RETRACTION: Novel Synthesis of Titanium Oxide Nanoparticles: Biological Activity and Acute Toxicity Study.

Titanium oxide nanoparticles (TiO2 NPs) have been attracting numerous research studies due to their activity; however, there is a growing concern about the corresponding toxicity. Here in the present study, titanium oxide nanoparticles were newly synthesized using propolis extract followed by antimicrobial activity, cytotoxicity assay using human cancer cell lines, and acute toxicity study. The physicochemical characterization of the newly synthesized TiO2 NPs had average size = 57.5 nm, PdI = 0.308, and zeta potential = −32.4 mV. Antimicrobial activity assessment proved the superior activity against Gram-positive compared to Gram-negative bacteria and yeast (lowest MIC values 8, 32, and 32, respectively). The newly synthesized TiO2 NPs showed a potent activity against the following human cancer cell lines: liver (HepG-2) (IC50 8.5 µg/mL), colon (Caco-2), and breast (MDA-MB 231) (IC50 11.0 and 18.7 µg/mL). In vivo acute toxicity study was conducted using low (10 mg/kg) and high (1000 mg/kg) doses of the synthesized TiO2 NPs in albino male rats. Biochemistry and histopathology of the liver, kidney, and brain proved the safety of the synthesized TiO2 NPs at low dose while at high dose, there was TiO2 NPs deposit in different vital organs except the cerebral tissue.

Recent improvements in advanced technology for toxic chemical remediation have involved the application of titanium oxide nanoparticles as a photocatalyst. However, the large energy bandgap associated with titanium oxide nanoparticles (3.0–3.20 eV) is a limitation for their application as a photocatalyst within the solar spectrum. Various structural modification methods have led to significant reductions in the energy bandgap but not without their disadvantages, such as electron recombination. In the current investigation, biochar was made from the leaves of an invasive plant (Acacia saligna) and subsequently applied as a support in the synthesis of titanium oxide nanoparticles. The characterization of biochar-supported titanium oxide nanoparticles was performed using scanning electron microscopy, Fourier transformer infrared, X-ray diffraction, and Brunauer–Emmett–Teller analyses. The results showed that the titanium oxide was successfully immobilized on the biochar’s external surface. The synthesized biochar-supported titanium oxide nanoparticles exhibited the phenomenon of small hysteresis, which represents the typical type IV isotherm attributed to mesoporous materials with low porosity. Meanwhile, X-ray diffraction analysis revealed the presence of a mixture of rutile and anatase crystalline phase titanium oxide. The synthesis of biochar-supported titanium oxide nanoparticles was highly efficient in the degradation of Orange II Sodium dye under solar irradiation. Moreover, 83.5% degradation was achieved when the biochar-supported titanium oxide nanoparticles were used as photocatalysts in comparison with the reference titanium oxide, which only achieved 20% degradation.

This study investigates the synthesis, characterisation, and application of titanium dioxide nanoparticles (TNP) as an adsorbent for effectively removing Methylene Blue (MB) dye from aqueous solutions. The TNP was synthesised through a biogenic route using Pseudomonas aeruginosa as a bio-reducing and stabilising agent. The synthesised nanoparticles were characterised using various analytical techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The UV–visible spectrophotometer was used to monitor nanoparticle formation at a wavelength of 393 nm. Results from the study showed that XRD confirmed the nanostructured and amorphous nature of TNP, while SEM–EDX analysis indicated a coarse and rough surface of the nanoparticles. TEM analysis revealed their uniform spherical morphology, and FTIR spectroscopy identified the presence of O–H, C-O, and N–H functional groups likely responsible for MB adsorption. The adsorption experiments examined factors such as initial dye concentration, adsorbent dosage, contact time, solution pH, and temperature via batch adsorption methods. Kinetic studies demonstrated that the pseudo-second-order model accurately described the complex dynamics of the adsorption process. The Langmuir isotherm model was found to be the best fit for the experimental data, indicating monolayer adsorption on the TNP surface. Thermodynamic studies provided insights into the energetics of the adsorption process, with positive ∆H (12.75 kJ) indicating an endothermic reaction, while positive ∆S (62.27 J/mol) suggested increased disorderliness between adsorbent and adsorbate. Negative values of ∆G (− 8.522 and − 13.967 kJ/mol) confirmed the feasibility and spontaneity of the adsorption system, demonstrating a strong affinity for MB. After five cycles of adsorption and desorption, the regeneration study revealed that TNP maintained an MB removal capacity of over 80%. Highlights from this research underscore the excellent potential of green-synthesised TNP as a promising adsorbent for the efficient removal of MB dye from aqueous solutions and for potential application in other wastewater treatments.

Room temperature synthesis of titanium dioxide nanoparticles of different phases in water in oil microemulsion

Aim: The present study focusses on the synthesis of titanium dioxide nanoparticles from the shell and the whole-body tissue ethanolic extracts of the blue crab Portunus pelagicus (Linnaeus, 1758). Materials and Methods: The nature and characteristics of the synthesized nanoparticles were analysed using various techniques including XRD, FTIR, SEM, EDS and UV-visible spectroscopy. The brine shrimp lethality assay of the synthesized nanoparticles was also evaluated. Results: The results revealed that the nanoparticles were spherical in shape, exhibited a tetragonal structure with an anatase phase, and were confirmed as titanium dioxide nanoparticles by EDS analysis. UV-visible spectral studies indicated a band gap energy of 3.14 eV. The brine shrimp lethality assay of the nanoparticles synthesized from ethanolic extract of shell demonstrated insignificant mortality at low doses with only a slight increase at 1500 µg/ml, while the nanoparticles synthesized from ethanolic extract of tissue exhibited dose dependent cytotoxic activity. Conclusion: Thus, the synthesized titanium dioxide nanoparticles exhibit promising potential for diverse applications.

In this paper, we focused on the green synthesis of titanium dioxide (TiO2) nanoparticles via an ecofriendly process using Citrus limon extract. Several analytical techniques were used to characterize the prepared samples: X-ray diffraction (XRD), infrared spectroscopy, Raman spectroscopy, Scanning Electron Microscopy (SEM) and X-ray photoelectrons spectroscopy (XPS). XRD diffractograms revealed an anatase crystal structure of TiO2. SEM analysis showed the presence of particles with nanometric sizes, and the Fourier transform infrared (FTIR) spectra confirmed the presence of the synthesized nanoparticles. The antibacterial activity of the green prepared TiO2 nanoparticles was assessed. Additionally, the antibacterial efficiency of the green prepared TiO2 nanoparticles was compared with TiO2 nanoparticles prepared via a chemical process. The results prove the efficacy of this ecofriendly process. This method can be used for the rapid and environmentally friendly biosynthesis of stable titanium oxide nanoparticles. This work is a contribution to the valorization of bio-sources for the synthesis of titanium dioxide crystals using Citrus limon fruit extract and tetrabutile titanate as a precursor.

Hydrothermal synthesis of titanium dioxide (TiO2) nanoparticles has been studied in situ using synchrotron radiation energy dispersive X-ray diffraction (EDXRD). The nanoparticles were produced from an acid (HNO3) and an alkaline (tetrabutylammonium hydroxide; TBA) peptized gel by hydrothermal treatment at 210 °C and 270 °C. The in situ EDXRD spectra clearly showed that pure TiO2 rutile phase nanoparticles were crystallized from HNO3 peptized gel, whereas pure anatase phase nanoparticles were produced from the TBA peptized gel. The EDXRD data shows that the rate of the particle formation increases with an increase in the process temperature for both processes. The powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) data confirms the in situ EDXRD results. The TEM images show that the anatase nanoparticles have relatively homogeneous particle size and morphology distribution whereas the rutile nanoparticles exhibit bimodal size and morphology distribution attributed to Ostwald ripening effect during the hydrothermal treatment.

Diabetes mellitus is one of the most prevalent metabolic disorders characterized by hyperglycemia due to impaired glucose metabolism. Overproduction of free radicals due to chronic hyperglycemia may cause oxidative stress, which delays wound healing in diabetic conditions. For people with diabetes, this impeded wound healing is one of the predominant reasons for mortality and morbidity. The study aimed to develop an Ocimum sanctum leaf extract-mediated green synthesis of titanium dioxide (TiO2) nanoparticles (NPs) and further incorporate them into 2% chitosan (CS) gel for diabetic wound healing. UV-visible spectrum analysis recorded the sharp peak at 235 and 320 nm, and this was the preliminary sign for the biosynthesis of TiO2 NPs. The FTIR analysis was used to perform a qualitative validation of the biosynthesized TiO2 nanoparticles. XRD analysis indicated the crystallinity of TiO2 NPs in anatase form. Microscopic investigation revealed that TiO2 NPs were spherical and polygonal in shape, with sizes ranging from 75 to 123 nm. The EDX analysis of green synthesized NPs showed the presence of TiO2 NPs, demonstrating the peak of titanium ion and oxygen. The hydrodynamic diameter and polydispersity index (PDI) of the TiO2 NPs were found to be 130.3 nm and 0.237, respectively. The developed TiO2 NPs containing CS gel exhibited the desired thixotropic properties with pseudoplastic behavior. In vivo wound healing studies and histopathological investigations of healed wounds demonstrated the excellent wound-healing efficacy of TiO2 NPs containing CS gel in diabetic rats.

ABSTRACTBiosynthetic procedure is the best alternative to the preparation of nonmaterials as the challenges faced by the scientist from the last few decades. Present research reports cost-effective, inexpensive eco-friendly synthesis of titanium dioxide nanoparticles using a methanolic extract of fruits peel agro-waste. X-ray diffraction spectrum of identified TiO2NPs found noncrystalline in nature. Fourier transform infrared showed O–H, C = O, C–O, and C–H functional groups present in the fruit peel involved in the biosynthesis of TiO2NPs. The prominent peak at 1708, 1720 and 1700 cm−1 observed in the spectrum attributed to O–Ti–O stretching in Plum, Kiwi and Peach mediated TiO2NPs. The SEM images of all three TiO2NPs revealed cylindrical in shape. The size of TiO2NPs synthesized from Plum, Kiwi and Peach were found to be 47.1 and 63.2, 54.1 and 85.1 and 200 nm, respectively. All the TiO2NPs exhibited size- and dose-dependent antibacterial and antioxidant activities.

Green synthesis and antifungal effect of titanium dioxide nanoparticles on oral Candida albicans pathogen

Green synthesis and characterization of titanium dioxide nanoparticles (TiO2 NPs) using Sesbania grandiflora and evaluation of toxicity in zebrafish embryos

The sizes of mono-dispersed titania nanoparticles (TNPs) can be precisely controlled within a diameter range of 70–650 nm by varying the concentration of water and titania precursor. The water content of the acetone solvent is varied, and ethylene glycol (EG)-stabilized titanium butoxide is used as the titania precursor. Increasing the amount of water can reduce the sizes of TNPs through the formation of a large number of small seeds in the initial reaction state. To obtain small TNPs without any aggregation, Tween 20 is used as a surfactant. Synthesis of TNPs using solvents and chelating agents other than acetone and EG, respectively, is also investigated. For example, other solvents, such as 1,4-dioxane and tetrahydrofuran, and chelating agents, such as triethylene glycol and catechol, are used for the synthesis and size control of TNPs.

Green synthesis of titanium dioxide nanoparticles: Development and applications

The objective of this study is to assess the safety profiles of Ayurvedic formulation Vyosadi guggulu (VG) in Wistar rats. Acute, subacute and subchronic toxicity studies were conducted in accordance with the guidelines of Organization for Economic Cooperation and Development (OECD) and the Committee for Control and Supervision of Experiments on Animals (CCSEA). Approvals from the Institutional Animal Ethics Committee (IAEC), Central Ayurveda Research Institute, Kolkata were obtained prior to carry out the animal experimental studies. Standardized trial drug VG supplied by Indian Medicine Pharmaceutical Corporation Limited (IMPCL), Uttarakhand. A single dose of VG at 2000mg/kg body weight was given to Wistar rats through oral gavage in acute toxicity study. Subchronic oral toxicity study was conducted out at three doses 250, 500 and 1000 mg/kg body weight and administered orally daily for 90 successive days. The doses were derived from a 28 days repeated dose oral toxicity study. Animals in the acute toxicity study were monitored for gross pathological examination, weekly feed and intake, mortality, weekly body weight changes, and general clinical symptoms. Animals were examined for mortality, weekly changes in body weight, general clinical signs, weekly feed and water intake, clinical biochemical investigations, hematological parameter analysis, examination for gross pathological changes, organ weight measurement, and histopathological investigations in the 90-day toxicity study. In acute toxicity study, the single dose of 2000mg/kg of VG was found to be safe. In 28 days and 90 days repeated dose oral toxicity studies all tested doses of VG were proven to be safe. In both studies, there was no significant adverse effect in food and water consumptions, hematological and clinical biochemistry parameters at any dose. No treatment related abnormal features were noticed during histopathological evaluation in 90 days oral toxicity study. The no observed adverse effect level from subchronic toxicity was found to be 1000mg/kg in Wistar rats. Major findings: The present study showed that Vyosadi guggulu is safe at single oral dose of 2000mg/kg in Wistar rats. In the subchronic toxicity studies all tested doses of VG were proven to be safe and the No Observed Adverse Effect Level was found to be 1000mg/kg body weight in Wistar rats.

P9 The effect of ethanolic extract of red betel vine leaves (Piper crocatum) to the livers and kidneys of DDY mice in acute and subchronic toxicity study