Combination of polydopamine and carbon nanomaterials coating enhances the piezoelectric responses and cytocompatibility of biodegradable PLLA nanofiber scaffolds for tissue engineering applications

Owing to their biodegradability, biocompatibility, and mechanical-to-electrical energy conversion ability, electrospun poly(L-lactic acid) nanofibers (PLF) have been actively applied in the biomedical field, including intelligent tissue scaffolds for stimulating tissue growth and regeneration, detecting medical problems and sensing vital biological forces. However, their high hydrophobicity, low piezoelectric outputs, and lack of biological recognition sites to interact with the cells are the major drawbacks concerning tissue engineering (TE) applications. Herein, we report a practical approach to fabricating PLF scaffolds with enhanced piezoelectric responses, improved surface properties, and good cytocompatibility (skin fibroblasts cells) by combining electrospinning with polydopamine (PD) and carbon nanomaterials (CM) coating strategies. First, PLF was prepared by electrospinning technique and then modified with CM (carboxylic-functionalized multiwalled carbon nanotubes and graphene oxide) using the polydopamine (PD) assisted one-step coating process. Systematic evaluation of the piezoelectric responses under cyclic loading-releasing conditions confirms the enhanced piezoelectric responses for the PD-CM coated PLF. The synergistic contribution of the piezoelectric effect from the dipoles of PLF and electrical conductivity and negative charges from the CM could be associated with the enhanced piezoelectric responses for the PD-CM coated PLF. The tensile test results reveal the enhanced mechanical properties of the PD-CM coated scaffolds compared to pristine PLF. Furthermore, the water contact angle results demonstrate the significantly improved hydrophilicity for the surface-modified PLF scaffolds. Consequently, PD-CM coated PLF scaffolds show remarkably higher cell attachment and proliferation (human skin fibroblasts) compared to pristine PLF. Altogether, our results suggest that the developed PLF scaffolds with tailored piezoelectric/conductive and surface properties could provide dynamic extracellular microenvironments for promoting tissue regeneration and healing.