Calcium phosphate polymer composite and method

Abstract

A bone-repair composite includes a core and a sheath. The core is a first primary unit including a combination of a first set of yarns coated with a calcium phosphate mineral layer. The first set of yarns being made from a first group of one ore more polymers. The sheath is a second primary unit a combination of a second set of yarns or one or more polymer coatings. The second set of yarns being made from a second group of one or more polymers, wherein the composite is made by covering the core with the sheath, and the composite is compression molded to allow the sheath to bond to the core. The bone-repair composite has a bending modulus comparable to that of a mammalian bone, such that the ratio of the core to the sheath is provided to maximize the mechanical strength of the bone-repair composite to mimic the mammalian bone.

1 . A bone-repair composite, comprising: 
 a core, the core being a first primary unit including a combination of a first set of yarns coated with a calcium phosphate mineral layer, the first set of yarns being made from a first group of one or more polymers; and    a sheath, the sheath being a second primary unit including a combination of a second set of yarns or one or more polymer coatings the second set of yarns being made from a second group of one or more polymers,    wherein the composite is made by covering the core with the sheath, and the composite is compression molded to allow the sheath to bond to the core.    
     
     
         2 . The bone-repair composite of  claim 1 , wherein the composite has a bending modulus comparable to that of a mammalian bone.  
     
     
         3 . The bone-repair composite of  claim 2 , wherein the ratio of the core to the sheath is provided to maximize the mechanical strength of the bone-repair composite to mimic the mammalian bone.  
     
     
         4 . The bone-repair composite of  claim 2 , wherein the bending modulus of the bone-repair composite is at least 3 GPa.  
     
     
         5 . The bone-repair composite of  claim 2 , wherein the bending modulus of the bone-repair composite is similar to a cortical bone.  
     
     
         6 . The bone-repair composite of  claim 1 , wherein with the one ore more polymer coatings include: a biodegradable polymer, a low melting temperature polymer, a copolymer, or a combination mixture thereof.  
     
     
         7 . The bone-repair composite of  claim 6 , wherein the sheath contains filling materials as aids in drug delivery, porosity or cohesion in the composite.  
     
     
         8 . The bone-repair composite of  claim 1 , wherein the composite is subject to a hot compression molding at an elevated temperature, whereby melting the polymers having a lower melting temperature, and thus binding the polymers having a higher melting temperature with the polymers having a lower melting temperature.  
     
     
         9 . The bone-repair composite of  claim 1 , wherein the composite is subject to a cold compression molding using a solvent, wherein the solvent is vaporized to melt the sheath, and thus binding the sheath to the core.  
     
     
         10 . The bone-repair composite of  claim 9 , wherein the solvent is selected from a group consisting of toluene, xylene, ethyl acetate, and acetone.  
     
     
         11 . The bone-repair composite of  claim 1 , wherein the composite is subject to an elevated temperature with a solvent, wherein the sheath is melted and binds to the core.  
     
     
         12 . The bone-repair composite of  claim 1 , wherein the second group of polymers includes a low-temperature melting polymer or a binding polymer.  
     
     
         13 . The bone-repair composite of  claim 1 , wherein the composite is unidirectional or multidirectional.  
     
     
         14 . The bone-repair composite of  claim 1 , further comprising filling materials including drugs or bioactive agents, wherein the filling materials is used as a binding material or for drug release.  
     
     
         15 . The bone-repair composite of  claim 1 , wherein the polymer is selected from a group consisting of collagen, hyaluronans, fibrin, chitosan, alginate, silk, polyesters, polyethers, polycarbonates, polyamines, polyamides, co-polymers, poly(L-lactic) acid (PLLA), polyglycolic acid (PGA), poly(D,L-lactide-co-glycolide) (PLGA), poly(ε-caprolactone) (PCL) and other similar polymers.  
     
     
         16 . The bone-repair composite of  claim 1 , wherein the calcium phosphate mineral layer is selected from a group consisting of ion-substituted apatite, calcium phosphate, carbonate hydroxyapatite, fluorinated hydroxyapatite, chlorinated hydroxyapatite, silicon-containing hydroxyapatite, tricalcium phosphate, tetracalcium phosphate, monotite, dicalcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, calcium phosphate monohydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, amorphosous calcium phosphate, biphasic calcium phosphate, calcium deficient hydroxyapatite, precipitated hydroxyapatite, oxyapatite, calcium sulfate, and other calcium containing minerals.  
     
     
         17 . The bone-repair composite of  claim 1 , wherein the calcium phosphate mineral layer is fully or partially aligned to a fiber axis or a polymer crystallites.  
     
     
         18 . The bone-repair composite of  claim 1 , wherein the calcium phosphate mineral layer is anchored to the polymer surface by electrostatic, coordinative, ionic or chemical tethering.  
     
     
         19 . The bone-repair composite of  claim 1 , wherein secondary and tertiary organized composite structures are formed from the primary unit by varying the ratio of the core and the sheath.  
     
     
         20 . A method for making a bone repair synthetic composite comprising the steps of: 
 forming an inner core structure with a plurality of a combination of a first set of yarns, the first set of yarns being made from a group of polymers, wherein the inner core structure is a first primary structure,    coating the first set of yarns with a mineral layer;    cutting the inner core structure into a length of a compression mold;    arranging the inner core structure into the compression mold; and    compression molding the inner core structure.    
     
     
         21 . The method of  claim 20 , further includes the step of treating the first set of yarns with a surface modifying chemical.  
     
     
         22 . The method of  claim 21 , further includes the step of forming an outer sheath structure with a plurality of a combination of a second set of yarns or one ore more polymer coatings, the second set of yarns being made from the group of polymers, wherein the outer sheath structure is a second primary structure.  
     
     
         23 . The method of  claim 22 , further includes the step of forming a secondary structure by combining an appropriate ratio of the inner core structure to the outer sheath structure to mimic the mechanical strength of a mammalian bone.  
     
     
         24 . The method of  claim 23 , further comprising: 
 coating the secondary structure with a binding material;    drying the coated secondary structure; and    compression molding the coated secondary structure at an elevated temperature.    
     
     
         25 . The method of  claim 24 , wherein the binding material has a lower melting point than the inner core structure and the outer sheath structure.  
     
     
         26 . The method of  claim 23 , further comprising: 
 coating the secondary structure with PCL;    drying the coated secondary structure; and    compression molding the coated secondary structure using a vaporized solvent to melt the PCL.    
     
     
         27 . The method of  claim 20 , wherein the inner core structure is formed by: 
 assembling a plurality of yarns together;    rolling a mesh structure, wherein the mesh structure is knitted, woven, non-woven, braided, stacked, flocked, or felted; or    rolling the plurality of yarns and the mesh structure together.    
     
     
         28 . The method of  claim 23 , further comprising the step of forming a tertiary structure of a desired shape by binding a plurality of the secondary structures or the primary structures with a binding material.  
     
     
         29 . The method of  claim 20 , wherein the inner core is designed to facilitate water access rate and cellular access rate both longitudinally and laterally.  
     
     
         30 . The method of  claim 29 , wherein the longitude access is controlled by time, degradation, and/or solubilization of the inner core.  
     
     
         31 . The method of  claim 29 , wherein the lateral access is controlled by braid density, coating, or binder of the binding material.  
     
     
         32 . The method of  claim 20 , wherein the surface modifying chemical is alkaline, acidic, oxidizing, ionic or electrostatic.  
     
     
         33 . The method of  claim 20 , wherein the polymer is selected from a group consisting of collagen, hyaluronans, fibrin, chitosan, alginate, silk, polyesters, polyethers, polycarbonates, polyamines, polyamides, co-polymers, poly(L-lactic) acid (PLLA), polyglycolic acid (PGA), poly(D,L-lactide-co-glycolide) (PLGA), poly(ε-caprolactone) (PCL), and other polymers.  
     
     
         34 . The method of  claim 20 , wherein the mineral layer is selected from a group consisting of ion-substituted apatite, calcium phosphate, carbonate hydroxyapatite, fluorinated hydroxyapatite, chlorinated hydroxyapatite, silicon-containing hydroxyapatite, tricalcium phosphate, tetracalcium phosphate, monotite, dicalcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, calcium phosphate monohydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, amorphosous calcium phosphate, biphasic calcium phosphate, calcium deficient hydroxyapatite, precipitated hydroxyapatite, oxyapatite, calcium sulfate, and other calcium containing minerals.  
     
     
         35 . The method of  claim 20 , wherein the mineral layer is hydrodynamically aligned/coated on the polymer fiber by dip or die coating of the polymer fiber using suspension of calcium phosphate particles in solvents or polymer solutions.  
     
     
         36 . The method of  claim 20 , wherein the mineral is coated using an alternating soaking technique, a simulated body fluid technique, supersaturated calcium phosphate solutions, dip coating, sol-gel coating, electrophoresis, electrochemical coating, extrusion coating, pultrusion, or brush-on coating methods.  
     
     
         37 . The method of  claim 20 , wherein growth factors or other biological agents is added to the core.  
     
     
         38 . A method for making a calcium phosphate-reinforced composite yarn, comprising: 
 treating an undrawn yarn with a surface modifying chemical;    coating the undrawn yarn with a calcium phosphate solution to form calcium phosphate particles, such that the calcium phosphate particles are anchored on the yarn to form a coated undrawn yarn; and    drawing the coated undrawn yarn to form a coated drawn yarn, such that the calcium phosphate particles are orientated in such a way that the calcium phosphate-reinforced composite mimic bone structures.    
     
     
         39 . The method of  claim 38 , wherein the surface modifying chemical is alkaline, acidic, oxidizing, ionic or electrostatic.  
     
     
         40 . The method of  claim 38 , wherein the calcium phosphate particles are hydrodynamically aligned/coated on the undrawn yarn by dip or die coating of the undrawn yarn using suspension of calcium phosphate particles in solvents or polymer solutions.  
     
     
         41 . The method of  claim 38 , wherein the calcium phosphate particles are coated using an alternating soaking technique, a simulated body fluid technique, supersaturated calcium phosphate solutions, dip coating, sol-gel coating, electrophoresis, electrochemical coating, extrusion coating, pultrusion, or brush-on coating methods.  
     
     
         42 . The method of  claim 38 , wherein the undrawn yarn can be lightly coated or heavily coated.  
     
     
         43 . The method of  claim 38 , further comprising the step of applying one or more layers of calcium phosphate to the coated drawn yarn.  
     
     
         44 . The method of  claim 38 , further comprising the step of treating the coated drawn yarn with bone growth enhancing agent.