Synergistic enhancement of UHMWPE properties using graphene oxide/MWCNT-COOH hybrid nanofillers: Evaluation of mechanical, thermal performance and cytocompatibility for orthopedic applications

Ultra-high molecular weight polyethylene (UHMWPE) remains a leading material for orthopedic bearing surfaces owing to its high wear resistance and established biocompatibility. However, long-term in vivo performance is challenged by factors such as oxidation, which can compromise mechanical integrity and contribute to implant failure. This study investigates the synergistic effects of incorporating graphene oxide (GO) and carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH) into UHMWPE. Nanocomposites containing 1 wt% GO, 1 wt% MWCNT-COOH, or a hybrid filler system (1 wt% GO + 1 wt% MWCNT-COOH) were fabricated via ball milling and compression molding. The materials were comprehensively characterized for their morphological, chemical, thermal, mechanical, and biological properties. FTIR and SEM analyses confirmed successful nanofiller integration and dispersion. All nanocomposites exhibited enhanced thermal stability and increased surface hydrophilicity compared to pristine PE. The hybrid UHMWPE-GO-CNT (U-GO-CNT) composite, in particular, demonstrated the most substantial improvements, showing a thermal decomposition temperature (T 3 ) approximately 20 °C higher than pristine PE, a 12% reduction in water contact angle indicating a more hydrophilic surface, a tensile strength of 33.5 MPa (a ∼24% increase) and a Shore D hardness of 67.8 (an ∼8% increase). This suggests a synergistic mechanism wherein 1D MWCNTs bridge 2D GO sheets, creating an efficient load-transfer and barrier network. Furthermore, MTT assays confirmed excellent cytocompatibility, exceeding 95% cell viability for all nanocomposites. These findings highlight the potential of U-GO-CNT hybrids to create advanced UHMWPE biomaterials with enhanced thermomechanical and cytocompatibility properties, positioning them as strong candidates for comprehensive tribological and long-term evaluation in orthopedic bearings.