Biological evaluation of pH-responsive eugenol-loaded CMC/ZnO-HA nanocomposites for enhanced bone wound healing and osteogenesis.

Bone regeneration necessitates biomaterials that provide structural support while facilitating bioactive signaling. This study created a eugenol-loaded carboxymethyl cellulose/zinc oxide-hydroxyapatite (EUG-CMC/ZnO-HA) nanocomposite, which was evaluated using FTIR, XRD, and SEM. The nanocomposites attained a substantial drug loading of 28.9% and an encapsulation efficiency of 97.6%. In vitro studies revealed a pH-responsive, sustained release profile, with 87.5% of EUG released at pH 5.5, in contrast to 47% at pH 7.4 over 24 h. The sustained release mechanism is predominantly regulated by hydrogen bonding and electrostatic interactions among CMC, HA, and EUG, in conjunction with Zn²⁺-mediated ionic interactions from ZnO. Furthermore, hydrophobic interactions within the CMC matrix augment drug retention, facilitating sustained release, which ensures prolonged availability of ZnO, while the gradual release of EUG mitigates local inflammation, collectively fostering osteogenic differentiation. The nanocomposite demonstrated strong antibacterial efficacy against four pathogens, as well as notable anti-inflammatory (82.5% inhibition) and antioxidant characteristics. Biocompatibility assessments on MG63 osteoblast-like cells demonstrated 97% survivability at 150 µg/mL, whereas scratch testing corroborated enhanced cell migration. RT-qPCR analysis revealed a significant, time dependent upregulation of osteogenic markers, with early-stage markers such as RUNX2 and BMP-2 exhibiting increased expression at initial time points, succeeded by elevated expression of mid-late-stage markers including COL1A1, OPN, and OCN, signifying progressive osteogenic differentiation. The transcriptional changes were associated with an 84% rise in calcium nodule accumulation, validating the composite's effectiveness in facilitating the progression from cellular commitment to full mineralization. The EUG-CMC/ZnO-HA nanocomposite functions as a sophisticated scaffold for bone wound healing by facilitating regulated medication administration and promoting tissue regeneration.