Antimicrobial and anticancerogenic activity of selenium nanoparticles obtained via pulsed laser ablation

SeNPs were synthesized via chemical reduction and physical pulsed laser ablation techniques. Stable, spherical nanoparticles with TEM diameters ranging from 20 to 150 nm (mean ± SD: 28.5 ± 7.2 nm and 33.8 ± 6.4 nm for the chemical and physical methods, respectively) were obtained. The characteristic absorption peaks at 310 nm and 371 nm were detected for SeNPs produced by chemical reduction and physical pulsed laser ablation, respectively. The band gap values were found to be 1.74 eV and 1.92 eV, respectively. Zeta potential analysis confirmed moderate colloidal stability (23.67 mV and 25.17 mV for chemical and physical reduction, respectively). The antibacterial activities of the SeNPs against E. coli, Klebsiella spp., Pseudomonas spp. and Staphylococcus spp. were evaluated using the agar well diffusion method. SeNPs synthesized by the chemical reduction method formed inhibition zones of 10, 14, 18, 20 and 27 mm (E. coli); 9-18 mm (Staphylococcus spp.); 10-17 mm (Klebsiella spp.); and 8-16 mm (Pseudomonas spp.). Particles synthesized by physical pulsed laser ablation formed equivalent zones of 9-24 mm, 8-16 mm, 9-17 mm, and 7-15 mm. A particularly notable result was the strain- and dose-dependent difference identified by one-way ANOVA (F = 3304.3, p < 1 × 10⁻¹²) at 1000 μg/mL for chemical SeNPs. Anticancer activity was evaluated against CaCo-2 colon adenocarcinoma cells using the MTT assay. Chemically synthesized SeNPs were found to reduce viability from 90 ± 4.5% (6.25 μg/mL) to 18 ± 1.1% (200 μg/mL) with an IC₅₀ of approximately 57 μg/mL (R² = 0.996). Physically prepared SeNPs were found to have viability ranging from 91.8% to 33.3%, with an IC₅₀ value of approximately 36 μg/mL. The Pearson correlation between log [dose] and viability was found to be highly negative (r = - 0.979 to - 0.992, p < 0.001). Overall, SeNPs exhibited dose-dependent antibacterial activity (> 27 mm inhibition) and anticancer activity (IC₅₀ ≤ 57 μg/mL), with the synthesis route affecting efficacy. These quantitative observations confirm the SeNPs' potential as multifunctional nanotherapeutics, necessitating in vivo studies to definitively determine pharmacokinetics (PK), safety, and mechanistic pathways.