Photocatalytic Fe-doped n-TiO2: From synthesis to utilization of in vitro cell models for screening human and environmental nanosafety

The utilization of different types nanomaterials (NMs) in environmental remediation and wastewater treatment requires information on the potential harmful effects on human and environmental health. In this light, the utilization of human cell models together with cells from lower organisms, representative of different environmental compartments, could represent a valuable tool for the in vitro screening of the potential toxicity of different NMs used in nanoremediation. Among NMs, n-TiO2, because of its peculiar optical and chemical properties, is widely applied for photosensitized UV oxidation of organic pollutants. Moreover, development in design of metal- and non metal- doped TiO2 with extended photocatalytic activity in the visible region represents the subject of ongoing research. In this work, the cytotoxic effects of three different types of recently synthetized Fe-doped n-TiO2 were compared in two cell models widely utilized for screening cellular toxicity of NMs in humans and aquatic organisms, human vascular endothelial cells (HECV) and immune cells (hemocytes) of the marine invertebrate, the mussel Mytilus spp, respectively. Parallel studies were carried out using N-doped n-TiO2. The results indicate both distinct and common behavior (agglomeration state) in different media (human cell culture medium and mussel hemolymph serum) and biological effects (cytotoxicity, nitric oxide production) of different types of doped- n-TiO2 in different cell models. Although in vitro studies represent a first step in the toxicological assessment of NMs, studies comparing their effects on human and aquatic invertebrate cells that take into account the effects of different exposure media represent an useful tool for evaluating potential cytotoxicity of those NMs, like TiO2-based photocatalytic NMs, widely applied in environmental remediation, and whose potential risks are poorly understood.