Improving Biodegradable Polymers to enhance osteointegration and antibacterial property for orthopedic applications

Abstract

Regardless of the advances in orthopedic implants, implant longevity is still a limitation due to implant-related host responses to wear and the release of corrosion debris from metallic implants which are frequently used today. This has led to an increased incidence of repeated surgeries known as revision surgeries. Development in orthopedics is now geared towards biomaterials, specifically polymers, that can degrade, interact with the tissue and offer physiochemical cues to ensure cell processes that promote replication or restoration of the natural tissue function. Biodegradable polymers can eliminate stress shielding and can ensure the transfer of loading to the bone as they degrade for optimum bone healing by bone ingrowth. Polymers as load-bearing materials, on the other hand, face an important and unique challenge because they lack the mechanical stability of orthopedic metals. To enhance the mechanical properties of polymers intended for use in orthopedic applications, additives are incorporated into the polymeric matrix. In this work, we tested the feasibilities of three different additives: nanodiamond (ND) to improve the mechanical stability of the resulting composite, hydroxyapatite (HA) to improve the osteointegrative property of the material and nanosilver (NAg) for antibacterial property. Here, we describe the manufacturing procedures carried out to incorporate the additives into a PDLG-polymer matrix and various analytical methods to investigate the improvement due to the addition of the additives. Methods used were Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy/ Energy Dispersive X-ray (SEM/EDS), Three-point bending, Osteoblast cell culture, Mineralization, and Degradation study. From the results, PDLG/ND composites fabricated with 1wt% HA had a fairly even distribution of the additive in the polymeric matrix and showed the highest ultimate tensile strength, yield strength, young’s modulus. This concentration had the least decline in mechanical property after mineralization. Although elemental analysis showed an expected reduction in Ca ions, it had the most increase in P ions. Recommendations are made for future studies to reach a conclusive decision based on enhanced mineralization.