Concentrations Of Titanium Dioxide Nanoparticles Research Articles

The interaction between titanium dioxide nanoparticles and light can have dualistic effects on the physiological responses of plants.

The model plant Arabidopsis thaliana was exposed to combined stress factors, i.e., titanium dioxide nanoparticles (TiNPs) and high light. The concentrations of TiNPs used for irrigation were 250, 500, and 1000μg/mL. This study shows that TiNPs alter the morphology and nanomechanical properties of chloroplasts in A. thaliana, which leads to a decrease in membrane elasticity. We found that TiNPs contributed to a delay in the thermal response of A. thaliana under dynamic light conditions, as revealed by non-invasive thermal imaging. The thermal time constants of TiNP-treated plants under excessive light are determined, showing a shortening in comparison to control plants. The results indicate that TiNPs may contribute to an alleviation of temperature stress experienced by plants under exposure to high light. In this research, we observed a decline in photosystem II photochemical efficiency accompanied by an increase in energy dissipation upon exposure to TiNPs. Interestingly, concentrations exceeding 250µg/mL TiNPs appeared to mitigate the effects of high light, as shown by reduced differences in the values of specific OJIP parameters (FV/FM, ABS/RC, DI0/RC, and Pi_Abs) before and after light exposure.

Development and evaluation of biodegradable starch-based films containing cellulose nanocrystals/titanium dioxide nanoparticles as an alternative for food packaging

Biodegradable starch-based films are an environmentally friendly solution to reduce the use of petroleum-derived polymers. Thus, this work aims to obtain corn starch films by incorporating 5% w/w of cellulose nanocrystals (CNC), different concentrations of titanium dioxide nanoparticles (TiO2) (0, 0.25, 0.5, 1, and 2% w/w), and 40% w/w of glycerol and sorbitol (plasticizers), in a 1:1 ratio. The films showed a high potential for UV-light barrier, with an increase of 307% incorporating only 2 wt% of TiO2 in relation to the film without incorporation of TiO2. The use of TiO2 increased the white pigmentation capacity of the samples and decreased the lower water solubility – a reduction of approximately 28% using 0.5 wt% TiO2 compared to the CNC control sample was observed. The incorporation of TiO2 nanoparticles increased the tensile strength by adding 1 wt% of TiO2 nanoparticles with 34% increase in the tensile strength of the film without incorporation of TiO2. The thermal stability of the films with 1 wt% TiO2 and 5 wt% CNC increased by 85°C. Thus, the addition of CNC and TiO2 enabled an improvement in the physical/thermal/chemical properties of the films, making them possible alternatives for use in food packaging.

The Effect of Concentration of Titanium Dioxide Nanoparticles on Their Antibacterial Activity in the Synthesis of Polyurethane Biopolymers

In the health sector, the use of polyurethane (PU) as a basic material for medical devices still causes problems related to local and systemic infections. One of the most appropriate ways to overcome this problem is to synthesize PU biopolymer with titanium dioxide (TiO2) nanoparticles. The use of nano-shaped materials in this synthesis has many advantages, including being easier to synthesize and being antibacterial. Meanwhile, starch is the result of isolation from banana weevils, where banana weevils are agricultural waste that has not been utilized properly. Particle size and the use of agricultural waste are a form of modification and innovation in PU synthesis, as well as a novelty in the development of this research. In PU synthesis, several characterization techniques are carried out, including polymer tests, namely strain and stress, functional group analysis using (Fourier Transform Infra-Red), and antibacterial tests. Based on the results of the FTIR test analysis, it show that at a wave number of 1724.36 cm-1, the N-H functional group is visible, and the absorption of urethane and TiO2 groups is in the range of 513.07 cm-1. The mechanical properties test shows the strain (28.92 - 21.88% GL) and young's modulus in the interval (5.484-3.268 MPa). The antibacterial test showed that the inhibitory power of test samples A1 and A4 with diameters of 8 mm and 8 mm proved to be very effective in killing E. Coli bacteria, while test samples A1¹, A2¹, A3¹, and A4 were not able to kill E. Coli bacteria. S. Aureus. bacteria. The characterization results show that PU biopolymer can be used as a basic material for making bacterial decontaminant medical devices.

A Novel Polyester Varnish Nanocomposites for Electrical Machines with Improved Thermal and Dielectric Properties Using Functionalized TiO2 Nanoparticles.

Recently, there has been a growing interest in polymer insulating materials that incorporate nanoscale inorganic additives, as they have shown significantly improved dielectric, thermal, and mechanical properties, making them highly suitable for application in high-voltage insulating materials for electrical machines. This study aims to improve the dielectric and thermal properties of a commercial polyester varnish by incorporating different concentrations of titanium dioxide nanoparticles (TiO2) with proper surface functionalization. Permafil 9637 dipping varnish is the varnish used for this investigation, and vinyl silane is the coupling agent used in the surface functionalization of TiO2 nanoparticles. First, nanoparticles are characterized through Fourier transform infrared spectroscopy to validate the success of their surface functionalization. Then, varnish nanocomposites are characterized through field emission scanning electron microscopy to validate the dispersion and morphology of nanoparticles within the varnish matrix. Following characterization, varnish nanocomposites are evaluated for thermal and dielectric properties. Regarding thermal properties, the thermal conductivity of the prepared nanocomposites is assessed. Regarding dielectric properties, both permittivity and dielectric losses are evaluated over a wide frequency range, starting from 20 Hz up to 2 MHz. Moreover, the AC breakdown voltage is measured for varnish nanocomposites, and the obtained data are incorporated into a finite element method to obtain the dielectric breakdown strength. Finally, the physical mechanisms behind the obtained results are discussed, considering the role of nanoparticle loading and surface functionalization.

Exposure to silver and titanium dioxide nanoparticles at supra-environmental concentrations decreased sperm motility and affected spermatozoa subpopulations in gilthead seabream, Sparus aurata.

Marine pollution by nanoparticles (NPs) can be reprotoxic for fish and disturb successful reproduction of wild populations. In gilthead seabream (Sparus aurata), a mild effect on sperm motility was observed after exposure to high concentrations of silver NPs. Considering the great heterogeneity traits within a sperm sample, it is possible that NPs affect spermatozoa accordingly, modulating subpopulation profile. Thus, this work aimed to analyse NP effects in sperm motility in general and considering spermatozoa population structure, using a subpopulation approach. Seabream sperm samples from mature males were exposed for 1 h to increasing concentrations of titanium dioxide (1, 10, 100, 1000 and 10,000 μg L-1) and silver (0.25, 25 and 250 μg L-1) NPs, including Ag NP and Ag+, dissolved in a non-activating medium (0.9 % NaCl). Concentrations chosen include realistic (10-100 and 0.25 μg L-1, respectively, for TiO2 and Ag) and supra-environmental values. The mean particle diameter was determined as 19.34 ± 6.72 and 21.50 ± 8.27 nm in the stock suspension, respectively, for titanium dioxide and silver. After the ex vivo exposure, sperm motility parameters were determined using computer-assisted sperm analysis, and sperm subpopulations were later identified using a two-step cluster analysis. Results revealed a significant reduction in total motility after exposure to the 2 highest concentrations of titanium dioxide NPs, while curvilinear and straight-line velocities were not altered. Exposure to silver NPs (Ag NP and Ag+) lowered significantly total and progressive motilities at all concentrations, while curvilinear and straight-line velocities were significantly lower only at the highest concentration. Sperm subpopulations were also affected by the exposure to both titanium dioxide and silver NPs. In both cases, the highest levels of NPs triggered a decrease in the percentage of fast sperm subpopulations (38.2% in TiO2 1000 μg L-1, 34.8.% in Ag NP 250 μg L-1, and 45.0% in Ag+ 250 μg L-1 vs 53.4% in the control), while an increase on slow sperm subpopulations. A reprotoxic effect was proven for both NPs, but only at supra-environmental concentrations.

Optimizing Sustainable Energy Generation in Ethanol Fuel Cells: An Exploration of Carrageenan with TiO2 Nanoparticles and Ni/CeO2 Composites.

Based on the search for new biodegradable materials that are low cost and easy to synthesize by environmentally friendly methods, we report the use of carrageenan membranes (mixture of κ and λ carrageenans) with different concentrations of titanium dioxide nanoparticles (TiO2 NPs) and Ni/CeO2 (10 wt % Ni) for the fabrication of a novel fuel cell electrode for the oxidation of ethanol. Each membrane was characterized to determine its physicochemical properties using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. Using impedance spectroscopy (IS), a maximum value of 2.08 × 10-4 S/cm in ionic conductivity was found for the carrageenan nanocomposite with a concentration of 5 wt % TiO2 NPs (CR5%). Due to its high conductivity values, the CR5% membrane was mixed with Ni/CeO2 to prepare the working electrode for cyclic voltammetry measurements. Using a solution of 1 M ethanol and 1 M KOH, the oxidation of ethanol over CR5% + Ni/CeO2 resulted in peak current density values at forward and reverse scan voltages of 9.52 and 12.22 mA/cm2, respectively. From our results, the CR5% + Ni/CeO2 membrane proves to be more efficient in the oxidation of ethanol compared with commercially available Nafion membranes containing Ni/CeO2.

Получение и исследование in situ композиционного материала “хитозан – диоксид титана” для сельского хозяйства

In the course of the study, granules of the composite material “chitosan - titanium dioxide” with different content of titanium dioxide nanoparticles for agricultural use were obtained. The average granule diameter was 35 mm. It is shown that a change in the concentration of titanium dioxide nanoparticles in a composite material within the studied limits does not affect the structure of its surface. Experiments were carried out in situ on the seeds of cucumber (Cucumis sativus). It was noted that during the first three weeks, the composite material has an inhibitory effect on plant growth, and then, after the beginning of the dissolution of the granules, it has a growth-stimulating effect. The best growth rates were observed when two granules of a composite material were added to the soil with a ratio of chitosan to titanium dioxide of 3 to 1. It was concluded that the obtained granules of a composite material can have a positive effect on the processes of plant growth and formation.

Additive effects of arbuscular mycorrhizae and TiO2 nanoparticles on growth and essential oils enhancement of peppermint

Peppermint is an important medicinal plant, particularly regarding its high essential oil (EO) content. The present study assesses the effects of two Arbuscular mycorrhiza fungi (AMFs) and three concentrations of Titanium dioxide nanoparticles (TiO2 NPs) (i.e., 100, 150, and 200 mg L−1) on growth characteristics, EO constituents, phenolic content and anti-oxidative enzymatic activities of peppermint. Applying a mixed treatment of Glomus intraradices and TiO2 NPs (150 mg L-1) enhanced peppermint's shoot-fresh and dry weight by 69% and 158%, respectively, compared with controls. Also, membrane stability index (MSI) and leaf relative water content (RWC) exhibited a maximum enrichment of 69.85% and 39%, respectively, over control. Some other plant physiological characteristics were also positively affected by applying either the single or combined treatment of G. intradices and TiO2 NPs (150 mg L−1). In this regard, total phenolic content increased by 300%, DPPH radical scavenging ability by 164%, catalase by 103%, and ascorbate peroxidase activities by 124% in mixed treatment of Glomus intraradices and TiO2 NPs (150 mg L−1). Moreover, AMF symbiosis and the implementation of TiO2 NPs intervention augmented the amount of peppermint EO compounds such as menthol, menthyl acetate, and 1, 8 cineole. The highest amount of menthol production (52.04%) was obtained by adding a mixture of G. intraradices and TiO2 NPs (150 mg L−1), which had more positive effects on the other studied characteristics. Overall, AMF symbiosis and TiO2 NPs application seem suitable for promoting plant growth, improving antioxidant activity, and incrementing major components of EOs in medicinal plants.

Impacts of prolonged exposure to low concentration of titanium dioxide nanoparticles on cell cycle control and DNA repair

Impacts of prolonged exposure to low concentration of titanium dioxide nanoparticles on cell cycle control and DNA repair

Shore hardness behavior of light‐cured dental composite resin filled with TiO2 nanoparticles

AbstractIn this study, the influence of light curing times, curing modes and concentrations of titanium dioxide nanoparticles on the Shore hardness number of top and bottom surfaces and hardness ratio of hybrid composite resin is investigated. Hybrid composite resin and titanium dioxide nanoparticles are the materials used in this study. Titanium dioxide nanoparticles are added to hybrid composite resin. The resulting paste is placed in plastic bars and cured using a visible light curing unit for 60 s, 80 s, 100 s and 120 s from both sides. The curing modes used are gradually strong, flashing and strong modes. Hardness number of top and bottom surfaces is measured using Shore D durometer test. The results show that the curing times, curing modes and concentrations of titanium dioxide nanoparticles have influence on the Shore hardness numbers. The Shore hardness numbers at 120 s is higher than that obtained for a 60 s cure time and flashing curing mode produce dental nanocomposite resin with higher Shore hardness numbers. The Shore hardness numbers of the studied hybrid composite is increased by adding 0.5 wt.% and 0.6 wt.% of titanium dioxide nanoparticles.

The Study the Influence of TiO2-Nanoparticles Doped in Polyvinyl Alcohol by Measuring Optical Properties of PVA Films

It was investigated how titanium dioxide nanoparticles affected the optical properties of polyvinyl alcohol. Polymer nanocomposites (PVA-TiO2) are created via stirring and casting. The results demonstrate that transmittance improves from 75% to 95% while titanium dioxide concentration enhances the absorbance of nanocomposites. Nanocomposite films made of PVA and TiO2 had reflectance values of 12 and 16 percent (weight percent=0.15 and 0.85%).The refractive index and coefficient of extinction rise with increasing density, and optical absorption and photon dispersion in the nanocomposite (PVA-TiO2) also rise as the concentration of titanium dioxide nanoparticles rises. Real dielectric (r) and imaginary dielectric I constants also rise as titanium dioxide nanoparticle concentration does. The results show that when the weight % of (TiO2) nanoparticles increased, the energy gap decreased from 3.32 to 2.23. Additionally, optical conductivity increased with the concentration of (TiO2) NPs. Nanocomposites of PVA and TiO2 are essential for optical applications.

Response of Saponaria officinalis L. hairy roots to the application of TiO2 nanoparticles in terms of production of valuable polyphenolic compounds and SO6 protein

Saponaria officinalis L. is a perennial plant from the Caryophyllaceae family whose various parts are used in traditional medicine as the treatment agent of skin diseases, blood purifier, diuretic, sudorific, and bile purifier. The cultivation system of hairy roots is a proper alternative for improving the valuable pharmaceutical compounds production compared to other in-vitro methods. The extensive nanotechnology applications in hairy roots cultivation is a sustainable production foundation to produce such active elements. In this study, the effect of various concentrations of titanium dioxide nanoparticles (TiO2 NPs) (0, 10, 20, 30, 50 mg L−1) with two treatments (24 and 48 h) was examined on the growth level, antioxidant capacity, total phenol and flavonoid contents, antioxidant enzyme activities, certain polyphenol compounds and SO6 protein in hairy roots of S. officinalis. According to the results, the maximum (3.09 g) and minimum (0.96 g) fresh weight (FW) of hairy roots were observed in treated culture media with 10 and 20 mg L−1 of TiO2 NPs after 24 and 48 h of exposure times, respectively. The highest rate of total phenol (9.79 mg GLA g−1 FW) and total flavonoid contents (1.06 mg QE g−1 FW) were obtained in the treated hairy roots with 50 and 30 mg L−1 of nano elicitor in 24 and 48 h of treatments, respectively. The maximum level of most polyphenols, such as rosmarinic acid, cinnamic acid, and rutin, was produced in 24 h of treatment. The use of TiO2 NP for 48 h with 50 mg L−1 concentration showed the highest production level of SO6 protein.

Antimicrobial Potential of Titanium Dioxide Nanoparticles in Urinary Tract Infections: An Experimental Study on the Growth Inhibitory Activity and Biofilm Inhibition

Background: T Microorganisms cause many diseases for the human body such as urinary tract infection and, therefore, it is highly important to eliminate and control them. Bacterial resistance to different types of antibiotics was increased and it is necessary to find alternative agents to eliminate these microbes. Methods: This study aimed was to evaluate the antimicrobial effect of different concentrations of titanium dioxide nanoparticles (TiO2 NPs) on some gram-positive bactria, gram-negative bacteria, and Candida albicans. TiO2 NPs were synthesized using the chemical methods, coated with carboxymethyl cellulose (CMC) and prepared in different concentrations (0.098, 0.196, 0.392, 0.784, 1.568, and 3.136 mg/mL). Eventually, a minimum inhibitory concentration (MIC) and a minimum biofilm inhibitory concentration (MBIC) were applied to investigate the effect of TiO2 NPs on microorganisms. Results: According to the study results, the MICs of TiO2 NPs were found to be 1.489, 1.208, and 1.166 mg/ mL for Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae as the Gram-negative bacteria, respectively; and they were discovered to be 0.512, 0.830, and 0.707 mg/mL for Streptococcus pneumoniae, Staphylococcus aureus, and Staphylococcus epidermidis as the Gram-positive bacteria, respectively. As for C. albicans, as the yeast strain, MIC was 0.253 mg/ mL. The MBIC of more than 90% of TiO2 NPs was 6.25 mg/mL for both Gram-negative and Gram-positive bacterial types and 1.562 mg/mL for C. albicans. Conclusions: It was concluded that TiO2 NPs were effective antimicrobial agents for Gram-positive bacteria, Gram-negative bacteria, and C. albicans, but their inhibitory effect on yeast was greater than that of bacteria.

3D Laser Nanoprinting of Optically Functionalized Structures with Effective-Refractive-Index Tailorable TiO2 Nanoparticle-Doped Photoresin.

The advanced direct laser printing of functional devices with tunable effective index is a key research topic in numerous emerging fields, especially in micro-/nano-optics, nanophotonics, and electronics. Photosensitized nanocomposites, consisting of high-index materials (e.g., titanium dioxide, TiO2) embedded in polymer matrix, are emerging as attractive platforms for advanced additive manufacturing. Unfortunately, in the currently applied techniques, the preparation of optically functionalized structures based on these photosensitized nanocomposites is still hampered by many issues like hydrolysis reaction, high-temperature calcinations, and, especially, the complexity of experimental procedures. In this study, we demonstrate a feasible strategy for fabricating micro-/nanostructures with a flexibly manipulated effective refractive index by incorporating TiO2 nanoparticles in the matrix of acrylate resin, i.e., TiO2-based photosensitized nanocomposites. It was found that the effective refractive index of nanocomposite can be easily tuned by altering the concentration of titanium dioxide nanoparticles in the monomer matrix. For TiO2 nanoparticle concentrations up to 30 wt%, the refractive index can be increased over 11.3% (i.e., altering from 1.50 of pure monomer to 1.67 at 532 nm). Based on such a photosensitized nanocomposite, the grating structures defined by femtosecond laser nanoprinting can offer vivid colors, ranging from crimson to magenta, as observed in the dark-field images. The minimum printing width and printing resolution are estimated at around 70 nm and 225 nm, indicating that the proposed strategy may pave the way for the production of versatile, scalable, and functionalized opto-devices with controllable refractive indices.

The effect of titanium dioxide nanoparticles on the relative expression of catalase, P450, SOD, diTDS and WRKY genes of Vitex agnus-castus L.

Each environmental factor is able to change the way genes are expressed. Application of nanoparticles also affects the expression of different genes in plants. The aim of this study was to investigate the effect of three different concentration of titanium dioxide nanoparticles, TiO2 (zero, 200 and 800 micrograms per milliliter) on the relative expression of catalase, P450, SOD, diTDS and WRKY genes in Vitex plant leaf tissue using qRT- PCR. Plant cultivation was carried out in 2018 in the greenhouse of Islamic Azad University of Mashhad. The experiment was arranged as completely random design with 5 replications. XRD measurements showed that applied TiO2 nanoparticles were in the form of anatase. Statistical analysis of gene expression in treated leaves of Vitex plant with TiO2 nanoparticles showed that this nanoparticle significantly affected the expression of catalase, P450, SOD, diTPS and WRKY genes. A concentration of 800 micrograms per milliliter of TiO2 nanoparticle increased the expression of catalase, P450, SOD and WRKY genes and decreased the expression of diTPS gene. In contrast, concentrations of 200 micrograms per milliliter only increased the expression of catalase and WRKY genes. The expression of the diTPS gene under treatments of 200 and 800 micrograms per liter of TiO2, compared with control, decreased by 2.1 and 0.46, respectively. Overall, the nanoparticle was able to influence the expression of genes in the biosynthetic pathway of terpenoids, as well as the plant's antioxidant enzymes, depending on the concentration of nanoparticles.

Inductive effect of titanium dioxide nanoparticles on the anticancer compounds production and expression of rosmarinic acid biosynthesis genes in Dracocephalum kotschyi transformed roots

Methoxylated flavonoids, mainly xanthomicrol and cirsimaritin that can be extracted from Dracocephalum kotschyi Boiss, have anticancer, antispasmodic and antiplatelet effects. The production of these valuable pharmaceutical compounds is one of the major goals of biotechnology studies. In this work, induced transformed roots were influenced by various concentrations of titanium dioxide nanoparticles (TiO2 NPs) at 24 or 48 h exposure time. The effects of TiO2 NPs were assessed on growth rate, activity of antioxidant enzymes, total phenol and flavonoid content (TPC and TFC) and rosmarinic acid (RA) and some flavonoids accumulation. The gene expression level of phenylalanine ammonia-lyase (pal) and rosmarinic acid synthase (ras) genes were assessed by real time PCR analysis. The transformed roots biomass was substantially increased in elicited roots in comparison with the control. The TPC, TFC and antioxidant enzymes activitywere affected by TiO2 NPs concentration and exposure time. Valuable flavonoids with anticancer characteristics along with xanthomicrol, cirsimaritin and isokaempferide exhibited an increase (70, 34.28 and 7.81-fold, respectively) versus the control. The maximum content of RA (530.5 μg g−1 FW), which was 4.30 times as great as that of control was detected in samples treated with TiO2 NPs (50 mg L−1) 24 h after elicitation. Real-time PCR analysis revealed a considerable increase in pal and ras expression rate engaged by TiO2 NPs levels and exposure time. Overall D. kotschyi transformed roots elicitation by TiO2 NPs led to a massive increment in the production of valuable anticancer flavonoids such as xanthomicrol, cirsimaritin and RA as polyphenol.

Effect of Different Concentrations of Titanium Dioxide Nanoparticles on the Potential Barrier of Organic Device

Abstract Present work has studied potential barrier of Phenosafranin dye based organic device and has observed influence of different concentrations of titanium dioxide nanoparticles on this parameter. We have made different devices by taking different weight ratios of the dye – nanoparticles blend which are 1:1, 1:2, 1:3 and 1:4. These organic devices have been formed by varying the concentrations of titanium dioxide nanoparticles keeping same dye content. One device is also formed without any nanoparticle to compare influence of nanoparticle on potential barrier of the device. These devices are formed by sandwiching the dye – nanoparticle blend in between the Indium Tin Oxide coated glass and Aluminium coated mylar sheet. The potential barrier is measured from device’s I-V plot and also by Norde function. These two methods remain in good agreement showing that potential barrier is mostly decreased when the concentration of the titanium dioxide nanoparticles is highest in the blend of Phenosafranin dye and titanium dioxide nanoparticles. The ratio of dye –nanoparticle blend of 1:4 shows lowest potential barrier and it is highest when Phenosafranin dye based organic device is made without any nanoparticle. The reduced potential barrier in the presence of higher concentration of nanoparticles can be ascribed to improved filling of traps. Lowered potential barrier at metal – organic contact will improve the charge flow resulting in better performance of the device.

Synthesis and Characterization of Polymeric (PMMA-PVA) Hybrid Thin Films Doped with TiO2 Nanoparticles Using Dip-Coating Technique

We report the synthesis of hybrid thin films based on Poly(MethylMethAcrylate) (PMMA) and Poly(VinylAlcohol) (PVA), doped with different concentrations of titanium dioxide nanoparticles (TiO2 NPs). As-prepared thin films of (PMMA-PVA) doped by TiO2 NPs (wt.% = 2%, 4%, 8%, and 16%) are deposited on glass substrate. Transmittance (T%), reflectance (R%), absorption coefficient (α), optical constants (n and k), and optical dielectric functions (ε1 and ε2) are deduced using the experimental transmittance and reflectance spectra. Furthermore, a combination of classical models such as Tauc, Urbach, Spitzer-Fan, and Drude models are applied to calculate the optical and optoelectronic parameters and the energy gaps of the prepared nanocomposite thin films. The optical bandgap energy of PMMA-PVA thin film is found to be 4.101 eV. Incorporation of TiO2 NPs into PMMA-PVA polymeric thin films leads to a decrease in the optical bandgap and thus bandgap engineering is possible. Fourier-transform infrared spectroscopy (FTIR) transmittance spectra of thin films are measured and interpreted to identify the vibrational modes. To elucidate the chemical stability, thermogravimetric (TGA) curves are measured. We found that (PMMA-PVA)/TiO2 NPs polymeric thin films are thermally stable below 110 °C enable them to be attractive for a wide range of optical and optoelectronic applications.

Environmentally relevant concentrations of titanium dioxide nanoparticles pose negligible risk to marine microbes.

Nano-sized titanium dioxide (nTiO2) represents the highest produced nanomaterial by mass worldwide and, due to its prevalent industrial and commercial use, it inevitably reaches the natural environment. Previous work has revealed a negative impact of nTiO2 upon marine phytoplankton growth, however, studies are typically carried out at concentrations far exceeding those measured and predicted to occur in the environment currently. Here, a series of experiments were carried out to assess the effects of both research-grade nTiO2 and nTiO2 extracted from consumer products upon the marine dominant cyanobacterium, Prochlorococcus, and natural marine communities at environmentally relevant and supra-environmental concentrations (i.e., 1 μg L−1 to 100 mg L−1). Cell declines observed in Prochlorococcus cultures were associated with the extensive aggregation behaviour of nTiO2 in saline media and the subsequent entrapment of microbial cells. Hence, higher concentrations of nTiO2 particles exerted a stronger decline of cyanobacterial populations. However, within natural oligotrophic seawater, cultures were able to recover over time as the nanoparticles aggregated out of solution after 72 h. Subsequent shotgun proteomic analysis of Prochlorococcus cultures exposed to environmentally relevant concentrations confirmed minimal molecular features of toxicity, suggesting that direct physical effects are responsible for short-term microbial population decline. In an additional experiment, the diversity and structure of natural marine microbial communities showed negligible variations when exposed to environmentally relevant nTiO2 concentrations (i.e., 25 μg L−1). As such, the environmental risk of nTiO2 towards marine microbial species appears low, however the potential for adverse effects in hotspots of contamination exists. In future, research must be extended to consider any effect of other components of nano-enabled product formulations upon nanomaterial fate and impact within the natural environment.

TiO2 nanoparticles effects on morphology and physiology of Artemisia absinthium L. under salinity stress

Providing strategies for coping and managing NaCl salinity stress is the goal of many researches. Titanium dioxide nanoparticles (TiO2 NPs) are widely used as photo-catalytic agents due to their strong oxidative properties, optical stability, lack of toxicity, cheapness and availability. Here, the effects of various concentrations of NaCl salinity and titanium dioxide nanoparticles on certain growth factors of the shoot and root, the protein content, activities of catalase, guaiacol peroxidase, superoxide dismutase and polyphenol oxidase enzymes in Artemisia absinthium L were studied. SDS–PAGE was used to analyze the protein expression of A. absinthium at different levels of NaCl salinity stress and TiO2 nanoparticles treatment. All the experiments were performed as a factorial in a completely randomized design in three replications. Data were analyzed using SPSS software. We found that the increase in the concentration of TiO2 NPs up to 20 mg L−1 leads to the enhancement in the length and dry/fresh weights of roots, while there is a reverse pattern for all the traits with the concentration of 30 mg L−1 of nanoparticles. Moreover, the results showed a significant enhancement in the antioxidant activity of catalase, peroxidase, superoxide dismutase, polyphenol oxidase and guaiacol peroxidase enzymes and also protein content in some salinity-stressed plants and those were treated with various concentrations of titanium dioxide nanoparticles in comparison with the control group. According to protein molecular weight in NCBI and SDS–PAGE, some isoenzymes were found for each of the evaluated antioxidant enzymes, and their expression highly differed among the evaluated samples. The increase in isoenzymes’ band intensity was related to the increase in their protein expression, isoenzymes accumulation in the cells or both of them. In some cases, enzymes’ activities were increased, but there was no change in the related band intensity in the SDS–PAGE. It seems that the increase in enzymes activities could be due to the effect of nanoparticles on the enzyme’s active site. Therefore, the increase in antioxidant enzymes activities was related to increase in gene expression, enzyme activity or both processes. In this study, the highest concentrations of the nanoparticles (30 mg L−1) had the negative effects on the NaCl salinity-treated samples and in several cases decreased growth of the shoot and root, proteins content and enzymes activities.