Laser Ablation In Deionized Water Research Articles

Silver Nanoparticles Produced by Laser Ablation and Re-Irradiation Are Effective Preventing Peri-Implantitis Multispecies Biofilm Formation

Implant-associated infection due to biofilm formation is a growing problem. Given that silver nanoparticles (Ag-NPs) have shown antibacterial effects, our goal is to study their effect against multispecies biofilm involved in the development of peri-implantitis. To this purpose, Ag-NPs were synthesized by laser ablation in de-ionized water using two different lasers, leading to the production of colloidal suspensions. Subsequently, part of each suspension was subjected to irradiation one and three times with the same laser source with which it was obtained. Ag-NPs were immobilized on the surface of titanium discs and the resultant materials were compared with unmodified titanium coupons. Nanoparticles were physico-chemically analysed to determine their shape, crystallinity, chemical composition, and mean diameter. The materials were incubated for 90 min or 48 h, to evaluate bacterial adhesion or biofilm formation respectively with Staphylococcus aureus or oral mixed bacterial flora composed of Streptococcus oralis, Actinomyces naeslundii, Veionella dispar, and Porphyromonas gingivalis. Ag-NPs help prevent the formation of biofilms both by S. aureus and by mixed oral bacterial flora. Nanoparticles re-irradiated three times showed the biggest antimicrobial effects. Modifying dental implants in this way could prevent the development of peri-implantitis.

Inhibition of Candida albicans biofilm by pure selenium nanoparticles synthesized by pulsed laser ablation in liquids

Selenoproteins play an important role in the human body by accomplishing essential biological functions like oxido-reductions, antioxidant defense, thyroid hormone metabolism and immune response; therefore, the possibility to synthesize selenium nanoparticles free of any contaminants is exciting for future nano-medical applications. This paper reports the first synthesis of selenium nanoparticles by femtosecond pulsed laser ablation in de-ionized water. Those pure nanoparticles have been successfully used to inhibit the formation of Candida albicans biofilms. Advanced electron microscopy images showed that selenium nanoparticles easily adhere on the biofilm, then penetrate into the pathogen, and consequently damage the cell structure by substituting with sulfur. 50% inhibition of Candida albicans biofilm was obtained at only 25 ppm. Finally, the two physical parameters proved to affect strongly the viability of Candida albicans are the crystallinity and particle size.

Blue luminescent silicon nanocrystals prepared by nanosecond laser ablation and stabilized in electronically compatible spin on glasses

We investigated the blue luminescent silicon nanocrystal (Si-nc) preparation in liquid spin on glass (SOG) by nanosecond laser ablation of the Si target in SOG. The confinement of laser-generated plasma in liquids significantly enhanced the formation of Si-nc. Furthermore, the silicon-dioxide-based SOG inhibited Si-nc aggregation compared to the case of laser ablation in de-ionized water. The silicon-dioxide-based SOG during the solidification process accelerated Si-ncs surface oxidation and passivation. As a result, visible room temperature photoluminescence (PL) of stabilized Si-ncs in solid SOG was achieved with a maximum located at 2.9eV. This PL spectrum was very similar to that from the Si-nc colloidal solution obtained by laser ablation of the Si target and subsequent aging for six months in de-ionized water. The mathematical description of dynamical Si-nc formation processes within laser plasma confined by liquid SOG was applied to qualitatively describe the obtained results. A Si-nc formation scheme could be described as serial processes of rapid formation and growth of embryotic Si particles, consecutive quick oxidation in SOG, and growth termination by quenching. The quantum confinement size effect and surface∕defect states in the surrounding silicon oxide were responsible for efficient blue PL. The solidification of Si-nc in SOG solution enabled the formation of self-supporting films with well-defined Si-nc concentrations that could be simply varied by laser fluence. The controllability of blue luminescent intensity from a film by laser fluence during laser ablation is of significance for optoelectronic applications.