Stokes and Anti-Stokes Luminescent Rare-Earth-Doped Tantalum Oxide Nanoparticles.

Doping of nano- and microparticles of oxides with rare earth elements (REEs) is used to fine-tune their structural, optical, and electrochemical properties. On the way to establish the structure-property relationship, we dope tantalum oxide (Ta2O5) particles with REEs to study their effect on the oxide structure and luminescence. Ta2O5 is highly perspective in medicine, catalysis, and optics, but its crystal structure is insufficiently studied. Two synthesis approaches (sol-gel and solvothermal) were used to obtain powders with different textures. Experimental and theoretical studies of amorphous and crystallized tantalum oxide NPs by means of X-ray powder diffraction, Rietveld analysis, EXAFS/XANES spectroscopy, and density functional theory calculations were performed. All samples (doped and undoped) crystallized in orthorhombic phase with no admixtures. It was demonstrated that Ta2O5 is a promising wide-spectrum luminescent material: by combining REEs, both Stokes and anti-Stokes luminescence in the visible region were obtained. By means of optical absorption spectroscopy, it was shown that the prepared samples could be classified as wide band gap semiconductors.

Fluorescent Hybrid Material Based on Natural Spider Silk and Carbon Dots for Bioapplication.

Since the outcome of an operation largely depends on the quality of wound healing, it is one of the most challenging stages in surgery. Today, wound closure is mostly undertaken by means of a surgical suture. Good surgical sutures are biocompatible and biodegradable and possess excellent mechanical properties. Preferably, these sutures demonstrate optical activity for bacteria detection as there is a risk of surgical site infections. In this study, a solution, which fulfills all the requirements for manufacturing a multifunctional hybrid material, is proposed. In this work, a method for the in situ modification of spider silk with fluorescent carbon dots has been developed. The basic concept is the use of silk fibers as both the main framework for tissue regeneration and a carbon source during carbon dot synthesis. The resulting hybrid material exhibits strong photoluminescence in the red region of the spectrum (590 nm) when irradiated with blue light (480 nm). The proposed approach potentially allows for simultaneous wound closure and pathogen detection.

Hafnium Oxide-Based Nanoplatform for Combined Chemoradiotherapy.

Recently, the combined therapy has become one of the main approaches in cancer treatment. Combining different approaches may provide a significant outcome by triggering several death mechanisms or causing increased damage of tumor cells without hurting healthy ones. The supramolecular nanoplatform based on a high-Z metal reported here is a suitable system for the targeted delivery of chemotherapeutic compounds, imaging, and an enhanced radiotherapy outcome. HfO2 nanoparticles coated with oleic acid and a monomethoxypoly(ethylene glycol)-poly(ε-caprolactone) copolymer shell (nanoplatform) are able to accumulate inside cancer cells and release doxorubicin (DOX) under specific conditions. Neither uncoated nor coated nanoparticles show any cytotoxicity in vitro. DOX loaded onto a nanoplatform demonstrates a lower IC50 value than pure DOX. X-ray irradiation of cancer cells loaded with a nanoplatform shows a higher death rate than that for cells without nanoparticles. These results provide an important foundation for the development of complex nanoscale systems for combined cancer treatment.

Application of extracted ß-glucan from oat for ß-carotene encapsulation.

ABSTRACT: The cell walls of cereals are rich sources of polysaccharide ß-glucan. In this study, the ß-glucan was extracted from oat bran using the hot-water extraction method and dried in a pure powder form. The concentration of the ß-glucan in the extract was determined using the l-cysteine sulfuric acid method. The results showed that the yield of ß-glucan using the hot-water extraction method is the highest compared to its yield achieved by enzymatic, acid, and alkaline methods. In this paper, the usage of the ß-glucan as a coating material for a water-insoluble carotenoid is considered. This study demonstrates for the first time the encapsulation of ß-carotene with modified octanoic acid ß-glucan. It implements to obtain a stable encapsulated polysaccharide-carotenoid system, which has been studied by a set of physicochemical methods and a cytotoxic analysis was performed on the HCT-116 cell line. The SEM image of the resulting encapsulated system is perfectly correlated with the DLS data, which has determined the size of MG capsules at 200 nm. The cytotoxic analysis demonstrates that the cell viability was more than 70%, which indicates its potential using in the food industry.

Hybrid Spider Silk with Inorganic Nanomaterials.

High-performance functional biomaterials are becoming increasingly requested. Numerous natural and artificial polymers have already demonstrated their ability to serve as a basis for bio-composites. Spider silk offers a unique combination of desirable aspects such as biocompatibility, extraordinary mechanical properties, and tunable biodegradability, which are superior to those of most natural and engineered materials. Modifying spider silk with various inorganic nanomaterials with specific properties has led to the development of the hybrid materials with improved functionality. The purpose of using these inorganic nanomaterials is primarily due to their chemical nature, enhanced by large surface areas and quantum size phenomena. Functional properties of nanoparticles can be implemented to macro-scale components to produce silk-based hybrid materials, while spider silk fibers can serve as a matrix to combine the benefits of the functional components. Therefore, it is not surprising that hybrid materials based on spider silk and inorganic nanomaterials are considered extremely promising for potentially attractive applications in various fields, from optics and photonics to tissue regeneration. This review summarizes and discusses evidence of the use of various kinds of inorganic compounds in spider silk modification intended for a multitude of applications. It also provides an insight into approaches for obtaining hybrid silk-based materials via 3D printing.

Hybrid cellulose nanocrystal/magnetite glucose biosensors.

There exists a high demand for simple and affordable blood glucose monitoring methods. For this purpose, new generations of biosensors are being developed for possible in vivo or dermal use. We present (non)sulphated cellulose nanocrystal/magnetite thin films to act as dermal and oral glucose biosensors. The biocompatible (N-CNC)-Fe3O4 and (S-CNC)-Fe3O4 hybrid systems exhibit peroxidase-like activity, indicated by an almost instant color change when in the presence of glucose and ABTS. Both types of biosensors detect glucose concentrations as low as 5 mM (which corresponds to the level of glucose in biological fluids), with (S-CNC)-Fe3O4 being 1.5 - 2 times as sensitive as (N-CNC)-Fe3O4. Hybrid catalytic activity is more pronounced at room temperature and in acidic environments. The hybrids can therefore be used to determine glucose levels by using sweat and saliva - non-blood bodily secretions which tend to be slightly to moderately acidic and have relatively low glucose levels.

Hybrid Materials Based on Carbon Nanotubes and Nanofibers for Environmental Applications.

With the advances in material science, hybrid nanomaterials with unique mechanical, electrical, thermal and optical characteristics have been developed. Among them, hybrids based on filamentous forms of carbon, such as carbon nanotubes and carbon nanofibers, in combination with inorganic nanoparticles attract particular attention. Due to the structure and morphology, charge and energy transfer processes lead to synergistic effects that allow the use of less material with higher productivity. To clarify these issues, this review will summarize and discuss the relevant studies of the use of inorganic compounds of various chemical groups in modifying carbon nanomaterials for ecological applications.

Recent Advances in Development of Functional Spider Silk-Based Hybrid Materials.

Silkworm silk is mainly known as a luxurious textile. Spider silk is an alternative to silkworm silk fibers and has much more outstanding properties. Silk diversity ensures variation in its application in nature and industry. This review aims to provide a critical summary of up-to-date fabrication methods of spider silk-based organic-inorganic hybrid materials. This paper focuses on the relationship between the molecular structure of spider silk and its mechanical properties. Such knowledge is essential for understanding the innate properties of spider silk as it provides insight into the sophisticated assembly processes of silk proteins into the distinct polymers as a basis for novel products. In this context, we describe the development of spider silk-based hybrids using both natural and bioengineered spider silk proteins blended with inorganic nanoparticles. The following topics are also covered: the diversity of spider silk, its composition and architecture, the differences between silkworm silk and spider silk, and the biosynthesis of natural silk. Referencing biochemical data and processes, this paper outlines the existing challenges and future outcomes.

Magnetite Hydrosols with Positive and Negative Surface Charge of Nanoparticles: Stability and Effect on the Lifespan of Drosophila melanogaster.

This paper presents sols of uncoated and citric acid-coated Fe3O4 nanoparticles obtained by a combination of coprecipitation and sonochemistry methods. A stable concentrated CA-Fe3O4 sol synthesized by a combination of coprecipitation with an inconvenient Fe2+/Fe3+ ratio, modification with citric acid and US treatment was obtained for the first time. A comparative analysis of the composition and morphology of nanoparticles was performed. The sols are oppositely charged and behave as a typical ferrofluid. The citric acid-modified sol is aggregatively stable over wider ranges of pH and electrolyte concentration, but it becomes less stable with the temperature increase. DLVO calculations showed that steric repulsion forces are a vital factor contributing to increased aggregative stability in a modified Fe3O4 sol. The experiments have revealed the magneto-optical effect in a modified Fe3O4 sol with an electrolyte concentration of 0.025-0.075 M caused by a high potential barrier and a deep secondary minimum in pairwise interaction curves. The "pK spectroscopy" mathematical model to describe the potentiometric curves of synthesized magnetite sols was used for the first time. According to potentiometric titration, the ions of the electrolyte practically do not contribute to formation of a surface charge in modified Fe3O4 with a change in pH due to blocking the magnetite surface by citric acid molecules. Drosophila melanogaster was used as a model to show that Fe3O4 in chronic exposure has a low toxic effect.

Environmentally friendly Au@CNC hybrid systems as prospective humidity sensors.

Both cellulose nanocrystals and gold nanoparticles show immense potential for biological and chemical applications. Gold nanoparticles, which tend to aggregate, are hybridized with cellulose nanocrystals to form stable inorganic-organic hybrids in which nanocellulose acts as a green supporting material for the catalytically active gold nanoparticles. A green synthesis approach was taken, and hydrothermal treatment was used to reduce electrostatic repulsion between the gold nanoparticles and the cellulose nanocrystals to promote heteroaggregation instead of homoaggregation. AFM analysis showed hybrid films to be hygroscopic, suggesting that they would respond to changes in humidity. Laser diffraction and fluorescence quenching were used to determine how hybrid films respond to changes in humidity. Hybrid films were found to respond to changes in humidity quickly, reversibly, and autonomously, making them ideal for use as or in a humidity sensor. Gold nanoparticles were shown to enhance the hybrid response to ambient moisture, causing them to show a linear dependence on changes in humidity, making the hybrid controllable, highly sensitive, and a viable prospective material for humidity sensing applications.

Application of Immobilized Enzymes in Food Industry.

Enzymes are macromolecular biocatalysts, widely used in food industry. In applications, enzymes are often immobilized on inert and insoluble carriers, which increase their efficiency due to multiple reusability. The properties of immobilized enzymes depend on the immobilization method and the carrier type. The choice of the carrier usually concerns the biocompatibility, chemical and thermal stability, insolubility under reaction conditions, capability of easy regeneration and reusability, as well as cost efficiency. In this review, we provide an overview of various carriers for enzyme immobilization, with the primary focus on food industry.

Upconversion metal (Zr, Hf, and Ta) oxide aerogels.

A major obstacle in developing upconversion aerogels is the incompatibility of the highly-developed porosity and the crystal structure required for converting light to a shorter wavelength. We propose a novel method for creating a sol-gel procedure for synthesizing metal (Zr, Hf, and Ta) oxide upconverison aerogels uniformly doped with Er3+ and Yb3+ by precisely adjusting the calcination conditions.

Designing selenium functional foods and beverages: A review.

A functional food is any food that has (a) specific nutrient(s) added to it for a specific functional purpose. Selenium (Se) is a metalloid that belongs to group 16 of the periodic table. It may be obtained from myriad sources like soil, water, and living organisms. Se is required to sustain proper health in both animals and humans due to its linkage with various biological functions in the immune system. Nature has made it impossible for us to obtain sufficient Se from the diet since some regions across the globe have been designated as Se-deficient while others are becoming Se-toxic. Se deficiency is associated with a compromised immune system and increased susceptibility to various diseases. Therefore, designing Se functional foods and supplements is the way forward in curbing the menace mentioned above, since geographical location will not have any effect on the Se content of these foods. Brewing yeast has the necessary enzymes to biotransform inorganic Se (Na2SeO3) to its bioactive organic form, which is incorporated in the aged selenized beer. S. cerevisiae was found to have better biotransformation efficiency than other yeast species. A traditional Slavic beverage, selenized kvass, was brewed using rye grains soaked and germinated in solutions of Na2SeO3. Fruit yeasts (Lesaffre) and Evitalia were utilized as the starter cultures. A Se enriched solution was extracted from Se-biofortified pak-choi cabbage and incorporated into the wort before fermentation. Selenized yeast and algae can be taken as supplements or as food additives. There have been some reports about microcystins (MCs) in Spirulina. Therefore, the safety of Se-algae is not guaranteed. Pasteurized dried selenized supplements (yeast and algae) were proposed in formulating Selenized enriched Tom-brown. This review seeks to propose some possible foods that could be enriched with Se. A large portion of the population adequately consumes these proposed foods on a regular basis hence the target goal would be a success.

Sol-gel derived boehmite nanostructures is a versatile nanoplatform for biomedical applications.

Alumina is one of the most promising carriers for drug delivery due to the long history of its usage as a vaccine adjuvant. Sol-gel synthesis provides excellent conditions for entrapment of biomolecules within an inorganic cage providing stabilization of proteins under the extremal conditions. In this paper, we show in vitro investigation of monodisperse alumina xerogel nanocontainers (AXNCs) using bovine serum albumin as a model protein entrapped in sol-gel alumina building blocks. Particularly, dose and cell-type dependent cytotoxicity in HeLa and A549 cancer cell lines were employed as well as investigation of antibacterial effect and stability of AXNCs in different biological media. It was shown, that the release of entrapped protein could be provided only in low pH buffer (as in cancer cell cytoplasm). This property could be applied for anticancer drug development. We also discovered boehmite nanoparticles effect on horizontal gene transfer and observed the appearance of antibiotic resistance by means of exchanging of the corresponding plasmid between two different E. coli strains. The present work may help to understand better the influence of AXNCs on various biological systems, such as prokaryotic and eukaryotic cells, and the activity of AXNCs in different biological media.

Toxicity Patterns of Clinically Relevant Metal Oxide Nanoparticles.

Nanostructured drugs are being approved for clinical use, although there is a serious deficit of systematic studies of these materials. Data on toxicity of nanoparticles (NPs) can vary due to different methods of preparation, size, and shape. We investigated the toxicity against cultured human cells, the acute toxicity in mice, and the influence on conjugative transfer of antibiotic resistance genes of clinically relevant NPs such as TiO2, ZrO2, HfO2, Ta2O5, Fe3O4, and AlOOH. NPs were synthesized as aqueous sols by the same method in aqueous solution, with almost identical size 2-10 nm. None of these NPs was cytotoxic at concentrations compatible with water solubility. Furthermore, TiO2, HfO2, Ta2O5, Fe3O4, and AlOOH were not toxic to mice after oral administration. However, ZrO2 showed rather high toxicity, with LD50 2277.8 mg/kg. Experiments with plasmid transfer between bacteria demonstrated that AlOOH NPs were the most hazardous since this material promoted the emergence of resistance to antibiotics. Thus, although our metal oxide NPs are largely non-toxic, their properties may differ in specific biological situations.