Arc-discharge synthesis of potent calcium-decorated MWCNTs as potential coating nanomaterials for orthopedic implants

Calcium-oxide–functionalized multiwalled carbon nanotubes (CaO@MWCNTs) were synthesized via arc-discharge, yielding a MWCNT with an outer diameter <10 nm decorated with CaO ≈65 nm. This approach produced high-purity CaO@MWCNTs with minimal chemical toxicity. Comprehensive physico-chemical characterization (HR-TEM, XRD, FTIR, UV, zeta potential, rheology) established stable, well-defined nanostructures suitable for biomedical interfaces. Biocompatibility and osteogenic potential were evaluated for orthopedic coating/scaffold applications. Cytocompatibility assessed by LDH and BrdU assays indicated non-cytotoxic performance in accordance with ISO 10,993–5:2009, with robust viability and proliferation. Anti-inflammatory activity was demonstrated by strong RAW 264.7 macrophage inhibition (IC50 = 4.7 μg/mL). Antimicrobial screening showed 2–16 μg/mL MICs across tested strains, indicating substantive antimicrobial efficacy. In vitro osteogenesis assays revealed preserved MC3T3-E1 viability, progressive ALP activity, and lowered inflammatory markers. Cytoskeletal integrity was evident via confocal imaging. RT-qPCR demonstrated upregulation of osteogenic markers (OCN, OPN, ALP) and enhanced ADSC differentiation, suggesting multi-stage osteoblastic maturation. Collectively, CaO@MWCNTs exhibit a balanced profile of biocompatibility, anti-inflammatory response, antimicrobial activity, and osteogenic promotion, supporting their potential as multifunctional coatings for improved osseointegration in orthopedic implants.