Helical conformation endows poly-l-lactic acid fibers with a piezoelectric charge under tensile stress

Abstract

Poly-l-lactic acid (PLLA) has been clinically used as a bioabsorbable material and attains a piezoelectric charge upon molecular orientation by the application of a shear force to the C-axis of the crystal line region. Previous studies showed that implanted drawn PLLA films or rods accelerate the ossification due to piezoelectric effect. In this study, we originally designed helically-twisted PLLA fiber to produce piezoelectricity in bioabsorbable suture upon tensile stress. The piezoelectricity of the helical PLLA fibers was evaluated using a lock-in amplifier system in vitro. The ossification induced by helical PLLA fibers was examined by implanting them in the rat patellar ligament supporting a physiological tensile load. We observed that 57° and 45° twisted PLLA fibers generated a higher piezoelectric potential than did 27° twisted fibers. The animal experiment showed that the formation of osseous tissue around helical PLLA fibers was more significant than around non-helical control fibers at 4 weeks after their implantation. These results suggest that helical PLLA fiber may be useful for the surgical suture or artificial ligament, which connects to the bone. © 2013 The Japanese Society of Veterinary Science.