Next-generation bone implants: multifunctional hydroxyapatite-CNT composites with embedded Ag/Cu nanoparticles

Bone-related disorders such as fractures, osteoporosis, and infections have accelerated the development of advanced materials for orthopaedic implants. Hydroxyapatite (HA), a bio-ceramic resembling the mineral phase of bone, offers excellent biocompatibility and osteoconductivity. However, its brittleness and poor fracture toughness limit its use in load-bearing applications. To overcome these limitations, this study presents a novel composite comprising hydroxyapatite reinforced with carbon nanotubes (CNTs) and silver/copper (Ag/Cu) nanoparticles. Functionalization of CNTs with carboxyl groups improves dispersion and bonding with the HA matrix, while Ag/Cu are incorporated via in-situ chemical reduction. The composite is densified using spark plasma sintering (SPS) to ensure structural integrity. A comprehensive set of characterization techniques was employed: FTIR and Raman spectroscopy confirm chemical bonding and CNT integration; SEM and TEM reveal morphology, dispersion, and interfacial interactions; XRD verifies phase composition; mechanical testing assesses hardness and toughness; and EIS is utilized to evaluate real-time infection sensing capability through CNT-based conductivity changes. The resulting CNT-HA-Ag/Cu composite can have improved mechanical performance, antimicrobial resistance, and potential for biofilm detection. This multifunctional material addresses key challenges in orthopedic implant technology by combining mechanical resilience, infection control, and smart sensing. Future studies will explore in vivo biocompatibility and clinical application to establish its suitability as a next-generation implant material.