Enhancing the bioactivity of melt electrowritten PLLA scaffold by convenient, green, and effective hydrophilic surface modification

As an emerging additive manufacturing (AM) technique, melt electrospinning writing (MEW) is used to fabricate three-dimensional (3D) submicron filament-based scaffolds with adjustable pore size and customized structure for bone regeneration. Poly(L-lactic acid) (PLLA) scaffold with excellent biodegradability and biocompatibility is first successfully manufactured using our self-assembled MEW device. However, the ultralow cell affinity and poor bioactivity severely hamper their practical applications in bone tissue engineering. These issues are caused by the severe inherent biologically inert, hydrophobicity as well as the smooth surface of the MEW PHA filaments. In this study, a green and robust alkaline method is applied to modify the scaffold surface and to improve the bioactivity of the MEW PLLA scaffold. Without deterioration in mechanical property but robust surface hydrophilicity, the optimal MEW PLLA scaffold shows promoted surface roughness, enhanced filament tensile modulus (similar to 2 folds of the as-prepared sample), and boosted aystallizability (ultrahigh WAXD intensity). Moreover, after being cultured with KUSA-Al cells, the 0.5 M NaOH, 2 h treated MEW PIM scaffold exhibits higher osteoinductive ability and increased immature bone tissue amounts (3 times of controlled scaffold). Thus, the flexible surface functionalization by the specific alkaline treatment was found to be an effective method for the preparation of bioactivated MEW PLLA scaffolds with promoted bone regeneration.

Automated summary

Melt electrospinning writing (MEW) is a promising technique for fabricating bone regeneration scaffolds, but the poor cell affinity and bioactivity of the scaffold limit its practical applications. In this study, a green alkaline method was used to modify the surface of the MEW PLLA scaffold, resulting in improved bioactivity and surface roughness. The modified scaffold showed enhanced filament tensile modulus and crystallizability. After culturing with cells, the treated scaffold exhibited higher osteoinductive ability and increased amounts of immature bone tissue. This study demonstrates the effectiveness of surface functionalization in preparing bioactivated MEW PLLA scaffolds for promoting bone regeneration.