Titanium dioxide (TiO₂) is one of the most extensively utilized food additives (E171) in the food industry. Along with nanotechnology development, the concern about the presence of nanostructured particles in E171 TiO₂ and commercial food products is growing. In the present study, the physicochemical properties of commercially available E171 TiO₂ particles, including particle size distribution, were investigated, followed by their cytotoxicity and intestinal transport evaluation. The fate determination and quantification of E171 TiO₂ in commercial foods were carried out based on the analytical procedure developed using simulated foods. The results demonstrated that TiO₂ is a material mainly composed of particles larger than 100 nm, but present as an agglomerated or aggregated particle in commercial foods with amounts of less than 1% (wt/wt). Titanium dioxide particles generated reactive oxygen species and inhibited long-term colony formation, but the cytotoxicity was not related to particle size distribution or particle type (food- or general-grade). All TiO₂ particles were mainly transported by microfold (M) cells, but also by intestinal tight junction. These findings will be useful for TiO₂ application in the food industry and predicting its potential toxicity. Full article

Nano-TiO₂ has always been one of the most important topics in the research of photocatalysts due to its special activity and stability. However, it has always been difficult to obtain nano-TiO₂ with high dispersion, a small particle size and high photocatalytic activity. In this paper, nano-TiO₂ powder was prepared by combining the high-gravity technique and direct precipitation method in an impinging stream-rotating packed bed (IS-RPB) reactor followed by Fe³⁺ in-situ doping. TiOSO₄ and NH₃·H₂O solutions were cut into very small liquid microelements by high-speed rotating packing, and the mass transfer and microscopic mixing of the nucleation and growth processes of nano-TiO₂ were strengthened in IS-RPB, which was beneficial to the continuous production of high quality nano-TiO₂. Pure TiO₂ and iron-doped nano-TiO₂ (Fe-TiO₂) were obtained in IS-RPB and were investigated by means of X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and Brunauer–Emmett–Teller (BET) analysis, which found that pure TiO₂ had a particle size of about 12.5 nm, good dispersibility and a complete anatase crystal at the rotating speed of packing of 800 rpm and calcination temperature of 500 °C. The addition of Fe³⁺ did not change the crystalline structure of TiO₂. Iron was highly dispersed in TiO₂ without the detection of aggregates and was found to exist in a positive trivalent form by XPS. With the increase of iron doping, the photoresponse range of TiO₂ to visible light was broadened from 3.06 eV to 2.26 eV. The degradation efficiency of gaseous toluene by Fe-TiO₂ under ultraviolet light was higher than that of pure TiO₂ and commercial P25 due to Fe³⁺ effectively suppressing the recombination of TiO₂ electrons and holes; the highest efficiency produced by 1.0% Fe-TiO₂ was 95.7%. Full article

Several in vitro studies have suggested that silica nanoparticles (NPs) might induce adverse effects in gut cells. Here, we used the human colon cancer epithelial cell line HCT116 to study the potential cytotoxic effects of ingested silica NPs in the presence or absence of serum. Furthermore, we evaluated different physico-chemical parameters important for the assessment of nanoparticle safety, including primary particle size (12, 70, 200, and 500 nm) and surface modification (–NH₂ and –COOH). Silica NPs triggered cytotoxicity, as evidenced by reduced metabolism and enhanced membrane leakage. Automated microscopy revealed that the silica NPs promoted apoptosis and necrosis proportional to the administered specific surface area dose. Cytotoxicity of silica NPs was suppressed by increasing amount of serum and surface modification. Furthermore, inhibition of caspases partially prevented silica NP-induced cytotoxicity. In order to investigate the role of specific cell death pathways in more detail, we used isogenic derivatives of HCT116 cells which lack the pro-apoptotic proteins p53 or BAX. In contrast to the anticancer drug cisplatin, silica NPs induced cell death independent of the p53–BAX axis. In conclusion, silica NPs initiated cell death in colon cancer cells dependent on the specific surface area and presence of serum. Further studies in vivo are warranted to address potential cytotoxic actions in the gut epithelium. The unintended toxicity of silica NPs as observed here could also be beneficial. As loss of p53 in colon cancer cells contributes to resistance against anticancer drugs, and thus to reoccurrence of colon cancer, targeted delivery of silica NPs could be envisioned to also deplete p53 deficient tumor cells. Full article

The purpose of the current study was green synthesis of ZnO-nanoparticles (NPs) from different tissues of Silybum marianum (L.) Gaernt. (i.e., seeds, wild plant, in vitro derived plantlets and callus cultures) followed by extensive characterization and evaluation of their biological potency. ZnO-NPs thus synthesized were subjected to characterization using standard techniques such as XRD, FTIR and SEM. Thermal stability of synthesized NPs was also evaluated using thermo-gravimetric analysis. Highly stable crystalline NPs with size ranging between 30.8 and 46.0 nm were obtained from different tissues of S. marianum. These NPs have revealed a wide range of biological applications showing antioxidant, moderate α-amylase inhibitor, antibacterial and cytotoxic potencies. The highest antibacterial activity (20 ± 0.98 mm) was shown by seed extract-mediated ZnO NPs against Staphylococcus aureus (ATCC-6538). Seed extract-mediated ZnO NPs also showed the most potent antioxidant activity (27.7 ± 0.9 µgAAE/mg, 23.8 ± 0.7 µgAAE/mg and 12.7 ± 1.9% total antioxidant capacity (TAC), total reducing power (TRP) and DPPH-free radical scavenging assay (FRSA), respectively). All of the synthesized ZnO NPs also showed cytotoxic activity against the hepato-cellular carcinoma (HepG2) human cells. Interestingly, these ZnO NPs were also highly biocompatible, as evidenced by the brine shrimp lethality and human red blood cells hemolytic assays. Among all of the NPs synthesized and used, the effect of seed extract-mediated NPs was found to be most promising for future applications. Full article

Microelectrodes offer higher current density and lower ohmic drop due to increased radial diffusion. They are beneficial for electroanalytical applications, particularly for the detection of analytes at trace concentrations. Microelectrodes can be fabricated as arrays to improve the current response, but are presently only commercially available with gold or platinum electrode surfaces, thus limiting the sensing of analytes that are more electroactive on other surfaces. In this work, gold (Au), copper (Cu), and palladium (Pd) are electrodeposited at two different potentials into the recessed holes of commercial microelectrode arrays to produce 3-dimensional (3D) spiky, dendritic or coral-like structures. The rough fractal structures that are produced afford enhanced electroactive surface area and increased radial diffusion due to the 3D nature, which drastically improves the sensitivity. 2,4,6-trinitrotoluene (TNT), carbon dioxide gas (CO₂), and hydrogen gas (H₂) were chosen as model analytes in room temperature ionic liquid solvents, to demonstrate improvements in the sensitivity of the modified microelectrode arrays, and, in some cases (e.g., for CO₂ and H₂), enhancements in the electrocatalytic ability. With the deposition of different materials, we have demonstrated enhanced sensitivity and electrocatalytic behaviour towards the chosen analytes. Full article

Multiwalled carbon nanotubes (MWCNTs) are interesting high-tech nanomaterials. MWCNTs oxidized and functionalized with itaconic acid and monomethylitaconate were demonstrated to be efficient additives for controlling nucleation of calcium carbonate (CaCO₃) via gas diffusion (GD) in classical as well as nonclassical crystallization, yielding aragonite and truncated calcite. For the first time, all amorphous calcium carbonate (ACC) proto-structures, such as proto calcite-ACC, proto vaterite-ACC and proto aragonite-ACC, were synthesized via prenucleation cluster (PNC) intermediates and stabilized at room temperature. The MWCNTs also showed concentration-dependent nucleation promotion and inhibition similar to biomolecules in nature. Incorporation of fluorescein-5-thiosemicarbazide (5-FTSC) dye-labeled MWCNTs into the CaCO₃ lattice resulted in fluorescent hybrid nanosized CaCO₃. We demonstrate that functionalized MWCNTs offer a good alternative for controlled selective crystallization and for understanding an inorganic mineralization process. Full article

The Nb3+ ion substituted Sr hexaferrites (SrNb_xFe_12−xO19 (x = 0.00–0.08) hexaferrites (HFs)) were fabricated via a citrate-assisted sol-gel approach. X-ray powder diffractometer analysis affirmed the pureness of all products. The crystallite sizes of the products which were estimated from Scherrer equation were in the 36–40 nm range. The chemical component of the samples was proved by Energy-dispersive X-ray spectroscopy (EDX) and Elemental mapping. The hexagonal morphology of all products was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM). The electrical conduction mechanisms and dielectric properties of a variety of Nb3+ions-substituted SrNb_xFe_12−xO19 HFs were investigated by a complex impedance system. Dielectric parameters such as conductivity, dielectric constant, dielectric loss, dielectric tangent loss and complex modulus, were studied at temperatures up to 120 °C in a frequency range varying from 1.0 Hz to 3.0 MHz for several Nb ratios. The frequency dependence of the conductivity was found to comply with the power law with diverse exponents at all frequencies studied here. Subsequently, incremental tendencies in dc conductivity with temperature indicate that the substituted Sr-HFs leads to a semiconductor-semimetal like behavior. This could be attributable to a feature of conduction mechanism which is based on the tunneling processes. Additionally, the dielectric dispersion pattern was also explained by Maxwell–Wagner polarization in accordance with the Koop’s phenomenological theory. Full article

Aiming to improve the treatment outcomes of current daily tuberculosis (TB) chemotherapy over several months, we investigated whether nanoencapsulation of existing drugs would allow decreasing the treatment frequency to weekly, thereby ultimately improving patient compliance. Nanoencapsulation of three first-line anti-TB drugs was achieved by a unique, scalable spray-drying technology forming free-flowing powders in the nanometer range with encapsulation efficiencies of 82, 75, and 62% respectively for rifampicin, pyrazinamide, and isoniazid. In a pre-clinical study on TB infected mice, we demonstrate that the encapsulated drugs, administered once weekly for nine weeks, showed comparable efficacy to daily treatment with free drugs over the same experimental period. Both treatment approaches had equivalent outcomes for resolution of inflammation associated with the infection of lungs and spleens. These results demonstrate how scalable technology could be used to manufacture nanoencapsulated drugs. The formulations may be used to reduce the oral dose frequency from daily to once weekly in order to treat uncomplicated TB. Full article

In the present study, we developed novel β-glucosidase-based nano-biocatalysts for the bioconversion of oleuropein to hydroxytyrosol. Using non-covalent or covalent immobilization approaches, β-glucosidases from almonds and Thermotoga maritima were attached for the first time on oxidized and non-oxidized porous carbon cuboids (PCC). Various methods were used for the characterization of the bio-nanoconjugates, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and fluorescence spectroscopy. The oxidation state of the nanο-support and the immobilization procedure play a key role for the immobilization efficiency or the catalytic activity of the immobilized β-glucosidases. The nano-biocatalysts were successfully used for the hydrolysis of oleuropein, which leads to the formation of its bioactive derivative, hydroxytyrosol (up to 2.4 g L⁻¹), which is a phenolic compound with numerous health benefits. The bio-nanoconjugates exhibited high thermal and operational stability (up to 240 h of repeated use), which indicated that they are efficient tools for various bio-transformations. Full article