• Title/Summary/Keyword: $TiO_2$ NPs

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TiO2 Nanoparticles from Baker's Yeast: A Potent Antimicrobial

  • Peiris, MMK;Guansekera, TDCP;Jayaweera, PM;Fernando, SSN
    • Journal of Microbiology and Biotechnology
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    • v.28 no.10
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    • pp.1664-1670
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    • 2018
  • Titanium dioxide ($TiO_2$) has wide applications in food, cosmetics, pharmaceuticals and manufacturing due to its many properties such as photocatalytic activity and stability. In this study, the biosynthesis of $TiO_2$ nanoparticles (NPs) was achieved by using Baker's yeast. $TiO_2$ NPs were characterized by X-ray Diffraction (XRD), UV-Visible spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray analysis (EDX) studies. The XRD pattern confirmed the formation of pure anatase $TiO_2$ NPs. According to EDX data Ti, O, P and N were the key elements present in the sample. SEM and TEM revealed that the nanoparticles produced were spherical in shape with an average size of $6.7{\pm}2.2nm$. The photocatalytic activity of $TiO_2$ NPs was studied by monitoring the degradation of methylene blue dye when treated with $TiO_2$ NPs. $TiO_2$ NPs were found to be highly photocatalytic comparable to commercially available 21 nm $TiO_2$ NPs. This study is the first report on antimicrobial study of yeast-mediated $TiO_2$ NPs synthesized using $TiCl_3$. Antimicrobial activity of $TiO_2$ NPs was greater against selected Gram-positive bacteria and Candida albicans when compared to Gram-negative bacteria both in the presence or absence of sunlight exposure. $TiO_2$ NPs expressed a significant effect on microbial growth. The results indicate the significant physical properties and the impact of yeast-mediated $TiO_2$ N Ps as a novel antimicrobial.

The Effect of SiO2 Shell on the Suppression of Photocatalytic Activity of TiO2 and ZnO Nanoparticles

  • Lee, Min Hee;Patil, Umakant Mahadev;Kochuveedu, Saji Thomas;Lee, Choon Soo;Kim, Dong Ha
    • Bulletin of the Korean Chemical Society
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    • v.33 no.11
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    • pp.3767-3771
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    • 2012
  • In this study, we investigate the potential use of $TiO_2@SiO_2$ and $ZnO@SiO_2$ core/shell nanoparticles (NPs) as effective UV shielding agent. In the typical synthesis, $SiO_2$ was coated over different types of $TiO_2$ (anatase and rutile) and ZnO by sol-gel method. The synthesized $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs were characterized by UV-Vis, XRD, SEM and TEM. The UV-vis absorbance and transmittance spectra of core@shell NPs showed an efficient blocking effect in the UV region and more than 90% transmittance in the visible region. XRD and SAED studies confirmed the formation of amorphous $SiO_2$ coated over the $TiO_2$ and ZnO NPs. The FESEM and TEM images shows that coating of $SiO_2$ over the surface of anatase, rutile $TiO_2$ and ZnO NPs resulted in the increase in particle size by ~30 nm. In order to study the UV light shielding capability of the samples, photocatalytic degradation of methylene blue dye on $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs was performed. Photocatalytic activity for both types of $TiO_2$ NPs was partially suppressed. In comparison, the photocatalytic activity of ZnO almost vanished after the $SiO_2$ coating.

Cytotoxicity of Ultra-pure TiO2 and ZnO Nanoparticles Generated by Laser Ablation

  • Jeong, Minju;Park, Jeong Min;Lee, Eun Jeong;Cho, Yea Seul;Lee, Chunghyun;Kim, Jeong Moo;Hah, Sang Soo
    • Bulletin of the Korean Chemical Society
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    • v.34 no.11
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    • pp.3301-3306
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    • 2013
  • This paper aims to address the cellular toxicity of ultra-pure titanium dioxide ($TiO_2$) and zinc oxide (ZnO) nanoparticles (NPs) frequently employed in sunscreens as inorganic physical sun blockers to provide protection against adverse effects of ultraviolet (UV) radiation including UVB (290-320 nm) and UVA (320-400 nm). In consideration that the production and the use of inorganic NPs have aroused many concerns and controversies regarding their safety and toxicity and that microsized $TiO_2$ and ZnO have been increasingly replaced by $TiO_2$ and ZnO NPs (< 100 nm), it is very important to directly investigate a main problem related to the intrinsic/inherent toxicity of these NPs and/or their incompatibility with biological objects. In the present study, we took advantage of the laser-assisted method called laser ablation for generation of $TiO_2$ and ZnO NPs. NPs were prepared through a physical process of irradiating solid targets in liquid phase, enabling verification of the toxicity of ultra-pure NPs with nascent surfaces free from any contamination. Our results show that $TiO_2$ NPs are essentially non-poisonous and ZnO NPs are more toxic than $TiO_2$ NPs based on the cell viability assays.

Aggregation Behavior of Silver and TiO2 Nanoparticles in Aqueous Environment (수환경 특성에 따른 은과 이산화티탄 나노입자의 응집 특성 연구)

  • Lim, Myunghee;Bae, Sujin;Lee, Yong-Ju;Lee, Sung-Kyu;Hwang, Yu Sik
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.5
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    • pp.571-579
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    • 2013
  • The aggregation behaviors of silver nanoparticles (AgNPs) and titanium dioxide ($TiO_2$) nanoparticles were investigated. Time-resolved dynamic light scattering (DLS) was used to study the initial aggregation of AgNPs and $TiO_2$ over a range of mono (NaCl) and divalent ($CaCl_2$) electrolyte concentrations. The effects of pH, initial concentration of NPs and natural organic matters (NOM) on the aggregation of NPs were also investigated. The aggregation of both nanoparticles showed classical Derjaguin-Landau-Verwey-Overbeek (DLVO) type behavior. Divalent electrolyte was more efficient in destabilize the AgNPs and $TiO_2$ than monovalent electrolyte. The effect of pH on the aggregation of AgNPs was not significant. But the aggregation rate of $TiO_2$ was much higher with increasing pH. Higher NPs concentration leads to faster aggregation. Natural organic matter (NOM) was found to substantially hinder the aggregation of both AgNPs and $TiO_2$. This study found that the aggregation behavior of AgNPs and $TiO_2$ are closely associated with environmental factors such as ionic strength, pH, initial concentration of NPs and NOM.

Preparation and characterization of rutile phase TiO2 nanoparticles and their cytocompatibility with oral cancer cells

  • Vu, Phuong Dong;Nguyen, Thi Kieu Trang;Yoo, Hoon
    • International Journal of Oral Biology
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    • v.44 no.3
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    • pp.108-114
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    • 2019
  • In the present study, rutile phase titanium dioxide nanoparticles ($R-TiO_2$ NPs) were prepared by hydrolysis of titanium tetrachloride in an aqueous solution followed by calcination at $900^{\circ}C$. The composition of $R-TiO_2$ NPs was determined by the analysis of X-ray diffraction data, and the characteristic features of $R-TiO_2$ NPs such as the surface functional group, particle size, shape, surface topography, and morphological behavior were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential measurements. The average size of the prepared $R-TiO_2$ NPs was 76 nm, the surface area was $19m^2/g$, zeta potential was -20.8 mV, and average hydrodynamic diameter in dimethyl sulfoxide (DMSO)-$H_2O$ solution was 550 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and morphological observations revealed that $R-TiO_2$ NPs were cytocompatible with oral cancer cells, with no inhibition of cell growth and proliferation. This suggests the efficacy of $R-TiO_2$ NPs for the aesthetic white pigmentation of teeth.

Physicochemical properties of different phases of titanium dioxide nanoparticles

  • Dong, Vu Phuong;Yoo, Hoon
    • International Journal of Oral Biology
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    • v.46 no.3
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    • pp.105-110
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    • 2021
  • The physicochemical properties of crystalline titanium dioxide nanoparticles (TiO2 NPs) were investigated by comparing amorphous (amTiO2), anatase (aTiO2), metaphase of anatase-rutile (arTiO2), and rutile (rTiO2) NPs, which were prepared at various calcination temperatures (100℃, 400℃, 600℃, and 900℃). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed that the phase-transformed TiO2 had the characteristic features of crystallinity and average size. The surface chemical properties of the crystalline phases were different in the spectral analysis. As anatase transformed to the rutile phase, the band of the hydroxyl group at 3,600-3,100 cm-1 decreased gradually, as assessed using Fourier transform infrared spectroscopy (FT-IR). For ultraviolet-visible (UV-Vis) spectra, the maximum absorbance of anatase TiO2 NPs at 309 nm was blue-shifted to 290 nm at the rutile phase with reduced absorbance. Under the electric field of capillary electrophoresis (CE), TiO2 NPs in anatase migrated and detected as a broaden peak, whereas the rutile NPs did not. In addition, anatase showed the highest photocatalytic activity in an UV-irradiated dye degradation assay in the following order: aTiO2 > arTiO2 > rTiO2. Overall, the phases of TiO2 NPs showed characteristic physicochemical properties regarding size, surface chemical properties, UV absorbance, CE migration, and photocatalytic activity.

A Study on the Photocatalytic Decomposition of Organic Dyes by Porous Polyethersulfone/TiO2 Composite Membrane (기공형 polyethersulfone/TiO2 복합체 멤브레인의 유기염료분해 반응에 대한 광촉매 특성 연구)

  • Chang Hyeon, Song;Youngeup, Jin;Won Ki, Lee;Seong Il, Yoo
    • Applied Chemistry for Engineering
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    • v.34 no.1
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    • pp.51-56
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    • 2023
  • Composite membranes consisting of TiO2 nanoparticles (NPs) and porous polymers have been widely utilized in photocatalytic water treatment because the composite membranes can allow an easy recovery of NPs after the photocatalytic reaction as well as the reduction of fouling in the membrane. However, the photocatalytic efficiency of the immobilized TiO2 NPs in the composite membranes has been discussed to a limited degree. In this study, we prepared polyethersulfone (PES)/TiO2 composite membranes to study the photocatalytic decomposition of organic dyes under light illumination. The decomposition kinetics of dye molecules by the PES/TiO2 composite membranes and colloidal TiO2 NPs have been compared to discuss the photocatalytic efficiency of NPs before and after their immobilization on the polymer membrane.

A Comparison Study on Quantum Dots Light Emitting Diodes Using SnO2 and TiO2 Nanoparticles as Solution Processed Double Electron Transport Layers (용액공정 기반 SnO2와 TiO2를 이중 전자수송층으로 적용한 양자점 전계 발광소자의 특성비교 연구)

  • Shin, Seungchul;Kim, Suhyeon;Jang, Seunghun;Kim, Jiwan
    • Journal of the Microelectronics and Packaging Society
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    • v.27 no.3
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    • pp.69-72
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    • 2020
  • In this study, the inverted structured electroluminescence (EL) devices were fabricated with double electron transport layers (ETLs). The conduction band minimum (CBM) of TiO2 NPs is lower than SnO2 NPs. Therefore, it is expected that inserting TiO2 NPs between the SnO2 layer and the emission layer (EML) will reduce the energy barrier and transport electrons smoothly. The quantum dot light emitting diodes (QLEDs) with double ETLs showed the enhanced emission characteristics than those with only SnO2 layer.

Effects of titanium oxide nanoparticles on Oryzias latipes embryos and sac-fry under different irradiation conditions

  • Nam, Sun-Hwa;Shin, Yu-Jin;An, Youn-Joo
    • Environmental Engineering Research
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    • v.22 no.4
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    • pp.426-431
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    • 2017
  • Some phototoxicity of titanium dioxide nanoparticles ($TiO_2$ NPs) has been reported in recent years in studies with fish embryos or larvae. However, it is necessary to focus on the potential effects of embryonic exposure due to irreversible abnormalities and mortalities observed in sac-fry, and to expand various fish embryos to generate multiple test species. The aim of this study was to evaluate the effects of $TiO_2$ NPs under different irradiation conditions in exposed Oryzias latipes (O. latipes) at the embryonic and sac-fry stages. The effects of different irradiation conditions were observed using ultra-violet (UV) and visible light, and the corresponding effects were monitored by determining cumulative mortality and abnormality. O. latipes were exposed for 8 d to 0, 1, 5, 10, or 50 mg/L $TiO_2$ NPs under UV ($4,818.86mW/m^2$ at the bottom of clear vials) or visible light, after which the embryos were transferred to NP-free embryo-rearing solution until 16 days post fertilization (dpf). Abnormalities of embryos and sac-fry increased at high $TiO_2$ NP concentrations under UV irradiation, compared to control samples treated with visible light or UV irradiation alone. This work provides information regarding the phototoxicity of $TiO_2$ NPs using O. latipes at the embryonic and sac-fry stages.

Synthesis of Au@TiO2 Core-shell Nanoparticle-decorated rGO Nanocomposite and its NO2 Sensing Properties

  • Kumar Naik, Gautam;Yu, Yeon Tae
    • Journal of Sensor Science and Technology
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    • v.28 no.4
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    • pp.225-230
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    • 2019
  • $Au@TiO_2$ core-shell decorated rGO nanocomposite (NC) was prepared using a simple solvothermal method followed by heat treatment for gas sensor application. The crystal structure and morphology of the composites were characterized by X-ray powder diffraction and transmission electron microscopy, respectively. The $NO_2$ sensing response of the $Au@TiO_2/rGO$ NC was tested at operating temperatures from $250^{\circ}C$ to $500^{\circ}C$, and was compared with those of the bare rGO and $Au@TiO_2$ core-shell NPs. The $Au@TiO_2/rGO$ NC-based sensor showed a far higher response than the rGO or $Au@TiO_2$ core-shell based sensors, with the maximum response detected when the operating temperature was $400^{\circ}C$. This improved response was due to the high rGO gas absorption capability for $NO_2$ gas and the catalytic effect of $Au@TiO_2$ core-shell NPs in oxidizing $NO_2$ to $NO_3$.