Fig. 1

Characterization of composite scaffold and schematic diagram of EMF device. The components of Thermo-sensitive PLGA-PEG-PLGA are Poly ethylene glycol (PEG), dl-Lactide (LA) and glycolide (GA). The molecular weight of PEG is 1500. LA (113.46 g), GA (30.48 g), PEG (60 g) were reacted in the solvent of Deuterated chloroform with the internal standard tetramethylsilane. A Thermo-sensitive PLGA–PEG–PLGA copolymers exhibited a free-flowing sol at ambient temperature (25 °C) and B spontaneously converted into a semi-solid hydrogel at body temperature (36 °C). Every 100 g of HAC scaffold contains 45 g of HA and 55 g of collagen. C Macroscopic observation of cylindrical HAC scaffold produced by hydroxyapatite and collagen I. D Image of scanning electron micrograph (SEM) showing porous microstructure of HAC. E Assembly of composite scaffold. The cell-loaded aqueous sol was injected on the top of HAC and then incubated at 37 °C for 30 min. Arrow: the site BMSCs loaded. F Presentation of electromagnetic fields (EMF) device consisting of waveform generator, oscilloscope, and Helmholtz coils. Cells were stimulated at the center of coils, which was placed in an incubator at 37 °C and 5% CO₂