Does nanoparticle activity depend upon size and crystal phase? (original) (raw)
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Oxidative Stress on Human Cells in the Presence of Nano-Sized Titanium Dioxide
Nanosized TiO 2 (nanoTiO 2) is one of the most widely used nanomaterials, with applications ranging from paints, self-cleaning coatings, pharmaceuticals, to food and cosmetics. In spite of this massive use of nanoTiO 2 , its biological activity and toxicity remains subject of the intense debate. In particular, there is still considerable uncertainty in the current understanding of the relationship between physico-chemical parameters of nanoTiO 2 , such as crystalline phase, size, aspect ratio, surface properties, surface defects and surface chemistry and its potential toxicological effects. Motivated by this general problem, this thesis provides a multidisciplinary experimental insight into to the toxicity and photo-toxicity of various forms of nanoTiO 2. Firstly, since all of the widely accepted models of nanoTiO 2 toxicity involve reactive oxygen species (ROS), electron spin resonance (ESR) in combination with spintrapping was used to measure ROS formation efficiency for the two most industrially important polymorphs of TiO 2 , anatase and rutile. The study was performed in an unprecedentedly broad range of particle sizes: 3.8 nm to 150 nm and 5 nm to 215 nm, for anatase and rutile nanoTiO 2 , respectively. Moreover, the photocatalytic and toxic properties of custom-made anatase-based TiO 2 nanowires (with a diameter of 35 nm and a length of 0.5-1 μm) were characterized for the first time. For pure anatase nanoTiO 2 , the maximum ROS generation efficacy was found for nanoparticle sizes in the range of 25-30 nm. The ROS generation efficacy of the custom-made TiO 2 nanowires was ca. 30% lower, being close to that of the commercial anatase nanoTiO 2 with primary grain sizes of 5.3 nm. Secondly, this thesis addressed challenging, complex and still poorly understood processes occurring when nanoTiO 2 particles are brought into contact with living cells. In particular, the comparative nanotoxicity study towards human melanoma Lu1205 and WM793 cell lines was performed for three selected nanomaterials: the custom-made anatase-based TiO 2 nanowires, the commercial anatase nanoTiO 2 with a primary particle size of 5.3 nm and similar in vitro ROS formation efficacy, and the industrial photocatalytic standard, P25 Degussa (a formulation consisting of 80% anatase and 20% rutile, with primary grain sizes of 25 nm). This comparative nanotoxicity study was performed using very low concentrations of nanoTiO 2 (2-2.5 μg/mL), considerably lower than that applied in the majority of previous ex vivo cell culture studies.
Materials Sciences and Applications, 2021
Recently, under the circumstances of pandemic of COVID-19 much attention has been paid to titanium dioxide TiO2 as bactericidal agent; however, conventional TiO2 requires ultraviolet radiation or visible light to exercise its photocatalytic properties and its induced antimicrobial activity. In order to expand its applications directed at wide civil life, antibacterial TiO2 being usable under dark conditions has been demanded. The present paper describes the powder characterization of newly developed potassium K and phosphorous P co-doped nanometer-size anatase TiO2 powders using X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM & TEM), Brunauer-Emmett-Teller method (BET), fourier-transform infrared spectroscopy (FT-IR), X-ray absorption fine structure (XAFS), electron spin resonance (ESR) and chemiluminescence (CL). It was found for the first time that thus prepared anatase TiO2 could submit much reactive oxygen species (ROS) even in the dark, which has c...
Environmental Monitoring and Assessment, 2020
Assessing the environmental hazard of nanoparticles can be a challenging task using various testing strategies. However, to our knowledge, no information is available about the impact of the sample preparation on the toxicity and toxicity mechanism of nanoparticles. For this aim, three sample preparation methods and their available toxicity procedures were conducted to examine the (eco) toxicity of TiO 2 nanoparticles using bacteria model system. To detail understanding of the effect of sample preparation, the key events on the inhibition were examined by physicochemical and antioxidant responses. The findings showed that the physicochemical and toxicological behavior of the tested TiO 2 NPs varied according to the sample preparation method.
Nanomaterials
Titanium dioxide nanoparticles (TiO2NPs) are increasingly used in consumer products, industrial and medical applications, raising concerns on their potential toxicity. The available in vitro and in vivo studies on these NPs show controversial results. Crystalline structure is the physicochemical characteristic that seems to influence mainly TiO2NPs toxicity, so its effect needs to be further studied. We aimed to study whether and how crystalline form influences potential cyto-genotoxic and inflammatory effects induced by two commercial TiO2NPs (TiO2-A, mainly anatase; TiO2-B, mainly rutile) in human alveolar A549 and bronchial BEAS-2B cells exposed to 1–40 µg/mL. Cell viability (WST-1), membrane damage (LDH release), IL-6, IL-8 and TNF-α release (ELISA) and direct/oxidative DNA damage (fpg-comet assay) were evaluated. Physicochemical characterization included analysis of crystalline form (TEM and XRD), specific surface area (BET), agglomeration (DLS) and Z-potential (ELS). Our resul...
The potential health challenges of TiO 2 nanomaterials
Titanium dioxide (TiO 2 ) nanomaterials (NMs) have found widespread applications owing to their attractive physical and chemical properties. As a result, the potential adverse impacts of nano-TiO 2 exposure on humans have become a matter of concern. This review presents the state-of-the-art advances on the investigations of the adverse effects of NMs, including the potential exposure routes of nano-TiO 2 (e.g. respiratory system, skin absorption and digestive system), the physico-chemical characterizations of nano-TiO 2 (e.g. crystal structure, shape,size, zeta potential, treatment media, aggregation and agglomeration tendency, surface characteristics and coatings), risk evaluation of nanotoxicity (e.g. cytotoxicity, ecotoxicity, phototoxicity, and phytotoxicity) and potential mechanisms of adverse effects (e.g. generation of reactive oxygen species, oxidative stress and organelle dysfunction). The review aims to facilitate scientific assessments of health risks to nano-TiO 2 , which would guide the safe applications of NMs in our daily life.
Chemical synthesis, Spectral Characterization and Invitro biological study of TiO 2 nanoparticles
In this present investigation, we purely demonstrated the synthesis and characterization of Titanium Oxide Nanoparticles by adopting wet chemical method. The prepared Titanium Oxide powder was synthesized from the precursor of potassium titanium oxalate and sodium hydroxide. This study mainly insists on the reducing property of prepared Titanium oxide nanoparticles thereby reducing the hydroxyl radicals and its optical characterization. It was experimentally strengthened by the following techniques such as Fourier transform infrared spectroscopy and X-ray diffraction. The XRD pattern clearly revealed that the prepared nanoparticles was exist in an Anatase phase. The surface texture and the size of the prepared nanoparticles can be examined through the Field Emission Scanning Electron Microscopy and the percentage composition of metal and oxygen present in the prepared Titanium oxide nanoparticles can be precised from the Energy Dispersive X-ray Analysis and elemental mapping.
A multi-integrated approach on toxicity effects of engineered TiO2 nanoparticles
Frontiers of Environmental Science & Engineering, 2015
The new properties of engineered nanoparticles drive the need for new knowledge on the safety, fate, behavior and biologic effects of these particles on organisms and ecosystems. Titanium dioxide nanoparticles have been used extensively for a wide range of applications, e.g, self-cleaning surface coatings, solar cells, water treatment agents, topical sunscreens. Within this scenario increased environmental exposure can be expected but data on the ecotoxicological evaluation of nanoparticles are still scarce. The main purpose of this work was the evaluation of effects of TiO 2 nanoparticles in several organisms, covering different trophic levels, using a battery of aquatic assays. Using fish as a vertebrate model organism tissue histological and ultrastructural observations and the stress enzyme activity were also studied. TiO 2 nanoparticles (Aeroxide® P25), two phase composition of anatase (65%) and rutile (35%) with an average particle size value of 27.6AE11 nm were used. Results on the EC 50 for the tested aquatic organisms showed toxicity for the bacteria, the algae and the crustacean, being the algae the most sensitive tested organism. The aquatic plant Lemna minor showed no effect on growth. The fish Carassius auratus showed no effect on a 21 day survival test, though at a biochemical level the cytosolic Glutathione-S-Transferase total activity, in intestines, showed a general significant decrease (p < 0.05) after 14 days of exposure for all tested concentrations. The presence of TiO 2 nanoparticles aggregates were observed in the intestine lumen but their internalization by intestine cells could not be confirmed.
Influence of the chemical synthesis on the physicochemical properties of N-TiO2 nanoparticles
Catalysis Today, 2013
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Nanotoxicology, 2014
Increasing the production and applications of TiO 2 nanoparticles (NPs) has led to grow concerns about the consequences for the environment. In this study, we investigated the effects of a set of TiO 2 NPs on the viability of mussel hemocytes and gill cells using neutral red and thiazolyl tetrazolium bromide assays. For this, we compared the cytotoxicity of TiO 2 NPs (0.1-100 mg Ti/L) produced by different techniques: rutile NPs (60 nm) produced by milling and containing disodium laureth sulfosuccinate (DSLS), rutile NPs (10, 40 and 60 nm) produced by wet chemistry and anatase/rutile NPs ($100 nm) produced by plasma synthesis. The commercially available P25 anatase/rutile NPs (10-20 nm) were also tested. Exposures were performed in parallel with their respective bulk forms and the cytotoxicity of the additive DSLS was also tested. Z potential values in distilled water indicated different stabilities depending on the NP type and all NPs tested formed agglomerates/aggregates in cell culture media. In general, TiO 2 NPs showed a relatively low and dose-dependent toxicity for both cell models with the two assays tested. NPs produced by milling showed the highest effects, probably due to the toxicity of DSLS. Size-dependent toxicity was found for NPs produced by wet chemistry (10 nm440 nm and 60 nm). All TiO 2 NPs tested were more toxic than bulk forms excepting for plasma produced ones, which were the least toxic TiO 2 tested. The mixture bulk anatase/rutile TiO 2 was more toxic than bulk rutile TiO 2 . In conclusion, the toxicity of TiO 2 NPs varied with the mode of synthesis, crystalline structure and size of NPs and can also be influenced by the presence of additives in the suspensions.
Crystal structure mediates mode of cell death in TiO 2 nanotoxicity
J Nanopart Res, 2009
Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface area, and surface chemistry. Early nanotoxicity studies evaluating TiO 2 have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO 2 toxicity. However, it is important to note that none of these studies examined size with the crystal structure composition controlled for or examined crystal structure while controlling the nanoparticle size. The goal of this study was to evaluate the role of size and crystal structure in TiO 2 nanotoxicity while controlling for as many other nanoproperties as possible using the HEL-30 mouse keratinocyte cell line as a model for dermal exposure. In the size-dependent studies, all the nanoparticles are 100% anatase, and aggregate sizes were determined in order to take into account the effect of agglomeration on size-dependent toxicity. In addition, varying crystal structures were assessed while the size of the nanoparticles was controlled. We were able to identify that both size and crystal structure contribute to cytotoxicity and that the mechanism of cell death varies based on crystal structure. The 100% anatase TiO 2 nanoparticles, regardless of size, induced cell necrosis, while the rutile TiO 2 nanoparticles initiated apoptosis through formation of reactive oxygen species (ROS).