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Titanium dioxide nanoparticles have great potential for use in photocatalytic applications, cosmetics, white pigments and so on. In this paper, the effect of milling time on particle size, morphology and phase composition of TiO₂ nanoparticles, prepared by mechanochemical method, was investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). TiO₂ nanoparticles were prepared by the use of high energy ball milling of titanyl sulphate (TiOSO₄) and NaCl powders as the starting mixture in different milling durations. The milled powder was annealed at 700°C for 30 min. The NaCl powder, used as the diluent phase, was removed by washing the annealed powder with distilled water. It was found that with increasing milling time, decrease in the size of equiaxed spherical particles and increase in temperature of anatase to rutile transformation (A → R) can be observed.

This paper reports the enhancement in the sensing properties of organic dye methyl orange (MO) by introducing TiO₂ nanoparticles. For this purpose, two surface type Ag/MO/Ag and Ag/MO:TiO₂/Ag multifunctional sensors were fabricated by spin coating a 3.0 wt.% solution of MO and 3.0:0.3 wt.% of MO:TiO₂ composite on pre-patterned silver (Ag) electrodes. The gap between Ag electrodes was 40 μm. The Ag/MO/Ag and Ag/MO:TiO₂/Ag structures were characterized to investigate their response towards humidity and temperature variations. The Ag/MO:TiO₂/Ag sensor exhibited better sensitivity and response time than Ag/MO/Ag sensor. The large surface to volume ratio of TiO₂ nanoparticles is the primary reason for the higher sensitivity of Ag/MO:TiO₂/Ag sensor. The sensors can be used to detect humidity variations from 30% to 95% RH and temperature variation from 30°C to 200°C with good stability. Surface morphologies of the film were investigated by scanning electron microscope (SEM).

The development of photocatalysts with low cost, high reactivity and easy recovery provides great potentials for environmental remediation. In this study, polyacrylonitrile (PAN) nanofibers containing titanium dioxide (${\mathrm{\text{TiO}}}_2$) nanoparticles were successfully fabricated using a facile electrospinning technique. The effects of ${\mathrm{\text{TiO}}}_2$ content, PAN concentration and thermal treatment on the adsorption and photocatalysis properties of ${\mathrm{\text{PAN/TiO}}}_2$ nanofibers have been investigated. The results indicate that the embedded ${\mathrm{\text{TiO}}}_2$ nanofibers possess the property to effectively decompose rhodamine B (RhB) under simulated sunlight irradiation. The enhanced photocatalytic activity can be attributed to the loading of ${\mathrm{\text{TiO}}}_2$ nanoparticles and the property of polymer matrix.

Ni–P–TiO₂ composite coatings were deposited on brass substrates using a sol-enhanced electrodeposition method. The cyclic voltammetry tests were used to study the effect of TiO₂ sol on Ni–P deposition. The surface morphologies of Ni–P–TiO₂ deposits were observed, and their elemental analysis was also conducted. The systematic tests were performed to characterize the mechanical and corrosion behavior of as-prepared coatings. The voltammetric studies showed that the addition of TiO₂ sol at 12.5 mL/L slightly promoted the Ni–P electrodeposition, while the excessive addition at 50 mL/L reduced it. The results showed that the in-situ generated TiO₂ nanoparticles ( ∼15 nm diameter) could be highly dispersed in the electrolytic bath. The addition of TiO₂ sol at 12.5 mL/L slightly promoted the Ni–P electrodeposition, while the excessive addition at 50 mL/L caused the opposite.

Ti_1-xMn_xO₂ (x = 0, 0.05) nanoparticles have been synthesized using chemically derived self-propagating combustion reaction method. X-ray diffraction studies demonstrate the formation of anatase phase of TiO₂ belonging to 141/amd space group in both samples without the formation of any impurity phase. The incorporation of 5 at.% Mn content does not produce any changes in crystal structure which reveals the exact substitution of Mn atoms at Ti sites. Some change in lattice parameters and crystallite size is observed in Mn-doped composition, attributed to the difference in ionic radii. The size of grains obtained using scanning electron micrographs shows the consistent trend with the crystallite size evaluated from X-ray diffraction analysis. Energy dispersive X-ray analysis confirms the incorporation of Mn content in TiO₂ structure. Ferromagnetic behavior detected only in Mn-doped TiO₂ composition correspond to the strong Mn d-shell contribution.

Nanomaterials can be employed in various medicinal industries because of their unique characteristics versus bulk materials. Nanosized particles of Titanium dioxide were fabricated using the laser irradiation technique in this work. After production, the physical properties of Titanium dioxide were identified by Ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectrum, X-ray diffraction, FTIR, and Transmission electron microscopy (TEM) techniques. Regarding TEM micrographs with various laser energies, the nanoparticles exhibit a spherical appearance, with average diameters ranging from 19nm to 26 nm based on the laser energy. X-ray diffraction results from combined Anatase and Rutile crystal structures in the prepared nanoparticles to indicate the production of Titanium dioxide nanoparticles. The FTIR analysis showed that the O-Ti-O mode includes a peak at approximately 480–550cm${}^{-1}$. In this study, the antibacterial efficacy of Titanium dioxide nanoparticles was investigated against Staphylococcus aureus and Escherichia coli, as well as anticancer assay against prostate cancer cell line (PC-3 cells). The result shows that the effectiveness of prepared nanoparticles against S. aureus is more significant than that in E. coli, and the findings indicate the ability of prepared nanoparticles as an antiproliferative agent against PC-3 cells. In conclusion, the prepared nanoparticles could be used as a future strategy for further biomedical applications.

Functional nanoscale materials that possess specific physical or chemical properties can leverage energy transduction in vivo. Once these materials integrate with biomolecules they combine physical properties of inorganic material and the biorecognition capabilities of bio-organic moieties. Such nano–bio hybrids can be interfaced with living cells, the elementary functional units of life. These nano–bio systems are capable of bio-manipulation or actuation via altering intracellular biochemical pathways. Thus, nano–bio conjugates are appealing for a wide range of applications from the life sciences and nanomedicine to catalysis and clean energy production. Here we highlight recent progress in our efforts to develop smart nano–bio hybrid materials, and to study their performance within cellular machinery under application of external stimuli, such as light or magnetic fields.

Well crystallized Aluminium (Al) doped Titanium dioxide (TiO₂) nanoparticles with various doping concentration (0, 0.05M, 0.07M, 0.09M and 0.11M) were synthesized successfully by sol–gel route to develop the photo anode of Dye Sensitized Solar Cell (DSSC). Anatase crystalline nature of TiO₂ nanoparticles was confirmed using X-ray diffraction (XRD) and Raman spectrophotometer. The Atomic Force Microscopy (AFM) was used to investigate the morphology of the photo anode (Al-doped TiO₂ nanoparticles). The photovoltaic performance of the DSSC in terms of Current, Voltage and efficiency was investigated with a standard illumination of AM1.5G having an irradiance 100mW/cm². Optimized values of Short Circuit Current density ($I_{\mathrm{\text{sc}}}$), Open Circuit Voltage ($V_{\mathrm{\text{oc}}}$) and efficiency ($\eta$) obtained was 247.62$\mu$A/cm², 359mV and 0.02456%, respectively for 0.07M Al doping concentration. Eco-friendly Eosin Y dye was used for sensitization of the photo anode. The optimized photovoltaic cell exhibits very good efficiency (80.05% more than the earlier reported work).

Nowadays the problem of antimicrobial resistance is the most important cause of morbidity and mortality in the treatment of infectious diseases worldwide. Treatment options for antimicrobial-resistant microorganisms are quite limited. Therefore, alternative treatment strategies are needed to control infectious diseases. Antimicrobial photodynamic therapy (aPDT) is one of the new treatment modalities proposed for a wide variety of infections. In the basic principle of aPDT, photosensitizers (PS) produce free radicals by irradiating them with harmless light at the appropriate wavelength, and this causes microorganism cell cytotoxicity.

In this study, light emitting diodes (LED) (630–700 nm, 17.4 mW/cm${}^2)$ were used on Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) at different light doses under the minimum inhibitory concentration (MIC) values of SubPc and SubPc-integrated TiO₂ nanoparticles (SubPc-TiO${}_2)$ concentration. Both compounds show good phototoxicity toward S. aureus when high light doses (16, 24J/cm${}^2)$ were applied. In addition, SubPc-TiO₂ were found to be more effective than SubPc in aPDT of S. aureus. In E. coli, the success of aPDT has been shown to be dependent on the increased light dose (20, 30J/cm${}^2)$ for both compounds. As a result, the aPDT activity of SubPc-TiO₂ is more effective than SubPc in increasing light doses.

Antibiotic resistance is an increasing healthcare problem worldwide. In the present study, the effects of antimicrobial photodynamic therapy (APDT) of ZnPc and ZnPc-integrated TiO₂ nanoparticles (ZnPc-TiO${}_2)$ were investigated against Staphylococcus aureus. A light emitting diode (LED) (630–700 nm, 17.4 mW/cm${}^2)$ was used on S. aureus at different light doses (8 J/cm² for 11 min, 16 J/cm² for 22 min, 24 J/cm² for 33 min) in the presence of the compounds under the minimum inhibitory concentration values. Both compounds showed similar phototoxicity toward S. aureus when high light doses (16 and 24 J/cm${}^2)$ were applied. In addition, the success of APDT increased with an increasing light dose.

Because of the decrease in the band gap and the carrier recombination rate, the visible light photocatalysis performance of the mixed-phase TiO₂ with oxygen vacancies is better than that of the pure-phase TiO₂. In this study, two different acids were separately applied in the hydrothermal synthesis of TiO₂ nanoparticles without any post-heat treatment. The reaction was carried out at a relatively low temperature not exceeding 140^∘C. Both kinds of crystallized TiO₂ powders show much more band gap reduction than that of commercial Degussa P25 TiO₂ nanoparticles, which can be attributed to the oxygen vacancies. Under the visible light illumination-assisted photocatalytic degradation of methyl orange in water, the two mixed-phase TiO₂ powders exhibited a steady photocatalytic activity upon increasing to five cycles. The highest photocatalytic efficiency of the two powders is 2.7 times than that of the P25 powder, which is regarded as an excellent photocatalyst for water purification.

A sol–gel method was used to synthesize TiO₂ nanoparticles doped with varying amounts of Mn. The physico-chemical properties of the synthesized nanoparticles were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and diffuse reflection spectroscopy (DRS). The XRD results indicated that the anatase phase was the major phase of TiO₂, while a minor rutile phase was observed in the Mn-doped TiO₂ 0.2 wt.% and 0.3 wt.% samples. The TEM analysis showed that the Mn atoms existed in different oxidation states, including Mn${}^{2+}$, Mn${}^{3+}$, Mn${}^{4+}$ and Mn${}^{7+}$, and that the nanoparticles had a spherical-like morphology with a size ranging from 10nm. The narrowest band gap of 2.80eV was observed in the Mn-doped TiO₂ 0.2 wt.% sample. The photocatalytic activity of the synthesized nanoparticles was evaluated for methylene blue (MB) photodegradation and Escherichia coli (E. coli) photokilling under visible light irradiation. The MB degradation efficiency was found to be the highest in the Mn-doped TiO₂ 0.2 wt.% sample, with a removal efficiency of 96% and a degradation rate constant of 0.08 1/min. The degradation efficiency decreased in the following order: Mn-doped TiO₂ 0.1 wt.%, 0.3 wt.% and undoped TiO₂. Similarly, complete E. coli photokilling was achieved only in the Mn-doped TiO₂ 0.2 wt.% sample, while some residual E. coli was observed in the other doping nanoparticles and undoped TiO₂. In summary, the results suggest that Mn doping significantly improved the photocatalytic activity of TiO₂ nanoparticles, and the Mn-doped TiO₂ 0.2 wt.% sample exhibited the highest efficiency in both MB photodegradation and E. coli photokilling under visible light irradiation.

Dye-sensitized solar cells (DSSCs) were built by using ZnO/TiO₂ films as electrodes consisting of ZnO nanorod arrays coated with TiO₂ nanoparticles (NPs) in sol or slurry form prepared by sol–gel methods. The addition of TiO₂ sol to ZnO arrays resulted in an improvement of cell performance, but the cell efficiency was not high. The cell efficiency was more improved by coating of ZnO arrays with TiO₂ slurry. The tetraethylammonium hydroxide surfactant was effective to control TiO₂ NPs suspension between sol and slurry. The penetration of TiO₂ sol or slurry into ZnO array was important, especially in the long nanorod array. The cell performance of ZnO/TiO₂ electrode increased more by TiO₂ slurry than by TiO₂ sol because TiO₂ sol shrank more during calcination.

Mesoporous g-C₃N₄ is prepared by a hard template method and is then decorated by carbon quantum dots (CQDs) and TiO₂ nanoparticles through an impregnation route followed by a hydrothermal method. The synthesized hybrids possess higher specific surface area up to 131cm²/g and show effective absorption of visible light range and improved instantaneous photocurrent response, which reveals the enhanced photo-generated carrier separation efficiency. The first-order kinetic reaction rate constant of photocatalytic degradation of gaseous benzene by TCPCN-2 is 5.5 times of the bulk g-C₃N₄. Its degradation rate is up to 96.08% with good photocatalytic stability. Thus, the TiO₂ nanoparticles and CQDs co-decorated g-C₃N₄ hybrids are promising photocatalysts.

Nanotechnology represents major scientific and economic issues for the future. TiO₂ is used as a reference nanoparticle (NP) for research and workplace exposure assessments due to its important industrial production. However, to date little consistent information exists about its human health effects. Approximately 50% of all TiO₂in vivo studies targeting the respiratory tract have been by inhalation and these exposures are often in the form of agglomerates rather than as individual NPs. Therefore, the size of the NP agglomerates represents the effective size interacting with the biological material and could thereby influence the NP mechanisms of action. Thus, interpretation of nanotoxicological data without considering the agglomeration state could partly explain the heterogeneous results found in the scientific literature for TiO₂ NPs. The objective of this review is to examine the literature concerning the importance of TiO₂ aerosol characterization in the assessment of pulmonary toxicity in rodents. In this way, this review reveals that the pulmonary responses following inhalation of TiO₂ NPs might not depend solely on the primary NP size, but also on the crystal phase, the NP agglomerate size, its structure and the mass concentration. It also shows that TiO₂ NPs may exert their toxicity mechanisms specifically because of the size of their agglomerates in aerosols, thus supporting the concept that aerosols composed essentially of small (< 100 nm) or large (> 100 nm) NP agglomerates do not seem to follow the same pulmonary toxicity mechanisms.

Antibiotic resistance is an increasing healthcare problem worldwide. In the present study, the effects of antimicrobial photodynamic therapy (APDT) of ZnPc and ZnPc-integrated TiO₂ nanoparticles (ZnPc-TiO₂) were investigated against Staphylococcus aureus. A light emitting diode (LED) (630–700 nm, 17.4 mW/cm²) was used on S. aureus at different light doses (8 J/cm² for 11 min, 16 J/cm² for 22 min, 24 J/cm² for 33 min) in the presence of the compounds under the minimum inhibitory concentration values. Both compounds showed similar phototoxicity toward S. aureus when high light doses (16 and 24 J/cm²) were applied. In addition, the success of APDT increased with an increasing light dose.