Читать книгу Sustainable Nanotechnology - Группа авторов - Страница 51

For the preparation of NMs, various metals, polymeric materials, and bioceramics have been used. For medical purpose, phospholipids, PEG, and natural polymers have been used for formulation. It is the phospholipid that makes NMs compatible with the human tissue as the cell walls are made up of the same phospholipid. The composition of ethosomes has made it possible for them to enter through the skin from the space smaller than their own diameter by deforming the structure. One important report on the effect of composition of NPs on few species having vital role in trophic levels showed that the nanosilver and nanocopper with their soluble forms caused toxicity in all tested organisms, whereas TiO₂ of the same dimensions did not cause any toxicity issues [41]. Crystal form of NPs also influences the toxicity, and it has been reported that crystalline TiO₂NPs show toxicity in the absence of light including oxidative DNA injury, whereas NPs of metastable form of the same material with the same size and chemical composition do not show such toxicity [25]. In one more report, the cytotoxicity was previously claimed due to the size and then due to ultrahigh reactivity of NMs itself [42]. Several such materials of composition, viz., metals, aluminum oxide, gold, copper oxide, silver, zinc oxide, iron oxide, and titanium oxide; nonmetals, such as carbon and silica; and polymeric materials, have shown toxicity not only in animals and humans but also in nature [43].