Silver nanoparticles inhibit the activity of the enzyme providing oxygen exchange in protozoa, such as pathogenic bacteria, viruses, and fungi (about 700 species of pathogenic flora and fauna) [1]. The transition from the ionic Ag⁺ form to metallic nanoclusters makes it possible to reduce silver’s toxicity to cells of higher organisms without suppression of the antimicrobial activity against pathogenic microflora. Silver nanoparticles, especially stabilized ones, have greater stability and prolonged action [2]. Sodium-carboxymethylcellulose (Na-CMC) - a water - soluble film forming biodegradable polymer widely used in the production of oral pharmaceuticals and drugs for external use primarily to increase the viscosities of ointments, in the production of pastes as hydrogel bases, and in the production of drugs for parenteral use - is of high interest as a stabilizer of silver nanoparticles. In addition, Na-CMC is utilized as a binding and disintegrating agent in the production of tablets. Na-CMC is one of the key components of adhesive absorbing systems employed to treat problematic wounds, to remove extravasates, sweat, and the contents of wounds, and to regulate the kinetics of release of active substances of systems contacting mucous membranes.

The aim of this study is to prepare stabilized silver nanoparticles in polymer films based on Na-CMC and to investigate their structures, physical and chemical properties, and microbicidal activities. Industrial samples of Na-CMC with degrees of substitution of 0.65-0.85 and degrees of polymerization of 200-600 obtained from cotton cellulose were used as polymer matrices after their purification from inorganic and organic admixtures. To prepare silver nanoparticles in the films based on CMC, AgNO₃ aqueous solutions of various concentrations were utilized. The bacterium Staphylococcus epidermidis and the yeast fungus Candida albicans - pathogens of humans and animals-were used as test cultures.

To form the films, 2-4% aqueous solutions of purified Na-CMC samples with various degrees of substitution and polymerization were employed after the removal of the gel fraction via centrifugation with a laboratory centrifuge at 2500 rpm for 20 min. Then, calculated amounts of 0.1-0.001 M aqueous solutions of AgNO₃ and 0.1-0.5% glycerol, which played the role of a plasticizer, were added under stirring to the gel free Na-CMC solutions, and the stirring was continued until homogeneous Ag⁺CMC^– hydrogels formed.

The photochemical reduction of silver ions in the Ag⁺CMC^– structure to nanoparticles was performed at 25°С through their irradiation with a DB-250 high pressure mercury lamp. The dispersions of silver nanoparticles were prepared via ultrasonic dispersion of the hydrogels with the use of UZDN-1 and U-4.2 ultrasonic dispersers.

With increasing DS, quota of soluble Na-CMC fraction in water was increased, and content of insoluble gel fraction decreased. With increasing DS, quota of gel fraction of Na-CMC, in water decreases. This can be explained by the fact that by increasing the DS, of Na-CMC, intensity of hydrogen bonds between the macromolecules Na-CMC decreases. Moreover, the compounds and properties of the gel fraction Na-CMC, depend on the type of cellulose row material and methods obtaining of Na-CMC.

It was found that the Na-CMC samples of cotton pulp, in all intervals DP and DS, the content of gel fraction is more than of the sample Na-CMC obtained from wood cellulose. This is explained by the different morphological structures of cotton and wood cellulose, and lower reactivity of cotton cellulose, subjected to carboxymethylation reaction. The above-described investigation provided as polymeric base for the obtaining hydrogel Na-CMC containing ions and silver nanoparticles. Further studies were investigations on the formation and stabilization of silver ions and nanoparticles in Na-CMC polymer base and studied their properties.

At the first step of the study, the films were prepared from aqueous solutions of a-CMC with various degrees of substitution and polymerization and their physical and mechanical parameters were examined. The films were applied onto glass plates from a 2% aqueous solution of Na-CMC. The Na-CMC film formed during water removal.

In the next step of the study, Na-CMC films stabilized with silver nanoparticles were formed and then photoirradiated. Photoreduction of silver cations at concentrations of 0.025-2.50 wt % was performed in a 2% solution of Na-CMC with a degree of substitution of 0.85 (pH 8.5) and a degree of polymerization of 600.

After an increase in the initial concentration of AgNO₃ from 0.025 to 2.5 wt %, the UV - induced color of the Na-CMC solution was found to change from pale yellow to brown. Such a change is likely due to the increase in the amount of formed silver nanoparticles of different sizes. Meanwhile, a pure Na-CMC solution did not change color and remained clear after UV-irradiation.

To confirm the formation of silver nanoparticles, electron microscopic investigations of CMC films were performed. Figure 1 shows the electron micrographs of Na-CMC films formed under UV - irradiation that contain 0.025-2.5 wt % silver nitrate.

For the purpose of determination of the forms and sizes of silver nanoparticles in structure Na-CMC were investigate of obtained samples by atomic fors microscope tipe АFМ - 5500 (Austria).

From Fig. 1a, it may be concluded that, during photoirradiation at a AgNO₃ concentration of 0.025 wt % AgNO₃, clusters and nanoparticles of silver with sizes 2-30 nm are formed in the structures of the films of Na-CMC. After the addition of 0.25 wt. % AgNO₃, 5 to 35 nm spherical silver nanoparticles are formed in the structures of the Na-CMC films (Fig. 1b).

An increase in the silver nitrate concentration in the Na-CMC structure up to 2.5 wt % induces an increase in the number of 5 to 35 nm silver nanoparticles, and rod shaped silver nanoparticles 50-140 nm [3] in length and 15-45 nm in width are formed simultaneously (Fig. 1c). Thus, an increase in the silver ion content in the Na-CMC films leads to a relatively narrow size distribution of the spherical and rod shaped silver nanoparticles formed during photoirradiation.

Diagnostics are important for a broad range of fields including infectious disease, health, food safety, and many other applications. These can provide a yes/no answer on the food we are about to eat is contaminated, or whether we are infected with a virus vs. a bacteria. Paper tests in the same format as pregnancy test possess many ideal characteristics, in that they are low cost, can be mass produced, and operated point of care by non-experts.¹ We discuss how different diagnostics work and their respective advantages and disadvantages. In particular, nanotechnology has enabled many innovations in point of care tests. The unique size and material dependent properties of nanoparticles can enhance sensitivity, enable multiplexing, and impart new capabilities to diagnostics. We will discuss some of these innovations that we have been developing in the lab for infectious disease and also the relevance of diagnostics for the ongoing COVID-19 outbreak

A method called the Heterodyne Resonance Mechanism (HRM)   predicted in BSM-SG unified theory [1] is studied in neutral plasma. It permits a deeper understanding of the Rydberg state of the atoms, regarded as ion-electron pairs and the Rydberg matter as clusters of such pairs. They exhibit specific oscillations that have a detectable magnetic field and a measurable spectral signature in the MHz frequency range. A properly activated neutral plasma generates a well-defined spectral signature of the HRM effect with identified spectral bands and high signal to noise ratio. The HRM spectra are completely different from the atomic, molecular, and ionic spectra [2]. The analysis based on the BSM-SG models leads to the conclusion that the electrons in the clusters of ion-electron pairs interact with the physical vacuum via the anomalous magnetic moment and spin the flipping of the electron. This takes place in a short transient process. Investigating the observations from natural lightning phenomena it is found that a similar process takes place in them and especially in the thunderstorms between clouds and ground. The conclusion is that the enormous energy released in the thunderstorm is from a similar transient process but in a large volume. [3,4]. Based on this conclusion a laboratory experiment was built permitting simulating a mini-lightning with a possibility for estimating the input and output energy. A study of the effect with noble gases in closed volume leads to the conclusion for existence of a process of plasma expansion that is not explainable by classical thermodynamics.

The present study describes two small organic compounds PTC1 and NG1, their self-assembling characteristics and its effect on their photophysical properties  PTC1 is a pyridothiazole based small organic compound which revealed aggregation induced emission properties as assessed by fluorescence and AFM studies. AFM study at supramolecular level shows when the aggregation of PTC1 is more fluorescence is also enhanced, while  the addition of Cu²⁺ ion causes disruption of self-assemblies leading  to  Fluoresecne quenching. Particularly, after the addition of amyloid fibre the fluorescence regeneration was observed which is accompanied by reaggregation. Hence, application of PTC1 in monitoring the amyloid fibrillation was assessed. The second molecules NG1 is acyl thiourea conjugate which assembles to fibrillar structures, Addidtion of Cu²⁺to NG1 solution also leads to disruption of iys fibrillar aggregates. However, in case of NG1 it was accompanied by a color change from colorless to yellow and fluorescence enhancement in blue region. Strikingly, addition of lactic acid regenerates the assembly and also change yellow color solution to colorless. Hence, NG1 was used for the sequential and cellular detection of Cu²⁺ ions and lactic acid. Notably, both.PTC1 and NG1 also exhibit panchromatic emission properties and reveal fluorescence under blue, green, and red filter. The studies pertaing to their panchromatic behavior and its application in cellular imaging is being currently pursued

Weak graphene plasmon is a major challenge for graphene based metasurfaces in the visible and near-infrared regions. This challenge emanates due to weak coupling between the graphene plasmons and the shorter wavelengths. This work shows numerical and theoretical designs of a hybrid metasurface that can enhance coupling between incident near-infrared light, and induce birefringence in the structure. Additionally, tunable birefringence performance, exhibiting wave-plate function are demonstrated. The metasurface comprises of graphene, silver metal, and a glass substrate. The metal rods are integrated to act as resonant dipole antennas that convert the incident light into localized surface plasmons (LSP). Launching of propagating surface plasmon over the graphene surface is initiated by the LSP. Birefringence tuning is obtained through variation of the number of layers of graphene, the Fermi energy of graphene and the physical dimensions of the metasurface. The design achieves a very high polarization conversion ratio (0.95) transforming the state of incident light from a linear state to a circular state, with a near unity value of ellipticity at a wavelength of 1500 nm. The thickness of the structure is about 0.5 λ which is ultrathin and suitable for integration into photonic sensing devices