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Humic substances (HS) are the most abundant forms of natural organic matter on the earth surface. Comprised of decomposed plant and animal materials rich in carbon, oxygen, hydrogen, nitrogen, and sulfur complexes, HS facilitate global carbon and nitrogen cycling and the transport of anthropogenic contaminants. While it is known that HS also interact with organisms at different trophic levels to produce beneficial and harmful effects whether HS exert these biological effects through accumulation remains unknown. Current radiolabeling techniques, which only detect the amount of accumulated radiolabels, cannot visualize the transport and accumulation behavior of HS. Here, using a label-free method based on pump-probe microscopy, we show HS entered the protozoan

Lysozyme adsorption complexes with graphene oxide (GO) and reduced GO were studied by means of radiotracer method using tritium as a label. The experiment includes adsorption study, with amount and...

The tightly bonded shielding coating on biomatrix significantly enhances the functionality of medical devices, bioprostheses in particular. In our work we have obtained a polyelectrolyte coating on a biomatrix by sequentially depositing chitosan and hyaluronic acid (HA) from solutions in carbonic acid under pressure. This approach makes it possible to obtain hybrid biomatrix with a firmly bonded polymer screen due to the electrostatic bonding of polyions. High-precision analysis using a tritium label shows a 3-fold increase in quantity of HA in carbonic acid under pressure compared to the conventional method. The presence of the chitosan layer increases the HA adsorption by 15-20 % due to electrostatic interaction of differently charged polymers. Antimicrobial results show the possibility of implementing an induced antimicrobial response, due to the lysis of the upper layer of the coating (HA) and the release of antimicrobial agents in the case of growth of pathogens on the bioprosthesis.

As the production of engineered nanomaterials (ENMs) expands, so might the potential for their release into the environment. Accurate risk assessment of ENMs in the environment is important for sustainable development and application of nanotechnologies. Nanodiamonds (NDs) occupy a special niche among ENMs and are ENMs at high risk of entering the environment. We evaluated interactions between NDs and a broad range of soils (retisols, phaeozems, chernozems, kastanozems, and solonetz) using tritium-labeled nanoparticles. The retention of NDs by the soils due to both binding to the solid phase of the soil and aggregation in the presence of soil solutes varied from 9.6 to 87.1 mg kg−1. Additionally, the effect of soil water-extractable components on NDs was studied in terms of alleviation of their size and ζ-potential. An increase in hydrodynamic diameter and a decrease in absolute value of the ζ-potential were observed in all cases except for solonetz where ζ-potential decreased from −22 to −34 mV. Data on deposition of NDs and their colloidal characteristics in the presence of soil solutes were statistically analyzed, which revealed leading factors governing retention of NDs by soil – ζ-potential of NDs in soil water-extracts and the presence of water-extractable Fe and Si. An abnormally low retention of NDs in solonetz was discovered and we hypothesize a key role of sodium as a peptizing agent.

The influence of hydrogen on the structure of thin cerium films formed by the method of magnetron sputter deposition was investigated in this work. Hydrogen-charging of the films was carried out by the method of Langmuir hydrogen dissociation on a tungsten substrate. The cerium hydride films were coated with a protective layer of nickel or chromium. It is demonstrated in this work that the used method of hydrogen charging can be used for introduction of hydrogen also into other hydride-forming metals and alloys.

The influence of nonionic surfactants on the bacteriolytic activity of lysozyme is studied on the model cells of Micrococcus luteus using Pluronics P123, L121, and F127, as well as Brij-35. These compounds form complexes with lysozyme through hydrogen-bonding interactions between the ethylene oxide fragments of surfactant and the amino acids residues of lysozyme surface. The bacteriolytic activity of lysozyme decreases in the order of F127 < P123 < L121 ≈ Brij-35, probably because of the steric hindrances of the protein’s interaction with the cells’ substrate.

A study of ion-molecular reactions of fluoro-substituted phenyl cations with benzopyridine derivatives demonstrated the following: (a) at present only the nuclear-chemical method enables the reaction of a direct phenylation of the nitrogen atom in benzopyridine derivatives, which makes it possible to obtain previously unknown quaternized structures, and (b) generation of nucleogenic phenyl cations with various substituents leads to a simultaneous introduction of the required substituents into the aromatic ring at the nitrogen heteroatom. Quantum-chemical calculations additionally confirmed the assumption about the pathways of the ion-molecular reactions with nucleogenic phenyl cations.

Chitosan adsorption complexes were obtained with nanodiamonds possess negative as well as positive zeta-potential in the aqueous suspensions. The application of tritium labeled chitosan all...

Nanodiamond-chitosan composites of definite composition were prepared to modify heart valve biological prostheses materials. The final material is characterized by higher failure stress and...

Graphene oxide was reduced by aspartic acid, β-mercaptoethanol in the acidic mixture, hydrothermal method and by atomic hydrogen (deuterium and tritium). Raman spectroscopy and FTIR indicat...

Quinazoline derivatives are well known to have a diverse array of therapeutic activities. Unfortunately, “classic” chemical synthesis does not provide an opportunity for the formation of N-phenyl quaternary 1,3-diazinium compounds. A devised nuclear-chemical method of synthesis based on chemical effects of nuclear transformations enables a new way of the direct nitrogen atom phenylation by the nucleogenic (generated by tritium β-decay) phenyl cations in 1,3-diazines, furnishing, based on our prediction, formation of previously unknown derivatives with N-phenyl quaternary quinazolinium scaffold.

Given the unique properties of nanodiamonds, such as biocompatibility, low cytotoxicity and high adsorption capacity, this material is considered to have potential in drug delivery platforms. In this study, we tested nanodiamonds with different surface properties in relation to quaternary ammonium surfactant (Myramistin). For all tested materials that possess positive and negative zeta potential adsorption of surfactants on the surface of nanodiamonds, aggregates in the aqueous suspension are described by the Langmuir adsorption equation.

The efficiency of tritium labeling of salts of pantothenic (HO–R–COOH), hopantenic (HO–R–CH2–COOH), and 4-D-phosphopantothenic [(HO)2P(=O)–O–R–COOH] acids [R = CH2C(CH3)2CHOH–CONH(CH2)2] with thermal activation of tritium at target temperatures of 77 and 295 K was studied. The phosphate group inhibits the isotope exchange. The tritium-labeled compounds were used for studying the adsorption of pantothenic acid derivatives from aqueous solutions and in the presence of 0.9% NaCl at 297 ± 3 K onto nanodiamonds prepared by detonation synthesis (NDs). Preparation of stable ND suspensions in advance enhances the ability of NDs to adsorb the compounds studied. The parameters of the equation describing the sorption isotherms at different ionic strengths of the solution were calculated. The strength of the adsorbate retention in contact with water, 0.9% NaCl solution, 0.01 M HCl solution, and 40 g L−1 bovine serum albumin (BSA) solution was determined. The data obtained allow two mechanisms of the adsorbate retention on the ND surface to be considered: reversible adsorption due to ionic interactions and irreversible binding due to hydrophobic interactions. The strongly bound molecules undergo slow desorption in the presence of BSA. The revealed trends confirm high potential of NDs as a drug delivery platform.

The paper studies the combined effects of beta-emitting radionuclide tritium and Humic Substances (HS) on the marine unicellular microorganism—luminous bacteria—under conditions of low-dose radiation exposures (&lt, 0.04 Gy). Tritium was used as a component of tritiated water. Bacterial luminescence intensity was considered as a tested physiological parameter. The bioluminescence response of the marine bacteria to tritium corresponded to the “hormesis” model: it included stages of bioluminescence inhibition and activation, as well as the absence of the effect. HS were shown to decrease the inhibition and activation effects of tritium, similar to those of americium-241, alpha-emitting radionuclide, studied earlier. Correlations between the bioluminescence intensity and the content of Reactive Oxygen Species (ROS) were found in the radioactive bacterial suspensions. The results demonstrate an important role of HS in natural processes in the regions of low radioactive contamination: HS can mitigate radiotoxic effects and adaptive response of microorganisms to low-dose radioactive exposures. The involvement of ROS in these processes was demonstrated.

Many natural substances exhibit anti-inflammatory activity and considerable potential in prophylaxis and treatment of allergies. Knowing exact molecular targets, which is required for developing these as medicinal products, is often challenging for multicomponent compositions. In the present study we examined novel polyphenolic substance, a water-soluble fraction of wood lignin (laboratory code BP-Cx-1). In our previous study, a number of polyphenolic components of BP-Cx-1 (flavonoids, sapogenins, phenanthrenes etc.) were identified as the major carriers of biological activity of BP-Cx drug family, and several molecular targets involved in cancer and/or inflammation signaling pathways were proposed based on the results of the in vitro and in silico screening studies. In the present study, half maximal inhibitory concentration (IC50) of BP-Cx-1 was established with a radioligand method and a range of IC50 values between 22.8 and 40.3 μg/ml were obtained for adenosine receptors A1, A2A and prostaglandin receptors EP2, IP (PGI2). IC50 for serotonin 5-HT1 and for glucocorticoid GR receptors were 3.0 μg/ml and 12.6 μg/ml, respectively, both being within the range of BP-Cx-1 concentrations achievable in in vivo models. Further, distribution of [3H] labelled BP-Cx-1 in NIH3T3 murine fibroblasts and MCF7/R carcinoma cells was studied with autoradiography. [3H]-BP-Cx-1 (visualized as silver grains produced by tritium beta particles) was mainly localized along the cell membrane, in the perinuclear region and in the nucleus, suggesting ability of BP-Cx-1 to enter cells and bind to membrane or cytosol receptors. In our experiment, we observed the effect of BP-Cx-1 on maturation of dendritic cells (DCs): downregulation of expression of the lipid-presentation molecule CD1a, co-stimulatory molecules CD80, CD83 and CD 40, decreased production of pro-inflammatory cytokines IL-4 and TNF-α and increased production of anti-inflammatory cytokine IL-10. It is hypothesized that [3H]-BP-Cx-1 detectable in the nucleus is part of the activated GR complex, known to be involved in regulation of transcription of genes responsible for the anti-inflammatory response. Based on IC50, cell distribution data and results of the experiment with DCs it is suggested that the in vivo effects of BP-Cx-1 are mediated via GR and 5-HT1 receptors thus promoting development of tolerogenic effector function in dendritic cells.

Surface concentration of oxidized nanodiamonds (NDs) and NDs modified with oleylamine in NDs–poly(vinyl alcohol) composite films has been determined by autoradiography using tritium-labeled NDs. It has been demonstrated that oxidized NDs are distributed uniformly in the composite films, and their surface concentration is the same at both sides of the film. After modification with oleylamine, ND concentration at the bottom side of the film exceeds that at the top side approximately tenfold. Zisman critical surface tension of the composite films as well as polar and non-polar contributions to the surface tension has been found. It has been shown that surface tension is determined by the polymer, and the addition of NDs does not affect its value.

Isotope exchange between dalargine applied onto various supports [glass, activated carbon, few-layer graphite (FLG)] and molecular tritium, performed with activation on a tungsten wire and on 5% Pd/C, 10% Pd/C, and 5% Pt/FLG catalysts was studied. Depending on the experiment conditions, the molar radioactivity of [3H]dalargine varied from 0.47 to 31 Ci mmol−1 with activation on a tungsten wire and from 0.63 to 5.5 Ci mmol−1 under the conditions of heating to 335 K in the presence of noble metal catalysts. Significant difference in the tritium distribution between amino acid residues of the peptide depending on the support and on the activation method is observed. Reactions of tritium atoms generated on tungsten led to the tritium incorporation mainly into aliphatic acid residues upon application of the peptide onto glass and into aromatic residues upon application onto activated carbon. The use of FLG as a support influenced the tritium redistribution between aliphatic and aromatic residues to a lesser extent. Upon tritium activation on 5% Pd/C, 10% Pd/C, and 5% Pt/FLD, tritium was mainly incorporated into aromatic residues, which is typical of electrophilic reactions. The study revealed strong effect of the support on the mechanism of the isotope exchange of hydrogen for tritium in dalargine. The intramolecular distribution of tritium in preparation of labeled compounds using thermal activation can be controlled by properly choosing a support onto which the substrate is applied.

Nanodiamonds produced by the detonation method are used as lubricants, polishing compositions, polymer composites, etc. To reveal how nanodiamonds differ in terms of surface properties and interact with natural organic matter, we used tritium-labelled humic substances to quantitively describe their adsorption onto the nanodiamond surface. It was shown that the adsorption of humic substances onto nanodiamonds resulted in fractionation of humic substances that was strongly dependent on the zeta potential of nanodiamonds in water but did not significantly affect the uptake of nanodiamonds by wheat seedlings. The uptake of nanodiamond particles by plants was determined by the functional composition of the particle surface.

For the first time the influence of pressure of chitosan solutions in carbonic acid on the adsorption of chitosan onto a collagen tissue of biological heart-valve prostheses and on the structure of the resulting biocomposite was studied. It turned out that the dependence of an amount of the chitosan adsorbed onto the collagen tissue has bell-shaped form reaching a maximum adsorption of about 0.8 weight. % at 30-40 MPa and then falling to 0.3 wt. % with further pressure increase up to 50 MPa. It was found that this treatment leads to a significant change of the morphology of the tissue surface which depends on the pressure in the system. It was also revealed that under pressure growth collagen fibrils are compacted in the tissue bulk which leads to the extrusion of the polymer embedded in the collagen matrix.

A radiotracer technique with tritium-labeled nanodiamonds (NDs) has been used to study the distribution of NDs in water/octane system. The surface of NDs has been modified by heat treatment (oxidation) in air and functionalization using oleylamine (OLA) as surfactant. It has been shown that oxidized NDs are concentrated in the aqueous phase, the distribution ratio (D = CO/CW) being 0.016 (CO and CW are the concentrations of the NDs in octane and water, respectively). The addition of OLA to the NDs hydrosol/octane system leads to increase in the distribution ratio and the concentration of NDs near the water/octane interface by a factor of three. The dispersion of NDs directly in a solution of OLA in octane followed by addition of water leads to more pronounced increase in the distribution ratio (by two orders of magnitude), and the major fraction of the nanoparticles (about 70%) is concentrated near the water/octane interface. Adsorption isotherm of OLA on NDs has been obtained; it has been found that the adsorption is irreversible due to the formation of ion pairs between surface carboxylic groups of NDs and amino groups of OLA. The nanoparticles and their dispersions have been investigated by Fourier transform infrared spectroscopy, dynamic light scattering, Boehm titration, interfacial tensiometry, optical microscopy, ζ-potential and pH measurements.

The task of protection of cultural heritage requires a better understanding of combined effects of mechanical and chemical factors involved in environmental deterioration of monuments. The present paper deals with extending some known physicochemical methods proposed for inhibiting the decay of unstressed materials to their study during water-assisted deformation. The tests have been carried out on natural limestone samples and calcite powders in CaCO3 saturated aqueous solutions under static loads causing measurable pressure solution creep. In the solutions containing 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilotriacetic acid, or ethylenediaminetetraacetic acid, the creep rate decreases considerably with increasing concentration of additives. The extent of creep deceleration has been found to be proportional to the independently estimated calcite surface area occupied by adsorbed species. This fact enables us to discriminate the adsorption-induced effect from other variables controlling the pressure solution rate and may be used in screening of compounds able to minimize the environmental impact on marble and limestone objects undergoing mechanical stresses.

The effect of the chemical nature of the surface of detonation nanodiamond on the adsorption of an antibiotic is revealed with the help of tritium-labeled amikacin. It is found that nanodiamonds with a carboxylated surface (Ssp = 283 ± 5 m2/g) chemisorbed twice as much amikacin as nanodiamonds with a hydrogenated surface (Ssp = 289 ± 5 m2/g): 48 and 22 mg/g, respectively. Maintaining nanodiamonds with immobilized amikacin in the form of hydrosol for 1 month results in a release of up to 9.6 and 6.4 mg/g of the antibiotic, respectively. The results demonstrate the possibility of creating an amikacin delivery system based on nanodiamonds.

The effect of a surface modification of the nanodiamonds on the mechanical and surface properties of composite films based on polyvinyl alcohol was investigated. Maximum Young’s modulus and tensile stress were obtained for composites with oxidized nanodiamonds. Hydrophobization of nanoparticles with adsorption layers of oleylamine results to a decrease in the strength of the films. Surface concentration of initial and modified nanodiamonds in the composite films was determined by autoradiography technique with the use of tritium-labeled nanodiamonds

Self-organization of proteins and non-ionic surfactants at the aqueous-air and aqueous-organic liquid interfaces is controlled by hydrophobic interactions. Unfortunately, little is quantitatively known about the effects of high- and low-molecular weight non-ionic surfactants on protein adsorption and aggregation at aqueous-air and aqueous-organic liquid interfaces. A tritium probe technique was applied to the systems lysozyme – Pluronic P123 and lysozyme – Brij-35. For complex analysis, UV and fluorescent spectrometry were also used for solutions with the chosen protein and surfactants concentrations. Non-ionic surfactants form a flexible complex with lysozyme at the aqueous-air interface. We observed that both Pluronic P123 and Brij-35 result in displacement of 40–75 % of protein, even in a surfactant concentration range less than the CMC and rotation of residual protein (or protein in complex with surfactant) in the mixed adsorption layer compared to the adsorption layer formed by free lysozyme. In the mixed adsorption layer, lysozyme globules are separated, and protein becomes more available for tritium atoms compared to free lysozyme.

Benzyldimethyl[3-[(1-oxotetradecyl)amino]propyl]ammonium chloride available as Miramistin is an effective antimicrobial agent, but its colloidal properties and interaction with proteins are not studied well. In present work we compared Miramistin with series of alkyltrimethylammonium bromides (DTAB, TTAB and CTAB) in the relationship to lysozyme. Complex analysis including coadsorption at the aqueous-air and aqueous-organic liquid interfaces, protein intrinsic fluorescence and enzymatic activity of lysozyme in the presence of surfactants was performed. By means of radiochemical and spectroscopic methods we have shown that cationic surfactants form complexes with lysozyme at the interfaces as well as in the bulk of the solution. Lysozyme and cationic surfactants replace each other in the adsorption layer. Miramistin binds to lysozyme surface as well as to its active site with high efficiency like surfactant with short hydrocarbon moiety (DTAB), nevertheless, it possesses low value of critical micelle concentration like CTAB. Quaternary ammonium surfactants increase enzymatic activity of lysozyme: Miramistin enhances the activity intensively then all alkyltrimethylammonium bromides. This result is explained by docking results indicated that in the case of Miramistin Asp52 residue does not form bond with the ligand unlike the cases with other alkyltrimethylammonium bromides.

The adsorption of lysozyme in the presence of high molecular weight (pluronic P123) and low molecular weight (Brij-35) non-ionic surfactants was studied at liquid-liquid and liquid-air interfaces. Using tritium-labeled compounds and liquid scintillation spectrometry of tritium, we investigated the competitive adsorption of lysozyme-pluronic P123 and lysozyme-Brij-35 at the aqueous-xylene interface. The substitution of protein by both polymer and low molecular weight surfactant was observed, while the presence of lysozyme does not influence the behavior of non-ionic molecules. We found that the ionic strength of the aqueous phase does not influence the strength of the effect, while it has a significant influence on the rate of diffusion and penetration of the adsorption layer by free protein. The thermodynamics of the competitive adsorption was described by the model suggested by Fainerman and co-authors, and the obtained parameters were used to describe the interfacial tension isotherms of the respective mixtures at the aqueous-air interface. Thus, the adsorption of each component of the mixture (protein and non-ionic surfactant) at the aqueous-air interface was revealed.

The self-organization of lysozyme with cationic (dodecyltrimethylammonium bromide) and anionic (sodium dodecylsufate) surfactants at an aqueous-air interface was studied by means of tritium planigraphy. It was found that even if the surfactant concentration is too low to induce significant structural changes in the protein globule, the surfactant can bind with the protein via both electrostatic and hydrophobic interactions and can displace the protein from the interface. Different mechanisms of complex formation are suggested for lysozyme mixed with SDS or DTAB. SDS molecules screen positively charged groups of amino acid residues via electrostatic interactions and form hydrogen bonds with polar groups of amino acid residues. SDS also penetrates the protein globule via hydrophobic interactions. In contrast, DTAB interacts with hydrophobic amino acid residues, screening them from tritium atoms. For both surfactants, it was found that lysozyme maintains a longways-on orientation in the mixed adsorption layer.

The kinetics and isotherm of lysozyme adsorption and the strength of lysozyme binding to two carbon materials, activated charcoal and carbon foil, were studied using tritium-labeled lysozyme. Polyethylene films were used as a model nonporous material. The lysozyme adsorption resulted in modification of the surface of the materials, making it more hydrophilic, and the rate at which the adsorption equilibrium was attained depended on the capability of the lysozyme solution to penetrate into pores of carbon materials. The specific coverage of the surface of graphite foil, activated carbon, and polyethylene with lysozyme appeared to be virtually equal when taking into account only pores accessible to the protein. The lysozyme adsorption on the polyethylene surface is reversible, whereas on the surface of activated charcoal and graphite foil it is practically irreversible. The possibility of modification of the carbon foil surface with a lysozyme solution to increase the adsorption zone was confirmed by autoradiography.

Films of poly-e-caproamide (PA), polyethylene (PE), and polyethylene terephthalate (PET) were used for detection of hydrogen spillover through the gas phase. The hydrogen used in the experiments contained tritium activated by two procedures (W wire, 2000 K; 5% Pd/C, 335 K). The radioactivity of the films was recorded by classical and digital autoradiography and by liquid scintillation counting. Under the action of “hot” atoms generated on a W wire, the maximal specific radioactivity of the films, equal to 420, 415, and 330 mCi cm–2 for PA, PE, and PET, respectively, was reached in 100 s. Preliminary thermalization of the atoms to a temperature of 77–335 K influenced the decrease in the film radioactivity differently. The effective activation energy of the reaction in the range 298–318 K was 21, 30, and 12.5 kJ mol–1 for PA. PE, and PET, respectively. Under the conditions of heating 5% Pd/C to 335 K for 25 min, the radioactivity of PA, PE, and PET was 1.6, 0.05, and 0.15 μCi cm–2, respectively. The revealed difference in the radioactivity of the films suggests different mechanisms of the interaction of tritium with organic molecules at different activation methods.

Lysozyme and Myramistin are able to associate when their molar ratio in solution reaches 1: 1. Lysozyme preserves its secondary structure in the complex, whose surface activity at the water–p-xylene interface represents a model for the drug interaction with cellular membrane.

Interaction between proteins and synthetic polymers that represent a perspective potential in drug delivery or/and already used in medicine plays a key role in biological functioning of both molecules along with a system as a whole. In present study association between hen egg white lysozyme and Pluronic triblock-copolymers (L121, P123 and F127) in the bulk of the solution as well as at the aqueous-air and liquid-liquid interfaces was analyzed by means of spectroscopic and radiochemical assay. In protein-Pluronic complexes lysozyme keeps the secondary structure (CD and SAXS data results), while fluorescence and UV-analysis indicates changes in the local surrounding of fluorophoric amino acid residues. Radiochemical assay in combination with molecular docking reveals the formation of the complexes, in which proline residues turned to the interface between water and hydrophobic medium.

Humic substances (HS) in the aqueous solutions can be considered as colloidal particles formed by amphiphilic units. HS form micelles-like structures at concentrations close to 5 g/L. However colloidal behavior of HS at concentrations below 100 mg/L is unknown. Using radiotracer assay we have shown that in this concentration range HS form rare adsorption layers at the liquid/liquid interface and penetrate into the organic phase with the distribution ratio close to 10−3. We found that pH and HS molecular weight strongly influence on the distribution ratio but do not significantly change the adsorption. Furthermore, colloidal properties of HS are strongly depending on its origin: the highest surface activity was shown for HS separated from peat and the least was observed for HS separated from soils. We anticipate our assay to be a helpful tool for detailed analysis and modeling HS and humic-like materials colloidal behavior in the environment.

An experimental study of protein-peptide binding was performed by means of radiochemical and spectroscopic methods. Lysozyme and dalargin were chosen due to their biological and physiological importance. By means of tensiometry and radiochemical assays, it was found that dalargin possesses rather high surface activity at the aqueous-air and aqueous-p-xylene interfaces to be substituted by protein. Dalargin forms a hydrophobic complex with lysozyme in which the secondary structure of lysozyme is preserved. When lysozyme forms a mixed adsorption layer with dalargin at the aqueous-air surface, the peptide prevents protein from concentrating in the subsurface monolayer. In the presence of p-xylene protein in the interface, reorganization occurs quickly, so there is no lag in the interfacial tension time dependence. The interfacial tension in this case is controlled by protein and/or protein-peptide complexes. An increase in the enzymatic activity of lysozyme in the presence of dalargin was confirmed by a docking model that suggests the formation of hydrogen bonds between dalargin and amino acid residues in the active site.

Formation of adsorption complex between hyaluronic acid and detonation nanodiamonds was studied. Nanodiamonds that possess negative and positive zeta-potential in an aqueous suspension were used. To determine the direct amount of hyaluronic acid on the nanodiamond surface tritium label was introduced into the polymer by means of tritium thermal activation method. It was found that hyaluronic acid irreversibly adsorbs on both positively and negatively charged nanodiamonds, but in different quantities. Adsorption of hyaluronic acid on nanodiamonds of positive zeta potential leads to the isoelectric point at the surface coverage close to 100 mg/g, while further increase in surface amount of hyaluronic acid results in the formation of negatively charged particles and the increase of its species diameter comparing with the initial material. In the case of negatively charged nanodiamonds adsorption of hyaluronic acid is also observed, but it was as much as 50 times lower than in the case of positively charged nanodiamonds. Even small amounts of hyaluronic acid adsorbed on nanodiamond surface results in the disaggregation of clusters of nanodiamonds that are formed in an aqueous suspension, while zeta potential was from − 50 to − 40 mV that is around of the value for non-modified material. On the basis of the experimental data, we can suggest that the adsorption mechanism of complex formation between hyaluronic acid and nanodiamonds includes both electrostatic interaction and formation of hydrogen bonds between surface functional groups and adsorbed water molecules.

The degree of adsorption of chitosan on the collagen matrices of bovine pericardium upon deposition from solutions in the two-phase H2O/CO2 system was studied as a function of pressure.

The effect adsorption layers of nonionic surfactant (pluronic P123) have on the distribution of nanodiamonds (NDs) between aqueous and organic phases is studied with radioactive tracers using compounds labeled with tritium. The values of reversible and irreversible adsorptions of P123 on NDs are determined. It is shown that the distribution coefficients of NDs modified by irreversibly adsorbed layers of P123 are several times higher than those of raw nanodiamonds. This result is explained by the hydrophobization of an ND’s surface, as is shown by data obtained via interfacial tensiometry and wetting.

Detonation synthesis nanodiamonds (ND) are among the most widely applied nanoparticles due to their low cost of production and broad scope of applications. However, the fate and behavior of NDs in the environment are largely unknown. The behavior of NDs is greatly affected by humic substances (HSs), which comprise 50 to 80 % of natural organic matter in water and soil ecosystems. The uptake of detonation NDs by wheat seedlings and its toxicity were evaluated in the presence of seven HSs of different origins, including humic acids (HA, HS fraction soluble in alkali and insoluble in acid) and fulvic acids (FA, soluble in both alkali and acid). To monitor the uptake of NDs by plants, tritium-labeled NDs were produced. Liquid scintillation spectrometry and autoradiography were used to determine the amount of NDs absorbed by plants. The photosynthetic activity of the plants was measured using light response curves. After a 24-h exposure period, the ND content in the plant roots was 1720 μg g−1. The introduction of HSs decreased the ND contents in the plant roots to 680–1570 μg g−1 (except for peat FA, for which the ND content did not differ from the blank value). The observed phenomenon was probably related mainly to the influence of HSs on the zeta potential of the NDs, which shifted from positive to negative. Based on chlorophyll fluorescence evaluation, the toxicity of NDs did not inhibit photosynthesis during illumination in the physiological range. However, NDs were slightly toxic to wheat plants under excessive light, likely due to the inhibition of electron transport between Q A and Q B and the disruption of the formation of a thylakoid transmembrane potential. The introduction of HA in a suspension of NDs obviously reduced the inhibiting effect of the NDs; however, the mitigating activities of FA were not so apparent. Our results demonstrate the urgent need for further studies of the influences of NDs on plant growth and development.

Carbon-based nanomaterials have piqued the interest of several researchers. At the same time, radioactive labeling is a powerful tool for studying processes in different systems, including biological and organic; however, the introduction of radioactive isotopes into carbon-based nanomaterial remains a great challenge. We have used the Langmuir hydrogen dissociation method to introduce tritium in single-walled carbon nanotubes and graphene oxide. The technique allows us to achieve a specific radioactivity of 107 and 27 Ci/g for single-layer graphene oxide and single-walled carbon nanotubes, respectively. Based on the analysis of characteristic Raman modes at 1350 and 1580 cm−1, a minimal amount of structural changes to the nanomaterials due to radiolabeling was observed. The availability of a simple, nondestructive, and economic technique for the introduction of radiolabels to single-walled carbon nanotubes and graphene oxide will ultimately expand the applicability of these materials.

Tritium was introduced by the thermal activation method into samples of single-walled carbon nanotubes modified with diaminotriethylene glycol. Chemical linking of the modifier considerably increased the specific radioactivity of the product. The maximal specific radioactivity was reached when “hot” (2000 K) tritium atoms acted on targets of modified nanotubes kept at 295 K. The main pharmacokinetic parameters of tritium-labeled modified carbon nanotubes upon intravenous administration into mongrel rats chosen as a model were determined.

Techniques for the determination of protein concentrations in the bulk of ionic fluids have been developed using tritiumlabeled proteins and adsorption at the water–ionic liquid interface with the aid of a sessile drop method.