Biosynthesized Palladium Nanoparticles Using Dalbergia sissoo: Ecotoxicological and Biosafety Evaluation Based on a...

Although palladium nanoparticles (PdNPs) are widely applied in catalytic, environmental, and biomedical contexts, the ecotoxicological and biosafety implications of biosynthesized PdNPs remain insufficiently characterized. In this study, PdNPs were synthesized using aqueous leaf extract of Dalbergia sissoo (DS-PdNPs). UV-Visible spectroscopy confirmed the reduction of PdCl₂ to Pd⁰, while FTIR analysis indicated biomolecules involved in the bio-reduction and stabilization of DS-PdNPs. TEM revealed an average particle size of 7.5 nm, and P-XRD confirmed the face-centered cubic (FCC) lattice structure. EDX indicated the elemental composition, and zeta potential measurements demonstrated good colloidal stability (-25 mV) of DS-PdNPs. The synthesized DS-PdNPs were evaluated for ecotoxicity and biosafety in Allium cepa (onion bulb) roots, Bacillus subtilis soil bacteria, and human keratinocyte (HaCaT) cells at concentrations of 1, 50, 100, 250, and 500 μg/mL. A dose-dependent response was observed, with A. cepa showing increased root growth inhibition after 3 days (84.37%), a decline in mitotic index (MI) of 66%, and elevated malondialdehyde (MDA) content (5.1 ± 0.14 nmol g^-1 FW). Conversely, HaCaT cells exhibited moderate cytotoxicity with an IC₅₀ value of 261 μg/mL and 49.4% cell viability, while the bacterial assay showed a low toxicity profile characterized by a minimal zone of inhibition (7 ± 0.0 mm) at 500 μg/mL. These findings indicate the varied toxicity of DS-PdNPs across different test systems, highlighting their selective biological interactions and the need for careful evaluation of their overall environmental impact.