Hardystonite Bioceramic Endowing Multifunctions of Polylactic Acid-Based Composites Favourable for Developing Next-generation Fixation Implants

Abstract

Developing multifunctional biodegradable internal fixing implants with appreciable anti-infection is crucial to enhancing their applications in regenerative medicine. Polylactic acid (PLA)-based polymers are attracting much attention in biomedicine because of their biocompatibility and biodegradability, whereas these biological performances are only the necessary conditions and suboptimal for internal fixation and tissue reconstruction. In order to address the potential of implant-associated anti-infections, this study developed the PLA-based composites with low crystalline hardystonite (HAR) powders with/without 5% Na doping via low-temperature calcining and melt-blending approach. The experimental results indicated that addition of HAR or Na-HAR powder into PLA may weakens the tensile strength and maintains flexural strength, but significantly enhance the Young’s/elastic modulus when adding 12% Na-HAR. It was evident that introduction of inorganic powders could accelerate the biodegradation in vitro and provide appreciable functional ions favorable for improving osteogenic stem cell viability and antibacterial efficacy (>90%) against Staphylococcus aureus and Escherichia coli. Moreover, the preliminary histological observation from the muscle embedding model confirmed that the methicillin-resistant Staphylococcus aureus-loaded implants could readily prevent local osmotic shock, alleviate acidosis, stimulate angiogenesis and overcome the infection in soft tissue microenvironment. Totally, these findings demonstrate that the development of PLA/HAR composites would balance many shortcomings of PLA substrate and exhibit multifunctional potential beneficial for diverse clinical needs, especially susceptible infection bone injury conditions.