Anatase titanium dioxide loaded polylactide membranous films: preparation,characterization, and antibacterial activity assessment

In this study, the preparation method and characteristics of anatase titanium dioxide (TiO₂) nanoparticle-loaded polylactide (PLA) films and their antibacterial efficacy against Klebsiella pneumoniae (ATCC 4352) and Staphylococcus aureus (ATCC 6538) bacterium were studied. A series of PLA nanocomposites containing, respectively, 0, 1, and 5% (wt.) titanium dioxide (TiO₂) nanoparticles were prepared by melt intercalation method. The effect of TiO₂ nanoparticles on the thermal and mechanical characteristics of the films was determined. Thermal analysis showed that the glass transition temperature, crystallization temperature, melting temperature, and decomposition temperatures (Td_0.5 and Td_0.05) decreased with the filler content. The results obtained from tensile tests showed that TiO₂ nanoparticles reduced the mechanical properties and moduli of the PLA films. On the other hand, the water absorption properties of the nanocomposite films increased with the addition of nanoparticles and nanocomposite films exhibited bacteriostatic and limited bactericidal efficacy according to AATCC 147. Consequently, nanocomposite films may be good materials for medical applications due to their membranous properties.     

Functional finishing of cotton fabrics using graphene oxide nanosheets decorated with titanium dioxide nanoparticles

This study examined an innovative approach for imparting multi-functional properties, i.e. self-cleaning, electrical conductivity, ultraviolet (UV) blocking as well as antimicrobial properties onto cotton fabric. Graphene oxide/TiO₂ nanocomposites were successfully prepared, by a simple method of mixing and sonication, and used for multi-functional treatment of cotton fabrics by dip-drying technique. The physicochemical properties of the prepared samples were characterized with field emission scanning electron microscope, transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. Self-cleaning performance, electrical resistance, antimicrobial properties, and UV blocking activity of treated fabrics were also assessed. The coated cotton fabrics with graphene oxide/TiO₂ nanocomposite showed excellent photocatalytic self-cleaning activity measured by degradation of methylene blue in aqueous solution under sunlight irradiation. Results showed that the electrical conductivity of the graphene oxide/titanium dioxide nanocomposite-coated fabrics was improved significantly after sunlight irradiation. Moreover, the nanocomposite finished cotton fabric demonstrated proper antimicrobial properties and UV blocking activity.     

Nanoscale three-point bending of single polymer/inorganic composite nanofiber

The pure polyvinyl acetate (PVAc) nanofiber and PVAc/titanium dioxide (TiO₂) composite nanofiber were prepared by sol–gel process with electrospinning. The effect of increasing TiO₂ contents on diameter distribution, surface morphology, and elastic modulus of nanofibers was characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM) equipped with picoforce. SEM images showed that the average diameter of composite nanofiber decreased with the increase in TiO₂. The three‐point bending test indicated that the elastic modulus of PVAc/TiO₂ nanofiber significantly increased as TiO₂ increased.     

Increasing the shelf life of pikeperch (Sander lucioperca) fillets affected by low-density polyethylene/Ag/TiO2 nanocomposites experimentally produced by sol-gel and melt-mixing methods

Sol-gel and melt-mixing processes, which are used for the synthesis of low-density polyethylene/silver/titanium dioxide nanocomposites, can inactivate pathogens. In the sol-gel method, the nanocomposites were used to treat four selected microorganisms using the disk-diffusion method. In the melt-mixing method, fish coverage films were used to examine the shelf life of fish. TiO₂ along with different concentrations of Ag (0%, 1%, 3%, and 5%) generated the nanocomposites. The maximum inhibition zone diameters (mm) for Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger in 3% Ag were measured. It was concluded that applying the LDPE/Ag/TiO₂ nanocomposites produced could be beneficial for inactivation of pathogens.     

Effect of TiO2 nanoparticles on basalt/polysiloxane composites: mechanical and thermal characterization

In the present investigation, a novel technique has been developed to fabricate composite materials containing TiO₂ nanoparticles, polysiloxane resin, and basalt fabric. A high-intensity ultrasonic probe was used to obtain a homogenous molecular mixture of TiO₂ nanoparticles and polysiloxane resin, thus the nanoparticles were infused into the resin through sonic cavitation. The loading effect of TiO₂ nanoparticles on the thermal and mechanical properties of basalt fabric reinforced polysiloxane composite materials has been investigated. Composite samples were prepared, each using two layers of basalt fabric with TiO₂ nanoparticles loading from 0.5, 1, 1.5, 2, 2.5, and 3% by weight. Size distribution of nanoparticles was observed by particle size analyzer and the prepared fabric nanocomposites were characterized by scanning electron microscopy, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Tensile testing was performed as per American standard for testing of materials (ASTM) standards. The dependence of dynamic mechanical parameters E′, E′′, tan (delta), T _g, and heat distortion temperature (HDT) are associated with the filler content and can be controlled by the curing conditions. Tensile results show that 1.5 wt.% loading of TiO₂ nanoparticles in the nanocomposites resulted in highest improvement in tensile modulus compared to the neat system. DMA studies also revealed that 1.5 wt.% doped system exhibits highest storage modulus as compared to the neat and other loading percentages. DSC and TGA studies show that T _g and HDT of the composite increases with the increase in wt.% of nanofillers in the composite. Based on these results, it is clear that miscibility of nanoparticles in the resin is of prime importance with regard to performance.     

Self-cleaning wool: effect of noble metals and silica on visible-light-induced functionalities of nano TiO2 colloid

This study intends to enhance the functionality of titanium dioxide (TiO₂) nanoparticles applied to wool fabrics under visible light. Herein, TiO₂, TiO₂/SiO₂, TiO₂/Metal, and TiO₂/Metal/SiO₂ nanocomposite sols were synthesized and applied to wool fabrics through a low-temperature sol–gel method. The impacts of three types of noble metals, namely gold (Au), platinum (Pt), and silver (Ag), on the photoefficiency of TiO₂ and TiO₂/SiO₂ under visible light were studied. Different molar ratios of Metal toTiO₂ (0.01, 0.1, 0.5, and 1%) were employed in synthesizing the sols. Photocatalytic efficiency of fabrics was analyzed through monitoring the removal of red wine stain and degradation of methylene blue under simulated sunlight and visible light, respectively. Also, the antimicrobial activity against Escherichia coli (E. coli) bacterium and the mechanical properties of fabrics were investigated. Through applying binary and ternary nanocomposite sols to fabrics, an enhanced visible-light-induced self-cleaning property was imparted to wool fabrics. It was concluded that the presence of silica and optimized amount of noble metals had a synergistic impact on boosting the photocatalytic and antimicrobial activities of coated samples. The fabrics were further characterized using attenuated total reflectance, energy-dispersive X-ray spectrometry, and scanning electron microscopy images.     

复合钛白粉性能及在装饰原纸中应用的研究

复合钛白粉是采用无机非金属矿物粒子作为内核,在其表面包覆一层TiO₂而制得。本研究主要分析了以不同工艺和内核加工的4种复合钛白粉的粉体性质及其在装饰原纸中的应用,以期替代价格昂贵的钛白粉。用扫描电子显微镜（SEM）对复合钛白粉内核(硅灰石和白炭黑)、复合钛白粉及钛白粉表面进行分析,结果表明,钛白粉很好地沉积在硅灰石和白炭黑的表面。在相同用量或者灰分相同时,复合钛白粉的遮盖力与钛白粉接近,加填纸的物理性能接近钛白粉加填纸的。     

Microstructure and adhesive properties of TiO2 coating on PU and PVC leathers

Titanium dioxide (TiO₂) films were deposited onto polyurethane (PU) and polyvinyl chloride (PVC) leather by magnetron sputtering, respectively. The crystal structure of the prepared film was studied using X-ray diffraction (XRD) and the surface morphology of the TiO₂ films was investigated by scanning electron microscopy (SEM) and atomic force microscope (AFM). The SEM and AFM observations revealed that the surface roughness of the substrates was an extremely important influencing factor on the morphology of the TiO₂ films. Moreover, a calculation formulation on the weight loss of per peeling force was proposed to determine the bonding strength between the TiO₂ films and the substrates. It was found that the adhesive performance of the TiO₂ nanofilms coating on PVC leather was better than that on the substrate of the PU leather.     

Absorption,Distribution and Excretion of Four Forms of Titanium Dioxide Pigment in the Rat

Titanium dioxide (TiO₂) is a white color additive that has a long history of global approval and use in food. There is, however, considerable confusion regarding the applicability of the biological effects of novel, engineered, nano‐sized forms of TiO₂ developed for nonpigmentary applications to the safety of oral exposure to food grade TiO₂ pigment. The objective of this study was to assess the absorption, distribution, and routes of excretion in rats after oral exposure to food grade TiO₂. Four different grades of TiO₂ (200 ppm) or control (0 ppm) diets were fed to rats for 7 consecutive days, followed by control diet only for 1, 24, or 72 h. Concentrations of titanium in liver, kidney and muscle were mainly below the limit of detection (<0.1 to < 0.2 mg/kg wet weight); tissue concentrations of titanium above the LOD were in the range of 0.1 to 0.3 mg/kg wet weight for all groups. Whole blood concentrations of titanium were <0.04 mg/L for all groups. Urinary excretion of titanium was equivalent to <2% daily dose/L of urine for all groups and was generally below the limit of quantification (<0.04 mg/L). Feces represented the predominant route of excretion. These results demonstrate that there is no accumulation of titanium in tissues following consumption of diets containing 200 ppm food grade TiO₂. No differences in systemic absorption of the 4 forms of TiO₂ were observed indicating that the bioavailability of TiO₂ is consistently low for the range of particle sizes and morphologies examined in this study.     

Modification of wool fabric treated with tetrabutyl titanate by hydrothermal method

Nanometer-sized TiO₂ particles prepared by hydrothermal precipitation method were first immobilized on the surface of wool fiber using tetrabutyl titanate, and then dyed with C.I. Reactive Blue 69. Scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and thermal gravimetric analyses were used to characterize the morphology, crystalline phase, chemical structure, and thermal stability of TiO₂-loaded fiber. The properties of diffuse reflectance spectrum, whiteness, dye exhaustion rate, fixation rate, K/S value, and color fastness for wool fabrics before and after treatment were also measured. The investigation indicated that when wool fabric was treated with tetrabutyl titanate aqueous solution at 120°C for 5?h, pure anatase TiO₂ particles aggregated by nanocrystalline grains of 10?nm or so were synthesized, and were grafted onto fiber surface by chemical reaction. When compared with the untreated wool fabric, the onset decomposition temperature of the TiO₂-loaded fabric increased. The capability of TiO₂-loaded fabric against ultraviolet radiation was enhanced. The fabric whiteness, exhaustion rate, fixation rate, and K/S value decreased to some extent because of the existence of the TiO₂ particles. The color fastnesses to dry and wet rubbing had no change. The K/S value of TiO₂-loaded fabric increased after being brushed. The color fastness to artificial light was also improved.     

In situ synthesis and exhaustion of nano TiO2 on fabric samples using laser ablation method

Abstract

In this research work, TiO₂ nanoparticles were in situ synthesized on cotton fabrics using laser ablation method. For producing the TiO₂ nanoparticles, the Ti plate were irradiated with Nd:YAG pulsed laser operating at 1064?nm in deionized water medium. Simultaneously, the cotton samples were placed near Ti plate in ablation container. Laser fluence was 1, 2 and 3?J/cm² for samples 1–3 to make nanoparticles with different sizes. The morphology and size of prepared nano particles were investigated using scanning electron microscope (SEM) and transmition electron microscope (TEM). The concentration, structure and crystalinity of synthesized nano TiO₂ was studied using absorption spectrophotometry and X-Ray diffraction method. The morphology changes of cotton samples after laser ablation and in situ synthesizing the TiO₂ nanoparticles was compared using SEM. The hydrophilicity changes of cotton were determined by water absorption time method. Finally the cotton samples were stained by one ml of diluted methylene blue and the color changes of samples after daylight irradiation were studied with reflective spectrophotometry. Results show that, by increasing the laser fluence, the concentration and size of synthesized TiO₂ nano particles increases. The self-cleaning and photocatalytic activity increases by increasing the concentration of TiO₂ nanoparticles.     

Evaluation of PLA nanocomposite films on physicochemical and microbiological properties of refrigerated cottage cheese

A novel antimicrobial packaging system was prepared by incorporating TiO₂ or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO₂, and PLA/TiO₂ + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO₂ and PLA/TiO₂+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO₂ or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days.

Practical applications

Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5–7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO₂ or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation.     

Modified Rice Straw as a Template in Syntheses of Nano TiO2 Loaded on Wool Fibers for Wastewater Treatment

Industrialization of textile produces large amounts of colored wastewater and recycling of that wastewater is recently under the scope. The current work is implemented to use rice straw as a template for preparation of nano TiO₂ to be applied in decolorization of wastewater of textile industries. Different treatments including silica removal and esterification were performed for rice straw to produce highly reactive nanotitanium dioxide. Size, morphological shape, and surface area of the so obtained TiO₂ nanoparticles were observed to be influenced by rice straw treatments. Percentage of anatase phase in titanium dioxide was increased from 41.6% to 75.0% after removing of silica and modification with citric acid of rice straw. The particle size of anatase was significantly reduced from 88.6 nm to 10.5 nm while the BET surface area of nanotitanium dioxide was enlarged from 41.2 m²/g to 84.7 m²/g. The prepared TiO₂ nanoparticles were loaded onto wool fibers and the photocatalytic properties of nano TiO₂ powder before and after loaded to fiber were measured against methylene blue dye. The dye removal percentage raised from 92.5 to 99.2 by using of nano TiO₂ powder-loaded wool fibers compared to nano TiO₂ powder.     

抗菌性无定型纳米二氧化钛/聚乳酸膜的制备及表征

溶胶-凝胶法水解异丙醇钛制备纳米二氧化钛（TiO2）溶液,进行粒径优化及表征。紫外光谱、红外光谱、X射线衍射、粒径测试结果表明制备的纳米TiO2为较高可见光利用率的无定型纳米粒子。采用溶液共混法制备聚乳酸/纳米二氧化钛（polylactic acid/nano-TiO2,PLA/nano-TiO2）复合膜,研究不同纳米TiO2质量分数对PLA/nano-TiO2复合膜的性质影响。结果表明,PLA/nano-TiO2复合膜中纳米TiO2质量分数为0.6%时拉伸强度达到最大值,为63.3 MPa,此时断裂伸长率最小,为2.3%。PLA/nano-TiO2复合膜接触角均低于纯PLA膜,从78.40°减小到72.83°;PLA/nano-TiO2复合膜的吸水率显著高于纯PLA膜,从0.56%提高为1.48%;PLA/nano-TiO2复合膜水蒸气透过率比纯PLA膜高,从3.46×10－8（g·m）/（m2·h·Pa）提高到4.66×10－8（g·m）/（m2·h·Pa）。由PLA/nano-TiO2复合膜的抑菌性实验可知,添加纳米TiO2的复合膜在紫外光照下有明显的抑菌效果。     

Lycopene: Heterogeneous Catalytic E/Z Isomerization and In Vitro Bioaccessibility Assessment Using a Diffusion Model

Highly efficient heterogeneous catalytic E/Z isomerization of lycopene was achieved using an iodine‐doped titanium dioxide (I‐TiO₂) catalyst prepared by sol‐gel method. The effects of reaction temperature and reaction time were investigated in detail. The maximum total Z‐ratio of lycopene exceeded 78% after 2 h of refluxing at 75 °C in ethyl acetate. Moreover, lycopene samples with a series of total Z‐ratios were prepared and the bioaccessibility of these samples was estimated using a diffusion model, the results showed that the bioaccessibility of lycopene markedly increased conforming to a linear regression model with increasing of the total Z‐ratio of lycopene from 3.6% to 78.5%. Furthermore, the specific role of the microstructure and melting point of 3.6% and 78.5% total Z‐ratio of lycopene was also investigated to understand the probable mechanism for the enhanced bioaccessbility of (Z)‐lycopenes.     

Analytical methods for SiO2 and other inorganic oxides in titanium dioxide or certain silicates for food additive specifications

An analytical method has been developed for the detection of SiO₂ and other oxides in titanium dioxide and certain silicates used in food additives using inductively coupled plasma (ICP) atomic emission spectrometry without hydrofluoric acid. SiO₂ and other oxides in titanium dioxide or certain silicates were resolved by alkali fusion with KOH and boric acid and then dissolved in dilute hydrochloric acid as a test solution for ICP. The recovery of SiO₂ and Al₂O₃ added at 0.1 and 1.0%, respectively, in TiO₂ was 88–104%; coefficient of variation was <4%. The limit of determination of SiO₂ and Al₂O₃ was about 0.08%, and the accuracy of the ICP method was better than that of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) test method. The recovery of SiO₂ and other oxides in silicates was 95–107% with a coefficient of variation of <4%. Using energy dispersive X-ray fluorescence spectrometry (EDX) with fundamental parameter determination, the content of SiO₂ and other oxide in titanium dioxide and silicate showed good agreement with the ICP results. ICP with alkali fusion proved suitable as a test method for SiO₂, Al₂O₃ and other oxides in titanium dioxide and certain silicates, and EDX proves useful for screening such impurities in titanium dioxide and componential analysis of certain silicates.     

Soluble soybean polysaccharide/TiO2 nanocomposites: Biological activity,release behavior,biodegradability, and biosafety

This study aimed to produce and characterize eco-friendly SSPS nanocomposites incorporated with various concentrations of TiO₂ nanoparticles (NPs) (1%, 3%, and 7%). The antimicrobial activity of the nanocomposite films against five strains of pathogenic bacteria was examined. Salmonella typhi PTCC 1609 was the most sensitive species to TiO₂ NPs at concentrations equal to the synthetic antibiotic. The migration of TiO₂ to ethanol and acetic acid, as two food simulants increased when the initial nano-TiO₂ content increased. The release profiles for TiO₂ in two simulants of ethanol and acetic acid indicated a non-Fickian release, and the release kinetics were concentration-dependent. SSPS/TiO₂ nanocomposites degraded easily and thus have the potential to be applied as an eco-friendly packaging system. Oral administration of doses of 1, 12.5, 25, 50, and 75 mg/kg TiO₂ revealed that the dose of 50 and 75 mg/kg increased malondialdehyde (p < .001) concentration in the liver tissue. In addition, it decreased glutathione (p < .001) concentration in the liver tissue.     

RSM optimized self-cleaning nano-finishing on polyester/wool fabric pretreated with oxygen plasma

In this study, polyester/wool blended fabric was coated with titanium dioxide nanoparticles. To enhance the adsorption and loading of nanoparticles on wool and polyester fibers, the samples were pretreated by low-temperature oxygen plasma. Citric acid was used to fix the TiO₂ nanoparticles on the fibers. The self-cleaning property of the finished samples was tested under UV-A light. The effect of plasma treatment time besides the concentrations of TiO₂ nanoparticles and citric acid on the self-cleaning properties of the samples was analyzed and optimized using response surface methodology. The surface chemistry and morphology of the samples were studied using Attenuated total reflectance-fourier transform infrared spectorscopy (ATR-FTIR) and field emission scanning electron microscope, respectively. The results showed that plasma treatment has a great effect on the loading of the nanoparticles on the surface of the fibers and enhancing the self-cleaning properties of the finished samples. The plasma-treated samples showed better water absorbency, enhanced tensile strength and approximately the same handle compared to raw samples after coating with TiO₂ nanoparticles.     

A simple gold plate electrode modified with Gd-doped TiO2 nanoparticles used for determination of trace nitrite in cured food

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO₂) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO₂ nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO₂ formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO₂ lattice surrounded by Gd³⁺. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10?mol?l^?1 sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0?×?10^?7 to 4.0?×?10^?4??mol?l^?1, with a detection limit of 5.0?×?10^?7?mol?l^?1 (S/N?=?3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5–104%, showing its promising application for food safety monitoring.     

The Improved Whitening of Minced Cod Flesh Using Dispersed Titanium Dioxide

A simple effective method of whitening fish mince using titanium dioxide has been developed. The whitener comprised a dispersed titanium dioxide (TiO₂) suspension stabilised with xanthan gum (20 g TiO₂/1 g xanthan gum/79 ml water) which produced significant whitening of fish mince derived from cod waste. The whitener was incorporated during the mixing stage of conventional fish mince manufacture, and achieved an even spread of coloration. The whitened fish mince was found to be stable to high temperature cooking systems, such as frying. Taste and texture of the fish mince were not affected by the level of xanthan gum and TiO₂ used. Xanthan gum and TiO₂ were sufficiently heat stable and inert with respect to taste, odour and chemical reactivity, to be suitable for use for such a purpose, unlike other compounds investigated and conventional dispersed fat/oil whiteners. A level of 1 g kg^-1 of TiO₂ in the fish mince was found to give optimal level. © 1997 SCI.