Nanoparticles in marine antifouling coatings: a case study

The problem of fouling of hydraulic structures, marine structures, ships and vessels has been acute since the beginning of the era of navigation. The formation of a biofilm of fouling reduces the speed of the vessel, worsens its controllability, increases fuel consumption, shortens the service life of hydraulic structures and increases the load on them. Many methods have been proposed to control fouling. One of the most promising coatings is considered to be based on the use of nanoparticles of biologically active metals and their oxides. The paper discusses various strategies for using nanoparticles to combat biofouling. The paper also presents preliminary results of a study of the antifouling efficiency of coatings modified with nanoparticles of metal oxides Fe-ZnO, ZnO, CuO. The study was carried out by exposing plates with experimental compositions at the sea test site in the Sevastopol Bay for a year, starting from August 2020. The species composition of a separate group of microperiphyton - microalgae - on plates with experimental coatings in the first two months of exposure, as well as the result of photographic fixation of the state of the surface of the plates from the point of view of macro-fouling, was investigated.

Functional state of the myometrium of rats under chronic in vivo effect of nanostructured ZnO and ТіО2 materials

The specificities of the structure and blood supply of the uterus facilitate a considerable accumulation of nanosized xenobiotics, including nanoparticles of metal oxides, in its tissues. Numerous in vitro and in vivo experiments demonstrated that nanoparticles of metal oxides (ZnO and TiO2) have significant cytotoxic activity, caused by oxidative stress induction. However, there is no information about the impact of these nanomaterials on the functional state of the myometrium under chronic exposure on the organism. Tenzometric methods and mechanokinetic analysis were used in our work to investigate the contractile activity of the myometrium of non-pregnant rats. The contractile activity was either spontaneous or induced by oxytocin (the uterotonic hormone) and acetylcholine (the agonist of muscarinic choline receptors) under chronic peroral intake of the ZnO and TiO2 aqueous nanocolloids into the organism. It was found that after burdening of rats with ZnO and ТіО2 aqueous nanocolloids there were no changes in the pacemaker-dependent mechanisms forming the frequency of spontaneous contractions in the myometrium, but there was a considerably induced increase in the AU index of contractions. It was shown that during the oxytocin-induced excitation of the myometrium under both chronic and short-term burdening of the rats with ZnO and TiO2 aqueous nanocolloids, the mechanisms that regulate the intracellular concentration of Ca2+ ions are the target for the nanomaterials. When the rats were burdened with ZnO aqueous nanocolloids for 6 months, during cholinergic excitation there was hyperstimulation of both M3-receptor-dependent mechanisms of Са2+ ions intake via the potential-governed Са2+-channels of L-type into the smooth muscles of the myometrium, and M2-receptor-dependent mechanisms, controlling the intracellular concentration of these cations. Thus, the regularities and mechanisms of the change in the functioning of uterine smooth muscles under chronic intake of the ZnO and TiO2 aqueous nanocolloids were determined in this study.

Natural and Synthetic Nanomaterials in Microbial Biotechnologies for Crop Production

Nanoparticles of various materials (up to 100 nm in size) are characterized by a large surface area, which significantly increases their reactive properties. This makes promissing the studies of their possible application in different technologies, including those in the agricultural production sector. This review summarizes the literature on the distribution and properties of natural nanoparticles in the environment. The features of the interaction between various types of microorganisms, nanoparticles of natural minerals, oxides of metals and carbon nanoparticles are analyzed. The review also summarizes the data on the effect of nanoparticles of different origin on microorganisms, plant growth and development. It also presents the information on the effectiveness of the use of clay mineral nanoparticles in the production of complex bacterial preparations for plant growing and the prospects of using nanoparticles of metal oxides in this industry.

Photocatalytic Applications of Metal Oxides for Sustainable Environmental Remediation

Along with industrialization and rapid urbanization, environmental remediation is globally a perpetual concept to deliver a sustainable environment. Various organic and inorganic wastes from industries and domestic homes are released into water systems. These wastes carry contaminants with detrimental effects on the environment. Consequently, there is an urgent need for an appropriate wastewater treatment technology for the effective decontamination of our water systems. One promising approach is employing nanoparticles of metal oxides as photocatalysts for the degradation of these water pollutants. Transition metal oxides and their composites exhibit excellent photocatalytic activities and along show favorable characteristics like non-toxicity and stability that also make them useful in a wide range of applications. This study discusses some characteristics of metal oxides and briefly outlined their various applications. It focuses on the metal oxides TiO2, ZnO, WO3, CuO, and Cu2O, which are the most common and recognized to be cost-effective, stable, efficient, and most of all, environmentally friendly for a sustainable approach for environmental remediation. Meanwhile, this study highlights the photocatalytic activities of these metal oxides, recent developments, challenges, and modifications made on these metal oxides to overcome their limitations and maximize their performance in the photodegradation of pollutants.

Formation of microfibrillar structure of polypropylene/copolyamide blends in the presence of nanoparticles of metal oxides

The influence of nanoparticles made of ifferent metals oxides (ZnO, Al2O3, TiO2, and ZnO/Al2O3) on the in situ formation of microfibrils by the components of a dispersed phase was studied in a thermodynamically incompatible blend of polypropylene/copolyamide (PP/CPA). The viscosity of the melts was determined by capillary viscometry method. Elastic properties were evaluated by the degree of extrudate swelling. The morphology of the compositions was studied by optical polarization microscopy. The method of image analysis was used to quantify the structural characteristics of the blends. It was established that the introduction of 1.0 wt.% of nanoparticles of the studied oxides made from different metals allows tuning the microstructure of the melt of the PP/CPA blend, which is realized in the course of extrusion. More perfect morphology is formed in nanofilled systems: the average diameter of PP microfibrils decreases and their mass fraction increases. The modifying effect of oxide nanoparticles is manifested due to their influence on interfacial phenomena and rheological properties of nanofilled PP melt. The viscosity of the PP melts increases and their elasticity decreases in the presence of nanoparticles of the studied metal oxides. The values of the ratio of the viscoelastic characteristics of the dispersed phase and the matrix in nanofilled systems depend on the nature of oxide and indirectly correlate with the microstructure of the extrudate. As these ratios approach unity, the diameter of PP microfibrils decreases and their share increases. The efficiency of the studied oxides to improve the microfibrillar structure increases in the following series: ZnO, Al2O3, TiO2, ZnO/Al2O3. The obtained results demonstrate the possibility to create the microfiber textile and filter materials with improved consumer characteristics by adjusting the phase morphology of the blends.

ВЛИЯНИЕ СТРОЕНИЯ НАНОЧАСТИЦ НА МЕХАНИЗМ ИХ ВЗАИМОДЕЙСТВИЯ С ЖИВЫМИ СИСТЕМАМИ

Биологическая активность наночастиц зависит от физико-химических характеристик частиц. Химическое взаимодействие наночастиц с жидкой средой, по-нашему мнению, является одним из определяющих факторов их биологической активности. Изменение рН среды за счет высокой восстановительной способности наночастиц повышает проницаемость мембран, способствуя биоаккумуляции наночастиц или усилению их биосовместимости. Данная способность зависит от той информации (тех свойств), которой обладают частицы разных размеров, состава и физико-химических характеристик. Высокой биологической активностью обладают наночастицы металлов железа, кобальта, меди размером 35-60 нм в количестве 0,01-10,0 г на тонну семян, полученные низкотемпературной металлизацией нанодисперсных порошков гидроксидов. Наночастицы оксидов металлов размером 20-80 нм снижают рост и развитие растений, и в отличие от наночастиц металлов, они аккумулируются в структурах растений, понижая активность фитогормонов и ферментов. При этом аномальная дозовая зависимость эффекта в области сверхнизких концентраций биологически активных веществ зарегистрирована на уровне ответа не только клетки или целостного организма (растения), но и отдельных биомакромолекул (ферментов). В наших исследованиях мы обнаружили, что всякий раз при введении сверхмалых доз биологически активного вещества в организм животного, клеточную культуру или в модельную систему, содержащую суспензиюмембран, отмечается изменение структурных характеристик мембран. В свою очередь изменения структуры мембран могут приводить к изменению функционального состояния клетки, а наличие полимодальности в ответе можно объяснить сменой механизма действия вещества в том или ином концентрационном интервале на структуру мембраныThe biological activity of nanoparticles depends on the physical-chemical characteristics of the particles. The chemical interaction of nanoparticles with a liquid medium, in our opinion, is one of the determining factors in their biological activity. A change in the pH of the medium due to the high reducing bility of nanoparticles increases the permeability of membranes, promoting bio-accumulation of nanoparticles or enhancing theirbio-compatibility. This ability depends on the information (those properties) of particles of different sizes, their composition and physical-chemical characteristics. Metal nanoparticles of iron, cobalt, copper of 35-60 nm in the amount of 0.01-10.0 g per ton of seeds, obtained by low-temperature metallization of nanodispersed hydroxide powders, possess high biological activity. Nanoparticles of metal oxides with a size of 20-80 nm reduce plant growth and development, and unlike metal nanoparticles, they accumulate in plant structures, reducing the activity of phytohormones and enzymes. In this case, an abnormal dose dependence of the effect of ultra-low concentrations of biologically active substances is recorded at the level of response not only of the cell or the whole organism (plant), but also of individual bio-macromolecules (enzymes). The studies showed that every time an ultra-low dose of a biologically active substance is introduced into an animal, a cell culture, or into a model system containing a suspension of membranes, a change in the structural characteristics of the membranes is noted. In turn, changes in the structure of membranes can lead to a change in the functional state of the cell, and the presence of polymodality in the response can be explained by a change in the mechanism of action of a substance in a particular concentration range on the membrane structure.

Metaloxide Nanomaterials and Nanocomposites of Ecological Purpose

The features of the properties and creation of nanocomposite metal oxide materials, especially TiO2, ZnO, SnO2, ZrO2, and Fe3O4, and their applications for ecology are considered in the article. It is shown that nanomaterials based on them are very promising for use in the ecological direction, especially as sorbents, photocatalysts, and sensitive layers of gas sensors. The crystallochemical characteristics, surface structure, and surface phenomena that occur when they enter the water and air environment are given for these metal oxides, and it is shown that they play a significant role in obtaining the sorption and catalytic characteristics of these nanomaterials. Particular attention is paid to the dispersion and morphology of metal oxide particles by which their physical and chemical properties can be controlled. Synthesis methods of metal oxide nanomaterials and ways for creating of nanocomposites based on them are characterized, and it is noted that there are many methods for obtaining individual nanoparticles of metal oxides with certain properties. The main task is the correct selection and testing of parameters. The prospects for the production of metal oxide nanocomposites and their application for environmental applications are noted, which will lead to a fundamentally new class of materials and new environmental technologies with their participation.