Degradable Three Dimensional-Printed Polylactic Acid Scaffold with Long-Term Antibacterial Activity

Abstract

Polylactic acid (PLA) is one of the most promising candidates to solve the present environmental and energy problems. The programmable three-dimensional (3D) fabrication technique also provides a convenient and green platform for PLA applications in bone tissue engineering. An innovative PLA scaffold that combined multiple functions including highly interconnected porosity, sufficient nutrient supply, and antibacterial activity was prepared through 3D printing. Porosity of the scaffold was 67%, which was quite desirable for cell adherence and immigration. Followed by dopamine polymerization on the surface of the substrate, grafting with gelatin/nanohydroxyapatite (nHA) and ponericin G1 was further conducted. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed the successful modification. MC3T3-E1 cell culture showed a uniform distribution all through the scaffold with high survival rate, which was also confirmed by live/dead staining. Polydopamine modification made the scaffold totally hydrophilic and caused an early increase in cell proliferation, but the gelatin-containing group began to take effect at the later alkaline phosphatase (ALP) secretion stage. Scaffolds that were modified with ponericin (S/D/G/nHA/P group) improved calcium deposition to a large extent, as confirmed by alizarin red-S (ARS) staining. Both Gram-positive and -negative bacteria (E. coli and S. aureus) were effectively inhibited up to 24 h, and the inhibition zone could remain for 72 h. The comprehensive results showed that a balance was achieved between promoting the adhesion of MC3T3-E1 cells and simultaneous inhibition of pathogenic microbes.