Hybrid biomaterial based on PCL, Mn-HA and Inulin-g-bPEI-PLA: evaluation of its antimicrobial potential

Bone regeneration is frequently compromised by post-surgical infections and the growing prevalence of antimicrobial resistance, underscoring the urgent need for biomaterials with intrinsic, non-leaching antibacterial properties that can mitigate the emergence of resistant strains (Sadowska et al., 2021).

In this study, a multifunctional hybrid biomaterial composed of polycaprolactone (PCL), manganese-doped hydroxyapatite (Mn-HA), and the amphiphilic copolymer inulin-g-branched polyethyleneimine-g-poly(D,L-lactide) (INU-bPEI-PLA) (Mazzacano et al., 2025) was developed and evaluated for its antimicrobial potential. PCL was selected as the structural matrix owing to its established biocompatibility, bioresorbability, mechanical stability, favorable processing characteristics, and controlled degradability (Tommasino et al., 2025). Mn-HA was incorporated as a bioactive inorganic phase capable of enhancing osteogenic responses (Bauer et al., 2024), while released Mn²⁺ ions have also been reported to exert antimicrobial effects (Kolmas et al., 2015). The copolymer INU-bPEI-PLA was introduced to modulate the intrinsic hydrophobicity of PCL, improve blend processability through its amphiphilic nature, and provide cationic PEI domains known to disrupt bacterial membranes (Gibney et al., 2012). We hypothesized that the combined presence of Mn²⁺ ions and PEI moieties could produce a synergistic antibacterial effect while preserving the regenerative functionality of the composite.

Blends with varying compositions were prepared by solvent casting to investigate both the individual and combined effects of Mn-HA and INU-bPEI-PLA on PCL processability and resistance to microbial colonization by selected nosocomial strains. Morphological (SEM), dimensional, and thermal (DSC) analyses confirmed the successful fabrication of homogeneous composite disks suitable for preliminary antibacterial screening.

Overall, this study establishes a rational basis for selecting optimized formulations for extrusion-based 3D printing and for the subsequent development of infection-resilient scaffolds for bone tissue regeneration.