Systemic Inflammation and the Breakdown of Intestinal Homeostasis Are Key Events in Chronic Spinal Cord Injury Patients

Our aim was to investigate the subset distribution and function of circulating monocytes, proinflammatory cytokine levels, gut barrier damage, and bacterial translocation in chronic spinal cord injury (SCI) patients. Thus, 56 SCI patients and 28 healthy donors were studied. The levels of circulating CD14^+highCD16⁻, CD14^+highCD16⁺, and CD14^+lowCD16⁺ monocytes, membrane TLR2, TLR4, and TLR9, phagocytic activity, ROS generation, and intracytoplasmic TNF-α, IL-1, IL-6, and IL-10 after lipopolysaccharide (LPS) stimulation were analyzed by polychromatic flow cytometry. Serum TNF-α, IL-1, IL-6 and IL-10 levels were measured by Luminex and LPS-binding protein (LBP), intestinal fatty acid-binding protein (I-FABP) and zonulin by ELISA. SCI patients had normal monocyte counts and subset distribution. CD14^+highCD16⁻ and CD14^+highCD16⁺ monocytes exhibited decreased TLR4, normal TLR2 and increased TLR9 expression. CD14^+highCD16⁻ monocytes had increased LPS-induced TNF-α but normal IL-1, IL-6, and IL-10 production. Monocytes exhibited defective phagocytosis but normal ROS production. Patients had enhanced serum TNF-α and IL-6 levels, normal IL-1 and IL-10 levels, and increased circulating LBP, I-FABP, and zonulin levels. Chronic SCI patients displayed impaired circulating monocyte function. These patients exhibited a systemic proinflammatory state characterized by enhanced serum TNF-α and IL-6 levels. These patients also had increased bacterial translocation and gut barrier damage.     

Titanium Dioxide Nanoparticles Exacerbate Allergic Airway Inflammation via TXNIP Upregulation in a Mouse Model of Asthma

Titanium dioxide nanoparticles (TiO₂NPs) are widely used in industrial and medicinal fields and in various consumer products, and their increasing use has led to an increase in the number of toxicity studies; however, studies investigating the underlying toxicity mechanism have been rare. In this study, we evaluated potential toxic effects of TiO₂NPs exposure on lungs as well as the development of asthma through the ovalbumin (OVA)-induced mouse model of asthma. Furthermore, we also investigated the associated toxic mechanism. TiO₂NPs caused pulmonary toxicity by exacerbating the inflammatory response, indicated by an increase in the number and level of inflammatory cells and mediators, respectively. OVA-induced asthma exposed mice to TiO₂NPs led to significant increases in inflammatory mediators, cytokines, and airway hyperresponsiveness compared with those in non-exposed asthmatic mice. This was also accompanied by increased inflammatory cell infiltration and mucus production in the lung tissues. Additionally, TiO₂NPs decreased the expression of B-cell lymphoma 2 (Bcl2) and the expressions of thioredoxin-interacting protein (TXNIP), phospho-apoptosis signal-regulating kinase 1, Bcl2-associated X, and cleaved-caspase 3 were escalated in the lungs of asthmatic mice compared with those in non-exposed asthmatic mice. These responses were consistent with in vitro results obtained using human airway epithelial cells. TiO₂NPs treated cells exhibited an increase in the mRNA and protein expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α with an elevation of TXNIP signaling compared to non-treated cells. Moreover, pathophysiological changes induced by TiO₂NP treatment were significantly decreased by TXNIP knockdown in airway epithelial cells. Overall, TiO₂NP exposure induced toxicological changes in the respiratory tract and exacerbated the development of asthma via activation of the TXNIP-apoptosis pathway. These results provide insights into the underlying mechanism of TiO₂NP-mediated respiratory toxicity.     

EPA and DHA Exposure Alters the Inflammatory Response but not the Surface Expression of Toll‐like Receptor 4 in Macrophages

Dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and their respective enrichment in cell membranes have been negatively associated with atherosclerotic lesion development. This effect may be mediated, in part, by dampened inflammatory response of macrophages triggered by toll‐like receptor 4 (TLR4) activation. This study investigated the influence of membrane fatty acid profile on TLR4‐mediated inflammation in RAW 264.7 macrophages. Cells pretreated with myristic acid (MA), EPA, DHA or vehicle control for 24 h were stimulated with ultra‐pure LPS, a specific TLR4 agonist, for 6 or 24 h, corresponding to early and late stages of TNFα and IL‐6 protein induction. Treatment significantly increased cell membrane MA, EPA, and DHA by 4.5‐, 20.6‐, and 8.9‐fold, respectively. MA significantly increased IL‐6 secretion 6 h post‐exposure to the fatty acid, but did not change TNFα secretion in response to any other treatment condition. EPA and DHA significantly reduced TNFα secretion by 36 and 41 %, respectively, in cells stimulated for 24 h but not 6 h. In contrast, EPA and DHA significantly reduced IL‐6 secretion at both 6 h (67 and 72 %, respectively) and 24 h (69 and 72 %, respectively). MA or DHA treatment had no significant effect compared to vehicle on factors influencing cellular LPS recognition, including LPS‐cell association, and cell surface expression of TLR4, TLR4‐MD2 complex, and CD14. These data suggest that membrane fatty acid profiles influence the TLR4‐mediated inflammatory response in macrophages, via mechanisms that occur downstream of TLR4 receptor activation.     

The Relevance of Physico-Chemical Properties and Protein Corona for Evaluation of Nanoparticles Immunotoxicity—In Vitro Correlation Analysis on THP-1 Macrophages

Alongside physiochemical properties (PCP), it has been suggested that the protein corona of nanoparticles (NPs) plays a crucial role in the response of immune cells to NPs. However, due to the great variety of NPs, target cells, and exposure protocols, there is still no clear relationship between PCP, protein corona composition, and the immunotoxicity of NPs. In this study, we correlated PCP and the protein corona composition of NPs to the THP-1 macrophage response, focusing on selected toxicological endpoints: cell viability, reactive oxygen species (ROS), and cytokine secretion. We analyzed seven commonly used engineered NPs (SiO₂, silver, and TiO₂) and magnetic NPs. We show that with the exception of silver NPs, all of the tested TiO₂ types and SiO₂ exhibited moderate toxicities and a transient inflammatory response that was observed as an increase in ROS, IL-8, and/or IL-1β cytokine secretion. We observed a strong correlation between the size of the NPs in media and IL-1β secretion. The induction of IL-1β secretion was completely blunted in NLR family pyrin domain containing 3 (NLRP3) knockout THP-1 cells, indicating activation of the inflammasome. The correlations analysis also implicated the association of specific NP corona proteins with the induction of cytokine secretion. This study provides new insights toward a better understanding of the relationships between PCP, protein corona, and the inflammatory response of macrophages for different engineered NPs, to which we are exposed on a daily basis.     

Oleacein Attenuates Lipopolysaccharide-Induced Inflammation in THP-1-Derived Macrophages by the Inhibition of TLR4/MyD88/NF-κB Pathway †

It is known that plant phenolic compounds exert anti-inflammatory activity through both anti-oxidant effects and modulation of pivotal pro-inflammatory factors. Recently, Olea europaea has been studied as a natural source of bioactive molecules; however, few studies have focused on the biological effect of oleacein (OLC), the most abundant secoiridoid. Therefore, the aim of this study was to investigate the potential anti-oxidant activity of OLC, as well as to study its anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated THP-1-derived macrophages. LPS brought a dramatic increase of both release and gene expression of pro-inflammatory cytokines (IL-6, IL-1β and TNF-α), as well as a decrease of anti-inflammatory ones (IL-10), the effects of which are reverted by OLC. Moreover, it reduced the levels of COX-2, NO and PGE₂ elicited by LPS exposure in THP-1 macrophages. Interestingly, OLC modulated inflammatory signaling pathways through the inhibition of CD14/TLR4/CD14/MyD88 axis and the activation of NF-κB. Finally, OLC showed relevant anti-oxidant capability, assessed by abiotic assays, and reduced the intracellular amount of ROS generated by LPS exposure in THP-1 macrophages. Overall, these results suggest that the anti-oxidant activity and anti-inflammatory effect of OLC may cooperate in its protective effect against inflammatory stressors, thus being a possible alternative pharmacological strategy aimed at reducing the inflammatory process.     

An experimental and theoretical understanding of a UV photodetector based on Ag nanoparticles decorated Er-doped TiO2 thin film

Glancing angle deposition (GLAD) was employed to synthesise plasmonic Silver (Ag) nanoparticles (NPs) on the chemically prepared Erbium-doped Titanium dioxide (Er:TiO₂) thin films (TFs). The impact of using Ag NPs on the morphological, optical, and electrical aspects of Er:TiO₂ TFs were sequentially analysed. From the field emission scanning electron microscopy (FESEM) image, the Ag NPs appeared spherical and uniformly distributed on the Er:TiO₂ TFs. The size (diameter) of the maximum number of Ag NPs was ~15 nm (calculated from FESEM image). Energy dispersive X-ray (EDX) spectra assured the presence of Ag NPs on the TFs. X-ray diffraction (XRD) pattern for Ag NPs decorated Er:TiO₂ TFs closely resembled the face centred cubic crystal structure of Ag NPs and body centred tetragonal Ag–O compound. The optical spectroscopy (UV–visible diffuse reflectance and photoluminescence) elucidated that the absorption of light was significantly enhanced in the UV–visible spectral range for the TFs in which Ag NPs were sandwiched between Er:TiO₂ TF layers (Er:TiO₂/Ag NPs/Er:TiO₂). The Schottky contact-based Au/Er:TiO₂/Si photodetector (PD) and Au/Er:TiO₂/Ag NPs/Er:TiO₂/Si (plasmonic) PD were constructed. The plasmonic PD offered a better photo-responsivity of ~4.5 fold higher as compared to Er:TiO₂ TF-based PD upon 380 nm illumination under ?6 V bias. An increase in detectivity and a decrease in noise equivalent power was observed for the plasmonic device compared to Er:TiO₂ device in the UV region. A theoretical approach had been adopted to calculate the wavelength-dependent responsivity for both devices. Further, the important parameters like photoconductive gain, electron transit time and electron mobility were calculated by simulating the experimental responsivity curves of the devices. These parameters exhibited improvement in the UV regime for the plasmonic PD. The fast temporal response with short rise and decay time proves the excellent efficiency of the plasmonic UV PD.     

Construction of Au/TiO2 Heterojunction with high photocatalytic performances under UVA illumination

Anatase TiO₂ nanoparticles (NPs) were successfully prepared through a hydrothermal approach, and Au NPs at various Au (0.1–2 wt%) contents were photodeposited onto the TiO₂ NPs surface. The photocatalytic efficiency for the Au/TiO₂ NPs for resorcinol photodegradation throughout UVA illumination was assessed. The TEM images and XPS findings indicated that the Au NPs are highly distributed onto TiO₂ surface in the metallic state. The 0.1%Au/TiO₂ NPs exhibited the highest photocatalytic efficiency of about 95.34%; however, 72.36% is given by pure TiO₂ NPs. It was found that the photodegradation rate of 0.1% Au/TiO₂ NPs exhibited 1.5 times of magnitude higher than pure TiO₂ NPs. 0.1%Au/TiO₂ NPs was considered to be the outstanding photoactive due to the ultimate efficient charge-carriers separation through charge transfer between Au and TiO₂ NPs. The Au NPs sizes, its dispersity on TiO₂ surface and surface plasmon resonance (SPR) were believed the critical factors for the higher photocatalytic performance of 0.1% Au/TiO₂ NPs. The prepared photocatalysts are found to be the promising materials for toxic organic compounds remediation and solar conversion.     

Asbestos, carbon nanotubes and the pleural mesothelium: a review of the hypothesis regarding the role of long fibre retention in the parietal pleura, inflammation and mesothelioma

Background

Increasing environmental and occupational exposures to nanoparticles (NPs) warrant deeper insight into the toxicological mechanisms induced by these materials. The present study was designed to characterize the cell death induced by carbon black (CB) and titanium dioxide (TiO₂) NPs in bronchial epithelial cells (16HBE14o- cell line and primary cells) and to investigate the implicated molecular pathways.

Results

Detailed time course studies revealed that both CB (13 nm) and TiO₂(15 nm) NP exposed cells exhibit typical morphological (decreased cell size, membrane blebbing, peripheral chromatin condensation, apoptotic body formation) and biochemical (caspase activation and DNA fragmentation) features of apoptotic cell death. A decrease in mitochondrial membrane potential, activation of Bax and release of cytochrome c from mitochondria were only observed in case of CB NPs whereas lipid peroxidation, lysosomal membrane destabilization and cathepsin B release were observed during the apoptotic process induced by TiO₂ NPs. Furthermore, ROS production was observed after exposure to CB and TiO₂ but hydrogen peroxide (H₂O₂) production was only involved in apoptosis induction by CB NPs.

Conclusions

Both CB and TiO₂ NPs induce apoptotic cell death in bronchial epithelial cells. CB NPs induce apoptosis by a ROS dependent mitochondrial pathway whereas TiO₂ NPs induce cell death through lysosomal membrane destabilization and lipid peroxidation. Although the final outcome is similar (apoptosis), the molecular pathways activated by NPs differ depending upon the chemical nature of the NPs.     

Regulation of Immune Activation by Optical Control of TLR1/2 Heterodimerization

The activation of toll-like receptors (TLRs) plays important roles in the immune response. The ability to control the activities of TLRs could be usable as a switch for immune response. Here we have rationally designed and synthesized a photoswitchable Pam₃CSK₄ derivative— P10 —to control the activation of TLR1/2. The ground-state trans- P10 was able to stimulate and activate antigen-presenting cells (APCs) by promoting TLR1/2 heterodimerization. However, cis- P10 , derived from UV irradiation of trans- P10 , reduced the activities of APCs by impeding the TLR1/2 heterodimerization. In the absence of UV radiation, the cis- P10 slowly returned to its ground trans state, restoring the activities of the APCs stimulation. Our results indicated that optical control of TLR1/2 heterodimerization mediated by the photoswitchable P10 offers the potential to regulate immune activation and inflammation.     

Effect of surface modification of titanium dioxide on the UV-C aging behavior of silicone rubber

Surface modification of titanium dioxide (TiO₂) nanoparticles (NPs) by silane coupling agents and the ultraviolet-C (UV-C) aging behavior of silicone rubber (SiR) incorporated with the modified TiO₂ NPs were investigated in this work. The SiR samples incorporated with TiO₂ NPs displayed excellent stability against the UV-C radiation. In order to improve the dispersion of TiO₂ NPs in the SiR matrix, the surface of TiO₂ NPs was modified with 3-aminopropyl triethoxysilane and 3-trimethoxysilyl propyl methacrylate, respectively. The surface modification of TiO₂ NPs was characterized by thermal gravimetric analysis and Fourier transform infrared spectroscopy. The dispersion stability of the pristine TiO₂ NPs and surface silane-modified TiO₂ NPs was evaluated in an organic solvent (toluene). Effect of surface modified TiO₂ NPs on the UV-C aging behavior of SiR was evaluated in terms of the change of surface morphology, tensile properties, hardness, crosslinking density, and surface microstructure before and after the UV-C aging. The results showed that surface modification of TiO₂ NPs with silane coupling agents could improve the dispersion of TiO₂ NPs in the SiR matrix. Moreover, the SiR with modified TiO₂ NPs showed an improved aging resistance to the UV-C radiation, compared with the samples with pristine TiO₂ NPs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47170.     

An experimental and theoretical study on the photocatalytic antibacterial activity of boron-doped TiO2 nanoparticles

Boron-doped titanium dioxide nanoparticles (B–TiO₂ NPs) were prepared by a sol-gel method. The physicochemical properties of B–TiO₂ NPs were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The band structure and electrical properties of B–TiO₂ NPs were investigated using the first-principle. The effects of the concentration gradient of doping B ions on the photocatalytic antibacterial activity of B–TiO₂ NPs under visible-light irradiation were investigated by the inhibition zone method and the shaking flask method. The experimental results show that B–TiO₂ NPs are mainly composed of the anatase phase, but no B-related phase was observed. With the increase of the doping amount of boron ions, the particle size decreases and the specific surface area increases. B atoms mainly exist in the form of substitutional dopant and interstitial dopant. Theoretical calculations reveal that B atoms in the TiO₂ matrix exist much more easily as interstitial dopant, but B–TiO₂ NPs composed of B substituted dopant have better photocatalytic performance. The results of the antibacterial assays show that B–TiO₂ NPs have strong antibacterial activities and some bactericidal activities. Finally, the mechanism of the antibacterial activity of B–TiO₂ NPs are examined.     

TiO2–BaTiO3 nanocomposite for electron capture in dye‐sensitized solar cells

Different compositions of TiO₂–BaTiO₃ nanocomposites are synthesized with various weight ratios for dye‐sensitized solar cell (DSSC) applications. TiO₂ and BaTiO₃ nanoparticles (NPs) are synthesized by sol‐gel and solvothermal methods, respectively and are employed as the photoanode electrodes. BaTiO₃ NPs have pure cubic perovskite crystal structure with an average size of 20‐40 nm, while TiO₂ NPs show pure anatase phase with 15‐30 nm size. The power conversion efficiency (PCE) enhancement of the cells is first attained by controlling the thickness of the films for light harvesting improvement. The fabricated DSSC composed of pure BaTiO₃ NPs with an optimal thickness of 25 μm shows efficiency of 6.83%, whereas that made of pure TiO₂ NPs with 14 μm thickness has cell efficiency of 7.24%. Further improvement of cell efficiency is achieved by preparation of binary oxide nanocomposites using TiO₂ and BaTiO₃ NPs with various weight ratios. The highest PCE of 9.40% is obtained for the nanocomposite with TiO₂:BaTiO₃=85:15 (wt%). The enhancement is assigned to less recombination of photo‐generated electrons and higher incident photon to current conversion yield as a result of rapid charge collection and higher dye sensitization.     

Aerosol processing of Ag/TiO2 composite nanoparticles for enhanced photocatalytic water treatment under UV and visible light irradiation

In this study, we investigated the effect of Ag addition on the photocatalytic reactivity of TiO₂ nanoparticles (NPs). Controlled amounts of Ag were incorporated in TiO₂ NPs using aerosol spray pyrolysis and subsequent calcination. Ag/TiO₂ composite NPs containing different amounts of Ag (e.g., 0, 0.5, 1, 2, and 5 wt%) were successfully fabricated. The photodegradation performances of the as-prepared Ag/TiO₂ composite NPs were tested using methylene blue (MB) solution under UV and visible light irradiation. Upon increasing the Ag content to 1 wt%, the resulting Ag/TiO₂ composite NPs exhibited increased photocatalytic reactivity due to lowered bandgap energy, which promoted both charge generation and separation. However, when the Ag content exceeded 1 wt%, the photocatalytic reactivity of the resulting Ag/TiO₂ composite NPs was considerably deteriorated due to the masking effect of the excess Ag on the reactive sites of TiO₂. Hence, the incorporation of an optimized amount of Ag in the TiO₂ matrix promotes the photocatalytic reactivity of Ag/TiO₂ composite NPs by controlling their bandgap energy and charge generation and separation processes. These results could lead to the development of photodegradation active substances for water treatment in organic solutions.     

INH14, a Small-Molecule Urea Derivative,Inhibits the IKKα/β-Dependent TLR Inflammatory Response

N-(4-Ethylphenyl)-N′-phenylurea (INH14) is a fragment-like compound that inhibits the toll-like receptor 2 (TLR2)-mediated inflammatory activity and other inflammatory pathways (i.e., TLR4, TNF-R and IL-1R). In this study, we determined the molecular target of INH14. Overexpression of proteins that are part of the TLR2 pathway in cells treated with INH14 indicated that the target lay downstream of the complex TAK1/TAB1. Immunoblot assays showed that INH14 decreased IkBα degradation in cells activated by lipopeptide (TLR2 ligand). These data indicated the kinases IKKα and/or IKKβ as the targets of INH14, which was confirmed with kinase assays (IC₅₀ IKKα=8.97 μm ; IC₅₀ IKKβ=3.59 μm ). Furthermore, in vivo experiments showed that INH14 decreased TNFα formed after lipopeptide-induced inflammation, and treatment of ovarian cancer cells with INH14 led to a reduction of NF-kB constitutive activity and a reduction in the wound-closing ability of these cells. These results demonstrate that INH14 decreases NF-kB activation through the inhibition of IKKs. Optimization of INH14 could lead to potent inhibitors of IKKs that might be used as antiinflammatory drugs.     

A mixture of anatase and rutile TiO2 nanoparticles induces histamine secretion in mast cells

Background  

Histamine released from mast cells, through complex interactions involving the binding of IgE to FcεRI receptors and the subsequent intracellular Ca²⁺ signaling, can mediate many allergic/inflammatory responses. The possibility of titanium dioxide nanoparticles (TiO₂ NPs), a nanomaterial pervasively used in nanotechnology and pharmaceutical industries, to directly induce histamine secretion without prior allergen sensitization has remained uncertain.     

Al nanoparticles decorated Er:TiO2 thin film based plasmonic photodetector

Aluminum (Al) nanoparticles (NPs) patterned Erbium-doped Titanium dioxide (Er:TiO₂) thin films (TFs) were synthesized by the combination of sol-gel and glancing angle deposition (GLAD) technique inside the thermal evaporation system. Effects of Al NPs on electrical and optical properties of the Er:TiO₂ TF were experimented and systematically analyzed. Size of NPs was estimated from the field emission scanning electron microscopy (FESEM) image. Diameter of the maximum number of Al NPs was determined to be ～13 nm. The presence of Al was confirmed from the energy dispersive X-ray (EDX) spectra. The optical absorption at around 315 nm revealed the plasmonic resonance of Al NPs. The Au/Er:TiO₂/Al NPs/Er:TiO₂/p-Si Schottky contact-based plasmonic photodetector (PD) was fabricated, which showed excellent photosensitivity under both forward and reverse bias conditions. The responsivity was calculated at an applied voltage of 1 V, which exhibited a high response in the UV region with peak responsivity at 330 nm and 380 nm. The device showed fast switching behaviors under the illumination of 350 nm with a rise time of ～0.55 s and fall time of ～0.13 s. A simple theoretical approach was adopted to evaluate some important parameters of the plasmonic device like photoconductive gain, transit time, and mobility of electrons. Detectivity (1.13 × 10¹² Jones) and noise equivalent power (NEP) (2.46 × 10^?14 W) at 330 nm indicate the suitability of the device as a sensitive UV PD. Hence, the embedded plasmonic Al NPs on Er:TiO₂ TF-based devices can commercially emerge as an efficient and cost-effective UV photodetector.     

Effects of differently shaped TiO<Subscript>2</Subscript>NPs (nanospheres,nanorods and nanowires) on the <Emphasis Type="Italic">in vitro</Emphasis> model (Caco-2/HT29) of the intestinal barrier

Background

The biological effects of nanoparticles depend on several characteristics such as size and shape that must be taken into account in any type of assessment. The increased use of titanium dioxide nanoparticles (TiO₂NPs) for industrial applications, and specifically as a food additive, demands a deep assessment of their potential risk for humans, including their abilities to cross biological barriers.

Methods

We have investigated the interaction of three differently shaped TiO₂NPs (nanospheres, nanorods and nanowires) in an in vitro model of the intestinal barrier, where the coculture of Caco-2/HT29 cells confers inherent intestinal epithelium characteristics to the model (i.e. mucus secretion, brush border, tight junctions, etc.).

Results

Adverse effects in the intestinal epithelium were detected by studying the barrier’s integrity (TEER), permeability (LY) and changes in the gene expression of selected specific markers. Using Laser Scanning Confocal Microscopy, we detected a different behaviour in the bio-adhesion and biodistribution of each of the TiO₂NPs. Moreover, we were able to specifically localize each type of TiO₂NPs inside the cells. Interestingly, general DNA damage, but not oxidative DNA damage effects, were detected by using the FPG version of the comet assay.

Conclusions

Results indicate different interactions and cellular responses related to differently shaped TiO₂NPs, nanowires showing the most harmful effects.

     

Iron Oxide and Titanium Dioxide Nanoparticle Effects on Plant Performance and Root Associated Microbes

In this study, we investigated the effect of positively and negatively charged Fe₃O₄ and TiO₂ nanoparticles (NPs) on the growth of soybean plants (Glycine max.) and their root associated soil microbes. Soybean plants were grown in a greenhouse for six weeks after application of different amounts of NPs, and plant growth and nutrient content were examined. Roots were analyzed for colonization by arbuscular mycorrhizal (AM) fungi and nodule-forming nitrogen fixing bacteria using DNA-based techniques. We found that plant growth was significantly lower with the application of TiO₂ as compared to Fe₃O₄ NPs. The leaf carbon was also marginally significant lower in plants treated with TiO₂ NPs; however, leaf phosphorus was reduced in plants treated with Fe₃O₄. We found no effects of NP type, concentration, or charge on the community structure of either rhizobia or AM fungi colonizing plant roots. However, the charge of the Fe₃O₄ NPs affected both colonization of the root system by rhizobia as well as leaf phosphorus content. Our results indicate that the type of NP can affect plant growth and nutrient content in an agriculturally important crop species, and that the charge of these particles influences the colonization of the root system by nitrogen-fixing bacteria.     

Lung Injury Induced by TiO2 Nanoparticles Depends on Their Structural Features: Size,Shape, Crystal Phases,and Surface Coating

With the rapid development of nanotechnology, a variety of engineered nanoparticles (NPs) are being produced. Nanotoxicology has become a hot topic in many fields, as researchers attempt to elucidate the potential adverse health effects of NPs. The biological activity of NPs strongly depends on physicochemical parameters but these are not routinely considered in toxicity screening, such as dose metrics. In this work, nanoscale titanium dioxide (TiO₂), one of the most commonly produced and widely used NPs, is put forth as a representative. The correlation between the lung toxicity and pulmonary cell impairment related to TiO₂ NPs and its unusual structural features, including size, shape, crystal phases, and surface coating, is reviewed in detail. The reactive oxygen species (ROS) production in pulmonary inflammation in response to the properties of TiO₂ NPs is also briefly described. To fully understand the potential biological effects of NPs in toxicity screening, we highly recommend that the size, crystal phase, dispersion and agglomeration status, surface coating, and chemical composition should be most appropriately characterized.     

Water-dispersible TiO2 nanoparticles via a biphasic solvothermal reaction method

A biphasic solvothermal reaction method has been used for the synthesis of TiO₂ nanoparticles (NPs). In this method, hydrolysis and nucleation occur at the interface of organic phase (titanium (IV) n-propoxide and stearic acid dissolved in toluene) and water phase (tert-butylamine dissolved in water) resulting in the nucleation of the stearic acid-capped TiO₂ NPs. These NPs are hydrophilic due to hydrophobic stearic acid ligands and could be dispersed in toluene, but not in water. These stearic acid-capped TiO₂ NPs were surface-modified with 2,3-dimercaptosuccinic acid (DMSA) in order to make them water soluble. The resultant TiO₂ NPs were easily redispersed in water without any noticeable aggregation. The Rietveld profile fitting of X-ray diffraction (XRD) pattern of the TiO₂ NPs revealed highly crystalline anatase structure. The average crystallite size of TiO₂ NPs was calculated to be 6.89 nm, which agrees with TEM results. These results have important implications for the use of TiO₂ in biomedical, environmental, and industrial applications.