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Abstract

Engineered nanofibers and nanoparticles are recognized as capable of inducing cellular perturbations according to the oxidative stress paradigm or by interacting directly with biological membranes. A number of authors in their investigations with the nanofibres and nanoparticles has reported the ability of nanofibers and nanotparticle to cause the different damage on the structure and function of the cells, tissues and organisms. The cell membrane, mitochondria and cell nucleus are considered as major cell compartments relevant for possible nanoparticle-induced toxicity. When nanofibers and nanoparticles interact with cell membranes, they cause defects such as physical disruptions, formation of holes and thinned regions. It was reported that cationic nano-objects pass through cell membranes by generating transient holes, a process undoubtedly associated with cytotoxicity. It is known that a range of nanofibres and nanoparticle affects in in vitro exposed systems the phagocytic ability of the cells.
Examples include the cytotoxicity to rat lung alveolar macrophages, human dermal fibroblast and human lung carcinoma cells, hepatic injury in mice, pathologic changes of gills in fish, decreasing of production and activity in some enzymes such as catalaza and glutathione-S- transferaza etc.
In many articles was proved that nanofibers and nanoparticle can negative impact to cells, tissues and organisms. Some of the effects were observed also in the aquatics environments.
The aim of this study was to test the effect of nanofibres and nanoparticles, ingested with food on test organism. After the study we will be able to answer in some questions:
a) Do ingested nanofibers or nanoparticle cause morphological defaces of gland cell epithelium cells like: shape changes of cells, changes of the cells size, loss of microvilli, loss of lipid droplets etc:
b) After how long these interactions will be detected, which is the minimal dose and exposed time that can affects in the cells morphology or in the digestive system.
For this study we used the Porcellio scaber Latreille,(1809, Isopoda, Crustaceae) as a test organism. Terrestrial isopods were already used in testing effects of ingested nanofibers and nanoparticles in many researches.
The animals were collected from the different unpolluted areas near Ljubljana city. Animals were collected in gardens under concrete blocks, pieces of decaying wood, and other organic wastes. The animals from each location were kept in separate glass tanks containing soil and leaf litter from their natural environment and at high relative humidity for the acclimatization.
The hepatopancreas of control and exposed group of animals after the dissection were prepared for SEM by the standard protocol for biological samples. Biological samples prepared for SEM need to be fixed and dried because of the high vacuum in the specimen chamber; they need to be additionally covered by gold conductive nanolayer to ensure good contrast of the images. Due to very high resolution of FEG-SEM it is expected that possible morphological changes in cell structures caused by nanofibres and nanoparticles will be observed and explained. A Field Emission Gun Scanning Electron Microscope (FEG-SEM) provides high spatial resolution and can operate at low accelerating voltage which makes it indispensable for biological examination.
Data obtained from the experiment with nanofibers have shown that nanofibers interact with digestive gland epithelial cells. They can cause a different changes in the structure of the surface epithelium such are: interaction with the membranes, penetration in the cells, makes a hole ect. Data obtained from the experiment with nanoparticles have shown that nanoparticles have caused morphological changes on surface microvilli of cells.
Studying the interaction between nanofibres and nanoparticles with cells in in vivo experiment could significantly contribute to the science and understanding of bio-nano interactions. Allso the dose and the time of exposed will be very significant to certain the limit value of this material in some products. This knowledge will contribute to assess the safety aspect of nanomaterials and use of them in the human life. In this case the interactions were detected and documented. A further bio-nanointeraction studies as well as toxicity studies will be needed to be sure for the potential of nanofiber and nanoparticles to interact and cause changes in different organisms.