Ti3+/Ti4+ and Co2+/Co3+ redox couples in Ce-doped Co-Ce/TiO2 for enhancing photothermocatalytic toluene oxidation.

Cerium and cobalt loaded Co-Ce/TiO2 catalyst prepared by impregnation method was investigated for photothermal catalytic toluene oxidation. Based on catalyst characterizations (XPS, EPR and H2-TPR), redox cycle between Co and TiO2 (Co2+ + Ti4+ ↔ Co3+ + Ti3+) results in the formation of Co3+, Ti3+ and oxygen vacancies, which play important roles in toluene catalytic oxidation reaction. The introduction of Ce brings in the dual redox cycles (Co2+ + Ti4+ ↔ Co3+ + Ti3+, Co2+ + Ce4+ ↔ Co3+ + Ce3+), further promoting the elevation of reaction sites amount. Under full spectrum irradiation with light intensity of 580 mW/cm2, Co-Ce/TiO2 catalyst achieved 96% of toluene conversion and 73% of CO2 yield, obviously higher than Co/P25 and Co/TiO2. Co-Ce/TiO2 efficiently maintains 10-hour stability test under water vapor conditions and exhibits better photothermal catalytic performance than counterparts under different wavelengths illumination. Photothermal catalytic reaction displays improved activities compared with thermal catalysis, which is attributed to the promotional effect of light including photocatalysis and light activation of reactive oxygen species.

Vacancy-Induced Symmetry Breaking in Titanium Dioxide Boosts the Photocatalytic Hydrogen Production from Methanol Aqueous Solution.

The key to optimizing photocatalysts lies in the efficient separation and oriented migration of the photogenerated carriers. Herein, we report that breaking continuous TiO6 tetragonal (D4h) symmetry in titanium dioxide material by oxygen vacancy engineering could induce a dipole field within the bulk phase and thus facilitate the separation and transfer of photogenerated electron-hole pairs. After further loading of Cu single-atom co-catalysts, the obtained catalyst attained a hydrogen (H2) yield rate of 15.84 mmol g-1 h-1 and a remarkable apparent quantum yield of 12.67% at 385 nm from methanol aqueous solution. This catalyst also demonstrated impressive stability for at least 24 h during the photocatalytic tests. The innovative concept of producing dipole fields in semiconductors by breaking the crystal symmetry offers a new perspective for designing photocatalysts.

Enhanced adsorption-photodegradation of tetracycline using Ce-N-co-doped AC/TiO2 photocatalyst: isotherms, kinetics, mechanism, and thermodynamic insight.

Excessive use of tetracycline (TC) is alarming owing to its increased detection in water systems. In this study, a photocatalyst was developed to degrade TC using a Ce-N-co-doped AC/TiO2 photocatalyst, denoted as Ce/N-AC/TiO2, prepared using the sol-gel method assisted by microwave radiation, speeding up the synthesis process. Ce/N-AC/TiO2 achieved maximum TC degradation of 93.1% under UV light with optimum sorption system conditions of an initial concentration of 10 mg L-1, pH 7, and 30 ℃, under 120 min. Scavenger experiments revealed that holes and superoxide radicals were the active species influencing the photodegradation process. The TC degradation was appropriately fitted with Langmuir isotherms and a pseudo-second-order (PSO) kinetic model. The change in enthalpy (ΔH) (2.43 kJ mol-1), entropy (ΔS) (0.024 kJ mol-1), and Gibbs free energy (ΔG) (- 4.941 to - 5.802 kJ mol-1) suggested that the adsorption process was spontaneous, favourable, and endothermic. Electrostatic interaction, hydrogen bonding, pore-filling, cationic-π, n-π, and π-π interaction were among the interactions involved between TC and Ce/N-AC/TiO2. Furthermore, Ce/N-AC/TiO2 stability was confirmed through 80% removal efficiency even after the fifth reuse cycle. Notably, this work provides new insight into the production of efficient, reusable, and enhanced photocatalysts using a rapid and cost-effective microwave-assisted synthesis process for pollutant remediation.

The enhanced antibacterial and antibiofilm properties of titanium dioxide nanoparticles biosynthesized by multidrug-resistant Pseudomonas aeruginosa.

The emergence of Multidrug-resistant (MDR) bacteria are becoming a major worldwide health concern, encouraging the development effective alternatives to conventional antibiotics. The study identified P. aeruginosa and assessed its antimicrobial sensitivity using the Vitek-2 system. Carbapenem-resistant genes were detected through Polymerase chain reaction (PCR). MDR- P. aeruginosa isolates were used to biosynthesize titanium dioxide nanoparticles (TiO2NPs) and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM). A study involving 78 P. aeruginosa isolates revealed that 85.8% were MDR, with meropenem and amikacin showing effectiveness against 70% of the isolates. The most prevalent carbapenemase gene was blaOXA-48, present in 83% of the isolates. Majority of the isolates formed biofilms, and biosynthesized TiO2NPs were able to reduce biofilm formation by 94%. TiO2NPs exhibited potent antibacterial action against MDR-Gram-negative bacilli pathogens and showed synergistic activity with antibiotics, particularly piperacillin, with a significant fold increase in areas (283%). A new local strain of P. aeruginosa, identified as ON678251 in the World GenBank, was found capable of producing TiO2NPs. Our findings demonstrate the potential of biosynthesized TiO2NPs to manage antibiotic resistance and regulate the formation of biofilms. This presents a promising direction for the creation of novel antimicrobial agents or substitutes for use in clinical settings, particularly in the management of isolates capable of resisting multiple drugs.

Effect of titanium dioxide nanoparticle (TiO2-NP) exposure in a novel Amur sturgeon Acipenser schrenckii hepatocyte cell line.

In vitro cell culture is crucial for predicting the toxicity of titanium dioxide nanoparticle (TiO2-NP). However, assessing the toxicity of TiO2-NPs in sturgeon remains difficult given the lack of sufficient cell lines. We established and characterized the first hepatocyte cell line from Acipenser schrenckii liver tissue (ASL). This ASL cell line proliferated well in Dulbecco's modified Eagle's medium at 25°C and 10% fetal bovine serum. ASL cells with a chromosome number of 244 were successfully transfected with the pEGFP-N3 plasmid. The ASL cell line's origin was verified as A. schrenckii through mitochondrial cytochrome C oxidase I and mitochondrial 16S ribosomal RNA (rRNA) sequencing. Using the ASL cell line as an in vitro model, we found that TiO2-NP exposure decreased the viability and promoted the damage of ASL cells (96-h LC50 = 331.8 µg mL-1). Increased reactive oxygen species and malondialdehyde levels in ASL cells suggested oxidative stress under TiO2-NP exposure. We also observed dysregulation of aspartate aminotransferase and alanine aminotransferase levels. By detecting calcium ions and mitochondrial membrane potential indicators, we found that the apoptotic pathway induced by endoplasmic reticulum stress played a major role at low concentrations of TiO2-NP-induced stress. Both mitochondria-mediated and endoplasmic reticulum stress promoted apoptosis under increasing TiO2-NP concentrations. In conclusion, the ASL cell line established in this study is a useful in vitro model for toxicological studies of TiO2-NP exposure in fish.

Evaluation of Antimicrobial Efficiency, Shear Bond Strength, and Adhesive Remnant Index of TiO2 Infiltrated Orthodontic Adhesive - An In Vitro Study.

Background: Enamel demineralization is an unavoidable adverse effect encountered with bonding brackets in orthodontic therapy. Introducing nanoparticles into the composite adhesive paste can prevent enamel demineralization. Titanium dioxide (TiO2) is known to exhibit direct antimicrobial efficiency. This study aimed to assess the antibacterial efficiency and shear bond strength (SBS) of an orthodontic bonding composite infiltrated with TiO2 nanoparticles. Materials and Methods: This in vitro study evaluated the efficiency of TiO2 nanoparticle-incorporated light-curing orthodontic composite paste (ENLIGHT, ORMCO). Twenty extracted premolars were randomly and equally allocated to the two study groups, N = 10. While a conventional composite was utilized for the bonding brackets in Group I, a TiO2-incorporated composite was used in Group 2. The adhesive remnant index (ARI) scores given by Artun and Bergland et al. and SBS were determined. Furthermore, the antimicrobial efficiency was estimated using the minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) and agar well diffusion assay for six composite disc specimens. The results were statistically analyzed using the chi-square test and Student's t test, at P < 0.05. Results: After 24 h of curing, no statistical mean difference was observed between the two groups in terms of ARI or SBS scores (P > 0.05). However, there was a significant increase in the antimicrobial efficiency of Group II when compared with Group I (P < 0.05). Conclusion: TiO2 nanoparticle-incorporated orthodontic composites improve the antimicrobial efficiency with no significant change in the SBS. The ARI scores indicate the presence of 50% remnant orthodontic composite on the tooth enamel surface post debonding.

Earth-abundant catalyst for modification of wheat straw to enhance ammonia mitigation from fertilized alkaline soil.

In this study, inexpensive earth-abundant catalyst of Co/TiO2 is coupled with a low-temperature modification approach to enhance NH3 adsorption capacity on wheat straw (WS). The highest NH3 uptake achieved is 111.9 mg/g, with 80.8 % retention even after 3 h of desorption. Mechanistic investigation indicates that the enhanced adsorption capacity stems from Co/TiO2, which facilitates generation of reactive oxygen species, leading improved ultra-micropore structure that enhances the interaction between NH3 and oxygen-containing functional groups through a trapping effect. The robust stability of adsorbed NH3 is attributed to the formation of amides or amines. Incorporation of only 1 wt% WS-Co to urea-fertilized alkaline soil reduced NH3 volatilization by 83.1 %. The significant effect is primarily attributed to the excellent adsorption capacity of WS-Co, rather than alterations in the relative abundance of the microbial community. These findings present a novel approach for development of effective fertiliser additive to mitigate NH3 volatilization from alkaline soil.

A multi-omics approach reveals differences in toxicity and mechanisms in rice (Oryza sativa L.) exposed to anatase or rutile TiO2 nanoparticles.

Titanium dioxide nanoparticles (TiO2 NPs) have been widely used in agriculture, which increased the risk to soil-plant systems. Studies have demonstrated that TiO2 NPs can induce phytotoxicity. However, the toxicity mechanisms, particularly under the stress of TiO2 NPs with different crystalline forms, remain inadequately reported. In this study, we combined transcriptomics and metabolomics to analyze the toxicity mechanisms in rice (Oryza sativa L.) under the stress of anatase (AT) or rutile (RT) TiO2 NPs (50 mg/kg, 40 days). The length (decreased by 1.1-fold, p = 0.021) and malondialdehyde concentration (decreased by 1.4-fold, p = 0.0027) of rice shoots was significantly reduced after AT exposure, while no significant changes were observed following RT exposure. Antioxidant enzyme activities were significantly altered both in the AT and RT groups, indicating TiO2 NPs induced rice oxidative damage (with changes of 1.1 to 1.4-fold, p < 0.05). Additionally, compared to the control, AT exposure altered 3247 differentially expressed genes (DEGs) and 56 significantly differentially metabolites in rice (collectively involved in pyrimidine metabolism, TCA cycle, fatty acid metabolism, and amino acid metabolism). After RT exposure, 2814 DEGs and 55 significantly differentially metabolites were identified, which were collectively involved in fatty acid metabolism and amino acid metabolism. Our results indicated that AT exposure led to more pronounced changes in biological responses related to oxidative stress and had more negative effects on rice growth compared to RT exposure. These findings provide new insights into the phytotoxic mechanisms of TiO2 NPs with different crystalline forms. Based on the observed adverse effects, the study emphasizes that any form of TiO2 NPs should be used with caution in rice ecosystems. This study is the first to demonstrate that AT is more toxic than RT in paddy ecosystems, providing crucial insights into the differential impacts and toxic mechanisms of TiO2 NPs with different crystalline forms. These findings suggest prioritizing the use of RT when TiO2 NPs are necessary in agricultural development to minimize toxicity risks.

Synthesis of Urchin-like Au@TiO2 Nano-Carriers as a Drug-Loading System Toward Cancer Treatment.

In recent years, improving the pharmaceutical properties of drug delivery for anti-cancer treatment has become increasingly important. This is necessary to address challenges related to absorption, distribution, and stability. One potential approach solution is to attach the drug to a carrier system, such as functional noble nanomaterials, in order to improve the control of drug release and stability. Core-satellite nanoparticles (CSN) with an anisotropic morphology have enormous potential for targeted drug delivery and cancer treatment because of their large surface area, exceptional stability, and biocompatibility. We used a simple seed-mediated approach to synthesize urchin-like gold nanoparticles (ULGNPs) with a high aspect ratio and a dense network of 49 nm-sized branches, using seed solution, silver nitrate, and ascorbic acid. The ULGNPs were synthesized without a surfactant and then encapsulated with thin layers of amorphous TiO2 (ULGNPs@TiO2), resulting in an average overall size of 136±15 nm with a 27.5 nm TiO2 layer. Doxorubicin (Dox) was chosen as a model drug to assess the distribution carrier ability of ULGNPs@TiO2 core-satellite nanoparticles. The results showed 86.5% Dox loading and 72.3% release capacity at pH 5.

Synergistic Action of Vanillic Acid-Coated Titanium Oxide Nanoparticles: Targeting Biofilm Formation Receptors of Dental Pathogens and Modulating Apoptosis Genes for Enhanced Oral Anticancer Activity.

The prevalence of bacterial and fungal infections is caused by S. aureus, S. mutans, E. faecalis, and Candida albicans are often associated with dental illnesses. In the present study, a unique strategy was used to combat these diseases by fabricating titanium dioxide nanoparticles (TiO2 NPs) conjugated with the plant-based molecule vanillic acid (VA). Molecular modeling investigations were performed to better understand the interactions among vanillic acid and dental pathogen receptors using the Autodock program. The findings indicated that VA-TiO2 NPs exhibited strong free radical scavenging activity. Additionally, they showed excellent antibacterial action towards dental pathogens, with a minimum inhibition level of 60 µg/mL. Furthermore, at doses of 15 µg/mL, 30 µg/mL, 60 µg/mL, and 120 µg/mL, VA-TiO2 NPs demonstrated concentration-dependent apoptotic impacts on human oral carcinoma cells. Apoptotic gene over-expression was identified by the molecular perspectives that revealed the anticancer mechanism of VA-TiO2 NPs on KB cells. This study highlights the promising suitability of VA-TiO2 NPs for dental applications due to their robust antioxidant, anticancer, and antimicrobial characteristics. These nanoparticles present an evident prospect for addressing oral pathogen challenges and improving overall oral health.

Ternary TiO2/MoS2/ZnO hetero-nanostructure based multifunctional sensing devices.

Novel sensing applications benefit from multifunctional nanomaterials responsive to various external stimuli such as mechanics, electricity, light, humidity, or pollution. While few such materials occur naturally, the careful design of synergized nanomaterials unifies the cross-coupled properties which are weak or absent in single-phase materials. In this study, 2D MoS2 integrated with ultrathin dielectric oxide layers forms hetero-nanostructures with significant impacts on carrier transport. The ternary TiO2/MoS2/ZnO hetero-nanostructures, along with their individual properties, improve the performance of multifunctional sensing devices. The synthesized hetero-nanostructure exhibits a responsivity of up to 16 mA/W to 700 nm light and responds to 5 ppm ammonia gas at room temperature. These enhancements are attributed to interface charge transfer and photogating effects. The ternary TiO2/MoS2/ZnO hetero-nanostructure is compatible with existing semiconductor fabrication technologies, making it feasible to integrate into flexible, lightweight semiconductor devices and circuits. These results may inspire new photodetectors and sensing devices based on two-dimensional (2D) layered materials for IoT applications.

Design of a hybrid nanoscaled skin photoprotector by boosting the antioxidant properties of food waste-derived lignin through molecular combination with TiO2 nanoparticles.

TiO2 nanoparticles loaded with pistachio shell lignin (8 % and 29 % w/w) were prepared by a hydrothermal wet chemistry approach. The efficient interaction at the molecular level of the biomacromolecule and inorganic component was demonstrated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Visible (UV-Vis), Fourier transform infrared (FT-IR), dynamic light scattering (DLS), and electron paramagnetic resonance (EPR) analysis. The synergistic combination of lignin and TiO2 nanoparticles played a key role in the functional properties of the hybrid material, which exhibited boosted features compared to the separate organic and inorganic phase. In particular, the hybrid TiO2-lignin nanoparticles showed a broader UV-Vis protection range and remarkable antioxidant performance in aqueous media. They could also better protect human skin explants from the DNA damaging effect of UV radiations compared to TiO2 as indicated by lower levels of p-H2A.X, a marker of DNA damage, at 6 h from exposure. In addition, the samples could protect the skin against the structural damage occurring 24 h post UV radiations by preventing the loss of keratin 10. These results open new perspectives in the exploitation of food-waste derived phenolic polymers for the design of efficient antioxidant materials for skin photoprotection in a circular economy perspective.

Titanium Dioxide Nanomaterials: Progress in Synthesis and Application in Drug Delivery.

Background: Recent developments in nanotechnology have provided efficient and promising methods for the treatment of diseases to achieve better therapeutic results and lower side effects. Titanium dioxide (TiO2) nanomaterials are emerging inorganic nanomaterials with excellent properties such as low toxicity and easy functionalization. TiO2 with special nanostructures can be used as delivery vehicles for drugs, genes and antigens for various therapeutic options. The exploration of TiO2-based drug delivery systems shows great promise for translating nanotechnology into clinical applications; Methods: Comprehensive data on titanium dioxide were collected from reputable online databases including PubMed, GreenMedical, Web of Science, Google Scholar, China National Knowledge Infrastructure Database, and National Intellectual Property Administration; Results: In this review, we discuss the synthesis pathways and functionalization strategies of TiO2. Recent advances of TiO2 as a drug delivery system, including sustained and controlled drug release delivery systems were introduced. Rigorous long-term systematic toxicity assessment is an extremely critical step in application to the clinic, and toxicity is still a problem that needs to be closely monitored; Conclusions: Despite the great progress made in TiO2-based smart systems, there is still a great potential for development. Future research may focus on developing dual-reaction delivery systems and single-reaction delivery systems like redox and enzyme reactions. Undertaking thorough in vivo investigations is necessary prior to initiating human clinical trials. The high versatility of these smart drug delivery systems will drive the development of novel nanomedicines for personalized treatment and diagnosis of many diseases with poor prognosis.

Electro-, photo-, and photoelectrochemical degradation of chloramphenicol on self-doping Ti nanotubes.

In this work, the photo-, electro-, and photo-electro-oxidation of chloramphenicol was investigated. The photo-experiments were carried out with different irradiation sources (an ultraviolet and a simulated solar source) using self-doped titanium nanotubes (SDTNT), a very promising and innovative material that deserves further investigations in the degradation of different pollutants. The photo-electrooxidation (j = 15 mA cm-2) under simulated solar irradiation presented the best efficiency, with ca. 100% degradation and kinetic constant of k = 0.04427 min-1. The FTIR analysis demonstrated a structural modification of the standard molecule occurred for all conditions used, suggesting a modification in functional groups responsible for the biological activity. Furthermore, the TOC analysis showed a significant mineralization of the pollutant (66% from the initial concentration). In addition, both photo-electrooxidation approaches have demonstrated a positive value of S, where the simulated solar irradiation reached the highest value S = 0.6960. The experimental results pointed out evidence that the methodology employed herein for chloramphenicol degradation is greatly interesting and the photo-electrooxidation under simulated solar irradiation is a promising approach for this purpose.

Comparative Evaluation of the Effect of Microwave, 1% Sodium Hypochlorite, and Sodium Perborate Disinfection on the Color Stability of Two Nanoparticle-Reinforced Heat-Polymerized PMMA Denture Base Resins: An In Vitro Study.

Introduction Older adults experience significant improvement in their quality of life by using removable prosthetics to replace missing teeth. Poly(methyl methacrylate) (PMMA) has become the most popular material for denture bases due to its ease of use and affordability. Recently, scientists have started adding nanoparticles like titanium dioxide (TiO2) and zirconium oxide (ZrO2) to PMMA to enhance its physical properties. These resins with nanoparticles need to stay the same color after being disinfected in different ways if they are going to be used for a long time. So, the purpose of this investigation was to assess whether or not there exists any difference between two kinds of thermally cured acrylic resin for artificial tooth bases strengthened with nanoparticles when subjected to various chemical sterilizers alongside microwave irradiation, as well as determine their comparative colorfastness levels.  Materials and methods In this lab experiment, we tested how well 5% TiO2 and 7% ZrO2 nanoparticle-reinforced PMMA resins held their color when exposed to microwave irradiation, 1% sodium hypochlorite, or sodium perborate disinfection. We made 120 specimens shaped like discs; half were treated using one method, while the other half were treated using a different method. Color was measured at baseline (T0), after one cycle (T1), after five cycles (T2), and after six months (T3) using a reflectance spectrophotometer, which calculates the color difference (∆E). Results All three methods of disinfection caused significant color changes (p<0.001); however, sodium perborate caused the least amount of change, followed by 1% sodium hypochlorite and microwave irradiation. The mean ∆E values showed that after one day, there was a change in color by 1.1 due to microwave disinfection, which increased to 5.7 after five days; on the other hand, for 1% sodium hypochlorite, the change was recorded as 0.7 after one month and 1.6 after three months and finally reached up to 2.6 after six months, while sodium perborate showed the least amount of change, with ∆E values recorded as 0.2 after one month, 0.5 after three months, and 0.8 after six months. Conclusion Sodium perborate proved to be the most effective disinfectant for maintaining color stability in 5% TiO2 and 7% ZrO2 nanoparticle-reinforced PMMA resins, thus making it ideal for routine disinfection. Therefore, according to this study, sodium perborate should be used as a disinfection method because it results in minimal color change in nanoparticle-reinforced PMMA dentures.

Pd Catalysts Supported on Mixed Iron and Titanium Oxides in Phenylacetylene Hydrogenation: Effect of TiO2 Content in Magnetic Support Material.

Recently, Pd catalysts supported on magnetic nanoparticles (MNPs) have attracted a great attention due to their ability of easy separation with an external magnet. Modification of MNPs is successfully used to obtain Pd magnetic catalysts with enhanced catalytic activity. In this work, we discussed the effect of titania content in TiO2/MNPs support materials on catalytic properties of Pd@TiO2/MNPs catalysts in phenylacetylene hydrogenation. TiO2/MNPs composites were prepared by simple ultrasound-assisted mixing of TiO2 and MNPs, synthesized by co-precipitation method. This was followed by deposition of palladium ions on the mixed metal oxides using NaOH as precipitant. The supports and catalysts were characterized using XRD, BET, STEM, EDX, XPS, and a SQUID magnetometer. Pd nanoparticles (5-6 nm) formed were found to be homogeneously distributed on support materials representing the well-mixed metal oxides with TiO2 content of 10, 30, 50, or 70%wt. Testing of the catalysts in phenylacetylene hydrogenation showed that their activity increased with increasing TiO2 content, and the process was faster in alkali medium (pH = 10). The hydrogenation rates of triple and double C-C bonds on Pd@70TiO2/MNPs achieved 9.3 × 10-6 mol/s and 23.1 × 10-6 mol/s, respectively, and selectivity to styrene was 96%. The catalyst can be easily recovered with an external magnet and reused for 12 runs without significant degradation in the catalytic activity. The improved catalytic properties of Pd@70TiO2/MNPs can be explained by the fact that the surface of the support is mainly composed of TiO2 particles, affecting the state and size of Pd species.

Characterization of Food-Additive Titanium Dioxide and Dietary Exposure to Titanium Dioxide Nanoparticles among the Chinese Population.

Titanium dioxide (TiO2) is a prevalent food additive, yet comprehensive data on particle size and dietary exposure are lacking in China. Transmission electron microscopy results revealed that the quantitative proportion of nanoparticles (NPs) in food-additive TiO2 was 37.7%, with a mass fraction of 9.89%. Laboratory test results showed that among the domestic products surveyed, candies excluding gum-based candies contained the highest content of TiO2. Using consumption data from the China Health and Nutrition Survey in 2018, the average dietary exposure for TiO2 and TiO2 NPs in the Chinese population were calculated at 34.84 and 3.44 µg/kg bw/day, respectively. The primary dietary sources were puffed food and powdered drinks. Exposure varied significantly across age and region, with children and Inner Mongolia residents having the highest intake. TiO2 NP exposure showed a negative correlation with age. Despite this, the dietary exposure risk of TiO2 NPs for the Chinese population remains deemed acceptable.

Toxicological Effects of Leachates Extracted from Photocatalytic Concrete Blocks with Nano-TiO2 on Daphnia magna.

The incorporation of titanium dioxide nanoparticles into concrete blocks for paving adds photocatalytic functionality to the cementitious matrix, providing self-cleaning and pollutant-degrading properties. However, wear and leaching from these pavements can release potentially toxic compounds into water bodies, affecting aquatic organisms. In this context, this study evaluated the toxicological effects of leachates from photocatalytic concrete containing nano-TiO2 with an average size of 10 nm and anatase crystallinity on Daphnia magna. Acute and chronic toxicity tests on neonates were conducted with two leachate extracts: one from reference concrete and one from photocatalytic concrete (with 9% nano-TiO2 added by mass of cement). In terms of acute toxicity, the reference concrete extract had an EC50 of 104.0 mL/L at 48 h, whereas the concrete with TiO2 had an EC50 of 64.6 mL/L at 48 h. For chronic toxicity, the leachate from reference concrete had a significant effect (p < 0.05) on the size parameter with an LOEC of 4 mL/L, whereas the leachate from concrete with 9% nano-TiO2 did not have significant toxicological effects on any of the analyzed parameters (longevity, size, reproduction, and age of first posture) (LOEC > 6.5 mL/L). Furthermore, FTIR analysis indicated that TiO2 nanoparticles were not detected in the leachates, suggesting efficient anchoring within the cementitious matrix. The results indicate that there was no increase in the chronic toxicity of the leachate from the cementitious matrix when nanoparticles were added at a 9% mass ratio of cement.

Impact of LED radiation intensity on gold nanoparticles photodeposition on TiO2 with physicochemical and photocatalytic characterization.

This study investigates the influence of LED radiation intensity on the photodeposition of gold nanoparticles onto TiO2 substrates, examining their physicochemical properties and photocatalytic activities. Utilizing a range of radiation intensities and wavelengths, TiO2-Au composites were synthesized and characterized through techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). The deposition process, markedly enhanced by shorter wavelengths and higher intensities, efficiently formed gold nanoparticles. This research distinctly highlights observable morphological changes in the nanoparticles; increased radiation intensity not only augmented the size but also altered their shape from spherical to hexagonal. These morphological transformations significantly improve the composites' light absorption and catalytic properties due to the surface plasmon resonance of the gold nanoparticles. Photocatalytic assessments, using metronidazole as a model pollutant, demonstrated that composites prepared with higher LED intensities showed significantly enhanced degradation capabilities compared to those synthesized with lower intensities. The findings underscore that manipulating photodeposition parameters can critically influence the structural and functional properties of TiO2-Au composites, potentially advancing their applications in environmental remediation and solar energy utilization.

Mechanisms of slow-release antibacterial properties in chitosan­titanium dioxide stabilized perilla essential oil Pickering emulsions: Focusing on oil-water interfacial behaviors.

Perilla essential oil (PLEO) offers benefits for food preservation and healthcare, yet its instability restricts its applications. In this study, chitosan (CS) and TiO2 used to prepare composite particles. TiO2, after being modified with sodium laurate (SL), was successfully introduced at 0.1 %-3 % into the CS matrix. The resulting CS-SL-TiO2 composite particles can be formed by intertwining and rearranging through intramolecular and intermolecular interactions, and form an O/W interface with stability and viscoelasticity. The Pickering emulsions stabilized by these particles exhibit non-Newtonian pseudoplastic behavior, shear-thinning properties, and slow-release characteristics, along with antibacterial activity. Emulsions with 0.5 % and 1 % CS-SL-TiO2 composites demonstrated superior antibacterial effects against Escherichia coli and Staphylococcus aureus. The study revealed that all emulsions undergo Fickian diffusion and a sustained release of PLEO, with the Ritger-Peppas model best describing this release mechanism. The slow-release behaviors positively correlates with interfacial pressure, composite particle size, composite particle potential, composite contact angle, emulsion particle size and emulsion potential, but negatively correlates with diffusion rate, penetration rate, release kinetics and release rate. The findings lay groundwork for developing slow-release antimicrobial emulsions within polysaccharide matrices, showcasing promise for antimicrobial packaging solutions and enhanced food preservation techniques.