Tailoring biocompatibility and cytotoxicity of PLAL-derived gold and copper nanoparticles

Abstract

The integration of nanotechnology into biomedical applications offers significant promise; however, its advancement is often constrained by an incomplete understanding of how nanoparticles (NPs) interact with biological environments. In this study, gold (Au) and copper (Cu) nanoparticles were synthesized via a clean, scalable, and surfactant-free technique-Pulsed Laser Ablation in Liquid (PLAL)-using distilled water as the ablation medium. This approach eliminates the need for chemical precursors or stabilizers, ensuring high-purity colloidal suspensions. The Au nanoparticles exhibited a uniform spherical morphology, a narrow size distribution (10-50 nm), and excellent colloidal stability, consistent with strong surface plasmon resonance (SPR) and metallic phase purity. In contrast, Cu nanoparticles displayed ultrasmall sizes (1-3 nm) within the quantum dot (QD) regime, along with partial surface oxidation, as confirmed by XPS and O 1s core-level analysis. The presence of both metallic and oxidized species was identified for both Au and Cu systems, with Cu exhibiting a higher degree of surface oxidation, in line with oxygen quantification from XPS data. These findings provide important insights into the structure-property relationships of PLAL-derived nanoparticles and highlight their tunable features, which are critical for designing biocompatible and functionally versatile nanomaterials for drug delivery, photothermal therapy, and other biomedical applications. To evaluate their biomedical potential, in vitro cytotoxicity assays were performed on SH-SY5Y (neuroblastoma) and C2C12 (myoblasts) cell lines. The results demonstrated that Cu-QDs induced a significantly higher cytotoxic response compared to Au-NPs, with pronounced apoptotic features at lower concentrations. These findings are consistent with the known pro-oxidant activity of copper and suggest that Cu-QDs may serve as effective candidates for cancer therapy. Conversely, AuNPs showed minimal cytotoxicity under similar conditions, supporting their continued exploration in drug delivery and imaging applications. The study highlights PLAL as a promising route for producing biocompatible and functionally tunable nanoparticles for biomedical use.