Packaging is an integral part of food industry that preserves the properties of food during storage. Food spoilage caused by foodborne microorganisms is a public health problem that imposes a ...significant burden on the healthcare systems. Moreover, packaging based on artificial and chemical materials such as plastic is destructive to the environment. Chitosan can be categorized as an active food packaging material because of its inherent antimicrobial properties and capacity to carry various active components. Combining chitosan and metallic nanoparticles can be used as a practical approach in antimicrobial packaging systems. This strategy has advantages of thermal stability, barrier properties, antioxidant and antimicrobial packaging. Titanium dioxide is one of these nanoparticles that plays a photocatalytic role by releasing reactive oxygen species, thereby leading to the destruction of microorganisms' cell wall and extension of food shelf life. This review elaborates on the antimicrobial applications of chitosan/titanium dioxide nanoparticles films in food packaging systems.
Global production of engineered nanoparticles (ENPs) continues to increase due to the demand of enabling properties in consumer products and industrial applications. Release of individual or ...aggregates of ENPs have been shown to interact with one another subsequently resulting in adverse biological effects. This review focuses on silver nanoparticles (AgNPs), which are currently used in numerous applications, including but not limited to antibacterial action. Consequently, the release of AgNPs into the aquatic environment, the dissociation into ions, the binding to organic matter, reactions with other metal-based materials, and disruption of normal biological and ecological processes at the cellular level are all potential negative effects of AgNPs usage. The potential sources of AgNPs includes leaching of intact particles from consumer products, disposal of waste from industrial processes, intentional release into contaminated waters, and the natural formation of AgNPs in surface and ground water. Formation of natural AgNPs is greatly influenced by different chemical parameters including: pH, oxygen levels, and the presence of organic matter, which results in AgNPs that are stable for several months. Both engineered and natural AgNPs can interact with metal and metal oxide particles/nanoparticles. However, information on the chemical and toxicological interactions between AgNPs and other nanoparticles is limited. We have presented current knowledge on the interactions of AgNPs with gold nanoparticles (AuNPs) and titanium dioxide nanoparticles (TiO2 NPs). The interaction between AgNPs and AuNPs result in stable bimetallic Ag-Au alloy NPs. Whereas the interaction of AgNPs with TiO2 NPs under dark and light conditions results in the release of Ag+ ions, which may be subsequently converted back into AgNPs and adsorb on TiO2 NPs. The potential chemical mechanisms and toxic effects of AgNPs with AuNPs and TiO2 NPs are discussed within this review and show that further investigation is warranted.
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•Silver nanoparticles interact with other nanoparticles in environment.•Natural organic matter and light are key factors regulating silver transformation.•Silver and gold ions form bimetallic nanoparticles in the presence of NOM and light.•Ionic iron species facilitate the transformation of silver nanoparticles.•Titanium oxide nanoparticles mitigate silver nanoparticle dissolution and toxicity.
Introduction of titanium dioxide nanoparticles (TiO2 NPs) to poly(methyl methacrylate) (PMMA) aims to improve the mechanical, microbiological and tribological properties of dental prosthesis bases. ...The aim of the research was to assess the polymerisation time and the change in the colour of the new biomaterial. Samples with the 1 wt% and 2 wt% content of TiO2 additionally modified by ultrasounds were created. The effectiveness of ultrasounds was assessed by comparing the average size of conglomerates in a liquid acrylic resin monomer by means of a dynamic light scattering (DLS) analysis. The biomaterial structure was assessed by the energy-dispersive X-ray spectroscopy (EDS) analysis. The colour change was analysed by means of a colorimetric test and provided in the CIE (Commission internationale de l’éclairage) L*a*b* and RGB (Red Green Blue) colour palette. It was observed during the DLS test that the ultrasonic homogenisation process caused an increase in the suspension heterogeneity. The EDS analysis confirmed the presence of nanoparticles sized below 100 nm, which constitutes a ground for calling the new biomaterial a nanocomposite. The addition of TiO2 NPs as well as the ultrasounds result in the reduction of the average PMMA polymerisation time. The obtained data reveal that the addition of both 1 wt% and 2 wt% causes a considerable change in the PMMA colour: its whitening. To summarise, the reduced polymerisation time of the new biomaterial fully enables performance of standard procedures related to creation of dental prosthesis bases. Due to the considerable change in the colour, the clinical application is limited to performance of repairs or relining of the prosthesis, where the new material is located in an unaesthetic zone.
•A method by AF4-MALS-ICP-MS on TiO2 particle sizing with various independent verifications was developed.•Stabilization of TiO2 NPs in suspensions was accomplished using proper surfactants.•Verified ...size calibration by polystyrene and TiO2 NPs standard suspensions was achieved.•Online MALS measurement enabled particle sizing complementarily to AF4 size calibration.•Nano-sized fractions of TiO2 NPs were detected in the studied powdered beverages.
The application of titanium dioxide as E171 food additive has become an issue of debate due to numerous reports that titanium dioxide nanoparticles (TiO2 NPs) inside the products may pose risks to human health. However, there is still a lack of an official standardized methodology for the detection and size characterization of TiO2 particles in foods containing E171. In this study, a method was presented for size characterization of TiO2 particles with various independent verifications in coffee creamer and instant drink powders, using Asymmetric Flow Field-Flow Fractionation hyphenated with Multi-Angle Light Scattering and Inductively Coupled Plasma Mass Spectrometry (AF4-MALS-ICP-MS). TiO2 particles from these products were well extracted, followed by their optimized AF4 separation using anionic surfactant Sodium Dodecyl Sulfate (SDS) (0.05%, pH 9) and mixed surfactant NovaChem (0.2%), respectively. Size determination of TiO2 NPs was conducted based on AF4 calibration with polystyrene nanospheres and verification with TiO2 NPs standard suspension of 100 nm under two different AF4 conditions. The TiO2 particle sizes detected ranged from 24.4 – 544.3 nm for coffee creamer and 27.7 – 574.3 nm for instant drink powders, with the TiO2 NPs detection recoveries of 75% and 92%, respectively. Hydrodynamic diameters from AF4 size calibration could be independently validated by the gyration diameters from online MALS measurement. The established approach was demonstrated to be reliable and pragmatic for size profiling of highly polydisperse TiO2 particles and thus useful for monitoring E171 in similar foodstuffs.
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•Nano-TiO2 intervention reduced Cd uptake and translocation in Cd-stressed cowpea plants.•APX and CAT activities were enhanced in roots and leaves after intervention.•Micro-nutrients (Zn, Mn and Co) ...increased in seeds upon nano-TiO2 intervention.•Nano-TiO2 intervention reduce dietary health risk in leaves but not in seeds.
The study was conducted to investigate the effects of foliar-intervention of nano-TiO2 on Cd toxicity in cowpea plants. Cowpea plants were exposed to Cd toxicity at 10 mg/kg soil for 21 days and afterwards, subjected to six episodes of foliar application of nano-TiO2 intervention. Results showed that foliar-applied nano-TiO2 significantly promoted chlorophyll b and total chlorophyll contents after Cd stress as compared to Cd-stressed plants without the intervention. Interestingly, Cd contents of roots, shoots and grains were significantly reduced (p < 0.05) after nano-TiO2 sprays compared to Cd-stressed plants. However, the Cd contents in edible tissues (leaves and seeds) after interventions remained above recommended threshold. Furthermore, nano-TiO2 interventions promoted stress enzymes activity in both roots and leaves as well as increased Zn, Mn and Co levels in seeds compared to Cd-stressed plants without intervention. Estimated daily intake of Cd in leaves and seeds for adult subpopulation exceeded the WHO recommended daily intake by some folds in Cd-stressed and nano-TiO2-treated plants. The health risk quotient (HQ) for adult subpopulation exceeded unitary in seeds from nano-TiO2 treatments (HQ = 1.75 and 1.96, respectively) while no potential risk was obtained for leaves. Overall, foliar application of nano-TiO2 portends significant ameliorative potential for Cd toxicity in cowpea plants.
Titanium dioxide nanoparticles (TiO2 NPs) exist in many nano-products and concerns have been raised about their potential toxicity on human beings. One such issue is their potential effects on ...placental function, and the studies on this topic are limited and the mechanism remains unclear. Here we employed human trophoblast HTR-8/SVneo cells to investigate the effects of TiO2 NPs on trophoblast. Results showed that TiO2 NPs could enter cells and were mostly distributed in lysosomes, with some in the cytoplasm. TiO2 NPs and protein aggregation were found in both fetal bovine serum (FBS) in culture medium and cytoplasm of HTR-8/SVneo cells. In consistence with that, proteostasis of HTR-8/SVneo cells was significantly disrupted and endoplasmic reticulum (ER) stress related markers including PERK, IRE1-α were increased. After high speed centrifugation, the proteins PERK and IRE1-α were dramatically decreased in the highest TiO2 NPs treatment group, which indicated interactions between TiO2 NPs and these two proteins. Meanwhile, the protein expressions of LC3-II/LC3-I and P62, the autophagy biomarkers, were increased and the autophagy flux was not blocked. Cellular ROS stress increased and mitophagy related genes including PINK and Parkin increased along with the increased co-localization of LC3 and mitochondria. Taken together, these results indicated that TiO2 NPs interacted with intracellular proteins and activated ER stress and mitophagy in HTR-8/SVneo cells, which might do damage to placental function.
•TiO2 NPs and intracellular protein aggregation was found in HTR-8/SVneo cells.•ER stress and mitophagy was activated after TiO2 NPs treatment.•Interaction between TiO2 NPs and proteins like PERK and IRE1-α was suggested.
The solution casting method was used to prepare nanocomposite films of chitosan/TiO2 nanoparticles (NPs) because of their applications in various fields. The effects of TiO2NP concentration on the ...structural, morphological, thermal, mechanical, and optical properties of such films were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, and thermal analysis (thermogravimetric analysis TGA and differential scanning calorimetry DSC). The XRD patterns reveal miscibility between the amorphous components of chitosan and TiO2NPs. The HRTEM and FESEM images illustrate the distribution and dispersion of TiO2NPs on the film surface. Data from FTIR spectroscopy, DSC, and TGA and the mechanical properties indicate the dependence of chitosan properties on the presence of TiO2NPs and the existence of interactions between chitosan and TiO2NPs. The reflectance and transmittance values obtained were used to calculate the CIE tristimulus values, color parameters, refractive index, absorption coefficient, dielectric spectra, optical conductivity, volume energy loss function (VELF), and surface energy loss function (SELF). The dependence of the absorption coefficient on the photon energy demonstrated that the optical transfer is permissible and direct. The variations of the dielectric spectra and optical conductivity indicate different interactions between photons and electrons in the films produced and relate to the electronic structure. The values of the VELF were found to be greater than those of the SELF, which confirms that the energy loss occurred mostly within the material. Films were also examined for water vapor transmission (WVT) and water vapor permeability (WVP), and the results showed that incorporation of TiO2NPs onto chitosan caused a decrease of WVT and WVP. In addition, the antimicrobial activity of the nanocomposite films against Gram-positive and Gram-negative bacteria was studied, and good antimicrobial activity was found, indicating their ability to inhibit bacterial proliferation at the culture site. The developed chitosan thin films supporting an optimized amount of TiO2NPs could be used to treat various diseases.
HRTEM images of TiO2NPs (a) and CS (c) SAED micrographs of TiO2NPs (b) and CS (d). Display omitted
•The solution casting method was used to prepare chitosan/TiO2 nanoparticle composite films.•Physicochemical properties of the prepared thin films were studied.•Miscibility between chitosan and TiO2 nanoparticles was studied.•There were interactions between TiO2 nanoparticles and chitosan.•Optical parameters of chitosan were affected by addition of TiO2 nanoparticles.
In this work, graphene and titanium dioxide nanoparticles nanocomposite modified glass carbon electrode (GR–TiO2/GCE) was developed to serve as a sensor for simultaneous determination of catechol ...(CC) and hydroquinone (HQ). The GR–TiO2 nanocomposite was characterized by using scanning electron microscopy and electrochemical impedance microscopy. The application of GR–TiO2 nanocomposite in simultaneous determination of CC and HQ was investigated by cyclic voltammetry and differential pulse voltammetry. The GR–TiO2 nanocomposites modified electrode displays excellent electrochemical catalytic activities toward CC and HQ, which could be attributed to high electrical conductivity and larger surface area of GR–TiO2 nanocomposites. The oxidation peak currents of CC and HQ were linear over the range of 0.5–100μM with the detection limits of 0.087μM for CC and 0.082μM for HQ, respectively. In addition, the modified sensor shows excellent anti-interference from resorcinol, phenol and nitrobenzol due to their different oxidation peak potentials. The proposed sensor was successfully applied in the simultaneous determination of CC and HQ in tap and lake water samples with satisfied results.
This study explored the combined effects of titanium dioxide nanoparticles (nano-TiO2) and triphenyl phosphate (TPhP) on the neurodevelopment of zebrafish larvae as well as the underlying mechanisms. ...With this regard, zebrafish embryos were exposed to nano-TiO2 of 100 μg·L−1, TPhP of 0, 8, 24, 72, and 144 μg·L−1, or their combinations until 120 h post-fertilization (hpf). Results indicated 100 μg·L−1 nano-TiO2 alone to be nontoxic to zebrafish larvae. However, obvious developmental toxicity manifested as inhibition of surviving rate, heart rate and body length as well as increased malformation was observed in the higher concentrations of TPhP (72 and 144 μg·L−1) alone and the co-exposure groups. Additionally, results suggested that nano-TiO2 significantly enhanced the bioaccumulation of TPhP in zebtafish larvae, and thus aggravated the abnormities of spontaneous movement and swimming behavior in zebrafish larvae induced by TPhP. Nano-TiO2 also exacerbated the TPhP-induced inhibition of the axonal growth on the secondary motor neuron, and aggravated the TPhP-induced decrease on expressions of neuron-specific green fluorescent protein (GFP) and neuronal marker genes (ngn1 and elavl3). Further, the content of neurotransmitter serotonin was not altered by TPhP alone exposure, but was decreased significantly in the co-exposure group of 144 μg·L−1 TPhP and nano-TiO2. Our data indicated that nano-TiO2 might aggravate the neuron abnormities and serotonin system dysfunction by enhancing the TPhP accumulation, leading to exacerbated abnormal locomotors in zebrafish larvae.
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•Nano-TiO2 aggravated accumulation and developmental toxicity of TPhP in zebrafish larvae.•Nano-TiO2 aggravated TPhP-induced abnormities of spontaneous movement and swimming behavior in zebrafish larvae.•Nano-TiO2 enhanced TPhP-induced inhibition of secondary motor neuron axon growth.•Nano-TiO2 enhanced TPhP-induced decreased expressions of the neuron-specific GFP.•Co-exposure of TPhP and nano-TiO2 leads to dysfunction of the 5-HT system.
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•Triticum aestivum L. was cexposed to 0, 20, 40, 60, 80 and 100 mg TiO2 NPs kg−1.•TiO2 NPs favored plant growth up to 60 mg kg−1.•Beyond 60 mg TiO2 NPs kg−1, chlorophyll content was ...reduced.•Overproduction of H2O2 and micronuclei formation resulted beyond 60 mg kg−1.
Titanium dioxide nanoparticles (TiO2 NPs) are used widely in commercial products. These high production levels have led to their increased release into natural ecosystems, where they may interact with plants and affect their physiological functions. The aim of this study was to assess the physiological responses of wheat (Triticum aestivum L.) to increasing concentrations of TiO2 NPs. TiO2 NPs with a particle size less than 20 nm were administered as soil spiked with 0, 20, 40, 60, 80, and 100 mg TiO2 NPs kg−1, and their physiological parameters, including root and shoot lengths, biomass, phytoavailability of phosphorus (P), chlorophyll content, H2O2 production, and micronuclei (MN) formation in the plants grown from seeds in NPs-spiked soils, were subsequently recorded. All experiments were repeated twice with four replicates per treatment. After 60 days exposure to the NPs, root and shoot lengths, and P uptake by plants was significantly (p < 0.05) higher between 20 and 60 mg kg−1 compared to the control (0 mg kg−1 TiO2 NPs), but was then lower at 80 and 100 mg kg−1 compared to 60 mg kg−1 TiO2 NPs. The application of TiO2 NPs led to chlorophyll content being higher by 32.3% at 60 mg kg−1 than in the control, but 11.1% lower content was observed at 100 mg kg−1. The results suggested that wheat could not tolerate concentrations of TiO2 NPs higher than 60 mg kg−1 owing to overproduction of H2O2 (84.4%) and MN formation (53.6%).
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