Laser re-irradiation of palladium nanoparticles for antibacterial applications

Bacterial resistant infections represent the second leading cause of mortality worldwide, being responsible for almost the 14% of the global deaths according to figures of 2019. Nanoparticles of noble metals have received special attention because of their outstanding bactericidal activity, that is intrinsically linked to their physico-chemical properties, an asset that makes them an appealing alternative to combat resistant microorganisms. So as to optimize their applications within the biomedical field, it becomes relevant to develop and employ means to influence and act upon nanoparticles’ physico-chemical characteristics. In this research, palladium nanoparticles were synthesized via laser ablation. A nanosecond Nd:YVO4 laser operating at 532 nm was employed to ablate a palladium target immersed in deionized water in order to obtain the colloidal suspension. Then, the previous suspension was passed twice through a re-irradiation system to narrow the size and size distribution of palladium nanoparticles. Bacterial assays with Staphylococcus aureus revealed an effect of size on the bactericidal behaviour of palladium nanoparticles.