Development of fibrous matrices of bioceramic-biopolymer nanocomposite offers great potential in the field of bone regeneration and tissue engineering. However, in order to produce electrospun fibers with homogeneous structure, it is essential for the ceramic powder to be fine and to remain stable in suspension. Herein, we developed a novel method whereby the bioceramic hydroxyapatite (HA) was kept in suspension in biopolymer poly(lactic acid) (PLA). The strategy was to introduce a surfactant hydroxysteric acid (HSA) between the hydrophilic HA powder and the hydrophobic chloroform-dissolved PLA. The HA nanopowder was dispersed effectively in HSA and mixed homogeneously with PLA. Continuous and uniform fibers were generated successfully with diameters of approximately 1-2 microm, and featured a well-developed nanocomposite structure of HA nanopowder-dispersed PLA. Initial cellular assays showed excellent cell attachment and proliferation and also enhanced expression of alkaline phosphatase at 7 days of culturing. The HA-PLA nanocomposite fibers may be potentially useful in tissue engineering applications, particularly as three-dimensional substrates for bone growth.

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Substrates with a nanofibrous morphology are considered as a prospective matrix to populate and support cells in the tissue regeneration area. Although the nanofibers made of synthetic degradable polymers, including poly(lactic acid) (PLA), have been well studied, their poor cell affinity has restricted wider applications. Herein, we produced blending nanofibers made of PLA and gelatin to improve the cellular responses of PLA. For this, both PLA and gelatin were dissolved in an organic solvent, varying the compositions of PLA:gelatin at 1:3 and 1:1 by weight, and the solutions were electrospun into nanofibers. At all compositions, nanofibers could be successfully generated with diameters of approximately hundreds of nanometers. The addition of gelatin into PLA markedly improved the wettability of the nanofibrous substrate. The osteoblastic cells attached and spread well on all the blending nanofibers and pure PLA. In particular, the cellular growth was significantly higher on the gelatin-blended PLA than on the pure PLA nanofiber. On the basis of this study, the PLA/gelatin blending polymeric nanofibers are considered to be useful as a bone cell supporting matrix in the tissue regeneration area.

Biomedical nanocomposites constituted of bioactive ceramic and resorbable polymer have shown promise for the successful regeneration of bone tissues. We developed herein a novel nanocomposite made up of a bioactive glass in a nanofibrous form and a degradable synthetic polymer, poly(lactic acid) (PLA). The glass nanofiber with a bioactive composition was generated via an electrospinning process with an average diameter of approximately 320 nm. The nanofiber was homogenized with PLA solution at various concentrations (up to 35% nanofiber), followed by drying and thermal pressing to produce dense nanocomposites. The nanocomposites showed an internal morphology of uniformly dispersed nanofibers within the PLA matrix. The nanocomposites induced rapid formation of a hydroxycarbonate apatite layer on the surface under a simulated physiological medium. As the amount of bioactive nanofiber increased (from 5 to 25%), the in vitro bioactivity of the nanocomposite was improved. The osteoblast responses to the nanocomposites (compositions with 5 and 25% nanofiber) were assessed in terms of cell proliferation, differentiation, and mineralization. Osteoblasts attached and grew well on the nanocomposites and secreted collagen protein at initial culturing periods. The differentiation of cells, as assessed by the expression of alkaline phosphatase, was significantly improved on the nanocomposites as compared to those on pure PLA. Moreover, the mineralized product by the cells was observed to be significantly higher on the nanocomposites with respect to pure PLA. The newly developed nanocomposite constituted of bioactive nanofiber and degradable polymer is considered as a promising bone regeneration matrix with its excellent bioactivity and osteoblast responses.

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