The modern global trend toward sustainable processes that meet the requirements of “green chemistry” provides new opportunities for the broad application of highly active, selective, and specific enzymatic reactions. However, the effective application of enzymes in industrial processes requires the development of systems for the remote regulation of their activity triggered by external physical stimuli, one of which is a low-frequency magnetic field (LFMF). Magnetic nanoparticles (MNPs) transform the energy of an LFMF into mechanical forces and deformations applied to enzyme molecules on the surfaces of MNPs. Here, we demonstrate the up- and down-regulation of two biotechnologically important enzymes, yeast alcohol dehydrogenase (YADH) and soybean formate dehydrogenase (FDH), in aggregates with gold-covered magnetic nanoparticles (GCMNPs) triggered by an LFMF. Two types of aggregates, “dimeric” (with the enzyme attached to several GCMNPs simultaneously), with YADH or FDH, and “monomeric” (the enzyme attached to only one GCMNP), with FDH, were synthesized. Depending on the aggregate type (“dimeric” or “monomeric”), LFMF treatment led to a decrease (down-regulation) or an increase (up-regulation) in enzyme activity. For “dimeric” aggregates, we observed 67 ± 9% and 47 ± 7% decreases in enzyme activity under LFMF exposure for YADH and FDH, respectively. Moreover, in the case of YADH, varying the enzyme or the cross-linking agent concentration led to different magnitudes of the LFMF effect, which was more significant at lower enzyme and higher cross-linking agent concentrations. Different responses to LFMF exposure depending on cofactor presence were also demonstrated. This effect might result from a varying cofactor binding efficiency to enzymes. For the “monomeric” aggregates with FDH, the LFMF treatment caused a significant increase in enzyme activity; the magnitude of this effect depended on the cofactor type: we observed up to 40% enzyme up-regulation in the case of NADP+, while almost no effect was observed in the case of NAD+.

Abstract Magnetic graphitized materials were synthesized in the temperature range T = 600–1000° With the method of single-stage pyrolysis of microcrystalline flax cellulose (MCC) modified with citric acid and homogeneously impregnated with FeCl3. The modification of the MCC with citric acid and the use of FeCl3 as a graphitization catalyst reduces the graphitization temperature from 800 to 600 °C and increases the degree of graphitization to 95%. Morphological and physicochemical properties of carbon composites were studied by scanning electron microscopy, infrared spectroscopy with Fourier transform, low-temperature adsorption-desorption of N2, X-ray diffraction analysis and zeta potential. A possible mechanism of pyrolysis of the cellulose matrix has been established by thermogravimetry. The carbon composite obtained at 700 °C has the highest adsorption capacity of the dyes methylene blue (МВ) and methyl orange (МО) was 127.4 mg/g and 23.7 mg/g, respectively. MO molecules have a monolayer character of the adsorbent surface coating, and for MВ, the character of the adsorbent surface coating depends on the pyrolysis temperature. It is established that the physical adsorption of dyes is due to the interaction between delocalized graphite π-electrons and free electrons in the aromatic rings of dye molecules, electrostatic and adsorption interactions. The resulting composites may be potential candidates as dye adsorbents for wastewater treatment.

Aim: To develop an optimized approach for encapsulating a 2-alkylthioimidazolone-based copper coordination compound within liposomes, which could offer treatment of cancer and bacterial infections by reactive oxygen species generation toxicity mechanisms. Materials & methods: For drug-loaded liposome preparation, lipids and drug mixture in organic solvents was injected into copper salt solution, forming a coordination compound simultaneously embedded in the lipid bilayer. In vitro tests were performed on MCF7 and MDA-MB-231 breast cancer cells. Results: Liposomes had a loading capacity of up to 1.75% (molar drug-to-lipid ratio). In vitro tests showed increased viability and accumulation of the liposomal formulation compared with free drug as well as lack of cytotoxicity in hepatocytes. Conclusion: This optimized technique for encapsulating large copper complexes in liposomes could be used to improve their delivery and better treat cancer and bacterial infections. This work introduces a new technique for copper-containing drugs encapsulation in a drug-delivery system. The drug, a promising copper compound, is embedded in lipid nanovesicles - tiny fat particles - for intravenous injection. In addition to chemical characterization of the obtained drug form, tests on cancer cells showed a noticeable effect, whereas healthy cell types were not harmed. Copper possesses not only anticancer effects but also antimicrobial properties, which are also shown by the drug form, and a test of combined suppression of cancer cell lines and bacteria was successful. Hence, the obtained drug form has the potential for dual treatment of cancer and bacterial infections.

Differential scanning calorimetry (DSC) was used to determine the thermodynamic parameters of intranuclear chromatin decondensation induced in rat liver nuclei by decreasing the concentration of magnesium ions from 5 to 0 mM. Core histones, relaxed DNA, and topologically constrained DNA were shown to be involved consecutively in chromatin melting in a temperature range of 70–100°C. Both Tm and ΔH of individual peaks proved also to depend on the Mg2+ concentration in the buffer. In nuclei with condensed chromatin, Mg2+ ions used at 5 mM significantly increased Tm of core histones (by 7°C) as compared with their Tm in unfolded chromatin, but decreased Tm of both relaxed and constrained nuclear DNA (by 2.5 and 7.5°С, respectively). The melting enthalpy of the peaks significantly increased in the presence of Mg2+. A decrease in the molecular weight of intranuclear DNA abolished the stabilizing effect of Mg2+ on core histones. A new peak with Tm above 100°С became detectable when the Mg2+ concentration exceeded 5 mM, possibly reflecting the thermal behavior of some Mg-induced aggregates. Possible mechanisms underlying the thermal behavior of chromatin within the nucleus are discussed.

We have studied the preparation of magnetic graphitic carbon composites, which combine the adsorption properties of activated carbon with magnetic properties and properties intrinsic to graphite. The preparation method is efficient; it comprises modifying flax shive cellulose with citric acid to enhance the chelating ability of the flax shive cellulose matrix, impregnating the modified cellulose with iron chloride, and pyrolysis in an inert atmosphere to control the composition, morphology, specific surface, and porosity of hybrid carbon materials. The scenario of cellulose matrix pyrolysis was suggested using thermogravimetry. X-ray structural analysis was used to characterize the graphitic composites. The citric acid modification of cellulose helps to prepare a high-graphite (74%) carbon composite where the graphitization level of the graphite structure approaches the graphitization level of commercially available graphite at 700°С. Low-temperature N 2 adsorption–desorption and ζ-potential measurements helped to suggest the adsorption mechanism for environmentally hazardous dyes. The greatest equilibrium adsorption of Methylene Blue (MB) and Methyl Orange (MO) dyes was 127.4 and 23.7 mg/g, respectively. The prepared composites can be used as adsorbents and fillers in polymer composite materials.

We have studied the preparation of magnetic graphitic carbon composites, which combine the adsorption properties of activated carbon with magnetic properties and properties intrinsic to graphite. The preparation method is efficient; it comprises modifying flax shive cellulose with citric acid to enhance the chelating ability of the flax shive cellulose matrix, impregnating the modified cellulose with iron chloride, and pyrolysis in an inert atmosphere to control the composition, morphology, specific surface, and porosity of hybrid carbon materials. The scenario of cellulose matrix pyrolysis was suggested using thermogravimetry. X-ray structural analysis was used to characterize the graphitic composites. The citric acid modification of cellulose helps to prepare a high-graphite (74%) carbon composite where the graphitization level of the graphite structure approaches the graphitization level of commercially available graphite at 700°С. Low-temperature N2 adsorption–desorption and ζ-potential measurements helped to suggest the adsorption mechanism for environmentally hazardous dyes. The greatest equilibrium adsorption of Methylene Blue (MB) and Methyl Orange (MO) dyes was 127.4 and 23.7 mg/g, respectively. The prepared composites can be used as adsorbents and fillers in polymer composite materials.

The spreading of microbial pathogens with more and more resistance to traditional low-molecular antibiotic agents demands new approaches to antibacterial therapy. The employment of bacteriophage enzymes capable of breaking bacterial cell walls has attracted much interest within this context. The specific features of the morphology of Gram-negative bacteria prevent the effective direct usage of lytic enzymes and require assistance from additional helpers to facilitate cell lysis. The current work is devoted to the study of boosting the lysis of Escherichia coli (E. coli) JM 109 and MH 1 strains induced by Lys394 bacteriophage endolysin by means of rod-like (56 × 13 nm) magnetic nanoparticles (MNPs) activated by a non-heating low-frequency magnetic field (LF MF) with a frequency of 50 Hz and a flux density of 68.5 mT in a pulse–pause mode (1 s on and 0.3 s off). According to theoretical assumptions, the mechanism of MNP assistance is presumably based upon the disordering of the outer membrane that facilitates enzyme permeation into peptidoglycans to its substrate. It is found that the effect of the LF MF reaches an almost a twofold acceleration of the enzyme reaction, resulting in almost 80 and 70%, respectively, of lysed E. coli JM 109 and MH 1 cells in 21 min. An increase in the membrane permeability was proven by two independent experiments employing β-lactamase periplasmic enzyme leakage and Nile Red (NR) hydrophobic dye fluorescence. It is shown that the outer membrane disordering of E. coli caused by exposure to LF MF nanoparticle movement leads to almost complete (more than 80%) β-lactamase release out of the cells’ periplasm to the buffer suspension. Experiments with NR (displaying fluorescence in a non-polar medium only) reveal a drastic reduction in NR fluorescence intensity, reaching a change of an order of magnitude when exposed to LF MF. The data obtained provide evidence of changes in the bacterial cell wall structure. The result shown open up the prospects of non-heating LF MF application in enhancing enzyme activity against Gram-negative pathogens.

Abstract Magnetic composites were synthesized in an inert medium within the temperature range T = 500–1000 °C by one-stage pyrolysis of microcrystalline flax shive cellulose modified by citric acid (MCCA) and homogeneously impregnated with Fe(NO3)3. Catalytic graphitization was studied by the thermogravimetric analysis method. The crystal structure, pore development, morphological structure and surface chemistry of carbon composites were characterized by the N2 adsorption-desorption, XRD, SEM and FTIR methods. The onset temperature of MCCA graphitization was found to be equal to 600 °C. The magnetic carbon materials were tested as adsorbents for removal of anionic methyl orange (MO) and cationic methylene blue (MB) dyes. The highest equilibrium adsorption capacity in MB and MO was found in the magnetic composites synthesized at 700 and 800 °C.

Magnetic composites were synthesized in a nitrogen medium by one-stage pyrolysis of microcrystalline flax shive cellulose modified with citric acid and homogeneously impregnated with Fe(NO 3 ) 3 . The mechanism of the catalytic graphitization was studied by thermogravimetric analysis. The morphological structure, pore size distribution, and surface chemistry of the carbon composites were analyzed by nitrogen adsorption–desorption, X-ray powder diffraction analysis, and scanning electron microscopy. The adsorption capacity of the obtained materials was determined with respect to the anionic dye methyl orange and the cationic dye methylene blue.

Enzymes conjugated to magnetic nanoparticles (MNPs) undergo changes in the catalytic activity of the nonheating low-frequency magnetic field (LFMF). We apply in silico simulations by molecular dynamics (MD) and in vitro spectroscopic analysis of the enzyme kinetics and secondary structure to study alpha-chymotrypsin (CT) conjugated to gold-coated iron oxide MNPs. The latter are functionalized by either carboxylic or amino group moieties to vary the points of enzyme attachment. The MD simulation suggests that application of the stretching force to the CT globule by its amino or carboxylic groups causes shrinkage of the substrate-binding site but little if any changes in the catalytic triad. Consistent with this, in CT conjugated to MNPs by either amino or carboxylic groups, LFMF alters the Michaelis-Menten constant but not the apparent catalytic constant kcat (= Vmax/[E]o). Irrespective of the point of conjugation to MNPs, the CT secondary structure was affected with nearly complete loss of alpha-helices and increase in the random structures in LFMF, as shown by attenuated total reflection Fourier transformed infrared spectroscopy. Both the catalytic activity and the protein structure of MNPCT conjugates restored 3 h after the field exposure. We believe that such remotely actuated systems can find applications in advanced manufacturing, nanomedicine, and other areas.

The application of carbon as an adsorbent is a well-known method of removal of chemical pollutants, including dyes, from waste waters. However, a lot of attention is now being paid to improving the adsorbent efficiency and searching for cheap precursors for activated carbon (AC) production. In this work, AC is obtained from flax shive by its physical and chemical activation with KOH. The pyrolysis process and mechanism of KOH activation are studied using thermogravimetric analysis. The methods of X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and low-temperature nitrogen adsorption are used to determine the AC characteristics. The AC ability to adsorb the methylene blue (MB) dye is studied. The effect of the properties of the synthesized AC on the MB equilibrium adsorption capacity is analyzed. The maximum BET surface area of the AC is equal to 1832.2 m2/g, which means its values lie in the range typical of industrial activated carbons. The maximum equilibrium adsorption capacity of MB is 464.2 mg/g. The AC adsorption capacity depends on the cellulose content in the flax shive and pore size distribution over the carbon matrix. The use of lignocellulosic biomass, namely flax shive, in the AC production is associated with solving environmental problems, such as agricultural waste recycling and disposal.

The thermogravimetric method was used to study one-stage pyrolysis of finely ground flax shive chemically activated by NH4NO3 (AN) and NH4Cl (NAC). Activated carbons (AC) were obtained and the chemical activation mechanism was determined. The morphology, surface area and pore size distribution of the AC samples were studied by the methods of scanning electron microscopy, low-temperature nitrogen adsorption, energy-dispersive X-ray spectroscopy and X-ray diffraction. The maximum methylene blue adsorption capacity of the obtained AC samples was determined. The optimal parameters of activated flax shive pyrolysis (temperature, time) required for obtaining AC with the maximum specific surface area and adsorption capacity were identified.

Concern on dyes-laden effluent has intensified over the years. Dyes are toxic, stable to light hardly bio-degraded and cause irreparable harm to living organisms. Adsorption is widely recognized as an effective way to remove colorants from wastewater. Nevertheless, the search for improving the efficiency of adsorption is constantly being carried out with the help of new cheap activated carbon (AC). For adsorption studies, we used activated carbon obtained by pyrolysis of flax shive activated with K2CO3. Using X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, IR spectroscopy, low-temperature nitrogen adsorption, thermogravimetry, the characteristics of the AC were obtained. The effect of AC characteristics on the equilibrium adsorption capacity of methylene blue (MB) was studied. The maximum BET surface area of the AC equals 1246.1 and 1468.0 m2/g, which means its values are in the range typical of commercial activated carbons. The maximum equilibrium capacity of the obtained AC samples to adsorb the MB dye is 319.1 and 388.5 mg/g. The capacity for the activated carbons depended on the pyrolysis temperature, and cellulose content in flax shive and pore size distribution in carbon matrix. Converting lignocellulosic biomass into activated carbon could solve environmental problems such as agricultural waste and water pollutions control.

The structure of tobacco mosaic virus (TMV) virions and stacked disk aggregates of TMV coat protein (CP) in solution was analyzed by synchrotron-based small-angle X-ray scattering (SAXS) and negative contrast transmission electron microscopy (TEM). TMV CP aggregates had a unique stability but did not have helical symmetry. According to the TEM data, they were stacked disks associated into transversely striated rod-shaped structures 300 to 800 Å long. According to modeling based on the crystallographic model of the 4-layer TMV CP aggregate (PDB: 1EI7), the stacked disks represented hollow cylinders. The calculated SAXS pattern for the disks was compared to the experimental one over the entire measured range. The best correlation with the SAXS data was found for the model with the repeating central pair of discs; the SAXS curves for the stacked disks were virtually identical irrespectively of the protein isolation method. The positions of maxima on the scatter curves could be used as characteristic features of the studied samples; some of the peaks were assigned to the existing elements of the quaternary structure (periodicity of aggregate structure, virion helix pitch). Low-resolution structural data for the repolymerized TMV CP aggregates in solution under conditions similar to natural were produced for the first time. Analysis of such nano-size objects is essential for their application in biomedicine and biotechnology.

Magnetite-gold hybrid magnetic nanoparticles of the dumbbell type were used to immobilize two proteins: α-chymotrypsin and the Bowman–Birk inhibitor. It is shown that under the influence of a low-frequency magnetic field (50 Hz), the activity of chymotrypsin bound in a complex with an inhibitor is drastically reduced depending on the magnetic field induction. We hypothesize that this effect is related to the aggregation of magnetic nanoparticles under the influence of a magnetic field.

Magnetic anionic liposomes (MALip) conjugated with magnetite magnetic nanoparticles (MNPs) are developed for the controlled release of a protease inhibitor (BBI) under exposure to a low-frequency nonheating magnetic field (LF AMF). It is shown that an increase of up to 35% of the protein release rate occurred when the MALip are exposed to the LF AMF (frequency 110 Hz, intensity 75–150 kA/m) for 5–15 min. The research provides prospects for the development of remotely controlled protein release from liposomes.

X-ray diffraction analysis was used to study the structural transformations of fibrous and microcrystalline flax, hemp, and jute cellulose, processed in aqueous-organic media containing sodium hydroxide. The thermal degradation of the initial and chemically modified cellulose was studied by thermogravimetry. The carbonization of cellulose in an inert atmosphere gave carbon materials. Common and specific features in the morphology and structure of the products were identified.