Biosynthesis of Gold Nanoparticles Within Bacterial Cells for Cancer Diagnosis and Therapy

The biological synthesis of metal nanoparticles presents an eco-friendly and sustainable alternative to traditional chemical and physical methods. In this study, gold nanoparticles (AuNPs) were synthesized in situ within bacterial cells, exploiting the organism’s intrinsic biomolecules as natural reducing and stabilizing agents. A selected bacterial strain was exposed to aqueous chloroauric acid (HAuCl₄) under optimized conditions to facilitate the intracellular reduction of Au³⁺ ions into elemental gold (Au⁰) nanoparticles. The successful formation of AuNPs was evidenced by a distinct color change and confirmed through UV–Vis spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses. The biosynthesized AuNPs displayed a characteristic surface plasmon resonance peak between 520–540 nm, confirming the production of stable, spherical nanoparticles within the bacterial matrix. Owing to their excellent biocompatibility and unique optical properties, these biologically synthesized AuNPs were evaluated for potential biomedical applications, particularly in cancer diagnosis and therapy. Their suitability for imaging enhancement and photothermal treatment highlights their promise in cancer theranostics. This study underscores the potential of bacterial systems as sustainable nanofactories for generating functional, biocompatible gold nanoparticles, paving the way for eco-friendly approaches in next-generation biomedical nanotechnology.