Tellurium and Nano-Tellurium: Medicine or Poison?

Tellurium (Te) is the heaviest stable chalcogen and is a rare element in Earth's crust (one to five ppb). It was discovered in gold ore from mines in Kleinschlatten near the present-day city of Zlatna, Romania. Industrial and other applications of Te focus on its inorganic forms. Tellurium can be toxic to animals and humans at low doses. Chronic tellurium poisoning endangers the kidney, liver, and nervous system. However, Te can be effective against bacteria and is able to destroy cancer cells. Tellurium can also be used to develop redox modulators and enzyme inhibitors. Soluble salts that contain Te had a role as therapeutic and antimicrobial agents before the advent of antibiotics. The pharmaceutical use of Te is not widespread due to the narrow margin between beneficial and toxic doses, but there are differences between the measure of toxicity based on the Te form. Nano-tellurium (Te-NPs) has several applications: it can act as an adsorptive agent to remove pollutants, and it can be used in antibacterial coating, photo-catalysis for the degradation of dyes, and conductive electronic materials. Nano-sized Te particles are the most promising and can be produced in both chemical and biological ways. Safety assessments are essential to determine the potential risks and benefits of using Te compounds in various applications. Future challenges and directions in developing nano-materials, nano-alloys, and nano-structures based on Te are still open to debate.

Nanofertilizers: A Smart and Sustainable Attribute to Modern Agriculture

The widespread use of fertilizers is a result of the increased global demand for food. The commonly used chemical fertilizers may increase plant growth and output, but they have deleterious effects on the soil, the environment, and even human health. Therefore, nanofertilizers are one of the most promising solutions or substitutes for conventional fertilizers. These engineered materials are composed of nanoparticles containing macro- and micronutrients that are delivered to the plant rhizosphere in a regulated manner. In nanofertilizers, the essential minerals and nutrients (such as N, P, K, Fe, and Mn) are bonded alone or in combination with nano-dimensional adsorbents. This review discusses the development of nanotechnology-based smart and efficient agriculture using nanofertilizers that have higher nutritional management, owing to their ability to increase the nutrient uptake efficiency. Additionally, the synthesis and mechanism of action of the nanofertilizers are discussed, along with the different types of fertilizers that are currently available. Furthermore, sustainable agriculture can be realised by the targeted delivery and controlled release of nutrients through the application of nanoscale active substances. This paper emphasises the successful development and safe application of nanotechnology in agriculture; however, certain basic concerns and existing gaps in research need to be addressed and resolved.

Machine learning predictions of concentration-specific aggregate hazard scores of inorganic nanomaterials in embryonic zebrafish

The possibility of employing computational approaches like nano-QSAR or nano-read-across to predict nanomaterial hazard is attractive from both a financial, and most importantly, where in vivo tests are required, ethical perspective. In the present work, we have employed advanced Machine Learning techniques, including stacked model ensembles, to create nano-QSAR tools for modeling the toxicity of metallic and metal oxide nanomaterials, both coated and uncoated and with a variety of different core compositions, tested at different dosage concentrations on embryonic zebrafish. Using both computed and experimental descriptors, we have identified a set of properties most relevant for the assessment of nanomaterial toxicity and successfully correlated these properties with the associated biological responses observed in zebrafish. Our findings suggest that for the group of metal and metal oxide nanomaterials, the core chemical composition, concentration and properties dependent upon nanomaterial surface and medium composition (such as zeta potential and agglomerate size) are significant factors influencing toxicity, albeit the ranking of different variables is sensitive to the exact analysis method and data modeled. Our generalized nano-QSAR ensemble models provide a promising framework for anticipating the toxicity potential of new nanomaterials and may contribute to the transition out of the animal testing paradigm. However, future experimental studies are required to generate comparable, similarly high quality data, using consistent protocols, for well characterized nanomaterials, as per the dataset modeled herein. This would enable the predictive power of our promising ensemble modeling approaches to be robustly assessed on large, diverse and truly external datasets.

Biomaterials for Three-Dimensional Cell Culture: From Applications in Oncology to Nanotechnology

Three-dimensional cell culture has revolutionized cellular biology research and opened the door to novel discoveries in terms of cellular behavior and response to microenvironment stimuli. Different types of 3D culture exist today, including hydrogel scaffold-based models, which possess a complex structure mimicking the extracellular matrix. These hydrogels can be made of polymers (natural or synthetic) or low-molecular weight gelators that, via the supramolecular assembly of molecules, allow the production of a reproducible hydrogel with tunable mechanical properties. When cancer cells are grown in this type of hydrogel, they develop into multicellular tumor spheroids (MCTS). Three-dimensional (3D) cancer culture combined with a complex microenvironment that consists of a platform to study tumor development and also to assess the toxicity of physico-chemical entities such as ions, molecules or particles. With the emergence of nanoparticles of different origins and natures, implementing a reproducible in vitro model that consists of a bio-indicator for nano-toxicity assays is inevitable. However, the maneuver process of such a bio-indicator requires the implementation of a repeatable system that undergoes an exhaustive follow-up. Hence, the biggest challenge in this matter is the reproducibility of the MCTS and the associated full-scale characterization of this system's components.

Patterned Fibers Embedded Microfluidic Chips Based on PLA and PDMS for Ag Nanoparticle Safety Testing

A new method to integrate poly-dl-lactide (PLA) patterned electrospun fibers with a polydimethylsiloxane (PDMS) microfluidic chip was successfully developed via lithography. Hepatocyte behavior under static and dynamic conditions was investigated. Immunohistochemical analyses indicated good hepatocyte survival under the dynamic culture system with effective hepatocyte spheroid formation in the patterned microfluidic chip vs. static culture conditions and tissue culture plate (TCP). In particular, hepatocytes seeded in this microfluidic chip under a flow rate of 10 μL/min could re-establish hepatocyte polarity to support biliary excretion and were able to maintain high levels of albumin and urea secretion over 15 days. Furthermore, the optimized system could produce sensitive and consistent responses to nano-Ag-induced hepatotoxicity during culture. Thus, this microfluidic chip device provides a new means of fabricating complex liver tissue-engineered scaffolds, and may be of considerable utility in the toxicity screening of nanoparticles.

Organically Modified Silica Nanoparticles Interaction with Macrophage Cells: Assessment of Cell Viability on the Basis of Physicochemical Properties

Silica nanoparticles have drawn a lot of attention for nanomedicine application, and this is attributed to their biocompatibility and ease of surface functionalization. However, successful utilization of these inorganic systems for biomedical application depends on their physicochemical properties. This study, therefore, discusses in vitro toxicity of organically modified silica nanoparticles on the basis of size, shape, and surface properties of silica nanoparticles. Spherical- and oval-shaped nanoparticles having hydroxyl and amine groups were synthesized in Tween 80 micelles using different organosilanes. Nanoparticles of similar size and morphology were considered for comparative assessment. "As-prepared" nanoparticles were characterized in terms of size, shape, and surface properties using ZetaSizer, transmission electron microscopy, and Fourier transform infrared to establish the above parameters. In vitro analysis in terms of nanoparticle-based toxicity was performed on J-774 (macrophage) cell line using propidium iodide-4',6-diamidino-2-phenylindol and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Fluorescent dye-entrapped nanoparticles were used to visualize the uptake of the nanoparticles by macrophage cells. Results from cell studies suggested low levels of toxicity for different nanoparticle formulations studied, therefore are suitable for nanocarrier application for poorly soluble molecules. On the contrary, the nanoparticles of similar size and shape, having amine groups and low net negative charge, do not exhibit any in vitro cytotoxicity.

Wear Debris Characterization and Corresponding Biological Response: Artificial Hip and Knee Joints

Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials.