High-strength high-modulus absorbable calcium polyphosphate fibre/polylactide composition

Biocompatibility is an essential aspect of the medical device industry. Biocompatibility testing ensures that devices do not contain materials or substances that could be harmful to patients during initial use or over the course of time. Biocompatibility tests can be used to detect many possible negative side effects of a product on patient. These may include effects on cells and physiological systems, tissue irritation and inflammation, immunological and allergic reactions and the possibility of cellular mutations leading to cancer.

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A high-strength high-modulus absorble material as intrabony fixing material is prepared from calcium polyphosphate fibres as reinforcing component and polylactide as substrate in wt ratio of (1-80):(20-99). Its advantages include high compatibility to bone tissue, no poison and untoward effect, bio-degradable, and low cost.

Currently biodegradable absorbent polymer is used primarily in clinical medicine - containing aliphatic polyester α- hydroxy acid derivatives, including polyglycolide (PGA) and polylactide (PLA) and its copolymers III categories. In vivo, PGA is hydrolyzed to glycolic acid under the action of glycerate oxidase, glycolic acid converted to glyoxylic acid; then transfected with IDO Gan oxygen acid action generated glycine; Gan oxygen acids may participate in protein synthesis or serine . Are being converted to pyruvate after, can participate in the citric acid cycle serine. PLA hydrolysis produces lactic acid, lactic acid can be metabolized to CO2 by acid cycle, and then excreted through the lungs. These polymers and copolymers may be of different plastics processing techniques is prepared as fibers, films or other shapes (e.g., rods, screws, plates, clips, etc.). Compared with metal or ceramic, its biggest advantage is easy to process and cost. They have been made of surgical sutures, fabric, bone fixation, porous composite materials, drug delivery and three-dimensional scaffolds in tissue engineering and clinical medicine widely used preparation techniques.

In this technique, we use a controllable degradation rate of CPP CPP fiber, which is the use of chemical composition similar to human bone mineral calcium metaphosphate as the main raw material, by adding an appropriate amount of Mg and Zn stabilizer barrier lowering agents by crushing, grinding and high temperature melting, drawing, and prepared. CPP fiber 。PDF CPP fiber slow degradation process occurs in the water: the fiber and its preparation process has been patented (Application No. 01101545.4). Manager of the mechanical properties and biocompatibility testing and evaluation of biological safety research shows that the fiber is a kind of bone tissue with good biocompatibility, the body non-toxic, non-teratogenic and mutagenic effects of high strength and high modulus biodegradable absorbent medical reinforcing material.

In order to enhance and improve the biodegradable absorbent fracture fixation within the mechanical properties and biological properties, so that it can be used in different parts of the body fractures, particularly higher prevalence discreet parts of the long bone shaft fracture fixation, and after the completion of its rigid internal fixation of the fracture with a suitable absorption rate degradation, we apply the basic principles and techniques of composite materials, fiber diameter 5-50μmCPP reinforcement, and 20-100 × 104D medium molecular weight (Mw) PLLA as matrix, according to CPP / PLLA weight ratio 1-80 / 99-20, using multi CPPf / PLLA film laminated hot filament or CPP CPP molded short fiber technology to prepare a series of CPPf high strength and high modulus enhanced bioavailability Medical absorbent composite degradation.

CPP above polylactide fiber and composite weight ratio may preferably 20-60 / 80-40, or more preferably 40-60 / 60-40. Molecular weight polylactide (PLLA) may preferably 40-60 × 104D.

Select the date or further degradation rate of 0.2-4%, 0.8-1.5% of calcium polyphosphate (CPPf), the diameter is preferably 5-25μm.

The composite material according to the different scope of application, such as for the preparation of the cortical bone screws and plates, pipes and intramedullary nail or screw used to take within the bone or fixed bar, there are some different methods for their preparation.

When used in the preparation of the cortical bone screws and plates, pipes and intramedullary nail, which was prepared according to the following steps: 1. Select the CPP fiber (CPPf), cut into long fibers 10-500mm; 2, weighing; 3, weighed purity of 99.9% of polylactide (PLLA), with the container in an organic solvent to dissolve 1:50-100; 4, with absolute ethanol 1:50-200 of polylactide (PLLA) was purified and extracted ; 5, the extract obtained polylactide (PLLA) particles and dried in vacuo at least 24 hours in an oven, temperature 30-60 ℃; 6, then polylactide (PLLA) The granules dissolved in an organic solvent 1:50-100 Organic 8, via step ⑦ treated CPPf / PLLA within the film; 7, via step ② weighed CPP filaments hand layup, simultaneously with step ⑥ by dissolving polylactide (PLLA) film; natural volatile solvent for 24 hours and then vacuum stripped in an oven for 24 hours at a temperature 30-60 ℃; 9, vacuum hot press mold with a plate pressing, temperature 120-220 ℃, pressure 20-80Mpa; 10, release, repair sample, packaging, sterilization, have high strength, high modulus of cortical bone screws or plates, tubes and intramedullary nail.

When present within the composite material used for making bone screws or fixing rods, which was prepared according to the following steps: 1, calcium phosphate fibers (CPPf), cut into short fibers 2-12mm; 2, weighed; 3, while Weigh 99.9 percent polylactide (PLLA), dissolved in dichloroethane using container 1:50-100; and 4, after step 2 weighed CPP staple fibers (CPPf) and by step ③ After the processing of polylactide (PLLA) mixed solution; 5, purified by extraction with anhydrous ethanol 1:100-200 mixture of step 4; 6, 5 obtained CPPf / PLLA mixture of the organic solvent by natural evaporation at least 24 hours , and then in a vacuum oven evacuated mentioned organic solvent is at least 24 hours, a temperature of 30-60 ℃; 7, using a plate pressing machine vacuum hot pressing mold, temperature 120-200 ℃, pressure 20-80Mpa; 8, release, repair sample packaging, sterilization was in the high strength and high modulus of bone fixation screws or rods.

The composite material in a CPP fiber as a reinforcing material, its main role is: ① to improve the flexural strength and flexural modulus of the composite material, especially for improving the flexural modulus of the most significant; ② Since the ingredients for preparing CPP fibers with human bone mineral composition similar, so after joining the CPP fiber, so CPPf / PLLA composite bone fixation obvious osteoinductive properties; ③ CPP fiber degradation due to controllable, and PLLA degradation time is longer, and therefore processed into CPPf / PLLA After the bone fixation, to meet the performance requirements of the bone fixation premise, first make CPP fiber degradation, so the holes, into the body fluid, increase the contact area with the body fluids PLLA and PLLA degradation rate of increase, reducing the bone degradation time fixture.

In summary, the increase in the number of CPP fiber, not only can CPPf / PLLA internal fixation of bone strength, stiffness and increased bone induction, and can shorten the time degradation of the bone, but more than a certain number of fibers CPP limit, its strength, but will reduce the stiffness, and therefore the relationship between the ratio CPPf / PLLA determined by performance optimization.

Manager of the mechanical properties and biocompatibility testing and evaluation of biological safety research shows that they are a class with good bone tissue biocompatibility, non-toxic to the body no teratogenic and mutagenic effects of high strength and high modulus Biodegradable medical absorbent composite. , Comparing the composite material within a fixture PLLA and copolymers of Bone and self-reinforced PGA, the performance advantages include: a significantly increased strength and rigidity, and the body of the cortical bone to reach 1.5 times and 1.3 times; ultrahigh strength can be used to prepare biological. biodegradable absorbable bone fixation and bone repair material; 2 has a suitable absorption rate in vivo degradation; 3. osteoconductive and osseointegration properties; 4 has a X-ray imaging of; 5 simple preparation process, the cost of low price.