in-surgical-implants.

Description

FIELD OF THE INVENTION [0001] The invention relates to a composite material comprising one or more silk elements in an acrylic or cross-lined protein matrix, its method of manufacture and its use in surgical implants. BACKGROUND [0002] Biodegradable polymer materials made of silk fibroin elements-are known, for example, from US-A-2004 / 0005363 (Tsukada et al.). This patent document teaches a composite material made from silk fibroin and another secondary substance, such as cellulose, chitin, chitosan (or derivatives), Keratin-or polyvinyl alcohol. The composite material can be used as a sustained release substrate for medicines, a biological cell growth substrate, a metal ion-absorbing material and a biodegradable water-absorbing material. [0003] Another example of a composite material in which proteins coat the surface of a surgical device is disclosed in WO-A-94 / 22584 entitled “Chronic Endothelial Cell Culture under flow”. In this patent application, the inner lumen of a hollow pol...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D06M11/38A61K35/64A61L27/48
CPCA61L27/48C07K14/43518C07K14/43586C08L89/00
Inventor KNIGHT, DAVID PHILIP
Owner OXFORD BIOMATERIALS LTD
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