Spectroscopic, electrical, and cytocompatibility properties of luminescent (metal nanoparticle/polyaniline) composites.

In recent years, the integration of metallic nanoparticles with conductive polymers has gained significant attention for biomedical applications, including biosensors and therapeutic agents. Here, we synthesized hybrid nanocomposites of polyaniline (PANI) with copper (Cu) and silver (Ag) nanoparticles using a straightforward and scalable one-pot synthesis method. These composites were characterized by a range of techniques, including UV-vis, Fourier Transform Infrared (FTIR) spectroscopy, Zeta Potential measurements, Dynamic Light Scattering (DLS), and photoluminescence (PL). Our analysis confirmed that the composites consist of the leucoemeraldine form of PANI, which exhibited dual fluorescence emission at 342 nm (UV region) and 667 nm (visible region), highlighting a synergistic interaction between the metal nanoparticles and PANI chains. The fluorescence quantum yield was determined to be 8.80 % for Cu/PANI and 10.05 % for Ag/PANI, indicating efficient luminescence and tunability based on the metal used. The cytocompatibility was evaluated through MTT assays on four cell lines (Vero cells, macrophages, HeLa cells, and fibroblasts), showing favorable biocompatibility across most cell types. Notably, macrophages (CC50 = 353.4 μg/mL) and Vero cells (CC50 = 324.5 μg/mL) showed higher sensitivity to Cu/PANI treatment, suggesting selective interactions compared to Ag/PANI and other similar composites reported in the literature. These results demonstrate that Cu/PANI and Ag/PANI composites combine promising fluorescence properties with cytocompatibility, making them suitable candidates for diverse biomedical applications, such as fluorescent markers, biosensors, and therapeutic agents.