Piezoelectric co-electrospun composite scaffolds with ECM-mimicking structure and enhanced bioactivities for potential bone regeneration application

Design and construction of novel bone scaffolds integrating great structural adaptability and enhanced biological activities are urgently required in clinics. Herein, a composite scaffold made from piezoelectric poly (L-lactic acid) (PLLA) microfibers and chitosan (CS)/polyethylene oxide (PEO) nanofibers was fabricated by using a co-electrospinning strategy. Moreover, the bioadditive, nano-hydroxyapatite (nHAP), was loaded into the PLLA nanofibers during co-electrospinning to generate nHAP/PLLA + CS/PEO micro-nano fiber scaffolds. The scaffold showed a bimodal fiber diameter distribution (282.5 ± 11.4 nm, 1910.5 ± 22.2 nm) and a pore size of ∼ 3.3 μm, mimicking the extracellular matrix (ECM) structure to support osteoblast proliferation. Compared with traditional PLLA scaffold, the composite scaffold exhibited better performance. The surface contact angle had decreased from 136.7° ± 3.5° to 72.9° ± 2.1°. The mechanical properties had increased from 3.2 ± 0.2 MPa to 5.5 ± 0.6 MPa. Furthermore, the addition of nHAP enhanced the piezoelectric properties of the fiber scaffold. Under a load of 2 N, its piezoelectric voltage could approximately reach 250 mV. The antibacterial test results demonstrated that nHAP/PLLA + CS/PEO achieved approximately 99% inhibition against Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ), potentially reducing post-implantation infection rates. Cell experiments further demonstrated that micro-nano fibrous composite scaffolds not only promoted the proliferation of osteoblasts but also enhanced the expression of key osteogenic proteins such as type I collagen (COL I), osteopontin (OPN), and osteocalcin (OCN). Overall, the nHAP/PLLA + CS/PEO fiber scaffolds held considerable promise for accelerating bone repair.