Immobilised rGO/TiO2 Nanocomposite for Multi-Cycle Removal of Methylene Blue Dye from an Aqueous Medium

This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, •OH, and e−) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles.

Investigation of environmental and therapeutic applications of holmium doped titanium dioxide (Ho-TiO2) nanocatalysts. Kinetic and thermodynamic study of the photocatalytic degradation of Safranin O dye

Titanium dioxide (TiO2) and Holmium doped Titanium dioxide(Ho-TiO2) nanoparticles (NPs) were synthesized through Sol Gel method. The synthesized NPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence spectroscopy. DNA binding, antibacterial, hemolytic and antioxidant assays of the synthesized nanoparticles were also carried out for finding their therapeutic applications. Successful doping of TiO2 with Ho reduced the band gap from 3.10 to 2.88 eV. SEM and XRD analysis showed that both TiO2 and Ho-TiO2 NPs exhibit tetragonal structure and as a result of doping the morphology of the particles improved and agglomeration reduced. PL emission intensity of TiO2 also reduced with doping.The holmium doped TiO2 were used for the first time against the degradation of Safranin O dye, DNA binding study and biocompatibility assay.The degradation of Safranin O dye over both the catalysts followed first order kinetics. The calculated activation energies for the photo degradation of given dye were found to be 51.7 and 35.2 kJ/mol using TiO2 and Ho-TiO2 NPs respectively. At 180 minutes time interval 84 and 87% dye degradation was observed using pure TiO2 and Ho-TiO2 NPs respectively. High percent degradation of dye was found at low concentration (20 ppm) and at optimal dosage (0.035 g) of both the catalysts. The rate of Safranin O dye degradation was found to increase with increase in temperature and pH of the medium. DNA binding study revealed that Ho-TiO2 NPs are more capable of binding to human DNA. Antibacterial activity study showed that Ho-TiO2 NPs were more efficient against both gram-negative and gram-positive bacterial strains as compared to pure TiO2. Hemolysis assay showed that TiO2 and Ho-TiO2 nanoparticles are non-biocompatible.Ho-TiO2 nanoparticles showed higher anti-oxidant activity as compared to bare TiO2.

Lack of pulmonary fibrogenicity and carcinogenicity of titanium dioxide nanoparticles in 26-week inhalation study in rasH2 mouse model

Background: With the rapid development of alternative methods based on the spirit of animal welfare, the publications of animal studies evaluating endpoints such as cancer have been extremely reduced. There have been no systemic inhalation exposure studies of titanium dioxide nanoparticles (TiO2 NPs) using CByB6F1-Tg(HRAS)2Jic (rasH2) 26-week study mice model for detecting carcinogenicity. Methods: Male and female rasH2 mice were exposed to 2, 8 or 32 mg/m3 of TiO2 NPs for 6 hours/day, 5 days/week for 26 weeks using a whole-body inhalation exposure system, with reference to the Organization for Economic Co-operation and Development principles of Good Laboratory Practice. All tissues including lungs, and blood were collected and subjected to biological and histopathological analyses. Additionally, Ki67 positive index were evaluated in mice lung alveolar epithelial type 2 cell (AEC2). Results: This study established a stable method for generating and exposing TiO2 NPs aerosol, and clarified the dose-response relationship by TiO2 NPs inhalation to rasH2 mice. TiO2 NPs exposure induced deposition of particles in lungs and mediastinal lymph nodes in a dose-dependent manner in each exposure group. Additionally, alveolar inflammation was only observed in 32 mg/m3 exposure group in both the sexes. Exposure to TiO2 NPs, as well as other organs, did not increase the incidence of lung tumors in any group, and pulmonary fibrosis and pre-neoplastic lesions were not observed in all groups. Finally, the cell proliferative activity of AEC2 was examined, and it was not increased by exposure to TiO2 NPs. Conclusions: This is the first report showing the lack of pulmonary fibrogenicity and carcinogenicity (no evidence of carcinogenic activity) of TiO2 NPs in 26-week inhalation study in rasH2 mice exposed up to 32 mg/m3, which is considered to be a high concentration. Macrophages undergoing phagocytosis due to TiO2 NPs exposure formed inflammatory foci in the alveolar regions of exposed mice but did not develop fibrosis or hyperplasia or tumors. Moreover, the cell proliferative ability of AEC2 in lesions was not increased. In addition, no carcinogenicity was observed for any organs other than the lungs in this study.

Investigation of Environmental and Therapeutic Applications of Holmium doped Titanium dioxide (Ho-TiO2) nanocatalysts. Kinetic and Thermodynamic study of the Photocatalytic degradation of Safranin O dye

Titanium dioxide (TiO2) and Holmium doped Titanium dioxide(Ho-TiO2) nanoparticles (NPs) were synthesized through Sol Gel method. The synthesized NPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence spectroscopy. DNA binding, antibacterial, hemolytic and antioxidant assays of the synthesized nanoparticles were also carried out for finding their therapeutic applications. Successful doping of TiO2 with Ho reduced the band gap from 3.10 to 2.88 eV. SEM and XRD analysis showed that both TiO2 and Ho-TiO2 NPs exhibit tetragonal structure and as a result of doping the morphology of the particles improved and agglomeration reduced. PL emission intensity of TiO2 also reduced with doping.The holmium doped TiO2 were used for the first time against the degradation of safranin O dye, DNA binding study and biocompatibility assay.The degradation of Safranin Odye over both the catalysts followed first order kinetics. The calculated activation energies for the photo degradation of given dye were found to be 51.7 and 35.2kJ/mol using TiO2 and Ho-TiO2 NPs respectively. At 180 minutes time interval 84% and 87 % dye degradation was observed using pure TiO2 and Ho-TiO2 NPs respectively. High percent degradation of dye was found at low concentration (20ppm) and at optimal dosage (0.035g) of both the catalysts. The rate of Safranin O dye degradation was found to increase with increase in temperature and pH of the medium. DNA binding study revealed that Ho-TiO2 NPs are more capable of binding to human DNA. Antibacterial activity study showed that Ho-TiO2 NPs were more efficient against both gram-negative and gram-positive bacterial strains as compared to pure TiO2. Hemolysis assay showed that TiO2 and Ho-TiO2 nanoparticles are non-biocompatible.Ho-TiO2 nanoparticles showed higher anti-oxidant activity as compared to bare TiO2.

The Effect of TiO2 Nanoparticles on the Composition and Ultrastructure of Wheat

The present work aims to follow the influence of TiO2 nanoparticles (TiO2 NPs) on bioactive compounds, the elemental content of wheat, and on wheat leaves’ ultrastructure. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). The concentration of phenolic compounds, assimilation pigments, antioxidant capacity, elemental content, as well as the ultrastructural changes that may occur in the wheat plants grown in the presence or absence of TiO2 NPs were evaluated. In plants grown in the presence of TiO2 NPs, the amount of assimilating pigments and total polyphenols decreased compared to the control sample, while the antioxidant activity of plants grown in amended soil was higher than those grown in control soil. Following ultrastructural analysis, no significant changes were observed in the leaves of TiO2-treated plants. Application of TiO2 NP to soil caused a significant reaction of the plant to stress conditions. This was revealed by the increase of antioxidant capacity and the decrease of chlorophyll, total polyphenols, and carotenoids. Besides, the application of TiO2 NP led to significant positive (K, Zn, Br, and Mo) and negative (Na, Mn, Fe, As, Sr, Sb, and Ba) variation of content.

Semiconductor Quantum Dots (CdX, X = S, Te, Se) Modify Titanium Dioxide Nanoparticles for Photodynamic Inactivation of Leukemia HL60 Cancer Cells

Titanium dioxide nanoparticles (TiO2-NPs) are highly efficient photosensitizers in traditional photodynamic therapy (PDT). The particle size of TiO2-NPs is small, only about 20 nm. However, the demands of ultraviolet light (UV) excitation feature shallow tissue penetration depth and may lead to severe tissue photon damage. Thus, in this research, TiO2-NPs are modified with semiconductor quantum dots (QDs) CdX (X = S, Te, Se) in various methods, such as ultrasonic, hydrothermal, sol-gel, aqueous phase, and hydrolysis precipitation. The transmission electron microscopy (TEM) images show that the size of CdSe-TiO2 is ranging from 6 to 14 nm. The ultraviolet-visible (UV-Vis) spectrum demonstrates that the CdX (X = S, Te, Se) modification can successfully extend the absorption range of TiO2-NPs into a different visible light region. CdSe QDs have the narrowest band gap compared with CdX (X = S, Te, Se) QDs. Visible light-activated CdSe-TiO2 nanocomposite shows the highest PDT inactivation efficiency toward HL60 cells compared with CdX-TiO2. The photogenerated carrier separation efficiency of CdSe-TiO2 nanocomposite is the highest shown in a fluorescence spectrum (FS). Furthermore, when conjugated with folic acid (FA), the prepared FA-CdX-TiO2 (X = S, Se) exhibits excellent cancer-targeting ability during PDT treatment. Optimum PDT efficiency of FA-CdSe-TiO2 indicates that photocatalytic and targeting ability is much higher than pure TiO2 and CdSe-TiO2. Our results provided a detailed investigation on the PDT performance of CdX (X = S, Te, Se) modified TiO2 and may act as a guide for further design of highly targeted performance visible-light response TiO2-NPs.

Effectiveness of Goji Berries (Lycium barbarum) Extract and Some Nanoparticles Loaded on Gelatin Film on Microbial Content of Labneh

This study was conducted to evaluate the effect of Lycium barbarum extract, Chitosan nanoparticles (ChNPs) and Nanotitanium dioxide (TiO2 NPs) loaded on Gelatin films on the microbial content of labneh during different storage periods. The samples were divided into seven treatments which included (T1) non-coated labneh, (T2) labneh coated with gelatin membranes, (T3) labneh coated with gelatin membranes and Lycium barbarum extract, (T4) labneh coated with gelatin films and ChNPs, (T5) labneh coated with gelatin films treated TiO2NPs, (T6) Labneh coated with gelatin films, Lycium barbarum and ChNPs, (T7) Labneh coated with gelatin films, Lycium barbarum and TiO2 NPs. The total number of bacteria decreased after loading with the membranes for each specific period of time, and the treatment with T7 was the best, as the total number of bacteria decreased to 9.93 log/gm compared to the two controls (T1, T2), which amounted to (15.58, 13.47 log/gm) after 14 days of storage, respectively. While the numbers of Lipolytic and Proteolytic bacteria, yeasts and molds did not show any growth at the time of one day, with the prolonged storage period, the gradual increase in the total count of bacteria occurred for all treatments, it reached the highest numbers at the time of 14 days. Treatment T7 was the best in reducing the numbers of both lipolytic and proteinolytic bacteria, as well as yeasts and molds.

Influence of Antimicrobial Nanoparticles on Flexural Strength and Hardness of Polymethylmethacrylate

BACKGROUND: Polymethylmethacrylate (PMMA) is commonly used for dental appliances but has several shortcomings that could benefit from improvement with the use of nanoparticles (NPs). AIM: The purpose of this study was to modify PMMA with three different antimicrobial NPs; Graphene oxide nanosheets (nGO), Titanium dioxide NPs (TiO2 NPs) and curcumin (CUR)-loaded graphene oxide nanosheets alone, and in combination and assess the flexural strength and hardness of the different groups. MATERIALS AND METHODS: The material used in this study was chemically cured PMMA that was modified with nGO, TiO2 NPs and GOCUR alone and in combination to give 6 groups; Group A: PMMA, Group B: PMMA with nGO, Group C: PMMA with TiO2 NPs, Group D: PMMA with TiO2 and GO NPs, Group E: PMMA with GOCUR, and Group F: PMMA with TiO2 NP, and GOCUR. The Six groups were tested for flexural strength and hardness. Statistical analysis was and data were expressed as means and standard deviation. Data was explored for normality using the Kolmogorov-Smirnov test of normality. The ANOVA test was used to compare between groups, followed by Bonferroni’s post hoc test for pairwise comparison. The significance level was set at p ≤ 0.05. RESULTS: The highest flexural strength was recorded in Group C (52.26 ± 5.48 MPa) and the lowest value was in Group A (24.94 ± 5.37 MPa). The highest hardness was recorded in Group F (23.29 ± 0.8 HV) and the lowest value was in Group A (15.88 ± 1.02 HV). CONCLUSION: The modification of PMMA with NPs with proven antimicrobial activity can increase the flexural strength and hardness of the material. GO, TiO2 and, GOCUR NPs were each used alone and in different combinations, and all the groups displayed higher flexural strength and hardness than the unmodified PMMA.