Calcium phosphate cements are of great interest for researchers and their applications in medical practice expanded.Nevertheless,they have a number of drawbacks including the insufficient level of mechanical propertie...Calcium phosphate cements are of great interest for researchers and their applications in medical practice expanded.Nevertheless,they have a number of drawbacks including the insufficient level of mechanical properties and low degradation rate.Struvite(MgNH4PO4)-based cements,which grew in popularity in recent years,despite their neutral pH and acceptable mechanical performance,release undesirable NH4+ions during their resorption.This issue could be avoided by replacement of ammonia ions in the cement liquid with sodium,however,such cements have a pH values of 9–10,leading to cytotoxicity.Thus,the main goal of this investigation is to optimize the composition of cements to achieve the combination of desirable properties:neutral pH,sufficient mechanical properties,and the absence of cytotoxicity,applying Na2HPO4-based cement liquid.For this purpose,cement powders precursors in the CaO-MgO-P2O5 system were synthesized by one-pot process in a wide composition range,and their properties were investigated.The optimal performance was observed for the cements with(Ca+Mg)/P ratio of 1.67,which are characterized by newberyite phase formation during setting reaction,pH values close to 7,sufficient compressive strength up to 22±3 MPa(for 20 mol.%of Mg),dense microstructure and adequate matrix properties of the surface.This set of features make those materials promising candidates for medical applications.展开更多
Regenerative bone implants promote new bone formation and ideally degrade simultaneously to osteogenesis.Although clinically established calcium phosphate bone grafts provide excellent osseointegration and osteoconduc...Regenerative bone implants promote new bone formation and ideally degrade simultaneously to osteogenesis.Although clinically established calcium phosphate bone grafts provide excellent osseointegration and osteoconductive efficacy,they are limited in terms of bioresorption.Magnesium phosphate(MP)based ceramics are a promising alternative,because they are biocompatible,mechanically extremely stable,and degrade much faster than calcium phosphates under physiological conditions.Bioresorption of an implant material can include both chemical dissolution as well as cellular resorption.We investigated the bioresorption of 3D powder printed struvite and newberyite based MP ceramics in vitro by a direct human osteoclast culture approach.The osteoclast response and cellular resorption was evaluated by means of fluorescence and TRAP staining,determination of osteoclast activities(CA II and TRAP),SEM imaging as well as by quantification of the ion release during cell culture.Furthermore,the bioactivity of the materials was investigated via SBF immersion,whereas hydroxyapatite precipitates were analyzed by SEM and EDX measurements.This bioactive coating was resorbed by osteoclasts.In contrast,only chemical dissolution contributed to bioresorption of MP,while no cellular resorption of the materials was observed.Based on our results,we expect an increased bone regeneration effect of MP compared to calcium phosphate based bone grafts and complete chemical degradation within a maximum of 1.5-3.1 years.展开更多
基金financially support by Russian Foundation for Basic Research(Grant No.18-33-20170).
文摘Calcium phosphate cements are of great interest for researchers and their applications in medical practice expanded.Nevertheless,they have a number of drawbacks including the insufficient level of mechanical properties and low degradation rate.Struvite(MgNH4PO4)-based cements,which grew in popularity in recent years,despite their neutral pH and acceptable mechanical performance,release undesirable NH4+ions during their resorption.This issue could be avoided by replacement of ammonia ions in the cement liquid with sodium,however,such cements have a pH values of 9–10,leading to cytotoxicity.Thus,the main goal of this investigation is to optimize the composition of cements to achieve the combination of desirable properties:neutral pH,sufficient mechanical properties,and the absence of cytotoxicity,applying Na2HPO4-based cement liquid.For this purpose,cement powders precursors in the CaO-MgO-P2O5 system were synthesized by one-pot process in a wide composition range,and their properties were investigated.The optimal performance was observed for the cements with(Ca+Mg)/P ratio of 1.67,which are characterized by newberyite phase formation during setting reaction,pH values close to 7,sufficient compressive strength up to 22±3 MPa(for 20 mol.%of Mg),dense microstructure and adequate matrix properties of the surface.This set of features make those materials promising candidates for medical applications.
基金funded by the Deutsche Forschungsgemeinschaft,grant number 417069397,as a collaboration project between the Ludwig Maximilians University Munich and the University Clinic of Würzburgthe DFG for funding the crossbeam scanning electron microscope Zeiss CB 340(INST 105022/58-1 FUGG)within the DFG State Major Instrumentation Programme。
文摘Regenerative bone implants promote new bone formation and ideally degrade simultaneously to osteogenesis.Although clinically established calcium phosphate bone grafts provide excellent osseointegration and osteoconductive efficacy,they are limited in terms of bioresorption.Magnesium phosphate(MP)based ceramics are a promising alternative,because they are biocompatible,mechanically extremely stable,and degrade much faster than calcium phosphates under physiological conditions.Bioresorption of an implant material can include both chemical dissolution as well as cellular resorption.We investigated the bioresorption of 3D powder printed struvite and newberyite based MP ceramics in vitro by a direct human osteoclast culture approach.The osteoclast response and cellular resorption was evaluated by means of fluorescence and TRAP staining,determination of osteoclast activities(CA II and TRAP),SEM imaging as well as by quantification of the ion release during cell culture.Furthermore,the bioactivity of the materials was investigated via SBF immersion,whereas hydroxyapatite precipitates were analyzed by SEM and EDX measurements.This bioactive coating was resorbed by osteoclasts.In contrast,only chemical dissolution contributed to bioresorption of MP,while no cellular resorption of the materials was observed.Based on our results,we expect an increased bone regeneration effect of MP compared to calcium phosphate based bone grafts and complete chemical degradation within a maximum of 1.5-3.1 years.
