Presence Of TiO2 Nanoparticles Research Articles

Electrospun synthesis of polyaniline and titanium dioxide nanofibers as potential electrode materials in electrochemical hydrogen storage

To meet the imperative of advancing sustainable energy, prioritizing storage systems for clean energy, such as hydrogen, is crucial. However, challenges exist in hydrogen storage, and focusing on nanofibers that incorporate appropriate nanoparticles emerges as a promising approach to enhance storage capacity. In this study, polyaniline/polyvinyl alcohol (PANI/PVA) nanofibers and polyaniline/polyvinyl alcohol/titanium dioxide (PANI/PVA/TiO2) nanofibers were synthesized using the electrospinning method under constant conditions. After characterization of the nanofibers by various techniques, the nanocomposites were used as novel electrode materials for a first time for electrochemical hydrogen energy. Electrochemical tests were conducted on the synthesized nanofibers, and an optimal current of 1.5 mA was determined. The electrochemical analyses obtained revealed a significant improvement in the maximum hydrogen storage capacity with the presence of TiO2 nanoparticles. It increased from 654.8 mAh/g for PANI/PVA nanofibers to 1250 mAh/g for PANI/PVA/TiO2 nanofibers. The difference in storage capacity is attributed to the addition of TiO2 nanoparticles.

Green titanium dioxide (TiO2 ) nanoparticles assisted biodegradation of anthracene employing Serratia quinivorans HP5.

The anthracene biodegradation potential of Serratia quinivorans HP5 was studied under a controlled laboratory environment. The green TiO2 nanoparticles (NPs) synthesized from Paenibacillus sp. HD1PAH was used to accelerate the biodegradation process. The synergistic application of TiO2 NPs and S. quinivorans HP5 resulted in a reduction of anthracene concentration by 1.2 folds in liquid-medium and 1.5 folds in contaminated soil. Gas-chromatography and mass-spectrometric investigation showed the production of four anthracene derivatives, namely 1,2-anthracene dihydrodiol, 6,7-benzocoumarin, anthrone, and 9,10-anthraquinoneat the termination of experimental periods. Furthermore, bacterial biomass increased by 23.3 folds in the presence of TiO2 NPs, and overall soil enzyme activities were enhanced by 4.2 folds in the treated samples. In addition, there was a negative correlation observed between the biomass of S. quinivorans HP5 and the concentrations of anthracene, suggesting the involvement of bacterium in anthracene biodegradation processes. The degradation pathway of anthracene revealed its transformation into the less toxic compound 9,10-anthraquinone. Overall, this study elucidates a novel biodegradation pathway for anthracene and highlights the potential of nano-assisted bacterial remediation as a promising approach for environmental cleanup.

Enhanced Crystallinity of MIL-53 (Fe) and Improved Pb2+ Ion Removal by MIL-53(Fe) in the Presence of TiO2

Water pollution due to improper disposal of various contaminants is one of the most serious threats faced by living beings all around the world. Lead (Pb) is a heavy metal which is commonly added to the environment by the industries such as battery manufacturing, paints etc. According to the world health organization, the maximum bearable Pb concentration of the human body is 70 μg dL- 1. However, in a contaminated water sample, this value could range from 200 to 500 mg L-1. Thus, the efficient removal of heavy metals from contaminated water is vital. Among various removal techniques available, adsorption plays a major role due to its high efficiency, low cost and ease of designing. MOFs are a class of crystalline porous adsorbent material that consists of a metal ion/cluster and an organic linker. Owing to their tailoring ability, high porosity, and high surface area they have been widely used in the removal of contaminants from wastewater. The main objectives of this study are to synthesize MIL-53 (Fe) MOF and MIL-53/TiO2 composite and determine the Pb (II) removal efficiency under light and dark conditions. MIL-53 (Fe) MOF was synthesized using iron (III) and 1, 4-dicarboxylic acid under solvothermal conditions. The composite was synthesized similarly in the presence of TiO2 nanoparticles. The successful synthesis of MIL-53 (Fe) MOF and MOF/TiO composite was confirmed by powder X-ray diffraction and Fourier-transform infrared spectroscopy. By the Debye−Scherrer equation, 79.06 nm and 65.46 nm of crystallite size were obtained by the MOF and the MOF/TiO22 composite. Atomic absorption spectroscopy was used to determine the metal ion concentration before and after adsorption. The optimum conditions for the Pb(II) removal are as; 50 mg L-1, 25 mg L-1 initial Pb ion concentration, 10 mg, 12.5 mg of adsorbent dose (for 25 ml of 50 mg L-1 Pb (II)) and 90 min, 90 min contact time for both adsorbents at light and dark conditions respectively. The pH of the solution was kept at a neutral level to ensure the reusability of wastewater after the removal of pollutants. The adsorption isotherms of both adsorbents were well fitted with the Langmuir model indicating the monolayer adsorption. Thus, at pH 7, 396.35 mg g-1 and 786.16 mg g-1 of maximum Pb (II) adsorption capacity were obtained by the MOF and the MOF/TiO2 composite respectively. Thus, a significant improvement in the Pb (II) ion removal was observed with the composite compared to the MOF. 
 Keywords: Adsorption, Heavy metal, Isotherm, MIL-53 (Fe)

Improved phenol degradation by catalytic wet air oxidation on the Co3O4 spinel catalysts supported on SBA-15 modified with TiO2

The removal of phenol from aqueous industrial effluents by catalytic wet-air oxidation (CWAO) is a challenging process that requires novel catalysts resistant to leaching of the active phases during residence time in a batch reactor. In this sense, this work demonstrated that this can be archived with the catalyst having the spinel phase Co3O4 supported on mesoporous silica SBA-15 doped with an optimized amount of TiO2 (3 wt%). In the phenol CWAO reaction carried out at 160 °C and 10 bar O2, this best Co3O4/TiO2/SBA-15 catalyst showed an increase of phenol conversion from 49.0 % to 68.3 % and of CO2 selectivity from 87 % to 98 %. The extensive catalyst characterization and overall activity results indicated that this was related to the strength and nature of the acid sites and the oxidation states of the cobalt oxide phases. Combined factors influenced the final behaviour of the catalyst, such as its intrinsic activity, dispersion of the active phase, inhibition of CoSiO4 phase formation, high Lewis acidity and the large amount of active Co3O4 spinel phase. The presence of TiO2 nanoparticles (NPs) decorating the support surface improved the stability of the catalyst by inhibiting the leaching of cobalt species during the reaction. After three reaction cycles, the most efficient Co/3Ti/S15 catalyst showed high CO2 selectivity (∼92.7 %) and low selectivity towards carboxylic acid (∼5.3 %) and polyphenolic compounds (∼2%). It is proposed that surface oxidation is the rate-determining step in the CWAO reaction over TiO2/SBA-15-supported Co3O4 spinel catalysts.

Thermodynamics of Mitochondrial Aspartate Aminotransferases in the Presence of Nanoparticles

Background and objectives. The nanoparticles are extensively used in the fields of biotechnology, the medical biochemistry and nanomedicne for enhancement and improvement drugs targeting in the chemotherapy. This study was conducted firstly, to understand the underlying mechanisms and potential applications of the thermo-inactivation kinetics of mitochondrial aspartate aminotransferase (mAspAT) in the presence of various nanoparticles, specifically TiO2 and Fe3O4, as well as gold nanoparticles (AuNP), secondly, to determine the impacts of nanoparticle concentration on the aggregation process and the influence the conformational stability and thermal behavior of mAspAT. Methods. The mAspAT was isolated from the pig heart, and SDS electrophoresis was used to determine the level of the protein's purity. A solution of native and modified dextran sulfate nanoparticles was prepared and incubated with mAspAT at various temperatures. The thermo-Inactivation was carried out at different temperatures (45, 50, 55, 60, 65, and 70 °C) and the aggregation of mAspAT was studied at 320 nm using spectrophotometry. The output data was manipulated (Calculations) and analyzed by Software Stadia 6.0. Results. TiO2 and Fe3O4 nanoparticles, both native and dextran sulfate-coated, demonstrated thermoprotective effects on mAspAT at temperatures above 60 °C. The interaction of mAspAT with TiO2 nanoparticles resulted in a decrease in thermoinactivation energy (Ea), indicating increased conformational stability. Therefore, constant thermoinactivation rate (kin) of mAspAT was significantly decreased in the presence of TiO2 nanoparticles. The dextran sulfate modification further enhanced this effect. Conclusion. The study concludes that the interaction of mAspAT with NP results in an increase in the conformation rigidity of the enzyme, which is primarily determined by the nature of NP and can be increased by coating the surface of NP with a polymer dextran sulfate. Also, Gold nanoparticles could potentially be used to increase the stability of mAspAT, preventing it from thermoaggregation.

Bioengineered Flagellin–TiO2 Nanoparticle-Based Modified Glassy Carbon Electrodes as a Highly Selective Platform for the Determination of Diclofenac Sodium

This study describes the incorporation of bioengineered flagellin (4HIS) protein in conjunction with TiO2 anatase nanoparticles into a chitosan (Chit) polymeric matrix as a highly sensitive electrode modifier for the determination of diclofenac sodium (DS) in wastewater. Two types of electrodes were prepared using a simple drop-casting method. The inner structure of the obtained modified electrode was characterized by scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy and isothermal titration calorimetry (ITC). The electrochemical and electroanalytical parameters of DS oxidation at the nanostructured interface of the modified electrode were obtained via cyclic voltammetry and square-wave voltammetry. The analytical parameters for diclofenac electro-detection showed a 50% decrease in LOD and LOQ at Chit + TiO2 + 4HIS/GCE-modified electrode compared with the Chit + 4HIS/GCE-modified electrode. The obtained tools were successfully used for DS detection in drug tablets and wastewater samples. Thus, it was demonstrated that in the presence of a histidine-containing flagellin variant, the electrode has DS recognition capacity which increases in the presence of TiO2 nanoparticles, and both induce excellent performances of the prepared tools, either in synthetic solution or in real samples.

Enhancing the multifunctional properties of cellulose fabrics through in situ hydrothermal deposition of TiO2 nanoparticles at low temperature for antibacterial self-cleaning under UV–Vis illumination

This study aimed to improve the multifunctional properties (including photocatalysis, stability reusability, self-cleaning, antibacterial effects, and thermal radiation shielding) of cellulose fabrics through incorporation of TiO2 nanoparticles. To achieve this, anatase TiO2 nanoparticles were synthesized in situ and deposited onto cotton fabrics through hydrothermal method. The presence of TiO2 nanoparticles in cellulose fabrics greatly enhanced the photocatalytic efficiency and adsorption range and did not damage the fabric fibers. The TiO2-coated cotton exhibited an outstanding photocatalytic efficiency, with dye removal rates of 92.20 % ± 0.015 % and 99.68 % ± 0.002 % under UV-A and visible illumination, respectively. In addition, the material exhibited thermal radiation shielding properties, in which no heat absorption was observed within 60 min at 40 °C–70 °C. To further enhance the hydrophobicity, the TiO2-coated cotton was surface-modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTS). The resulting PFDTS/TiO2-coated cotton was superhydrophobic with a water contact angle of 156.50° ± 0.05° with a sliding angle of 4.33° ± 0.47° and roughness of 67.35 nm. The superhydrophobicity of the PFDTS/TiO2-coated cotton also facilitated self-cleaning through water injection to remove soil impurities. Furthermore, the PFDTS/TiO2-coated cotton exerted antibacterial effects against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria under UV-A or visible illumination. These nanocomposite fabrics with multifunctional properties have potential for industrial, military, and medical applications.

Biomimetic nanonet membranes with UV-driven self-cleaning performance for water remediation

Water pollution caused by industrial and natural contaminants has placed a significant burden on environment and human health. The present filtration membranes, however, suffer from a series of issues involving low permeation fluxes and easy fouling issue during long-term water remediation, which seriously restricts their practical applications. Herein, inspired by royal water lily leaf, we construct biomimetic nanonet membranes (BNMs) composed of fractal network and mastoid structures by one-step phase inversion of PVDF/TiO2 solution using electrospun fibrous membrane as substrates. Benefit from the distinct structures, the BNMs show sub-micro pores, high porosity, and intriguing hydrophilicity, which result in excellent removal performance for 0.3 μm solid particle (efficiency of 99.88%, permeation flux of 3439 L m−2 h−1), E. coli (log reduction value = 8.39, permeation flux of 1242 L m−2 h−1), and oil-in-water emulsions (efficiency of 99.0%, permeation flux of 8312 L m−2 h−1). Importantly, the presence of TiO2 nanoparticles with UV-driven catalytic activity effectively endows the BNMs with desirable biocidal efficiency (LRV = 8.5) and excellent self-cleaning properties (flux recovery ratio of 98.1%). The synthesis of such membranes may open new avenues in the design of high-performance filtration membranes for remediation of large volumes of wastewater.

TiO2/BP/g-C3N4 heterojunction photocatalyst for the enhanced photocatalytic degradation of RhB.

The efficiency of graphite carbon nitride (g-C3N4, CN) as a photocatalyst is limited due to its quick recombination of photogenerated carriers and layer re-stacking. To enhance its photocatalytic activity, a multi-heterojunction photocatalyst was developed using TiO2 and black phosphorus (BP) coupled with CN through a liquid-phase ultrasonic method. The composite, TiO2/BP/CN, demonstrated a wider range of light response and higher photo-induced carrier separation efficiency. The presence of TiO2 nanoparticles on CN nanolayers reduced interlayer stacking and increased specific surface area, thereby providing more reactive sites. As a result, the optimized TiO2/BP/CN composite demonstrated enhanced photocatalytic efficiency for the degradation of Rhodamine B (RhB), with a first-order kinetic constant of 2.8, 4.3, and 6.4 times that of CN, TiO2, and BP, respectively. Active substance capture experiments confirmed that superoxide radical (·O2) was the primary reactive species. This study highlights the potential of the developed TiO2/BP/CN composite as a promising photocatalyst for environmental remediation applications.

The impact of various carbon nanomaterials on the morphological, behavioural, and biochemical parameters of rainbow trout in the early life stages

With the increasing production and the number of potential applications of carbon nanomaterials, mainly from the graphene family, their release into the natural environment, especially to aquatic ecosystems, is inevitable. The aim of the study was to determine the effects of various carbon nanomaterials (graphene nanoflakes (GNF), graphene oxide (GO), reduced graphene oxide (RGO) and silicon carbide nanofibers (NFSiC) in the concentration of 4 mg L−1 on the early life stages of the rainbow trout Oncorhynchus mykiss. The survival rates of O. mykiss were not affected after 36 days of exposure to studied materials, except for RGO, which caused significant mortality of both embryos and larvae compared to the control conditions. Larvae exposed to GO and NFSiC were characterized by a smaller standard body length at hatch, whereas at the end of the experiment, the growth of fish exposed to all materials was accelerated, especially in GO and RGO treatment, in which higher body weight and length were accompanied by lower volume of the yolk sac. Neither the markers of the oxidative damage nor the antioxidant enzymes activities were significantly affected in embryos, newly hatched larvae and larvae after 26-day exposure to studied carbon nanomaterials. Also, no neurotoxic effect expressed by the activity of the whole-body acetylcholinesterase was observed. Nevertheless, the significant increase in the velocity and the overall activity of larvae exposed to GNF (not investigated after exposure to other materials) must be highlighted. The most pronounced effect of RGO might be connected with its large particle size, sharp edges, and the presence of TiO2 nanoparticles. The results indicate for the first time that various carbon nanomaterials potentially released into aquatic ecosystems may have serious developmental implications for the early life stages of salmonid fish.

Lego-Inspired Glass Capillary Microfluidic Device: A Technique for Bespoke Microencapsulation of Phase Change Materials.

We report a Lego-inspired glass capillary microfluidic device capable of encapsulating both organic and aqueous phase change materials (PCMs) with high reproducibility and 100% PCM yield. Oil-in-oil-in-water (O/O/W) and water-in-oil-in-water (W/O/W) core-shell double emulsion droplets were formed to encapsulate hexadecane (HD, an organic PCM) and salt hydrate SP21EK (an aqueous PCM) in a UV-curable polymeric shell, Norland Optical Adhesive (NOA). The double emulsions were consolidated through on-the-fly polymerization, which followed thiol-ene click chemistry for photoinitiation. The particle diameters and shell thicknesses of the microcapsules were controlled by manipulating the geometry of glass capillaries and fluid flow rates. The microcapsules were monodispersed and exhibited the highest encapsulation efficiencies of 65.4 and 44.3% for HD and SP21EK-based materials, respectively, as determined using differential scanning calorimetry (DSC). The thermogravimetric (TGA) analysis confirmed much higher thermal stability of both encapsulated PCMs compared to pure PCMs. Polarization microscopy revealed that microcapsules could sustain over 100 melting-crystallization cycles without any structural changes. Bifunctional microcapsules with remarkable photocatalytic activity along with thermal energy storage performance were produced after the addition of 1 wt % titanium dioxide (TiO2) nanoparticles (NPs) into the polymeric shell. The presence of TiO2 NPs in the shell was confirmed by higher opacity and whiteness of these microcapsules and was quantified by energy dispersive X-ray (EDX) spectroscopy. Young's modulus of HD-based microcapsules estimated using micromanipulation analysis increased from 58.5 to 224 MPa after TiO2 incorporation in the shell.

Light-Powered Liquid Crystal Polymer Network Actuator Using TiO2 Nanoparticles as an Inorganic Ultraviolet-Light Absorber.

Recently, the design and fabrication of light-powered actuators have attracted immense attention because of the manufacturing of intelligent soft robots and innovative self-regulating devices. Accordingly, a liquid crystal polymer network (LCN) provides a promising platform due to its reversible and multistimulus-responsive shape-changing behaviors. In particular, doping nanoparticles with exclusive properties into the LCN can produce interesting results. In this work, we investigated a TiO2 nanoparticle-based LCN polymer light-powered actuator. TiO2 nanoparticles as an inorganic ultraviolet (UV)-light absorber can substantially affect the LCN polymer's oscillatory behavior. Our results demonstrate that the oscillation characteristics are directly influenced by the presence of nanoparticles, and we studied the influencing factors. The effectiveness of the elastic modulus, thermomechanical force, and curvature was investigated using different weight percentages of TiO2 nanoparticles. Our results show that, in the presence of TiO2 nanoparticles, the polymer chain order and inter-chain interactions in the polymer matrix as well as the structural deformation of relevant polymer surfaces are changed.

Enhancement of Light Induced Transport Properties in Beetroot Dye-Based Biological Schottky Device Using Titanium Dioxide (TiO2) Nanoparticles

In response to the growing demand for electronics, scientists are actively investigating alternative nonconventional, bio-compatible electronic materials suitable for electronic and optoelectronic device applications. This study focuses on enhancing the photoconductivity and photosensitivity of a beetroot (BR) dye-based Schottky device through the incorporation of Titanium dioxide (TiO2 ) nanoparticles. To achieve this, ITO(Indium tin oxide)/BR/Al (Aluminium) and ITO/BR+TiO2 /Al devices were fabricated through the spin coating technique, and their light-induced charge transport properties were examined. The thin films were also characterized through UV-Vis and FESEM analyses. Initial measurements of photoconductivity, sensitivity, and photoresponsivity of the device yielded unsatisfactory results, indicating the need for improvement to enable effective device applications. To address this, we incorporated Titanium dioxide nanoparticles with the dye by making nano-composite, leading to a remarkable enhancement in photoconductivity, increasing from 2.78×10 -8 S/m to 1.75×10 -7 S/m, and a significant boost in photosensitivity, rising from 1131.03 to 2157.67. Furthermore, we estimated other light transport properties, including diffusion length, transit time, and effective mobility, for a comprehensive analysis of the device's performance. These additional parameters also exhibited notable enhancements in the presence of TiO2 nanoparticles. This research contributes valuable insights into the application of TiO2 nanoparticles in enhancing the performance of organicbased optoelectronic devices, and it offers potential avenues for further exploration and refinement of bio-compatible electronic materials in electronic and optoelectronic applications.

Roles of nanoparticles in arsenic mobility and microbial community composition in arsenic-enriched soils

Environmental effects of nano remediation engineering of arsenic (As) pollution need to be considered. In this study, the roles of Fe2O3 and TiO2 nanoparticles (NPs) on the microbial mediated As mobilization from As contaminated soil were investigated. The addition of Fe2O3 and TiO2 NPs restrained As(V) release, and stimulated As(III) release. As(V) concentration decreased by 94% and 93% after Fe2O3 addition, and decreased by 89% and 45% after TiO2 addition compared to the Biotic and Biotic+Acetate (amended with sodium acetate) controls, respectively. The maximum values of As(III) were 20.5 and 27.1 µg/L at 48 d after Fe2O3 and TiO2 NPs addition, respectively, and were higher than that in Biotic+Acetate control (12.9 µg/L). The released As co-precipitated with Fe in soils in the presence of Fe2O3 NPs, but adsorbed on TiO2 NPs in the presence of TiO2 NPs. Moreover, the addition of NPs amended with sodium acetate as the electron donor clearly promoted As(V) reduction induced by microbes. The NPs addition changed the relative abundance of soil bacterial community, while Proteobacteria (42.8%-70.4%), Planctomycetes (2.6%-14.3%), and Firmicutes (3.5%-25.4%) were the dominant microorganisms in soils. Several potential As/Fe reducing bacteria were related to Pseudomonas, Geobacter, Desulfuromonas, and Thiobacillus. The addition of Fe2O3 and TiO2 NPs induced to the decrease of arrA gene. The results indicated that the addition of NPs had a negative impact on soil microbial population in a long term. The findings offer a relatively comprehensive assessment of Fe2O3 and TiO2 NPs effects on As mobilization and soil bacterial communities.

Enhanced Cd2+ adsorption and toxicity for microbial biofilms in the presence of TiO2 nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) easily combine with other pollutants such as heavy metals because of their excellent physiochemical properties. However, how such an interaction may affect the binding behavior of metals onto biofilms remains largely unclear. This study, examined the effects of TiO2 NPs on Cd2+ accumulation and toxicity for natural periphytic biofilms were examined. The adsorption kinetics showed that adding 0.1 and 1 mg/L TiO2–NPs increased the Cd2+ adsorption of biofilms at equilibrium by 23.5% and 35.8%, respectively. However, adding 10 mg/L TiO2 NPs increased the Cd2+ adsorption of biofilms at equilibrium by only 1.9%. The adsorption isotherms indicate that the presence of TiO2 NPs considerably increased the Cd2+ adsorption capacity of the biofilms; however, this effect became less prominent at high TiO2 NP concentrations. The optimum pH for Cd2+ adsorption increased with increasing Cd2+ and TiO2 NP contents. At low concentrations, the coexistence of Cd2+ and TiO2 NPs may facilitate their respective accumulation by stimulating the secretion of extracellular polymeric substances and enhancing the microbial activity of the biofilm. The presence of TiO2 NPs increases the surface binding energy between Cd2+ and functional groups such as carboxyl groups, enhancing the Cd2+ accumulation on the biofilm.

Photocatalytic Degradation of reactive violet 1 by Polyorthotoluidine/Titanium dioxide nanocomposite

<p>Conducting poly(o-toluidine) (POT)/titanium dioxide (TiO2) nanocomposite have been synthesized by in situ chemical oxidation polymerization of o-toluidine in the presence of TiO2 nanoparticles. The various composites were synthesized by changing the percentage load of titanium dioxide nanoparticles in poly-ortho-toluidine matrix. The synthesized nanocomposites were characterized by using Scanning electron microscopy (SEM), X-Rays diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The POT/TiO2 nanocomposites were further employed to evaluate the photocatalytic potential of the composite materials towards reactive violet 1.</p>

Smoothies Reduce the "Bioaccessibility" of TiO2 (E 171) in the Model of the In Vitro Gastrointestinal Tract.

The food colorant E171 (TiO2) containing nano fractions can cause potential health problems. In the presented work, we used a “gastrointestinal tract” model (oral→large intestine) to “digest” a fruit smoothie in the presence of TiO2 nanoparticles and the Lactiplantibacillus plantarum B strain. The TiO2 migration was measured using the microfiltration membrane (0.2 µm; model of “TiO2 bioacessability”). We observed that the addition of the smoothie reduced the Ti content in the microfiltrate (reduced “bioacessability”) at the “mouth”, “stomach” and “large intestine” stages, probably due to the entrapment of Ti by the smoothie components. A significant decrease in Ti “bioaccessibility” at the “gastric” stage may have resulted from the agglomeration of nanoparticles at a low pH. Additionally, the presence of bacterial cells reduced the “bioaccessibility” at the “large intestine” stage. Microscopic imaging (SEM) revealed clear morphological changes to the bacterial cells in the presence of TiO2 (altered topography, shrunk-deformed cells with collapsed walls due to leakage of the content, indentations). Additionally, TiO2 significantly reduced the growth of the tested bacteria. It can be stated that the interactions (most probably entrapment) of TiO2 in the food matrix can occur during the digestion. This can influence the physicochemical properties, bioavailability and in vivo effect of TiO2. Research aimed at understanding the interactions between TiO2 and food components is in progress.

Photoinduced oxidation of nickel in Ni(II)EDTA with TiO2 nanoparticles

TiO2 nanoparticles are well-known for their attractive photocatalytic properties for degradation of adsorbed species. Another area of interest is the use of TiO2 nanoparticles for preparation of photoelectrochromic materials, which are those designed to reversibly change color upon illumination and change of applied potential. This work explored conditions of photo-induced reactions of Ni(II)EDTA in the presence of TiO2 nanoparticles and detected a reversible oxidization reaction to Ni(III)EDTA as a result ultraviolet and visible irradiation. Once irradiation was terminated, the Ni(III)EDTA complex reverted back to Ni(II)EDTA, demonstrating its reversibility. The progress of the reaction was monitored by UV–vis absorption spectroscopy. The photo-induced oxidation reaction was examined for the effect of irradiation time, solution pH and metal–ligand complex concentration. The reaction favors acidic conditions and can be detected for concentrations on the order to 10-3 to 10-1 M Ni(II)EDTA.

Potential impacts of titanium dioxide nanoparticles on trace metal speciation in estuarine sediments

Engineered titanium dioxide (TiO2) nanoparticles (NPs) are widely used and consequently released into the environment. The subsequent accumulation of TiO2 NPs in depositional environments may affect the geochemical behavior of trace metals, which needs to be assessed. Here, we performed experiments to investigate the speciation change for molybdenum and tungsten in the presence of TiO2 NPs. Laboratory results show that the rate constant for MoS42− hydrolysis associated with TiO2 NPs is ~1.75 × 10−9 L m−2 s−1, whereas it is 5.95 × 10−10 L m−2 s−1 for WS42− hydrolysis. In addition, we estimated the maximum rate for MoS42− hydrolysis to be ~1.24 × 10−1 μM hr−1, whereas the maximum rate for WS42− hydrolysis is ~4.91 × 10−2 μM hr−1. However, the modeling results suggest that the TiO2 NPs accumulated in estuarine sediments might play a relatively minor role in affecting the speciation of trace metals prior to the current time. This is because the relatively low accumulation (i.e., < 8 × 10−3 mol kg−1) of TiO2 NPs before 2021 results in the lower rate (>100 times) for speciation changes of both molybdenum and tungsten compared to the rate for natural geochemical processes. On the other hand, our results suggest that TiO2 NPs will likely impact the oxyanion cycling in the near future owing to the increasing accumulations of TiO2 NPs in estuarine sediments.

Electrophoresis of Phosphoproteins on a Tandem Polymerized Gel.

A substrate with n phosphorylated sites may have 2n phosphor-forms for temporal-spatial regulation of biological events. Because phosphates do not significantly change molecular masses but net charges of proteins, those isoforms cannot be separated by regular mass-based sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). A tandem polymerized gel was developed to resolve phosphor-isoforms with different masses, charges, and posttranslational modifications. Without the usage of SDS, the electrophoresis was primarily performed on three adjacent acidic polyacrylamide gels. After being concentrated on a stacking gel, protonated proteins were then separated on the Zr4+ immobilized gel through the coordination of metal ions with phosphates followed by further charge and mass (z/m)-based electrophoretic separation on a TiO2 containing gel. The presence of TiO2 nanoparticles in the third gel is aimed for the initiation of the polymerization of acrylamide in acidic conditions upon ultraviolet irradiation. Distinct isoforms of α-S1-casein, α-S2-casein, β-casein, and κ casein model proteins located on 11, 8, 8, and 7 different bands of the tandem gel were unambiguously identified, respectively. With the tandem polymerized gel electrophoresis, new phosphorylation events that may occur simultaneously or sequentially were discovered in not only model proteins but also complex biological samples including human saliva, chicken egg, and sprouting maize. This provides a new tool to dissect complex biological processes that are triggered by dynamic phosphorylation events.