Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritic...Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical C02 foaming in which hydroxyapatite acted as heterogeneous nucleation agent. Bimodal porous scaffolds were prepared under certain conditions, i.e. hydroxyapatite addition of 5%, depressurization rate of 0.3 MPa. min-1, soaking temperature of 55 ℃, and pressure of 9 MPa. And scaffolds presented specific structure of small pores （122 μM ± 66 μm） in the cellular walls of large pores （552 μm ±127 μm）. Furthermore, multimodal porous PLGA scaffolds with micro-pores （37 μM ± 11μM） were obtained at low soaking pressure of 7.5 MPa. The interconnected porosity of scaffolds ranged from （52.53 ± 2.69）% to （83.08±2.42）% by adjusting depressurization rate, while compression modulus satisfied the requirement of bone tissue engineering. Solvent-free CO2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step, and bioactive particles for osteogenesis could serve as nucleation agents.展开更多
Poly(L-lactide)-b-poly(ethylene glycol)(PLLA-PEG) microspheres containing dexamethasone(Dex) have been fabricated using a spray-drying technique.Porous poly(lactic-co-glycolic acid)(PLGA) scaffolds were prepared using...Poly(L-lactide)-b-poly(ethylene glycol)(PLLA-PEG) microspheres containing dexamethasone(Dex) have been fabricated using a spray-drying technique.Porous poly(lactic-co-glycolic acid)(PLGA) scaffolds were prepared using a method combining thermally induced phase separation and porogen leaching.A post-seeding technique was used to immobilize Dex-containing PLLA-PEG microspheres on porous PLGA scaffolds,and drug-containing microspheres-scaffolds(MS-S) were obtained.Simple Dex-containing scaffolds(D-S) were also made as the control by directly dissolving Dex in the PLGA solution during scaffold fabrication.The morphologies of microspheres and scaffolds were studied by scanning electron microscopy.Drug release profiles of both MS-S and D-S were determined under cyclic loading and shaking water bath,respectively.The cumulative release of Dex was measured using an ultraviolet visible spectrophotometer.The results show that the incorporation of Dex and microspheres had little effect on the overall morphology of the porous PLGA scaffolds.Cyclic loading significantly accelerated the release of Dex from the drug-containing scaffolds.Compared with D-S,MS-S reduced the drug release rate.The controlled drug delivery of tissue engineering scaffolds under cyclic loading is a key factor to mimic the in vivo mechanical environments and achieve optical clinical efficacy.展开更多
The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/...The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/PCL)composite scaffold with porous structure was fabricated by thermally induced phase separation(TIPS).Dexamethasone(DEX)was incorporated into PLGA microspheres and then loaded on the PLLA/PLGA/PCL scaffoldtopreparethedesiredcompositescaffold.The physicochemical properties of the prepared composite scaffold were characterized.The morphology of rat bone marrow mesenchymal stem cells(BMSCs)grown on scaffolds was observed using scanning electron microscope(SEM)and fluorescence microscope.The resultsshowedthatthePLLA/PLGA/PCLscaffoldhad interconnected macropores and biomimetic nanofibrous structure.In addition,DEX can be released from scaffold in a sustained manner.More importantly,DEX loaded composite scaffold can effectively support the proliferation of BMSCs as indicated by fluorescence observation and cell proliferation assay.The results suggested that the prepared PLLA/PLGA/PCL composite scaffold incorporating drug-loaded PLGA microspheres could hold great potential for bone tissue engineering applications.展开更多
基金Support by the National Natural Science Foundation of China(21276225,21476196)
文摘Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical C02 foaming in which hydroxyapatite acted as heterogeneous nucleation agent. Bimodal porous scaffolds were prepared under certain conditions, i.e. hydroxyapatite addition of 5%, depressurization rate of 0.3 MPa. min-1, soaking temperature of 55 ℃, and pressure of 9 MPa. And scaffolds presented specific structure of small pores （122 μM ± 66 μm） in the cellular walls of large pores （552 μm ±127 μm）. Furthermore, multimodal porous PLGA scaffolds with micro-pores （37 μM ± 11μM） were obtained at low soaking pressure of 7.5 MPa. The interconnected porosity of scaffolds ranged from （52.53 ± 2.69）% to （83.08±2.42）% by adjusting depressurization rate, while compression modulus satisfied the requirement of bone tissue engineering. Solvent-free CO2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step, and bioactive particles for osteogenesis could serve as nucleation agents.
基金support from the National Natural Science Foundation of China (Grant Nos 10672015 & 30828008)
文摘Poly(L-lactide)-b-poly(ethylene glycol)(PLLA-PEG) microspheres containing dexamethasone(Dex) have been fabricated using a spray-drying technique.Porous poly(lactic-co-glycolic acid)(PLGA) scaffolds were prepared using a method combining thermally induced phase separation and porogen leaching.A post-seeding technique was used to immobilize Dex-containing PLLA-PEG microspheres on porous PLGA scaffolds,and drug-containing microspheres-scaffolds(MS-S) were obtained.Simple Dex-containing scaffolds(D-S) were also made as the control by directly dissolving Dex in the PLGA solution during scaffold fabrication.The morphologies of microspheres and scaffolds were studied by scanning electron microscopy.Drug release profiles of both MS-S and D-S were determined under cyclic loading and shaking water bath,respectively.The cumulative release of Dex was measured using an ultraviolet visible spectrophotometer.The results show that the incorporation of Dex and microspheres had little effect on the overall morphology of the porous PLGA scaffolds.Cyclic loading significantly accelerated the release of Dex from the drug-containing scaffolds.Compared with D-S,MS-S reduced the drug release rate.The controlled drug delivery of tissue engineering scaffolds under cyclic loading is a key factor to mimic the in vivo mechanical environments and achieve optical clinical efficacy.
基金National Natural Science Foundations of China(Nos.31271028,31570984)Innovation Program of Shanghai Municipal Education Commission,China(No.13ZZ051)+2 种基金International Cooperation Fund of the Science and Technology Commission of Shanghai Municipality,China(No.15540723400)Open Foundation of State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,China(No.LK1416)“111 Project” Biomedical Textile Materials Science and Technology,China(No.B07024)
文摘The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/PCL)composite scaffold with porous structure was fabricated by thermally induced phase separation(TIPS).Dexamethasone(DEX)was incorporated into PLGA microspheres and then loaded on the PLLA/PLGA/PCL scaffoldtopreparethedesiredcompositescaffold.The physicochemical properties of the prepared composite scaffold were characterized.The morphology of rat bone marrow mesenchymal stem cells(BMSCs)grown on scaffolds was observed using scanning electron microscope(SEM)and fluorescence microscope.The resultsshowedthatthePLLA/PLGA/PCLscaffoldhad interconnected macropores and biomimetic nanofibrous structure.In addition,DEX can be released from scaffold in a sustained manner.More importantly,DEX loaded composite scaffold can effectively support the proliferation of BMSCs as indicated by fluorescence observation and cell proliferation assay.The results suggested that the prepared PLLA/PLGA/PCL composite scaffold incorporating drug-loaded PLGA microspheres could hold great potential for bone tissue engineering applications.
