Synergistic effects of thermal treatment and encapsulation of calcium phosphate nanoparticles on enhancing dimensional stability and osteogenic induction potential of free-standing PLGA electrospun membranes

Abstract

Limited dimensional stability and osteogenic induction property of poly (lactide-co-glycolide) (PLGA) electrospun membranes hampered their applications in bone tissue engineering. Thermal treatment of fixed PLGA membranes at 50 °C for 2 h and further immersion in 75% ethanol at free-standing state were adopted in order to obtain a high stability and well-maintained fiber morphology. After the process, free-standing membranes were stable during incubation in PBS at 37 °C, the volumetric ratio was 59.0%, fibers became curved, and the average diameter was 816 nm. For as-electrospun PLGA membranes, the volumetric ratio was only 35.3%, showing that thermal treatment was effective to improve the dimensional stability. The addition of calcium phosphate nanoparticles in P5-T-F further increased the volumetric ratio (64.0%) and significantly improved the mechanical properties. The mineralization capacity of PLGA membranes was enhanced because of thermal treatment. Hemolysis ratios of all samples were ∼2% indicating good hemocompatibility of PLGA electrospun membranes. Proliferation of adipose derived stem cells from rats (rADSCs) on treated PLGA membranes was significantly faster than that on untreated one, especially for sample P-T-F. In addition to thermal treatment, the addition of calcium phosphate nanoparticles showed synergistic effects on improving mineralization property and osteogenic differentiation of rADSCs. When compared with P-T-F, P5-T-F had 153.0% higher ALP activity and 518% higher calcium mineral deposition based on alizarin red assay. Thermal treatment along with encapsulation of calcium phosphate nanoparticles in PLGA electrospun membranes demonstrated a great prospect for applications in bone tissue engineering.