Development and characterization of a bioactive composite based on polylactic acid

Abstract

Aim.  Development and experimental characterization of a bioactive composite based on polylactic acid, modified with hydroxyapatite and gentamicin, for implant applications. Materials and methods.  PLA-based composites were prepared by solution mixing followed by hot pressing, with variation of the hydroxyapatite content (0 40 wt. %). The microstructure and distribution of the inorganic filler were analyzed using scanning electron microscopy and energy-dispersive X-ray analysis. Mechanical properties were evaluated by three-point bending tests with determination of flexural strength and Young’s modulus in accordance with ISO 178:2019. Antimicrobial activity was assessed in vitro by the agar diffusion method against standard test strains of  Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa,  and  Candida albicans. Results and discussion.  The developed composite fabrication approach was shown to provide a homogeneous microstructure with a dispersed distribution of hydroxyapatite within the polymer matrix without pronounced macro-agglomeration. An increase in hydroxyapatite content resulted in a systematic decrease in flexural strength accompanied by a moderate increase in Young’s modulus, reflecting the trade-off between stiffness and resistance to bending deformations characteristic of particulate-filled polymer systems. Gentamicin-containing composites exhibited pronounced antimicrobial activity against Gram-positive and Gram-negative bacteria. Conclusions.  The obtained results confirm the potential of PLA-based composites modified with hydroxyapatite and gentamicin as functional biodegradable materials for implant applications in regions with moderate mechanical loading, combining mechanical support, bioactivity, and local antimicrobial protection.