Morphological and Physicochemical Characterization of Agglomerates of Titanium Dioxide Nanoparticles in Cell Culture Media

Titanium dioxide nanoparticles (TiO2 NP) are possible carcinogenic materials (2B-IARC) and their toxicity depends on shape, size, and electrical charge of primary NP and on the system formed by NP media. The aim of this work was to characterize agglomerates of three TiO2 NP by evaluating their morphometry, stability, and zeta potential (ζ) in liquid media and their changes with time. Sizes of agglomerates by dynamic light scattering (DLS) resulted to be 10–50 times larger than those obtained by digital image analysis (DIA) given the charged zone around particles. Fractal dimension (FD) was highest for agglomerates of spheres and belts in F12K, and in E171 in FBS media. E171 and belts increased FD with time. At time zero, using water as dispersant FD was larger for agglomerates of spheres than for of E171. Belts suspended in water had the smallest values of circularity (Ci) which was approximately unchanged with time. All dispersions had ζ values around −30 mV at physiological pH (7.4) and dispersions of NP in water and FBS showed maximum stability (Turbiscan Lab analysis). Results help in understanding the complex NP geometry-size-stability relationships when performing in vivo and in vitro environmental-toxicity works and help in supporting decisions on the usage of TiO2 NP

Evaluation of chromosome organization and microtubule arrangement in goat (capra aegragrus) oocytes after vitrification, in vitro maturation and fertilization, and early embryo development

Objective: Evaluate the use of Ethylene Glycol (EG), Dimethyl Sulfoxide (DMSO), Sucrose and Fetal Bovine Serum (FBS) as cryoprotectants and their effect on the organization of chromosomes and the arrangement of microtubules, during the vitrification process in goat oocytes matured in vitro and in the development of preimplantation embryos produced in vitro. Design/methodology/approach: In vitro matured oocytes were divided into 3 groups (control group, cryoprotectant exposed group, vitrified group). A mixture of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS was used for the vitrification using the Cryotop device. In vitro matured oocytes were warmed and afterwards each group was divided into two more groups. Both groups were subjected to immunofluorescence, the first group to observe the damage produced to the chromosomes and microtubules and the second group to observe the effect on the in vitro embryo development. Results: The combined use of 15% EG, 15% DMSO, 0.4 M Sucrose and 20% FBS during vitrification did not prevent cryoinjuries in goat oocytes and in vitro produced embryos, since embryo development was disrupted before the blastocyst stage by stopping cleavage at the morula stage. This disruption was associated with chromosome decondensation and the absence of a microtubule network, thereby hindering chromosomal segregation. Limitations on study/implications: The effect of conventional cryoprotectants on chromosomes and microtubules arrangement on vitrified goat oocytes and in vitro embryo production. Findings/conclusions: The combined use of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS as vitrification cryoprotectants did not prevent cryoinjuries in caprine oocytes and did not improve caprine embryo development in vitro

Differences in cytotoxicity of lung epithelial cells exposed to titanium dioxide nanofibers and nanoparticles: Comparison of air-liquid interface and submerged cell cultures.

Air Liquid Interface (ALI) system has emerged as a useful tool for toxicity evaluation of nanomaterials related to inhalation since the system mimics the aerosol exposure. We compared the biological responses of lung epithelial cells exposed to titanium dioxide (TiO2) nanofibers and nanoparticles in ALI and submerged cell cultures systems. Cells were exposed to 2 and 10 μg/cm2 for 24 h, 48 h and 72 h and LDH release, TiO2 internalization, DNA-double strand breaks (DSBs) and ROS production were assessed. LDH release was similar in both systems and particles had higher cytoplasmic uptake in submerged systems. Both TiO2 types were located in the cytoplasm but nanofibers had nuclear uptake regardless to the system tested. Cells exposed to TiO2 nanofibers had higher DSBs in the ALI system than in submerged cell cultures but cells exposed to TiO2 nanoparticles had similar DSBs in both systems. ROS production was higher in cells exposed to TiO2 nanofibers compared to cells exposed to TiO2 nanoparticles. In conclusion, cytotoxicity of lung epithelial cells was similar in ALI or submerged cell cultures, however cells exposed to TiO2 nanofibers displayed higher toxicity than cells exposed to TiO2 nanoparticles

The Effects of the Food Additive Titanium Dioxide (E171) on Tumor Formation and Gene Expression in the Colon of a Transgenic Mouse Model for Colorectal Cancer

Titanium dioxide (TiO2) is present in many different food products as the food additive E171, which is currently scrutinized due to its potential adverse effects, including the stimulation of tumor formation in the gastrointestinal tract. We developed a transgenic mouse model to examine the effects of E171 on colorectal cancer (CRC), using the Cre-LoxP system to create an Apc-gene-knockout model which spontaneously develops colorectal tumors. A pilot study showed that E171 exposed mice developed colorectal adenocarcinomas, which were accompanied by enhanced hyperplasia in epithelial cells, and increased tumor size. In the main study, tumor formation was studied following the exposure to 5 mg/kgbw/day of E171 for 9 weeks (Phase I). E171 exposure showed a statistically nonsignificant increase in the number of colorectal tumors in these transgenic mice, as well as a statistically nonsignificant increase in the average number of mice with tumors. Gene expression changes in the colon were analyzed after exposure to 1, 2, and 5 mg/kgbw/day of E171 for 2, 7, 14, and 21 days (Phase II). Whole-genome mRNA analysis revealed the modulation of genes in pathways involved in the regulation of gene expression, cell cycle, post-translational modification, nuclear receptor signaling, and circadian rhythm. The processes associated with these genes might be involved in the enhanced tumor formation and suggest that E171 may contribute to tumor formation and progression by modulation of events related to inflammation, activation of immune responses, cell cycle, and cancer signaling

Reply to Kaminski, N.E.; Cohen, S.M. Comment on “Bischoff et al. The Effects of the Food Additive Titanium Dioxide (E171) on Tumor Formation and Gene Expression in the Colon of a Transgenic Mouse Model for Colorectal Cancer. <i>Nanomaterials</i> 2022, <i>12</i>, 1256”

We appreciate the interest in our article describing transcriptome changes in a transgenic mouse model carrying an APC gene mutation and would like to reply to the reader [...

Correction: Bischoff et al. The Effects of the Food Additive Titanium Dioxide (E171) on Tumor Formation and Gene Expression in the Colon of a Transgenic Mouse Model for Colorectal Cancer. 2022, , 1256.

In the published publication [...]