Fabrication of 3D microfibrous composite polycaprolactone/hydroxyapatite scaffolds loaded with piezoelectric poly (lactic acid) nanofibers by sequential near-field and conventional electrospinning for bone tissue engineering

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Near-field electrospinning (NFES) has recently gained considerable interest in fabricating tissue engineering scaffolds. This technique combines the advantages of both 3D printing and electrospinning. It allows for the production of fibers with smaller resolution and the ability to make regular structures with suitable pores. In this study, a microfibrous composite scaffold of polycaprolactone (PCL)/hydroxyapatite (HA) was prepared by NFES in the first step. The microfibrous scaffold had a fiber spacing of 414.674 ± 24.9 μm with an average fiber diameter of 94.695 ± 16.149 μm. However, due to the large fiber spacing, the surface area was insufficient for cell adhesion. Therefore, the hybrid scaffold was prepared by adding aligned and random electrospun poly (L-lactic acid) (PLLA) nanofibers to the microfibrous scaffold. Cellular studies showed that cell adhesion to the hybrid scaffold increased by 334 % compared to the microfibrous scaffold. These nanofibers also exhibited piezoelectric properties, which helped stimulate bone regeneration. Aligned nanofibers in the hybrid scaffold enhanced alkaline phosphatase activity and the intensity of alizarin red staining 1.5 and 1.6 times, respectively, compared to the microfibrous scaffold. Furthermore, the elastic modulus and ultimate tensile strength increased by 268 % and 130 %, respectively, by adding aligned nanofibers to the microfibrous scaffold. Therefore, the hybrid microfibrous composite scaffold of PCL/HA containing aligned electrospun PLLA nanofibers with improved properties showed the potential for bone regeneration.