# Catharanthus roseus Extract-Loaded Zn-Substituted Hydroxyapatite Nanocomposites as a Multifunctional Antioxidant and Anticancer Therapeutic Applications

## TL;DR

A new nanocomposite made from fish bone waste and plant extract shows strong antioxidant and anticancer properties.

## Contribution

A Zn-HA/CR nanocomposite is developed with enhanced antioxidant and anticancer effects for therapeutic applications.

## Key findings

- The Zn-HA/CR nanocomposite showed improved surface morphology and increased microhardness.
- It exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli.
- The nanocomposite caused significant morphological changes and reduced viability in osteosarcoma cancer cells.

## Abstract

During recent decades, bone cancer-related diseases have remained hard to treat because of poor diagnosis, systemic toxicity, and restricted conventional treatments. Hence, the fabrication of functionalised nanoparticles offers a promising alternative by limiting side effects and improving therapeutic outcomes. In this study, zinc-substituted hydroxyapatite (Zn-HA) nanoparticles were fabricated from biogenic tuna fish bone waste via a thermal decomposition method and subsequently functionalised with Catharanthus roseus (CR) flower extract to synthesise a Zn-HA/CR nanocomposite. Structural and compositional characterisations verified Zn ions incorporation into the HA lattice and efficient CR-derived phytochemical functionalisation without altering the hexagonal HA phase. Compared to pure hydroxyapatite, the Zn-HA/CR nanocomposite exhibited improved surface morphology, enhanced swelling behaviour and degradation, and increased microhardness. The nanocomposite demonstrated significantly enhanced antibacterial activity against Staphylococcus aureus and Escherichia coli. The Zn-HA/CR nanocomposite also showed strong, dose-dependent antioxidant activity in DPPH assays. Furthermore, in vitro cytotoxicity studies using MG-63 (HOS) osteosarcoma cancer cells revealed that the proposed nanocomposite leads to pronounced morphological alterations and reduced cell viability. The prepared Zn-HA/CR nanocomposite would be a potential nanocomposite for enhanced antioxidant and anticancer activity, which highlights this composite as a multifunctional biomaterial platform for therapeutic applications.