Biodegradable Materials for Bone Repairs: A Review

Biodegradable Polymers in Drug Delivery

The hydration behavior, intermediate water content and platelet adhesion level of four different aliphatic carbonyl polymers that have subtle differences in the backbone structure were investigated. The platelet adhesion was strongly related to the surface hydration and intermediate water content for the hydrated polymers. The ether bonds in the main chain has a significant role in hydration and poly(p-dioxanone) exhibits the lowest platelet adhesion level among four polymers. The other three polymers showed similar platelet adhesion levels. However, carbonate bonds contribute to the formation of more intermediate water than ester bonds.

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Evaluation of the hemocompatibility of hydrated biodegradable aliphatic carbonyl polymers with a subtle difference in the backbone structure based on the intermediate water concept and surface hydration

A series of biodegradable polymers was prepared by solution co-precipitation of poly(para-dioxanone) (PPDO) and poly(lactic-co-glycolic acid) (PLGA) in various blend ratios. Samples were compression-molded into bars using a platen vulcanizing press. The miscibility, thermal and mechanical properties of the materials were investigated using differential scanning calorimetry (DSC), polarized optical microscopy, and scanning electron microscopy (SEM). Dynamic contact angle was used to characterize the water wettability of PLGA/PPDO blends. The mechanical properties of blends and pure polymers were measured by tensile tests. The position of the glass transition temperatures (T
 g
 ) was dependent upon composition. When 10 % PLGA was added into PPDO, the DSC curve revealed only one T
 g
 (−7.35 °C) which was located between the T
 g
 values of PPDO and PLGA. When 20 % PLGA was added into the blend, two independent T
 g
 values for PPDO/PLGA blends were observed, and such characteristics improved further upon addition of 30 % PLGA. SEM images of fractured surfaces displayed evidence of the morphology of PPDO/PLGA blends that were consistent with the DSC results. Hence, a relationship was found between homogeneity and the contents of PLGA in the blend. The compatibility of the blends increased with addition of small amounts of PLGA, followed by a leveling-off at higher content.

Miscibility, Thermal and Mechanical Properties of Poly(para-dioxanone)/Poly(lactic-co-glycolic acid) Blends

The effect of poly(D,L-lactide-co-para-dioxanone) (PLADO) as the compatibilizer on the properties of the blend of poly(para-dioxanone) (PPDO) and poly(D,L-lactide) (PDLLA) has been investigated. The 80/20 PPDO/PDLLA blends containing from 1% to 10% of random copolymer PLADO were prepared by solution coprecipitation. The PLADO component played a very important role in determining morphology, thermal, mechanical, and hydrophilic properties of the blends. Addition of PLADO into the blends could enhance the compatibility between dispersed PDLLA phase and PPDO matrix; the boundary between the two phases became unclear and even the smallest holes were not detected. On the other hand, the position of the Tg was composition dependent; when 5% PLADO was added into blend, the Tg distance between PPDO and PDLLA was shortened. The blends with various contents of compatibilizer had better mechanical properties compared with simple PPDO/PDLLA binary polymer blend, and such characteristics further improved as adding 5% random copolymers. The maximum observed tensile strength was 29.05 MPa for the compatibilized PPDO/PDLLA blend with 5% PLADO, whereas tensile strength of the uncompatibilized PPDO/PDLLA blend was 14.03 MPa, which was the lowest tensile strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(para-dioxanone)/poly(D,L-lactide) blends compatibilized with poly(D,L-lactide-co-para-dioxanone)

In this work, poly(para-dioxanone) (PPDO) was mixed with 1% (by weight) calcium carbonate (CaCO(3)), beta-tricalcium phosphate (beta-TCP), or calcium sulphate dihydrate (CSD) by solution co-precipitation. Samples were compression molded into bars using a platen-vulcanizing press. The morphology, thermal and mechanical properties, and crystalline structure of the composites were investigated using differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy, and X-ray diffraction. All results suggest that three types of inorganic particle in this system promote the crystallinity of PPDO and act as an effective nucleating agent: the relative degree of crystallinity of PPDO increased from 30.74% to 100%, and the crystallization temperature of PPDO was increased by 18 degrees C. On the other hand, the mechanical properties of PPDO were changed by the presence of inorganic particles: the tensile strength of PPDO/CSD increased by 11.46%.

Poly(para‐dioxanone)/inorganic particle composites as a novel biomaterial

The invention relates to an absorbable implant material in a bone and a preparation method thereof The absorbable implant material in the bone comprises the following materials by weight percent: 80%-99% of L-lactide-glycolide copolymer and 1%-20% of hydroxyapatite and/or beta-tricalcium phosphate The absorbable implant material in the bone adopts the way of blending the L-lactide-glycolide copolymer with certain crystallization capacity and the hydroxyapatite and/or beta-tricalcium phosphate for modifying the material The absorbable implant material in the bone has the following advantages: 1) the content of L-lactide in the copolymer is higher, so that the material has the certain crystallization performance and can ensure that the strength of the material is equivalent to that of L-polylactic acid; 2) the existence of a small quantity of glycolide can accelerate degradation and absorption of the material; and 3) hydroxyapatite is compounded in the material, thereby having great bone compatibility, being capable of being combined with a new bone and being conductive to growth of the new bone The absorbable implant material in the bone can be used for manufacturing fracture internal fixation screws, plates and binding tapes, as well as fixation and repair devices for tendons, ligaments, meniscus and cartilages

Dujuan Zhang

Papers

Poly(para‐dioxanone)/inorganic particle composites as a novel biomaterial

Absorbable implant material in bone and preparation method thereof