Phosphate Bone Cement Research Articles

Study on modification of hydroxyapatite/magnesium phosphate bone cement by N-acetyl-l-cysteine

Magnesium phosphate cement has good biological activity and degradation performance. However, it still has the defects of poor strength and water resistance. N-acetyl-l-cysteine has good osteogenic properties. The nano-hydroxyapatite/magnesium phosphate cement was modified by N-acetyl-l-cysteine, and the effects of N-acetyl-l-cysteine on the strength, degradation and biological activity of nano-hydroxyapatite/magnesium phosphate cement were studied. The results showed that the compressive strength of 0.5 wt% N-acetyl-l-cysteine modified nano-hydroxyapatite/magnesium phosphate cement could reach 76.1 ± 1.4 MPa after soaking in simulated body fluid for 28 days, which was 6.3% higher than that of the control group (the content of N-acetyl-l-cysteine was 0 wt%), and the softening coefficient of each age was higher than that of the control group. Cell experiments proved that N-acetyl-l-cysteine could effectively promote cell proliferation and improve the expression of osteogenic related genes and proteins. After implanting the composite bone cement into rats’ femurs for 12 weeks, the materials were gradually wrapped and absorbed, and the new bone tissue grew from outside to inside, indicating that N-acetyl-l-cysteine bone cement had an good ability to promote bone formation. Therefore, the composite bone cement of this study has potential application prospects in clinical bone repair.

Injectable graphite-modified Fe3O4/calcium phosphate bone cement with enhanced heating ability for hyperthermia

ABSTRACT Graphite-modified magnetite (Fe3O4) has been incorporated to brushite bone cement to prepare novel injectable magnetic bone cement (NIMC) for hyperthermia. The results reveal that NIMC with a setting time of 30 min is injectable and anti-washout. Under the magnetic field of 1.59 × 106 A/m, the saturation magnetisation of NIMC is 28.01 A·m2/Kg, higher than that of the contrast with non-modified magnetite. Moreover, after exposed to an alternating magnetic field (340 kHz, 1.13 × 103 A/m) for 200 s, the specific absorption rate values of NIMC and the contrast are 30.20 W/g and 18.75 W/g, respectively. NIMC displays much better heating ability than the contrast. Moreover, IMBC has no cytotoxicity to MG-63 cells, and MG-63 cells can adhere and spread on the cement after co-culturing for 7 days. Therefore, this novel magnetic bone cement has the potential to be used for hyperthermia.

Self‐setting collagen‐calcium phosphate bone cement: Mechanical and cellular properties

Calcium phosphate cement (CPC) can conform to complex bone cavities and set in-situ to form bioresorbable hydroxyapatite. The aim of this study was to develop a CPC-collagen composite with improved fracture resistance, and to investigate the effects of collagen on mechanical and cellular properties. A type-I bovine-collagen was incorporated into CPC. MC3T3-E1 osteoblasts were cultured. At CPC powder/liquid mass ratio of 3, the work-of-fracture (mean +/- sd; n = 6) was increased from (22 +/- 4) J/m(2) at 0% collagen, to (381 +/- 119) J/m(2) at 5% collagen (p < or = 0.05). At 2.5-5% of collagen, the flexural strength at powder/liquid ratios of 3 and 3.5 was 8-10 MPa. They matched the previously reported 2-11 MPa of sintered porous hydroxyapatite implants. SEM revealed that the collagen fibers were covered with nano-apatite crystals and bonded to the CPC matrix. Higher collagen content increased the osteoblast cell attachment (p < or = 0.05). The number of live cells per specimen area was (382 +/- 99) cells/mm(2) on CPC containing 5% collagen, higher than (173 +/- 42) cells/mm(2) at 0% collagen (p < or = 0.05). The cytoplasmic extensions of the cells anchored to the nano-apatite crystals of the CPC matrix. In summary, collagen was incorporated into in situ-setting, nano-apatitic CPC, achieving a 10-fold increase in work-of-fracture (toughness) and two-fold increase in osteoblast cell attachment. This moldable/injectable, mechanically strong, nano-apatite-collagen composite may enhance bone regeneration in moderate stress-bearing applications.

Physicochemical and Mechanical Properties of Composite of Chitosan Microspheres/Calcium Phosphate Cement

The aim of this work is to improve the mechanical properties of calcium phosphate bone cement (CPC) by appending chitosan microspheres to CPC base. That chitosan degrades rapidly than bone cement has been proved by previous investigations. Porous CPC has low compressive strength because of the pores in it weakening the structure. Additive chitosan microspheres can improve the mechanical properties by bearing the compress with the CPC base and produce pores after degradation. This study investigates the effect of chitosan microspheres on the setting time, mechanical properties, phase evolution and morphology of CPC. The additive proportion of chitosan microspheres ranges from 0 wt% to 30 wt%. Compared with original CPC, the modified CPC has higher compressive strength, without significantly affecting the chemical properties. The phase composition of the CPC is tested by XRD. The microstructures of CPC are observed using SEM. The final setting times range from 5~15 minutes and can be modulated by using different liquid and powder (L/P) ratio.

Processing of Calcium Phosphate Porous Materials by 'Self-Setting'

Macroporous biomaterials based on a-tricalcium phosphate (a-TCP) bone cement with porous structures suitable for implantation purposes were prepared in the present work. According to the reversible swelling/deswelling behavior of gelatin at a single temperature or pH, a “self-setting” method that uses gelatin granules as pore formers was developed to process the porous microstructure. By mixing gelatin powder and bone cement powder (BCP), and adding water (1% solution of NaH2PO4×HO) to form pastes which set within 15 to 30 min, this setted cement was then immerged in deionized water of temperature 25°C or 32°C for hydration. During the hydration, the pH of deionized water after cement pastes were introduced at 32°C changed from 8.6 to 7.2 which caused by the transformation of a-TCP to hydroxyapatite (HA). Meanwhile, gelatin particles will swell by water uptake to form large size spheres in cementmatrix. This swelling behavior is sensitive to the variation of pH value. After hydration for 4 day, a body containing gelatin gel spheres was obtained. Then heating the deionized water to temperature 50°C, gelatin spheres in cement matrix were solved and porous microstructure composed of larger pore sizes corresponding approximately to the average size of the swelling gelatin granules was obtained. The porous bodies by this technique were found to have tractable and interconnected porosity in the range of 60~84%, with typical pore sizes ranging from 100~300 microns. This new processing technique can be used in the manufacture of unsintered biomaterials.

Osteogenesis capacity of a novel BMP/ α-TCP bioactive composite bone cement

To improve the osteogenesis ability of a-tricalcium phosphate (α-TCP) bone cement, a novel BMP/ α-TCP composite bone cement was prepared. By measuring the setting time and compressive strength, the hydration characteristic of bone cement was evaluated. Animal experiments including histological observation, radiographic investigation as well as digital image analyses reveal the difference of osteogenesis ability among BMP,a-TCP bone cement and BMP/α-TCP composite bone cement. Results show that α-TCP bone cement possesses excellent hydration and setting properties as well as high mechanical property. Comparison experiments show that BMP/ α-TCP composite bone cement has a stronger osteogenesis ability. The gross observation of the implant site does not exhibit any inflammation or necrosis. Histological analyses reveal that the material has good osteointegration with host bone, and new bone formation is detected within the materials, which are degrading. Strong osteogenesis ability of the composite is due to not only the excellent osteoconductive potential but also the osteoinductive potential contributed by active BMP releasing and the material degradation. Large skull defect could be well-healed by filling BMP/α-TCP composite bone cement. This novel material proves itself to be an absorbable and bioactive bone cement with an osteogenesis ability.