Preparation and characterization of nanohydroxyapatite strengthening nanofibrous poly(L‐lactide) scaffold for bone tissue engineering

Abstract

A biomimetic nanofibrous poly(L-lactide) scaffold strengthened by nanohydroxyapatite particles was fabricated via a thermally induced phase separation technique. Scanning electron microscopy results showed that nanohydroxyapatite particles uniformly dispersed in the nanofibrous poly(L-lactide) scaffold (50-500 nm in fiber diameter) with slight aggregation at a high nHA content, but showed no influence on the interconnected macroporous and nanofibrous structure of the scaffold. The nanofibrous poly(L-lactide) scaffold presented a specific surface area of 34.06 m 2 g À1 , which was much higher than that of 2.79 m 2 g À1 for the poly(L-lactide) scaffold with platelet structure. Moreover, the specific surface area of the nanofibrous scaffold was further enhanced by incorporating nanohydroxyapatite particles. With increasing the nanohydroxyapatite content, the compressive modulus and amount of bovine serum albumin adsorbed on the surface of the nanofibrous composite scaffold were markedly improved, as opposed to the decreased crystallinity. In comparison to poly(L-lactide) scaffold, both the nanofibrous poly(L-lactide) and poly(L-lactide)/nanohydroxyapatite scaffolds exhibited a faster degradation rate for their much larger specific surface area. The culture of bone mesenchymal stem cell indicated that the composite nanofibrous poly(L-lactide) scaffold with 50 wt % nanohydroxyapatite showed the highest cells viability among various poly(L-lactide)-based scaffolds. The strengthened biomimetic nanofibrous poly(L-lactide)/nanohydroxyapatite composite scaffold will be a potential candidate for bone tissue engineering.

Improvement of compatibility and mechanical properties of the poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) blends and films by reactive extrusion with chain extender

“…The rumples of layered structure lay parallel to the notch of highly drawn material. The occurrence of rumples can be ascribed to the considerable tearing ahead of the crack tip before unstable fracture sets in, which was a typical feature of a ductile fracture [44]. This result was in consistent with the tear strength data from Table 2.…”

Engineered poly(lactic acid)‐talc biocomposites for melt processing: Effects of co‐blending with poly(butylene succinate) and poly(butylene terephthalate) on thermal and mechanical behavior

“…Chemical compatibilization of PLA with other polymeric phases obtained by reactive species and intermediates during the so-called reactive extrusion process strategies constitutes a keystone for ensuring the optimum properties of the resulting blends, in order to guarantee a good transfer of the stresses inside the material under external load. Maleate and glycidyl methacrylate grafted polymers, including nonacrylate [16][17][18][19][20][21][22] and acrylate [23][24][25][26][27][28][29][30][31][32][33] are rather typical additives employed as reactive intermediates in extrusion compounding processes of PLA, due to their affinity with the polymer matrix. To increase the affinity of the compatibilizing reactive additives with the PLA phase and to limit the use of noncompostable phases in accordance with the regulatory frame, maleate and glycidyl methacrylate grafted PLAs have been developed and previously tested, showing the possibility to effectively tune the properties of the resulting PLA compounds [34,35].…”

Influence of methyl methacrylate‐butadiene‐styrene copolymer on plasticized polylactide blown films

“…The processability of blowing film and the mechanical properties of the PLA resin can be improved through branching reactions, or blending with other polymers, or plasticizers or nucleants [8,9]. For example, PLA could be blended with other more flexible such as poly(butylene-succinate-co-adipate) (PBSA) [10], poly (butyl acrylate) (PBA) [11], and poly(butylene-adipate-coterephthalate) (PBAT) [12] core-shell structural acrylate copolymer (ACR) [13,14], glycidyl methacrylate-functionalized methyl methacrylate-butadiene [15], epoxy-functionalized grafted acrylonitrile butadiene styrene [16], and methyl methacrylate-butadienestyrene (MBS) [17,18].…”

“…The typical methyl methacrylate-butadiene-styrene (MBS) particle often has a soft core of a random styrene-butadiene copolymer and a glassy shell composed of a random copolymer of polymethyl methacrylate (PMMA) [17,19,20]. MBS has displayed a significant impact-modifying effect at low temperature and is the most common impact modifier used to improve the impact strength of poly(vinyl chloride) (PVC) and poly(propylene carbonate) (PPC) [21][22][23][24], there are also used to toughen polylactic acid (PLA) [17,18].…”

“…The typical methyl methacrylate-butadiene-styrene (MBS) particle often has a soft core of a random styrene-butadiene copolymer and a glassy shell composed of a random copolymer of polymethyl methacrylate (PMMA) [17,19,20]. MBS has displayed a significant impact-modifying effect at low temperature and is the most common impact modifier used to improve the impact strength of poly(vinyl chloride) (PVC) and poly(propylene carbonate) (PPC) [21][22][23][24], there are also used to toughen polylactic acid (PLA) [17,18]. MBS as the modifiers are used regularly to improve the toughness of PLA due to the major attractive features, the rubbery core of a random styrenebutadiene copolymer provides resistance to impact, especially at low temperatures, whereas the grafted glassy shell of polymethyl methacrylate (PMMA) gives "good adhesion" with PLA because of the similar structures, which PLA just has a chemical structure like that of PMMA, and provides rigidity and compatibility with the polymer matrix, keeping the particles desired shape and dispersibility.…”