Unravelling the bone regeneration capability of polylactic acid nanocomposite films embedded with hydroxyapatite functionalized halloysite nanotubes

Abstract

This study focuses on the fabrication of nanocomposite films based on poly(lactic acid) (PLA) reinforced with hydroxyapatite-coated halloysite nanotubes (HNTs). Surface functionalization of HNTs with hydroxyapatite significantly enhanced their compatibility with the PLA matrix, contributing to improved dispersion and interfacial adhesion. A suite of analytical techniques—FTIR, XRD, DSC–TGA, FESEM, TEM, and AFM—was employed to characterize the hydroxyapatite-HNTs and the resulting PLA nanocomposites. Compared with neat PLA, the nanocomposites exhibited superior chemical, thermal, and morphological properties. Their biological performance was assessed through in vitro enzymatic degradation and hemolysis assays, which confirmed the non-toxic and hemocompatible nature of the composites. Alkaline phosphatase (ALP) assays demonstrated enhanced cellular adhesion on the PLA/HNT films, while MTT assays revealed improved cell proliferation proportional to increasing HNT content. Fluorescence staining using acridine orange–ethidium bromide (AO–EB) further confirmed the cell viability, and the attachment of mouse embryonic fibroblast cells on films containing 1 and 5 wt% HNTs affirmed the synergistic effect of the PLA matrix and bioactive HNTs. Transmission electron microscopy (Fig. 4) displayed detailed micrographs of rod-shaped hydroxyapatite structures on HNTs: image (a) showed aggregated HNTs, image (b) highlighted an individual hydroxyapatite-coated rod, and image (c) provided high-resolution confirmation of surface nanostructures. These morphological features validated the controlled and effective functionalization process essential for improved biological response. Collectively, these results underline the potential of hydroxyapatite-HNT-reinforced PLA nanocomposites as promising candidates for bone regeneration applications.