ABSTRACT
The PDLLA/HA compound fibers with excellent properties could be obtained by melt-spinning. This study inquired about the mechanical properties, change rule and influencing factors. The results showed that the composites fibers of mechanical properties were good in the PDLLA(molecular weight 120,000) to which were added the 4-20 microm HA particles. In the matrix of PDLLA with accretion (10%) of HA particles, the tensile strength of the compound fibers was the highest, compared with the others. The tensile strength of the compound fibers of PDLLA (molecular weight 20,000-300,000) was high. The tensile strength of the compound fibers decreased with the increase of the fiber diameter, and the PDLLA/HA fibers 40-60 micrometers in diameter had the highest elongation at break.
Subject(s)
Biocompatible Materials , Chemistry , Bone Substitutes , Chemistry , Durapatite , Chemistry , Lactic Acid , Chemistry , Polyesters , Polymers , Chemistry , Tensile Strength , Tissue Engineering , MethodsABSTRACT
BACKGROUND: In the clinical therapy for orthopedic diseases, the traditional administration easily induces the great fluctuation of drug concentration and side effect, and implanted drug carrier material hydroxyapatite (Hap) cannot be used in human's load bearing parts due to its poor mechanical performances, and poly-L-lactic acid (PLLA) is effortlessly degraded to acid byproducts. Drug carriers made from Hap/PLLA are supposed to not only persist releasing drug onto the lesion and reduce the side effect,but also obtain strength enhancement and eliminate tissue inflammatory reaction in favor of bone regeneration.OBJECTIVE: To observe the preparation of absorbable target control-release drug carrier and simulate the application of drugs.DESIGN: Observation trial.SETTING: Chongqing Institute of Technology and Wuhan University of Technology.MATERIALS: Tails of albino rats and PLLA (offered by Biological Center of Wuhan University of Technology), pepsin (1:10 000, Sigma company), Ca(OH)2, strong phosphoric, NaOH, glacial acetic acid, phosphate buffer (pH=7.4), 1,4-dioxane, absolute alcohol (Analytical reagent available on market).METHODS: The experiment was carried out in Chongqing Institute of Technology and Wuhan University of Technology. ①Type Ⅰ collagen (Col)was prepared by acid dissolution and alkali purification methods. Hap/Col bone-like biomimetic composite was synthesized through self-assembly mechanism of materials simulating in vitro biomineralization process of nature bone. X ray diffraction analysis and transmission electron microscope were applied to observe the characterization of composite's structure and morphology. ②The resultant product of HAP/Col composite was further synthesized with PLLA to prepare the three-dimensional porous reservoir type carrier for controlled release of drug employing thermal-induced phase separation technique. Scanning electron microscope, material test machine and specific gravity test method were used to investigate the pore structure and mechanical property of carrier material. ③The prepared Hap/Col/PLLA drug carrier was loaded with bromothymol blue to investigate in vitro control-release characteristic in simulated body fluid.MAIN OUTCOME MEASURES: ①Characterization of structure and morphology of Hap/Col bone-like biomimetic composite; ②Evaluation on the property and preparation technique of Hap/Col/PLLA drug carrier; ③Assessment on results of in vitro control-release trail of model composite.RESULTS: ①Hap nanocrystals formed as slender needles aligning with its crystalline c-axis preferentially oriented.②Hap/Col/PLLA drug carrier possessed apt pore configuration and physical properties for drug controlrelease.③In vitro release test by model compound revealed an approximate zero-orderslow release prior to its 80% release percentage.CONCLUSION: Hap/Col composite material is similar with natural bone, and Hap/Col/PLLA reservoir carrier can control drug release.
ABSTRACT
To evaluate the sealing potential of self-designed root canal filling material made of calcium phosphate cement (alpha-TCP/TTCP, CPC), the apices of root canals of six adult dogs were purposely perforated and enlarged up to the No 40 instrument. Then CPC was used to fill the root canal. Mean while either calcium hydroxide (Ca(OH)2) paste or hydroxyapatite (HA) paste was used as control. The animals were killed at 4, 12, 20 weeks postoperatively. The different materials about ways of apical closure, restoration periapocal tissues and adaptability to the dentinal surface were observed by histomorphology and scanning electron microscopic. This study revealed that CPC had excellent biocompatibility and adaptability to the dentinal wall. Its osteoconduction can promote the formation of calcific barriers and healing of periapical tissue. The apex can be closed completely. Compared with the control pastes it has advantages of ease of manipulation and better sealing capability. The results showed that CPC could be used as a root canal filling material for pupless teeth with open apex and destructive periapical tissue.
Subject(s)
Animals , Dogs , Calcium Phosphates , Pharmacology , Root Canal Filling Materials , Pharmacology , Root Canal TherapyABSTRACT
The inhibitory effect of hydroxyapatite ultrofine powder (HAUFP) on tumor and the effect on the immunity function of body were investigated. The levels of IL-2 in the spleen cells and serum TNF levels in the tumor-bearing mice at the 7th day and 14th after peritoneal injection of HAUFP were detected by using the methods of colorimetric analysis of MTT and crystal purple decoration, respectively. The disappearance of the ascites of the mice was observed. The results showed that the levels of IL-2 and TNF in the tumor-bearing mice were higher obviously in the drug-treated group than in the control group (P<0.01), the ascites growth was inhibited. It was suggested that HAUFP could increase the levels of IL-2 and TNF of the tumor-bearing mice and improve the immune function of body.
ABSTRACT
The inhibitory effect of hydroxyapatite ultrofine powder (HAUFP) on tumor and the effect on the immunity function of body were investigated. The levels of IL-2 in the spleen cells and serum TNF levels in the tumor-bearing mice at the 7th day and 14th after peritoneal injection of HAUFP were detected by using the methods of colorimetric analysis of MTT and crystal purple decoration, respectively. The disappearance of the ascites of the mice was observed. The results showed that the levels of IL-2 and TNF in the tumor-bearing mice were higher obviously in the drug-treated group than in the control group (P<0.01), the ascites growth was inhibited. It was suggested that HAUFP could increase the levels of IL-2 and TNF of the tumor-bearing mice and improve the immune function of body.