# Green Synthesis of Au-Pd Bimetallic Nanoparticles Using Aspalathin and Their Toxicity Study

## TL;DR

This paper describes a green method to synthesize Au-Pd bimetallic nanoparticles using rooibos and aspalathin, and finds they are non-toxic and have potential biomedical uses.

## Contribution

The novel use of pure aspalathin in green synthesis allows precise control over nanoparticle properties and improved cellular uptake.

## Key findings

- Au-Pd nanoparticles synthesized with aspalathin form core–shell structures, while total extract forms alloys.
- ASP-conjugated nanoparticles showed higher cellular uptake compared to total extract-based nanoparticles.
- The nanoparticles exhibited no significant cytotoxicity, suggesting good biocompatibility for biomedical applications.

## Abstract

Bimetallic nanoparticles have garnered significant attention in scientific literature due to their diverse applications and unique properties. Concurrently, green synthesis methodologies have emerged as environmentally friendly alternatives, reducing the ecological footprint of nanoparticle production. In this study, the efficient synthesis of Au-Pd bimetallic nanoparticles is presented, utilizing Aspalathus linearis (Burm.f.) R. Dahlgren, commonly known as green rooibos (GR), and its pure bioactive compound, Aspalathin (ASP). Integrating ASP as a pure compound into the green synthesis process offers precise control over nanoparticle characteristics, including size, morphology, and composition. Interestingly, the total extract forms an Au-Pd nanoparticle alloy, while aspalathin forms core–shell nanoparticles. Furthermore, cytotoxicity testing was carried out on selected cell lines to assess their impact on cell viability. The cytotoxicity test on cell lines and cellular uptake analysis demonstrated that none of the tested samples exhibited significant cytotoxic effects. ASP-conjugated bimetallic increased the uptake of the NPs by the cells more than the total extract. The results demonstrated that the Au-Pd bimetallic nanoparticles hold promise for biomedical applications, owing to their enhanced biocompatibility and tailored properties.