rus
Issue #6/2024
A.V.Blinov, Z.A.Rekhman, A.S.Askerova, E.D.Nazaretova, A.A.Gvozdenko, А.V.Kozlikin, М.N.Veryovkina
SELENIUM-CONTAINING NANOSCALE SYSTEMS STABILIZED WITH HYDROXYETHYL CELLULOSE: SYNTHESIS, STABILITY, PROPERTIES
SELENIUM-CONTAINING NANOSCALE SYSTEMS STABILIZED WITH HYDROXYETHYL CELLULOSE: SYNTHESIS, STABILITY, PROPERTIES
INTRODUCTION
Nowadays, the problem of oxidative stress in a human body is relevant in various fields of science. It is caused by emergence of many pathologies, in particular, oncological diseases [1]. The free radicals emergence due to various factors creates danger, as they are aggressive molecules capable of reacting with a cell membrane and transforming its constituents into free radicals [2].
One of the promising materials for preventing formation of free radicals is selenium in its organic, inorganic or nanoscale form. Due to its high antioxidant activity, various forms of selenium, when introduced into a body, have a preventive or therapeutic effect [3]. The study of the forms of the essential trace element selenium allowed us to conclude that nanoscale selenium has less toxicity compared to organic and inorganic forms [4–6]. Thus, in [7], cytotoxicity of selenium nanoparticles was studied using the methyltetrazolium test, which allows assessing viability of cells in culture. As a result, it was found that nanoscale selenium has low cytotoxicity. The ability of selenium nanoparticles to neutralise free radicals was confirmed in [8], where the effect of selenium particle size on their ability to directly scavenge free radicals was studied. The study concluded that in the range from 5 to 200 nm, the size effect insignificantly affects this ability.
In order to preserve properties of nanosized selenium, it is necessary to develop methods to increase the aggregative and sedimentation stability of the obtained particles. One of the promising ways to solve this problem is the use of various stabilisers during the selenium nanoparticles synthesis [9–11]. In [12], selenium nanoparticles stabilised by gummiarabic were prepared using a chemical reduction method. It was found that the average size of selenium particles is 35 nm and the use of stabiliser prevents aggregation of selenium nanoparticles. It is also found that the obtained nanoparticles have high antioxidant activity.
The aim of this work is to synthesise, and study stability and properties of selenium-containing nanoscale systems stabilised by B30K hydroxyethyl cellulose.
RESEARCH METHODS
The synthesis of selenium-containing nanoscale systems stabilised by hydroxyethylcellulose was carried out in aqueous medium using a chemical reduction method, where selenitic acid (H2SeO3) was used as a precursor, ascorbic acid (C6H8O6) as a reducing agent and hydroxyethylcellulose B30K (HEC) as a stabiliser.
In order to determine the optimal concentrations of substances used in preparation of selenium-containing nanoscale systems, an optimisation of the synthesis technique was carried out, where the molar concentration of precursor and reducing agent, as well as the mass of stabiliser were considered as input parameters, and the average hydrodynamic radius, which was obtained using the method of dynamic light scattering on the Photocor Complex (Antec-97 Ltd., Russia), and ζ-potential, which was obtained using the method of acoustic and electroacoustic spectroscopy, were considered as output parameters. The synthesis was carried out by dissolving suspensions of selenic acid and HEC in 10 cm3 of distilled water according to the experimental matrix (Table 1). In the next step, a suspension of ascorbic acid was dissolved in 5 cm3 of distilled water according to Table 1. Then, the ascorbic acid solution was added to the selenic acid and HEC solution and stirred at 600 rpm for 5 minutes. The obtained data were processed using Statistica software.
To determine influence of HEC on the quantum-chemical characteristics of selenium-containing nanoscale systems, a computer simulation of the elementary act of interaction between a selenium atom and a monomeric link of HEC was carried out using the molecular editor IQmol. The calculations were performed in QChem software on the equipment of the data processing centre (Schneider Electric) of the Federal State Autonomous Educational Institution of Higher Education of the North-Caucasus Federal University. Interaction of selenium atom with different HEC groups of HEC was considered. The values of the total energy of the molecular complex (E), the energies of the highest occupied (EHOMO) and lowest free (ELUMO) molecular orbitals were calculated by computer modelling. On the basis of these quantum-chemical parameters, we obtained the values of the difference between the total energy of the monomeric HEC molecule and the elementary act of interaction of a selenium atom with the monomeric HEC link (∆E), as well as the chemical rigidity (η), equal to half of the difference between the energies of the lowest free and highest populated molecular orbitals. The calculations were performed with the following parameters: method: B3LYP, basis: 6–31G*, convergence – 5, force field – Ghemical.
Influence of temperature, stirring time and pH of the medium was studied by synthesis of selenium-containing nanoscale systems stabilised by HCE with the optimal ratio of components at different parameters of pH of the medium, temperature and stirring time in accordance with the matrix of the experiment on optimisation of technological parameters of the reaction medium (Table 2). The average hydrodynamic radius and ζ-potential of the obtained samples were studied.
Influence of pH environment on the selenium-containing nanoscale systems stability was studied by adding buffer solutions with the following pH values to the obtained samples: 1.81; 2.21; 3.29; 4.56; 5.76; 6.8; 7.96; 9.15; 10.38; 11.58; 11.98. After this, the values of mean hydrodynamic radius and ζ-potential were measured.
RESULTS
At the first stage, optimization of the methodology for the synthesis of selenium-containing nanoscale systems stabilised by HCE was carried out. The obtained values of the average hydrodynamic radius and ζ-potential are presented in Table 3.
As a result of obtained data processing, ternary dependences of the mean hydrodynamic radius and ζ-potential on molar concentration of selenic acid and ascorbic acid, as well as the mass of stabiliser were formed, presented in Fig.1.
At the next stage, computer modelling of the elementary act of interaction of selenium atom with the monomeric link of HCE was carried out. The results are presented in Table 4 and Fig.2.
At the next stage, we optimised the technological parameters of the reaction medium for the synthesis of selenium-containing nanoscale systems stabilised by HCE. The obtained values of the mean hydrodynamic radius and ζ-potential are shown in Table 5.
As a result of obtained data processing, ternary dependences of the mean hydrodynamic radius and ζ-potential on temperature, pH of the medium and time of measurement were formed, presented in Fig.3.
As a result of the study of pH influence of the medium on stability of selenium-containing nanosystems stabilised by HCE, the dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, presented in Fig. 4, was obtained.
DISCUSSION
As a result of methodology optimisation for selenium-containing nanoscale systems synthesis stabilised by HCE, it was found that the optimal concentrations and masses of the components are: C(H2SeO3) = 0.3536 mol/L; m (HCE) = 0.015 g; C(C6H8O6) = 0.7938 mol/L. At this ratio, the lowest value of mean hydrodynamic radius (R = 125.0 nm) and the highest value of ξ-potential (ξ = 8.2 mV) are observed.
Analysis of the computer modelling results allowed us to conclude that interaction of selenium atom with the monomeric link of HCE is energetically advantageous (∆E ≥ 2399.586 kcal/mol) and chemically stable (0.076 ≤ η ≤ 0.093 eV). On the basis of the obtained data, we can conclude that the most probable variant of interaction is connection of selenium atom with the monomeric link of HCE through the hydroxyl group attached to C6 of glucopyranose residue, since this interaction has optimal values of total energy difference (∆E = 2399.640 kcal/mol) and chemical rigidity (η = 0.093 eV).
The analysis of ternary dependences of the mean hydrodynamic radius and ζ-potential on temperature, pH of the medium and time of measurement allowed us to conclude that the optimal synthesis parameters are pH = 11, t = 25 °C, τ = 15 min, since at this value of the parameters particles with a mean hydrodynamic radius equal to 65 nm and ξ-potential equal to -19.2 mV are formed.
Based on the analysis of dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, it was found that there is no significant change in the mean hydrodynamic radius and ζ-potential with increasing pH of the medium. At pH of medium = 1.81, the highest values of mean hydrodynamic radius and ζ-potential of 141 ± 7 nm and 1.84 mV were observed, respectively. At medium pH = 6.8, the lowest values of mean hydrodynamic radius and ζ-potential were observed, equal to 120 ± 6 nm and 0.23 mV, respectively.
CONCLUSIONS
In this paper we have optimised methodology for the synthesis of selenium-containing nanoscale systems stabilised by hydroxyethyl cellulose. Based on the obtained data, concentrations of the reaction components (molar concentration of selenic acid and ascorbic acid, mass of hydroxyethyl cellulose) at which the sample has the smallest average hydrodynamic radius and electrokinetic potential were determined.
Using computer simulations, it was found that hydroxyethyl cellulose is an optimal stabiliser, and the most probable configuration of interaction of selenium-containing nanoscale systems with hydroxyethyl cellulose was determined. It was found, that the bounding is more energetically favourable (∆E ≥ 2399.586 kcal/mol) and chemically stable (0.076 ≤ η ≤ 0.093 eV).
As a result of synthesis parameters optimisation, the optimum values of pH medium, temperature and mixing time were determined: pH = 11, t = 25 °C, τ = 15 min. It was found that when these parameters are observed, the sample of selenium nanoparticles stabilised by HCE contains particles with an average radius of less than 100 nm.
Based on the analysis of the dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, it was found that the sample has the greatest stability in the medium with neutral pH.
ACKNOWLEDGMENTS
The research was supported by the Russian Science Foundation grant No. 23-16-00120, https://rscf.ru/project/23-16-00120/.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Nowadays, the problem of oxidative stress in a human body is relevant in various fields of science. It is caused by emergence of many pathologies, in particular, oncological diseases [1]. The free radicals emergence due to various factors creates danger, as they are aggressive molecules capable of reacting with a cell membrane and transforming its constituents into free radicals [2].
One of the promising materials for preventing formation of free radicals is selenium in its organic, inorganic or nanoscale form. Due to its high antioxidant activity, various forms of selenium, when introduced into a body, have a preventive or therapeutic effect [3]. The study of the forms of the essential trace element selenium allowed us to conclude that nanoscale selenium has less toxicity compared to organic and inorganic forms [4–6]. Thus, in [7], cytotoxicity of selenium nanoparticles was studied using the methyltetrazolium test, which allows assessing viability of cells in culture. As a result, it was found that nanoscale selenium has low cytotoxicity. The ability of selenium nanoparticles to neutralise free radicals was confirmed in [8], where the effect of selenium particle size on their ability to directly scavenge free radicals was studied. The study concluded that in the range from 5 to 200 nm, the size effect insignificantly affects this ability.
In order to preserve properties of nanosized selenium, it is necessary to develop methods to increase the aggregative and sedimentation stability of the obtained particles. One of the promising ways to solve this problem is the use of various stabilisers during the selenium nanoparticles synthesis [9–11]. In [12], selenium nanoparticles stabilised by gummiarabic were prepared using a chemical reduction method. It was found that the average size of selenium particles is 35 nm and the use of stabiliser prevents aggregation of selenium nanoparticles. It is also found that the obtained nanoparticles have high antioxidant activity.
The aim of this work is to synthesise, and study stability and properties of selenium-containing nanoscale systems stabilised by B30K hydroxyethyl cellulose.
RESEARCH METHODS
The synthesis of selenium-containing nanoscale systems stabilised by hydroxyethylcellulose was carried out in aqueous medium using a chemical reduction method, where selenitic acid (H2SeO3) was used as a precursor, ascorbic acid (C6H8O6) as a reducing agent and hydroxyethylcellulose B30K (HEC) as a stabiliser.
In order to determine the optimal concentrations of substances used in preparation of selenium-containing nanoscale systems, an optimisation of the synthesis technique was carried out, where the molar concentration of precursor and reducing agent, as well as the mass of stabiliser were considered as input parameters, and the average hydrodynamic radius, which was obtained using the method of dynamic light scattering on the Photocor Complex (Antec-97 Ltd., Russia), and ζ-potential, which was obtained using the method of acoustic and electroacoustic spectroscopy, were considered as output parameters. The synthesis was carried out by dissolving suspensions of selenic acid and HEC in 10 cm3 of distilled water according to the experimental matrix (Table 1). In the next step, a suspension of ascorbic acid was dissolved in 5 cm3 of distilled water according to Table 1. Then, the ascorbic acid solution was added to the selenic acid and HEC solution and stirred at 600 rpm for 5 minutes. The obtained data were processed using Statistica software.
To determine influence of HEC on the quantum-chemical characteristics of selenium-containing nanoscale systems, a computer simulation of the elementary act of interaction between a selenium atom and a monomeric link of HEC was carried out using the molecular editor IQmol. The calculations were performed in QChem software on the equipment of the data processing centre (Schneider Electric) of the Federal State Autonomous Educational Institution of Higher Education of the North-Caucasus Federal University. Interaction of selenium atom with different HEC groups of HEC was considered. The values of the total energy of the molecular complex (E), the energies of the highest occupied (EHOMO) and lowest free (ELUMO) molecular orbitals were calculated by computer modelling. On the basis of these quantum-chemical parameters, we obtained the values of the difference between the total energy of the monomeric HEC molecule and the elementary act of interaction of a selenium atom with the monomeric HEC link (∆E), as well as the chemical rigidity (η), equal to half of the difference between the energies of the lowest free and highest populated molecular orbitals. The calculations were performed with the following parameters: method: B3LYP, basis: 6–31G*, convergence – 5, force field – Ghemical.
Influence of temperature, stirring time and pH of the medium was studied by synthesis of selenium-containing nanoscale systems stabilised by HCE with the optimal ratio of components at different parameters of pH of the medium, temperature and stirring time in accordance with the matrix of the experiment on optimisation of technological parameters of the reaction medium (Table 2). The average hydrodynamic radius and ζ-potential of the obtained samples were studied.
Influence of pH environment on the selenium-containing nanoscale systems stability was studied by adding buffer solutions with the following pH values to the obtained samples: 1.81; 2.21; 3.29; 4.56; 5.76; 6.8; 7.96; 9.15; 10.38; 11.58; 11.98. After this, the values of mean hydrodynamic radius and ζ-potential were measured.
RESULTS
At the first stage, optimization of the methodology for the synthesis of selenium-containing nanoscale systems stabilised by HCE was carried out. The obtained values of the average hydrodynamic radius and ζ-potential are presented in Table 3.
As a result of obtained data processing, ternary dependences of the mean hydrodynamic radius and ζ-potential on molar concentration of selenic acid and ascorbic acid, as well as the mass of stabiliser were formed, presented in Fig.1.
At the next stage, computer modelling of the elementary act of interaction of selenium atom with the monomeric link of HCE was carried out. The results are presented in Table 4 and Fig.2.
At the next stage, we optimised the technological parameters of the reaction medium for the synthesis of selenium-containing nanoscale systems stabilised by HCE. The obtained values of the mean hydrodynamic radius and ζ-potential are shown in Table 5.
As a result of obtained data processing, ternary dependences of the mean hydrodynamic radius and ζ-potential on temperature, pH of the medium and time of measurement were formed, presented in Fig.3.
As a result of the study of pH influence of the medium on stability of selenium-containing nanosystems stabilised by HCE, the dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, presented in Fig. 4, was obtained.
DISCUSSION
As a result of methodology optimisation for selenium-containing nanoscale systems synthesis stabilised by HCE, it was found that the optimal concentrations and masses of the components are: C(H2SeO3) = 0.3536 mol/L; m (HCE) = 0.015 g; C(C6H8O6) = 0.7938 mol/L. At this ratio, the lowest value of mean hydrodynamic radius (R = 125.0 nm) and the highest value of ξ-potential (ξ = 8.2 mV) are observed.
Analysis of the computer modelling results allowed us to conclude that interaction of selenium atom with the monomeric link of HCE is energetically advantageous (∆E ≥ 2399.586 kcal/mol) and chemically stable (0.076 ≤ η ≤ 0.093 eV). On the basis of the obtained data, we can conclude that the most probable variant of interaction is connection of selenium atom with the monomeric link of HCE through the hydroxyl group attached to C6 of glucopyranose residue, since this interaction has optimal values of total energy difference (∆E = 2399.640 kcal/mol) and chemical rigidity (η = 0.093 eV).
The analysis of ternary dependences of the mean hydrodynamic radius and ζ-potential on temperature, pH of the medium and time of measurement allowed us to conclude that the optimal synthesis parameters are pH = 11, t = 25 °C, τ = 15 min, since at this value of the parameters particles with a mean hydrodynamic radius equal to 65 nm and ξ-potential equal to -19.2 mV are formed.
Based on the analysis of dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, it was found that there is no significant change in the mean hydrodynamic radius and ζ-potential with increasing pH of the medium. At pH of medium = 1.81, the highest values of mean hydrodynamic radius and ζ-potential of 141 ± 7 nm and 1.84 mV were observed, respectively. At medium pH = 6.8, the lowest values of mean hydrodynamic radius and ζ-potential were observed, equal to 120 ± 6 nm and 0.23 mV, respectively.
CONCLUSIONS
In this paper we have optimised methodology for the synthesis of selenium-containing nanoscale systems stabilised by hydroxyethyl cellulose. Based on the obtained data, concentrations of the reaction components (molar concentration of selenic acid and ascorbic acid, mass of hydroxyethyl cellulose) at which the sample has the smallest average hydrodynamic radius and electrokinetic potential were determined.
Using computer simulations, it was found that hydroxyethyl cellulose is an optimal stabiliser, and the most probable configuration of interaction of selenium-containing nanoscale systems with hydroxyethyl cellulose was determined. It was found, that the bounding is more energetically favourable (∆E ≥ 2399.586 kcal/mol) and chemically stable (0.076 ≤ η ≤ 0.093 eV).
As a result of synthesis parameters optimisation, the optimum values of pH medium, temperature and mixing time were determined: pH = 11, t = 25 °C, τ = 15 min. It was found that when these parameters are observed, the sample of selenium nanoparticles stabilised by HCE contains particles with an average radius of less than 100 nm.
Based on the analysis of the dependence of the mean hydrodynamic radius and ζ-potential on the pH of the medium, it was found that the sample has the greatest stability in the medium with neutral pH.
ACKNOWLEDGMENTS
The research was supported by the Russian Science Foundation grant No. 23-16-00120, https://rscf.ru/project/23-16-00120/.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Readers feedback
