Electrospun silica/PLLA hybrid materials for skeletal regeneration

This paper presents the electrospinning of new silica/poly(L-lactic acid) (PLLA) based organic/inorganic sol-gel hybrid materials for skeletal defect regeneration. Here, hybrids are defined as inorganic and organic species interacting at the molecular level such that there are no distinguishable phases above the nanoscale. In previous hybrids, calcium has not been successfully incorporated into the silica network, limiting bioactivity. Here, an alkoxide source of calcium (calcium methoxyethoxide (CME)) was successfully used with a modified dual syringe reactive electrospinning (DSRS) setup to produce a calcium and silica containing PLLA sol-gel hybrid fibermat. Fibermats with continuous and homogeneous fibers were successfully produced that showed controlled and tailorable release of soluble silica in aqueous media. The CME-derived PLLA hybrid was observed to be hydrophilic and showed indication of bone-like apatite formation within 12 h of soaking in simulated body fluid (SBF). After soaking in SBF, the entire fiber surface was coated by a homogeneous thickness of apatite that had a plate-like crystal structure. The reversal of PLLA's hydrophobicity has tremendous implications on the biological properties of the material. All the electrospun materials were easy to handle and could be easily shaped into complex shapes. The tensile strength of the hybrid fibermats was found to be enhanced by the addition of silica, where a twofold increase in the tensile strength of 20 wt% silica containing PLLA fibermats compared to that of PLLA fibermats was observed.