Biodegradation of Tricalcium Phosphate Ceramics by Osteoclasts

Biodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discs in vitro in this study. Osteo-clasts were isolated from newborn SD rat's marrow of long bone and cultured on TCP discs. The culture terminated at the 48th h and 96th h respectively. Under an inverted microscope, the osteoclasts imparted round or oval body with multinu-clear and many thin processes. These cells were positively stained for tartrate-re-sistance acid phosphatase (TRAP). Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 μm. Osteoclasts were located in the lacunae. At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration. It is suggested that osteoclasts possess ability to re-absorb TCP ceramics under in vitro culturing condition.

Macrophages in Degradation of Calcium Phosphate Compound Artificial Bone： An in vitro Study

The isolated mice peritoneal macrophages in degradation of calcium phosphate compound artificial bone - collagen/hydroxylapatite (CHA). hydroxylapatite (HA), beta-tricalcium phosphate (TCP) ceramics, have been studied by use of both Ca++, P concentration assay in cultured supernatant and scanning electron microscopy (SEM). The solubility of Ca++ . composition of materials increased more significantly when macrophages were inoculated than when macrophages were not seeded (P< 0.001), and it was shown that the ground materials were wrapped and phagocytized or resorbed extracellularly by macrophages under SEM, suggesting that macrophages could mediate the degradation of calcium phosphate compound artificial bone by phagocytizing and/or degrading extracellularly.

The Effects of Fe₂O₃and B₂O₃on the Glass Structural, Thermal, <i>in Vitro</i>Degradation Properties of Phosphate Based Glasses

Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composition of 48P2O5-12B2O3-(25-X)MgO-14CaO-1Na2O-(X)Fe2O3 (X = 6, 8, 10) and 45P2O5-(Y)B2O3-(32-Y)MgO-14CaO-1Na2O-8Fe2O3 (Y = 12, 15, 20), was prepared via a melting quenching process. The effect of replacing MgO with Fe2O3 and B2O3 on the structural, thermal, degradation properties of phosphate based glass was investigated. Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopy analysis confirmed the polymerisation of phosphate based glass network with addition of Fe2O3, thus the processing window was observed to increase whilst the dissolution rate was reduced, attributed to the formation of Fe-O-P cross-link. As the effect on the glass structure stability was demonstrated by both B2O3 and MgO, the nonlinear variation of thermal stability and degradation behaviour was observed for glass system with substitution of MgO by B2O3. However, due to the lower dissolution rate of glass system when compared to the biocompatible phosphate based glass in preliminary study, the expected cytocompatibility could be confirmed in the downstream activities.

Predicting the Degradability of Bioceramics through a DFT-based Descriptor

Bioceramics have attracted extensive attention for bone defect repair due to their excellent bioactivity and degradability.However,challenges remain in matching the rate between bioceramic degradation and new bone formation,necessitating a deeper understanding of their degradation properties.In this study,density functional theory(DFT)calculations was employed to explore the structural and electronic characteristics of silicate bioceramics.These findings reveal a linear correlation between the maximum isosurface value of the valence band maximum(VBM_(Fmax))and the degradability of silicate bioceramics.This correlation was subsequently validated through degradation experiments.Furthermore,the investigation on phosphate bioceramics demonstrates the potential of this descriptor in predicting the degradability of a broader range of bioceramics.This discovery offers valuable insights into the degradation mechanism of bioceramics and holds promise for accelerating the design and development of bioceramics with controllable degradation.

Biodegradation pathway and mechanism of tri (2-chloropropyl) phosphate by Providencia rettgeri

Tri(2-chloropropyl)phosphate(TCPP)was an emerging contaminant of global concern because of its frequent occurrence,potential toxic effects,and persistence in the environment.Microbial degradation might be an efficient and safe removal method,but limited information was available.In this study,Providencia rettgeri was isolated from contaminated sediment and showed it could use TCPP as unique phosphorus source to promote growth,and decompose 34.7%of TCPP(1 mg/L)within 5 days.The microbial inoculation and the initial concentration of TCPP could affect the biodegradation efficient.Further study results indicated that TCPP decomposition by Providencia rettgeri was mainly via phosphoester bond hydrolysis,evidenced by the production of bis(2-chloropropyl)phosphate(C_(6)H_(13)Cl_(2)PO_(4))and mono-chloropropyl phosphate(C_(3)H_(8)ClPO_(4)).Both intracellular and extracellular enzymes could degrade TCPP,but intracellular degradation was dominant in the later reaction stage,and the presence of Cu^(2+) ions had a promoting effect.These findings developed novel insights into the potential mechanism of TCPP microbial degradation.

A Feasible Way of Degrading Malathion Pesticide under Laboratory Condition Using Phosphate Solubilizing Bacteria

An experiment was carried out for identification and determination of malathion degrading phosphate solubilizing bacteria isolated from the agricultural fields. In this study, malathion degrading phosphate solubilizing bacteria were identified using NBRIP (National Botanical Research Institute’s phosphate growth medium) media. A number of bacterial colonies were screened from agricultural fields. From primarily screened colonies 4 isolates were identified as phosphate solubilizing bacteria through qualitative and quantitative analysis. The isolated 4 bacterial colonies were inoculated in NBRIP broth media enriched with malathion pesticides to observe degradation of malathion pesticide under incubation study at three different temperatures (25°C, 30°C and 37°C). However, all the four isolates showed capability in degrading malathion pesticide. The study clearly revealed that phosphate solubilizing bacteria can be used in bioremediation of environmental pollution caused by malathion pesticide.

Photocatalytic degradation of dyes by AgBr/Ag_3PO_4 and the ecotoxicities of their degraded products

Ag3PO4 powders were prepared through a precipitation reaction between AgNO3 and precipitating agent solutions that were prepared by adjusting the amount of H3PO4 in the Na3PO4 solutions. The Ag3PO4 powders prepared from the precipitation solution with a pH of 6 showed the highest photocatalytic activity for decolorizing the methylene blue and rhodamine B dyes. These Ag3PO4 powders were further modified by the addition of KBr solutions to obtain AgBr/Ag3PO4 powders and these photocatalysts can decolorize the anionic dyes as reactive orange and methyl orange. The reactive species involved in the photocatalytic degradation process were evaluated for their inhibitory activity using the appropriate scavengers. After photocatalysis, mass spectrometry confirmed that the dyes were degraded to smaller molecules. The ecotoxicities of the dye solutions before and after treatment were evaluated by studying their ability to inhibit the growth of the bioindicator Chlorella vulgaris.

Effect of Adding Sb on Microstructure, Mechanical Properties and in <i>Vitro</i>Degradation Behavior of as Cast Mg-4wt% Zn Alloy for Medical Application

Magnesium (Mg) and its alloys are one of a novel kind of biodegradable metallic implants which attracted much fundamental research to develop its clinical application. Nevertheless, it has more restrictions in biomedical applications because it degrades too fast at the early stage after implantation, thus commonly leading to some problems such as early fast mechanical loss, hydric bubble aggregation, gap formation between the implants and the tissue. This work aims to study the effect of 0.5 wt% Sb addition on the microstructure, mechanical properties and degradation behavior of as cast Mg-4wt% Zn alloy. The evaluation process was conducted using optical and scanning electron microscopy, X-ray diffraction, tensile and compression tests, in addition to a corrosion study by immersing in simulated body fluid (SBF). Results showed that Sb refines the grain size of the base alloy and also enhances its mechanical properties and degradation rate as well. These were due to the formation of the secondary phase of Mg3Sb2. To get better degradation rate, the Mg-4wt% Zn and Mg-4wt% Zn-0.5wt% Sb alloys are coated with Ca-P using autocatalytic technique. The results demonstrated that the formed coat layer improves the degradation rate of samples under the condition of this study. The current study shows that Mg-4wt% Zn-0.5wt% Sb alloy has good mechanical properties and when it coated by Ca-P, it gave a better corrosion resistance that makes it ideal for biodegradable medical application.

Ultrastructural Analysis on the Osteogenesis and Transformation of Calcium Phosphate Ceramics in Vivo

To study the osteogenesis and transformation process of calcium phosphate bioceramic in vivo, biodegradable porous β-tricalcium phosphate ceramics (β-TCP, φ5×8 mm) were implanted in the tibia of rabbits. β-TCP ceramics with surrounding bone tissue were retrieved and observed by SEM, TEM and EPMA every month after implantation. The results showed that osteogenesis was active and β-TCP ceramics bonded to bones directly. The new bones were forming and maturing as materials were continuously degrading, and materials were finally replaced by new bone. Parts of the materials were degraded, absorbed and recrystallized, while the rest were dispersed to the spongy bone and the Haversian lamella in an irregular arrangement, becoming incorporated into bone formation directly by remodeling the structure. Some β-TCP crystals cleaved along its (001) rhombohedral plane and formed lath-like crystals in vivo.

PROMOTION EFFECT OF MELAMINE ON FLAME RETARDANCY OF EPOXY RESINS CONTAINING CAGED BICYCLIC PHOSPHATE

Caged bicyclic phosphate （CBP） and its dimelamine salt （PDS） were synthesized and added to epoxy resins to obtain the flame retarded epoxy resin composites. The flammability of the composites was characterized by the limiting oxygen index （LOI） and cone calorimeter tests. The LOI values of flame retarded composites increase consistently with the increase of flame retardant amounts, and they are almost the same when the loading of CBP is the same as that of PDS, although the phosphorus content of PDS is much lower than that of CBP. The total heat release increases in the order of CBP30/ER 〈 PDS30/ER 〈 PDS15/ER 〈 CBPI5/ER, whereas that of specific extinction area is CBP15/ER 〉 CBP30/ER 〉 PDS30/ER ≌ PDS15/ER. PDS exhibits more effective inhibition of oxidation of combustible gases. In the tests of thermogravimetric analyses （TG） and Fourier transform infrared spectroscopy （FT-IR）, it is found that the degradation of the composites is influenced greatly by the addition of flame retardants. By scanning electron microscopy （SEM）, a thick and tight char-layer is observed for PDS30/ER, resulting from the interaction of nitrogen species with phosphorus species. Therefore, the combination of CBP with melamine in the flame retarded system can improve the flame retardancy greatly.

The Transformation of Calcium Phosphate Bioceramics in Vivo

To study the transformation process of calcium phosphate bioceramic in vivo,biodegradable porous β-tricalcium phosphate ceramics (β-TCP) were used in this experiment. The materials (5×8mm) were implanted in the tibia of rabbits. The β-TCP ceramics with bone tissue were retrieved and treated for histology, and then observed by using a scanning electron microscope (SEM) and an electron probe X-ray microanalyzer (EMPA) every month. The results show that β-TCP ceramics bond to bone directly,new bones are forming and maturing with materials continuous degrading,and the materials are nearly replaced by the formed bone finally.Parts of the materials were degraded,absorpted and recrystallized,the others dispersped on the cancellous bone and the Haversian lamella with an irregular arrangement incorporating in bone formation directly by remodeling structure.

In vitro degradation behavior of chitosan based hybrid microparticles

The degradation properties of the MPs is important to the long-term benefits of the use of the chitosan (CS) based hybrid MPs in bone tissue-engineering, because the degradation kinetics could affect a multitude of processes within the cell, such as cell growth, tissue regeneration, and host response. The aim of this study was to investigate the degradation of solid, hybrid CS microparticles (MPs), CS-10% calcium phosphate (CaHPO4, w/w), and CS-10% calcium carbonate (CaCO3, w/w) MPs in phosphate buffered solution (PBS) over a 30-week period. The hybrid MPs were synthesized by emulsification technique, cross-linked with 64% sodium tripolyphosphate (TPP), purified and air dried overnight. Each sample had 30 mg of MPs was placed in a glass vial with 9 ml of PBS added and then the vial was closed to prevent evaporation. Every week 4 ml of the incubated solution was removed for sample measurement and all samples were replaced with an equivalent amount of fresh medium. The samples were maintained at 37oC under continuous shaking. The hybrid MPs were measured for pH and calcium release, every week in triplicate. At 0, 5, 10, 15, 20, 25, and 30 weeks, surface and bulk morphology were analyzed with a scanning electron microscope (SEM). The degradation data suggested that the hybrid MPs were stable at least up to 25 week and maintain the physiologically relevant pH. Therefore, we can use these hybrid MPs to apply in the bone tissue engineering applications since they do not degrade within a short period.

Determination of Di-n-Butyl Phosphate in Organic Streams of FBTR Mixed Carbide Fuel Reprocessing Solution by Gas Chromatographic Technique

The present work describes the amount of Di-n- butyl phosphate (DBP) produced when PUREX solvent (30%tri-n-butyl phosphate (TBP) mixed with 70% hydrocarbon diluent) is exposed to intensive radiolytic and chemical at- tack during the separation of uranium and plutonium from fission products of FBTR mixed carbide fuel reprocessing solution. DBP is the major degradation product of Tri-n-butyl phosphate (TBP). Amount of DBP formed in the lean organic streams of different fuel burn-up FBTR carbide fuel reprocessing solutions were analyzed by Gas Chromatographic technique. The method is based on the preparation of diazo methane and conversion of non-volatile Di-n-butyl phosphate in to volatile and stable derivatives by the action of diazomethane and then determined by Gas Chromatography (GC). A calibration graph was made for DBP over a concentration in the range from 200 to 1800 ppm with correlation coefficient of 0.99587 and RSD 1.2%. The degraded 30% TBP-NPH solvent loaded with heavy metal ions like uranium was analyzed after repeated use and results are compared with standard ion chromatographic technique. A column comparison study to select of proper gas chromatographic column for the separation of DBP from other components in a single aliquot of injection is also examined.

兼具显影与成骨功能多聚磷酸锶在磷酸钙骨水泥中的应用

背景:课题组前期研究发现,添加硫酸钡可以提高磷酸钙骨水泥的力学性能与显影性能,但伴随磷酸钙降解残存的显影剂难以降解,在植入部位产生的占位效应及破骨效应影响骨修复进程,因此需要开发一种可生物降解的新型显影材料。目的:探讨生物活性可降解材料多聚磷酸锶的显影能力及其对磷酸钙骨水泥理化性能与成骨效应的影响。方法:①分别制备磷酸钙骨水泥(CPC)、淀粉改性磷酸钙骨水泥(CPS)与含多聚磷酸锶(占骨水泥粉末的质量分数为20%)淀粉改性磷酸钙骨水泥(20%SrPP-CPN),表征3组骨水泥的理化性能。②将3组骨水泥浸提液分别与大鼠骨髓间充质干细胞共培养,检测细胞增殖、能量代谢与成骨分化能力。③在24只SD大鼠颅顶部两侧各制作直径5 mm的骨缺损,随机分为对照组(不进行任何干预)、CPC组、CPS组与20%SrPP-CPN组进行干预,每组6只。干预4,12周后取材进行相关检测。结果与结论:①与其他两组骨水泥比较,20%SrPP-CPN的显影能力增强、抗压强度与降解速率升高、固化时间延长,并且20%SrPP-CPN在降解过程中可稳定释放Sr^(2+)。②CCK-8实验显示20%SrPP-CPN不影响骨髓间充质干细胞的增殖;细胞饥饿实验(无血清培养)显示相较于其他两组骨水泥,20%SrPP-CPN可促进骨髓间充质干细胞的增殖;相较于其他两组骨水泥,20%SrPP-CPN可提升骨髓间充质干细胞内ATP浓度。碱性磷酸酶与茜素红染色显示,相较于其他两组骨水泥,20%SrPP-CPN可促进骨髓间充质干细胞的成骨分化。③在大鼠颅骨缺损实验中,Micro-CT扫描、组织学(苏木精-伊红、Masson染色)观察显示相较于CPC组、CPS组,20%SrPP-CPN组骨水泥降解明显,并且大量新生骨组织分散于降解的骨水泥中;免疫组化染色显示相较于CPC组、CPS组,20%SrPP-CPN组缺损处Runx2蛋白表达升高(P<0.01)。④结果表明,20%SrPP-CPN具有良好的显影性能与促成骨性能。

硫化零价铁-微生物复合吸附剂对磷酸三(2-氯乙基)酯的吸附-降解机制

氯代有机磷阻燃剂(chlorinated organophosphate flame retardants,Cl-OPFRs)已在环境中被广泛检出,由于其稳定、易迁移及具有生物毒性,因此已成为不可忽视的新兴有机污染物。本文选择环境中检出率较高的磷酸三(2-氯乙基)酯[tris(2-chloroethyl)phosphate,TCEP]为研究对象,以硫化零价铁(S/ZVI)和TCEP耐受降解菌(缓生新鞘氨醇菌,Novosphingobium tardaugens,N_(1))为研究材料,制备S/ZVI-微生物复合吸附剂(S/ZVI-N_(1)),并对其去除TCEP的性能和降解途径进行探究。结果显示,S/ZVI-N_(1)对TCEP的去除符合准一级动力学方程和Langmuir模型,表明该过程主要为单分子层的物理吸附作用,且根据准二级动力学方程的相关系数可知,在反应过程中同样存在化学吸附过程,S/ZVI-N_(1)作用于TCEP 12h,去除率达58.9%,显著高于仅依靠Novosphingobium tardaugens的去除率(32.9%)和仅依靠S/ZVI的去除率(31.2%)。产物分析表明,S/ZVI-N_(1)作用下TCEP较单独零价铁(zero-valent iron,ZVI)作用下降解更彻底,证明复合吸附剂中S/ZVI和Novosphingobium tardaugens之间存在协同作用,其最佳的反应条件为pH 5~7和30~35℃。微观分析显示,微生物和S/ZVI均参与了TCEP的降解。通过产物分析推导,S/ZVI-N_(1)对TCEP主要有2条降解途径,分别为S/ZVI主导的C—Cl键断裂和Novosphingobium tardaugens主导的O—P键断裂,最终生成磷酸三乙酯(triethyl phosphate,TEP)和磷酸(H_(3)PO_(4))。

Factors hindering the degradation of pharmaceuticals from human urine in an iron-activated persulfate system

This study investigated the degradation of clofibric acid(CFA),bezafibrate(BZF),and sulfamethoxazole(SMX)in synthetic human urine using a novel mesoporous iron powderactivated persulfate system(mFe-PS system),and identified the factors limiting their degradation in synthetic human urine.A kinetic model was established to expose the radical production in various reaction conditions,and experiments were conducted to verify the modeling results.In the phosphate-containing mFe-PS system,the 120 min removal efficiency of CFA decreased from 95.1%to 76.6%as the phosphate concentration increased from 0.32 to 6.45 mmol/L,but recovered to 90.5%when phosphate concentration increased to 16.10 mmol/L.Meanwhile,the increased concentration of phosphate from 0.32 to 16.10mmol/L reduced the BZF degradation efficacy from 91.5%to 79.0%,whereas SMX removal improved from 37.3%to 62.9%.The m Fe-PS system containing(bi)carbonate,from 4.20 to166.70 mmol/L,reduced CFA and BZF removal efficiencies from 100%to 76.8%and 80.4%,respectively,and SMX from 83.5%to 56.7%within a 120-min reaction time.In addition,alkaline conditions(pH≥8.0)inhibited CFA and BZF degradations,while nonacidic pH(pH≥7.0)remarkably inhibited SMX degradation.Results of the kinetic model indicated the formation of phosphate(H_(2)PO_(4)^(·)/HPO_(4)^(·-))and/or carbonate radicals(CO_(3)^(·-))could limit pharmaceutical removal.The transformation products(TPs)of the pharmaceuticals revealed more incompletely oxidized TPs occurred in the phosphate-and(bi)carbonate-containing m Fe-PS systems,and indicated that H_(2)PO_(4)^(·)/HPO_(4)^(·-)mainly degraded pharmaceuticals via a benzene ring-opening reaction while CO_(3)^(·-)preferentially oxidized pharmaceuticals via a hydroxylation reaction.

Separation and characterization of degradation/interaction products of codeine phosphate in ibuprofen arginate/codeine phosphate combination formulation by HPLC coupled with MS analysis

A simple HPLC method was developed and validated according to the ICH guidelines to detect and quantify the related substances of codeine phosphate in the raw material and in its combination formulation with ibuprofen before and after forced degradation. These products were further identified by using HPLC-TOF/MS and MS/MS techniques. Good separations were obtained on a C18 （250 min×4.6 mm, 5 μm） column maintained at 50 ℃ with linear gradient elution by a mixture of mobile phase A （ammonium acetate （pH 6.0 regulated with acetic acid, 0.04 M）-acetonitrile （92：8, v/v）） and mobile phase B （acetonitrile） at a flow rate of 1 mL/min. UV detection was set at 245 nm. Codeine was found to be instable under oxidation with the production of mainly two stereoisomers of codeine N-oxide. A new degradation product, not reported previously, was detected under alkaline hydrolysis, which was identified as 6-hydroxy-3-methoxy-17-methyl-7,8-didehydromorphinan-5-ol and shortly named as deshydrolevomethorphandiol. The esterification of codeine by ibuprofen occurred in very small amount and only under acidic stress. These results contribute to the understanding of the degradation behavior of codeine and its interaction with ibuprofen. The developed method is sensitive and precise and could be applied for the quality control of codeine bulk drug, preparations of codeine phosphate, and its combination with ibuprofen.

MACROPHAGES IN DEGRADATION OF COLLAGEN / HYDROXYLAPATITE(CHA), BETA-TRICALCIUM PHOSPHATE CERAMICS (TCP) ARTIFICIAL BONE GRAFT AN IN VIVO STUDY

The macrophages mediated biodegradation of two biomaterials, collagen / hydroxylapatite (CHA) and beta-tricalcium phosphate ceramics (TCP), was studied in 24 male Kunming mice and 20 male C57BL / 6 mice with histopathologic, histochemical and ultrastructural observation. It was demonstrated that macrophages infiltrated after CHA, TCP were implanted. The macrophages could be differentiated from fibroblasts and the other infiltrated cells for special cellular profile and strong acid phosphatase activity. Morphologically, monocyte macrophages and infused multinuclear giant cell degraded CHA and TCP by phagocytosis and extracellular resorption. The carbonic anhydrase activity of macrophages was demonstrated by histochemical technique. It suggested that macrophages secreted H+ and accomplished the decalcification of calcium phosphate compound of CHA and TCP. We conclude that macrophages are the main mediating cells which degraded CHA and TCP intracellularly and extracellularly.

Degradation and biological performance of porous osteomimetic biphasic calcium phosphate in vitro and in vivo

The combination between biphasic calcium phosphate(BCP)and the osteomimetic porous microstructure obtained via freeze casting is hoped to achieve excellent bone regeneration,while the effects of HA and b-TCP ratio changes on the degradation and biological performance of the BCP scaffolds with this unique microstructure need to be determined.Here,we prepared the osteomimetic BCP scaffolds with different HA/b-TCP ratios(HA30/b-TCP70,HA50/b-TCP50,HA70/b-TCP30)and the effects of different HA/b-TCPHA/b-TCP ratios on the degradation and biological performance were studied in vitro and vivo.These BCP scaffolds with different HA/b-TCP ratios exhibited similar microstructure,mechanical performance,and protein absorption capability,while HA70/b-TCP30 BCP scaffolds showed an advisable degradation rate.Study in vitro confirmed the bio-compatibility and promotion on the proliferation,differentiation of MG63 cells in the porous osteomimetic BCP scaffolds with a HA/b-TCP ratio at 30:70.Implantation experiments also showed that the porous osteomimetic BCP scaffolds with a HA/b-TCP ratio at 30:70 had excellent bone regeneration capacity and proper degradation rate compatible with bone growth.These results reveal that the porous osteomimetic BCP scaffold with a HA/b-TCP ratio at 30:70 is a potential candidate of biodegradable bone substitutes used for bone repair.