Biological applications of nanoparticles produced by laser ablation method

Abstract

Pulsed laser ablation in liquid (PLAL) is a promising top-down approach for nanoparticle production and it allows production of wide variety of nanoparticles such as metal, metal oxide, nitride and semiconductor nanocrystals. PLAL has numerous advantages compared to other nanoparticle production methods such as successful production of colloidal, pure and contamination-free nanoparticles. Pulsed laser ablation method was used for the production of a number of dierent nanoparticles both in liquids and gas environments. Moreover, both powder and bulk starting materials were employed for nanoparticle production. In the context of nanoparticle production and characterization, a systematic study for indium nitride nanocrystal (InN-NC) production was completed. The road-map for the production of ultra-smal hexagonall InN-NCs (<5 nm in diameter) was demonstrated to be produced from InN powder target in ethanol by using PLAL technique. A real time nanoparticle exposure setup was designed and developed to reveal the health risks of laser material processing in the industry. In our study, adolescent rats were exposed to copper, tin and aluminum nanoparticles (CuNP, SnNP and AlNP, respectively) in the real-time exposure setup. We aimed to demonstrate the distribution of nanoparticles in the body by exposing the rats to the laser material processing environment. For this purpose, we dened the amount and characteristics of nanoparticles released during material processing by laser ablation. We also showed the eect of nanoparticles on learningmemory and mood of rats exposed to those nanoparticles via behavioral tests, electrophysiological and molecular methods. ICP-MS and TEM analysis revealed the presence of nanoparticles in almost all organs, including dierent regions of brain, indicating nanoparticles gained access to systemic circulation by inhalation. Both behavioral tests and in vivo electrophysiology experiments revealed that 3 months of CuNP, SnNP and AlNP exposure did not lead to any alterations in the learning and memory process of the rats. In hippocampi collected from rats exposed to SnNP and AlNP, the expression levels of NMDA receptor subunits, namely NMDAR1 and NMDAR2a, were found to be increased, and the protein levels of NMDAR1 decreased upon CuNP exposure. On the other hand, the toxicity of nanoparticles produced by pulsed laser ablation method in liquids was investigated for silver nanoaparticles (AgNPs) in hippocampal slices and CuNP, SnNP and AlNP nanoparticles in SH-SY5Y cell line in in vitro conditions. The cellular uptake mechanism of pure AgNPs was demonstrated as phagocytosis. Furthermore, AgNP led to dose-dependent toxicity in hippocampal slices. laser ablation is a considerably useful method for studying nanoparticle toxicity since it provides pure nanoparticles mimicking the ones encountered in the industry. Finally, it was shown that CuNP, SnNP and AlNP led to a dose-dependent cytotoxicity in SH-SY5Y cells. Moreover, it was shown that NMDAR subunits NMDAR1 and NMDAR2a mRNA expressions and NMDAR1 protein levels were altered after CuNP, SnNP and AlNP administration. This study showed, for the first time in the literature, that the nanoparticles produced during the laser material processing in the atmospheric environment are taken into the body via inhalation. These nanoparticles are distributed to a number of organs including lung, heart, liver, kidney, testis and so on. Moreover, these nanoparticles were detected in different brain regions, which indicates the severity of the risk for the people working in these industrial fields. We did not observe significant alterations in behavioral and electrophysiological evaluations in 3 months. However, in long-term exposures, accumulation of nanoparticles in brain may impose a high risk for dementias and mental disorders since these nanoparticles are made up of heavy metals which were shown to cause neurodegeneration.