Nanoparticles have been widely used in various fields due to the superior physicochemical properties and functions. As a result, human exposure to nanoparticles increases dramatically. Previous researches have shown that nanoparticles could travel through the respiratory, digestive system, or skin into the blood and then to the secondary organs such as the brain, heart, and liver. Besides, the nanoparticle toxicity is controversial and dependent on the sensitivity of the cell type, route of exposure, and condition, as well as their characteristics. Similarly, cobalt ferrite nanoparticles (CoFeO-NPs) have been used in different industrial fields, and have also various application possibilities in medical and biomedical fields. CoFeO-NPs induce toxic responses in various organisms such as human, mice, and algae. However, there is a serious deficit of information concerning their effects on human health and the environment. We aimed to investigate the toxic effects of CoFeO-NPs on liver (HepG2), colon (Caco-2), lung (A549), and neuron (SH-SY5Y) cells, which reflect different exposure routes in vitro, by using various toxicological endpoints. The cytotoxicity, genotoxicity, oxidative damage, and apoptosis induction of CoFeO-NPs (39 ± 17 nm) were evaluated. After 24 h, the nanoparticles decreased cell viability at ≤100 μg/mL, while increasing viability at >100 μg/mL. CoFeO-NPs induced DNA and oxidative damage with increased malondialdehyde (MDA) and 8-hydroxy deoxyguanosine (8-OHdG) levels and decreased glutathione (GSH) levels with no change in protein carbonyl (PC) levels. CoFeO-NPs had apoptotic effect in HepG2 and Caco-2 cells in a concentration-dependent manner and necrotic effects on SH-SY5Y and A549 cells. Consequently, the adverse effects of CoFeO-NPs should raise concern about their safety in consumer products.

Cobalt oxide (CoO) nanoparticles have applications in nanomedicine and nanotechnology; therefore, any possible adverse effects require thorough investigation. The present study investigated the effects of CoO nanoparticles on four different cell lines: liver, HepG2 hepatocellular carcinoma cells; lung, A549 lung carcinoma cells; gastrointestinal, Caco-2 colorectal adenocarcinoma cells; and nervous system, SH-SY5Y neuroblastoma cells. A difference was observed in cell sensitivity toward CoO nanoparticles. CoO nanoparticles were taken up by all the cell types. However, no cell death was observed in HepG2, Caco-2, or SH-SY5Y cells; only A549 cells showed cytotoxicity at relatively high exposure concentrations. CoO nanoparticles did not induce DNA damage or apoptosis in the cell lines tested except in A549. Interestingly, CoO nanoparticles induced cellular oxidative damage in all cell types except Caco-2, resulting in increased malondialdehyde and 8-hydroxydeoxyguanosine levels and decreased glutathione levels. According to our results, it could be indicated that high concentrations of CoO nanoparticles affected the pulmonary system but were unlikely to affect the liver, nervous system, or gastrointestinal system. CoO nanoparticles might be safely used for industrial, commercial, and nanomedical applications if dose rates are adjusted depending on the route of exposure. However, further in vivo and in vitro studies are required to confirm the safety of CoO nanoparticles.

ÖZAmaç: Sert manyetik kobalt ferrit nanopartiküllerinin (CoFe 2 O 4 -NP) dikkate değer özellikleri ve fizikokimyasal kararlılıkları farklı endüstri ve tıp alanlarında çeşitli uygulamalarda kullanılmalarına yol açmaktadır. CoFe 2 O 4 -NP'lerin bazı toksik etkilere neden olduğu bildirilmiş olsa da böbrek üzerindeki etkileri hakkında ciddi bilgi eksikliği vardır. Bu çalışmada, CoFe 2 O 4 -NPs'lerinin NRK-52E böbrek hücreleri üzerine toksik etki potansiyellerinin araştırılması amaçlanmıştır. Gereç ve Yöntemler: Partikül karakterizasyonu ve hücresel alım transmisyon elektron mikroskopu, dinamik ışık saçılma tekniği ve indüktif eşleştirilmiş plazma-kütle spektrometrisi ile gerçekleştirildi. Sonra, sitotoksisite MTT ve nötral kırmızı alım testi, genotoksisite comet tekniği ve apoptotik potansiyel propidyum iyodürlü Annexin V-FITC apoptoz tayini ile değerlendirildi. Bulgular: CoFe 2 O 4 -NP'lere (39±17 nm) 100-1000 μg/mL arasında değişen konsantrasyonlarda 24 saat süre ile maruz bırakılan böbrek hücrelerinde hücre canlılığının etkilenmediği, ancak ≤100 μg/mL'de önemli ölçüde DNA hasarı meydana geldiği gözlenmiştir. Maruz kalan hücrelerde apoptotik veya nekrotik etki gözlenmedi. Sonuç: Elde edilen sonuçlara göre, CoFe 2 O 4 -NP'ler çeşitli uygulamalarda güvenli kullanımı vaat etmektedir. Bununla birlikte, etki mekanizmalarının tam olarak anlaşılabilmesi için in vivo çalışmalara ihtiyaç vardır. Anahtar kelimeler: DNA hasarı, hücre ölümü, apoptoz, kobalt ferrit nanopartikülü Objectives: The remarkable properties of hard magnetic cobalt ferrite nanoparticles (CoFe 2 O 4 -NPs) and their physicochemical stability lead to various applications in different industrial and medical fields. Although CoFe 2 O 4 -NPs have been reported to cause toxic effects, there is a serious lack of information concerning their effects on the kidneys. In this study, it was aimed to investigate the toxic effects of CoFe 2 O 4 -NPs on NRK-52E kidney cells. Materials and Methods: The particle characterisation and cellular uptake were determined using transmission electron microscopy, dynamic light scattering and inductively coupled plasma-mass spectrometry. Then, the cytotoxicity was evaluated by MTT and neutral red uptake assays, the genotoxicity by comet assay, and the apoptotic potentials by Annexin V-FITC apoptosis detection assay with propidium iodide. Results: After 24 h exposure to CoFe 2 O 4 -NPs (39±17 nm), it was observed they did not affect the cell viability at concentration ranging from 100 to 1000 μg/mL, but significantly induced DNA damage at concentration ≤100 μg/mL. No apoptotic or necrotic effect was observed in the exposed cells. Conclusion: According to the results obtained, CoFe 2 O 4 -NPs are promising for safe use in various applications. However, further in vivo studies are needed to fully understand their mechanisms of action.

Cobalt oxide (Co 3 O 4 ) nanoparticles have been extensively used in various industrial and medical applications due to their special optical, magnetic, and electrical activity features. However, there is a lack of information about their toxicity and adverse effects on human health, especially concerning the kidney, which is considered to be a secondary target organ. We investigated the toxic potentials of Co 3 O 4 nanoparticles on NRK-52E kidney epithelial cells by in vitro assays. Co 3 O 4 nanoparticles were taken up by the kidney cells, and caused a decrease in cell viability, by significantly inducing apoptosis/ necrosis at 100 µg/mL. However, no significant DNA damage was observed. Co 3 O 4 nanoparticles induced cellular toxicity in kidney cells. These results should raise concern about the safety of Co 3 O 4 nanoparticles in their various applications. Further studies are needed to elucidate their toxic mechanism.

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