Porous poly(L-lactic acid)/apatite composites created by biomimetic process

Abstract

Highly porous poly(L-lactic acid)/apatite composites were prepared through in situ formation of carbonated apatite onto poly(L-lactic acid) foams in a simulated body fluid. The highly porous polymer foams (up to 95% porosity) were prepared from polymer solution by solid-liquid phase separation and subsequent sublimation of the solvent. The foams were then immersed in the simulated body fluid at 37 degrees C to allow the in situ apatite formation. After incubation in the simulated body fluid for a certain period of time, a large number of characteristic microparticles formed on the surfaces of pore walls throughout the polymer foams. The microparticles were characterized with scanning electron microscopy, energy dispersive spectroscopy, Fourier transform IR spectroscopy, and X-ray diffractometry. These porous spherical microparticles were assemblies of microflakes. They were found to be carbonated bonelike apatite. A series of composite foams with varying sizes and concentrations of the apatite particles was obtained by varying incubation time and conditions. These porous composites may be promising scaffolding materials for bone tissue engineering and regeneration because the excellent bone-bonding properties of the apatite may provide a good environment for osteoblast and osteoprogenitor cells' attachment and growth.

Porous poly(α-hydroxyacid)/Bioglass® composite scaffolds for bone tissue engineering. I: preparation and in vitro characterisation

“…Both EDXA and XRD techniques confirmed the formation of a crystalline HA layer after a few days of in vitro incubation. The HA formation rate was fast, as compared to other studies in which PLLA foams were immersed into SBF to grow apatite [21]. These results confirms that Bioglass ® 45S5 has a higher bioactivity index than HA, which is why it is being increasingly used as substituting material for bone tissue engineering as such or as a filler [10].…”

“…Each processing method has advantages that suit different tissue engineering applications. In situ apatite formation can also be induced by a biomimetic process in which polymer foams were incubated into a simulated body fluid [21]. In recent studies [22,23], particles of 45S5 bioglass ® , a commercially available bioactive glass powder (US Biomaterials), have been used to produce bioactive coatings on commercially available sutures (Vicryls) and on PDLLA foams.…”

Biomimetic materials for tissue engineering

“…The phase separation of polymer solutions has been explored in our laboratory and others to generate porous structures as tissue engineering scaffolds [11,[82][83][84][85][86][87][88]. When phase separation occurs, a polymer solution separates into two phases, a polymer-rich phase (with a high polymer concentration) and a polymer-lean phase (with a low polymer concentration).…”

Physical properties and cellular responses to crosslinkable poly(propylene fumarate)/hydroxyapatite nanocomposites

“…However, it is very brittle and cannot be applied to the load-bearing site directly [3][4][5]. To overcome these limitations, HA has been incorporated with natural biomacromolecules such as collagen [6][7][8] and gelatin [9,10], or synthetic polymers such as poly (α-hydroxyl acids) [11][12][13][14][15], poly (ε-caprolactone) (PCL) [16,17], polyamide [18], and polymethylmethacrylate (PMMA) [19] to prepare composites using a variety of methods including surface coating, grafting, direct mixing, and biomimetic precipitation [10,11,[20][21][22][23]. Particularly, polymer/HA nanocomposites have improved mechanical properties and enhanced cell attachment, spreading, and proliferation on their surfaces by adding nano-sized HA to modify the polymer's characteristics and/or strengthen the polymer matrix [24,25].…”