Three-dimensional Printing And Biological Properties Of Functional Mesoporous Bioactive Composite Scaffolds

The development of bone tissue engineering has changed the traditional treatment modes for bone defects.Bone tissue engineering has three important elements-seed cells,scaffolds and signaling molecules.The three dimensional?3D?porous scaffold is the basic carrier material,and plays a very important role in bone tissue engineering.In this dissertation,we fabricated three different kinds of functional mesoporous bioactive composite scffolds,including strontium-containing mesoporous bioactive glass/polyvinylalcohol?Sr-MBG/PVA?scaffolds,magneticFe₃O₄nanoparticles/mesoporousbioactiveglass/polycaprolactone?Fe₃O₄/MBG/PCL?compositescaffoldsandCeO₂-incorporatedmesoporouscalcium-silicate/polycaprolactone?CeO₂-MCS/PCL?scaffolds,using a three dimensional?3D?printing technique.The physiochemical properties,drug delivery and biological properties of the functional mesoporous bioactive composite scffolds were systematically investigated.The results are described as follows:?1?MBG and Sr-MBG powders were prepared by hydrothermal treatment.The substitution of Sr for Ca in MBG did not change the mesoporous channels of MBG.3D porous MBG/PVA and Sr-MBG/PVA composite scaffolds have been fabricated by a 3D printing technique.The results showed that Sr-MBG/PVA scaffolds had uniform macropores,high porosity and excellent compressive strength?⁹ MPa?,which can meet the requirement of the compressive strength of human trabecular bone?²-12MPa?.Sr-MBG/PVA scaffolds possessed good apatite-forming ability and sustained drug delivery ability,similar to MBG/PVA scaffolds.More important,Sr-MBG/PVA scaffolds can stimulate osteoblast cells'proliferation,alkaline phosphatase?ALP?activity,osteogenesis-related gene expression?RUNX2,OCN,BSP,BMP-2 and COL-1?and extracelluar matrix mineralization?ECM?,which were significantly better than those on MBG/PVA scaffolds?P<0.05?.In vivo results revealed that Sr-MBG scaffolds had good osteogenic capability and stimulated new blood vessel formation in critical-sized rat calvarial defects within 8 weeks.?2?MBG powders with highly ordered two-dimensional hexagonal mesoporous channels were synthesized by evaporation-induced self-assembly?EISA?process.Superparamagnetic Fe₃O₄ nanoparticles were prepared by a coprecipitation method.3D porous Fe₃O₄/MBG/PCL composite scaffolds have been fabricated by a 3D printing technique.The results showed that Fe₃O₄/MBG/PCL scaffolds had uniform macropores,high porosity and excellent compressive strength?13-16 MPa?.Fe₃O₄/MBG/PCL scaffolds possessed excellent apatite-forming ability and sustained drug delivery ability.Furthermore,the incorporation of Fe₃O₄ nanoparticles in Fe₃O₄/MBG/PCL scaffolds endowed excellent magnetic heating ability and significantly stimulated proliferation and differentiation of human bone marrow-derived mesenchymal stem cells?h-BMSCs?.More important,in vivo results revealed that 15Fe₃O₄/MBG/PCL scaffolds significantly enhanced osteogenic capability in rabbit models of femoral defect within 8 weeks compared to MBG/PCL scaffolds.?3?CeO₂-incorporated mesoporous calcium-silicate?CeO₂-MCS?powders have been successfully synthesized by sol-gel method.CeO₂-MCS powders had ordered mesoporous channels,but the ordering degree exhibited a little decrease with the increase amount of CeO₂ incorparation.3D porous MCS/PCL and CeO₂-MCS/PCL composite scaffolds have been fabricated by a 3D printing technique.The results showed that CeO₂-MCS/PCL scaffolds had uniform macropores,high porosity and excellent compressive strength?⁷ MPa?.CeO₂-MCS materials had sustained drug delivery ability and the CeO₂-MCS/PCL scaffolds possessed good apatite-forming ability,similar to MCS/PCL scaffolds.Moreover,CeO₂-MCS/PCL scaffolds can stimulate human bone marrow-derived mesenchymal stem cells'proliferation and differentiation,which would be beneficial for bone tissue engineering.In summary,the functional Sr-MBG/PVA bioactive composite scffolds had good bone-forming bioactivity,sustained drug delivery ability,enhanced mechanical strength and biological properties,which could be used for potential application in osteoporosis bone defect repair.The magnetic Fe₃O₄/MBG/PCL composite scaffolds had the excellent physiochemical properties,in vitro bioactivity,anticancer drug delivery,mechanical strength,magnetic heating and cell response ability,which showed the potential multifunctionality of enhanced osteogenic activity,local anticancer drug delivery and magnetic hyperthermia.The functional CeO₂-MCS/PCL composite scaffold had good bone-forming bioactivity,drug delivery ability,enhanced mechanical strength and biological properties,which could be used for potential application in antimicrobial therapy and bone regeneration.