rus
Issue #5/2023
A.V.Blinov, A.A.Blinova, Z.A.Rekhman, A.A.Gvozdenko, A.B.Golik, D.D.Filippov, A.G.Khramtsov , M.A.Kolodkin, T.N.Bakholdina
STUDY OF SELENIUM NANOPARTICLES REDUCTION PROCESS
STUDY OF SELENIUM NANOPARTICLES REDUCTION PROCESS
DOI: https://doi.org/10.22184/1993-8578.2023.16.5.288.296
This paper presents the results of study of selenium nanoparticles reduction process of using various reducing agents. Nanoparticles were obtained by chemical reduction in an aqueous medium, selenious acid was used as a precursor, and cocamidopropyl betaine was chosen as a stabilizer. The average hydrodynamic radius of the samples was studied by photon correlation spectroscopy, and the ζ potential was studied by acoustic and electroacoustic spectroscopy. It has been established that selenium nanoparticles obtained using ascorbic acid have an average hydrodynamic radius of 12.93 nm, with sodium borohydride – 23.16 nm, with timurea – 21.85 nm. Samples obtained using hydrazine, sodium thiosulfate, and L-cysteine coagulated for some time after synthesis, while with reducing agents such as urotropine, sodium citrate, glucose, and urea, selenium nanoparticles were not formed. The optimal ratios of the precursor and reducing agent were determined, and the dependences of the average hydrodynamic radius of the obtained samples were obtained. An analysis of the obtained results showed that the optimal reducing agent for obtaining selenium nanoparticles is ascorbic acid with a precursor to reducing agent ratio of 1:4 and an average hydrodynamic radius of 14 nm.
This paper presents the results of study of selenium nanoparticles reduction process of using various reducing agents. Nanoparticles were obtained by chemical reduction in an aqueous medium, selenious acid was used as a precursor, and cocamidopropyl betaine was chosen as a stabilizer. The average hydrodynamic radius of the samples was studied by photon correlation spectroscopy, and the ζ potential was studied by acoustic and electroacoustic spectroscopy. It has been established that selenium nanoparticles obtained using ascorbic acid have an average hydrodynamic radius of 12.93 nm, with sodium borohydride – 23.16 nm, with timurea – 21.85 nm. Samples obtained using hydrazine, sodium thiosulfate, and L-cysteine coagulated for some time after synthesis, while with reducing agents such as urotropine, sodium citrate, glucose, and urea, selenium nanoparticles were not formed. The optimal ratios of the precursor and reducing agent were determined, and the dependences of the average hydrodynamic radius of the obtained samples were obtained. An analysis of the obtained results showed that the optimal reducing agent for obtaining selenium nanoparticles is ascorbic acid with a precursor to reducing agent ratio of 1:4 and an average hydrodynamic radius of 14 nm.
Теги: acoustic and electroacoustic spectroscopy reducing agent selenium nanoparticles акустическая и электроакустическая спектроскопия восстановитель наночастицы селена
INTRODUCTION
Selenium is an essential trace element, the biological role of which is widely studied and presented in a number of original publications and reviews [1, 2]. It has a significant influence on the processes of immune system functioning and also has pronounced antioxidant properties [3]. The main function of Se in the human body, is to participate in the formation and action of the organic molecule glutathione peroxidase – one of the most important antioxidant enzymes, which prevents oxidative processes of free-acting radicals [4]. In addition, sufficient selenium content in the human body helps to reduce the risk of cardiovascular diseases and stimulates metabolic processes in the body [5, 6].
Due to their unique properties, nanoscale forms of selenium find their application in various fields of science and technology. Thus, this nanomaterial is used as preparations in veterinary medicine and medicine, as well as a biologically active feed additive and antioxidant preparation for products of the perfume and cosmetic industry [7–11].
It is worth noting that nanosized selenium is characterised by low toxicity compared to inorganic selenium [12]. However, selenium nanoparticles do not exhibit aggregative stability in aqueous medium without the use of stabilisers and are prone to coagulation, which complicates their practical application [13]. In this regard, the development of methods for the production of selenium nanoparticles and the selection of optimal synthesis conditions is an urgent issue [14–16]. Thus, the aim of this work was to study the formation of selenium nanoparticles using different reducing agents.
RECEARCH METHODS
Selenium nanoparticles were synthesised by chemical reduction of selenium precursor in aqueous medium in the presence of stabilisers. Selenic acid (H2SeO3) was used as selenium precursor. In the process, selenium nanoparticle sols were investigated using the following reducing agents: sodium borohydride (NaBH4), ascorbic acid (C6H8O6), thiourea (CH4N2S), sodium thiosulfate (Na2S2O3), hydrazine hydrochloric acid (N2H5Cl), L-cysteine (C3H7NO2S), sodium citrate (Na3C6H5O7), glucose (C6H12O6), urea ((NH2)2CO), and urotropine (C6H12N4). The surfactant cocamidopropyl betaine was used as a stabiliser.
The synthesis of selenium nanoparticles was carried out as follows: at the first stage 0.036 M selenic acid solution was prepared in which the stabiliser suspensions were dissolved, then 0.088 M solutions of the used reducing agents were prepared. Finally, the solutions of reducing agents were added dropwise to the selenitic acid solutions and the obtained samples were stirred for 5–10 minutes.
The average hydrodynamic radius of the obtained samples of selenium nanoparticles was determined by photon correlation spectroscopy on the Photocor-Complex unit (Antec-97 Ltd., Russia). The ζ-potential of the obtained samples was determined by acoustic and electroacoustic spectroscopy on the DT-1202 unit manufactured by Dispersion Technology Inc., USA.
RESULTS
At the first stage, the synthesis of selenium nanoparticles was carried out using different reducing agents, samples of selenium nanoparticle sols were obtained, the images of which are presented in Fig.1.
The values of the average hydrodynamic radius and ζ-potential of the obtained samples are presented in Table 1.
To better visualise the reduction process, the selenium nanoparticle formation reactions are presented in Table 2.
In the second step, to determine the optimum ratio of precursor and reducing agent on the stability and size of selenium nanoparticles, the synthesis of selenium nanoparticles with different concentration ratio of reducing agent and selenium precursor selenic acid was carried out.Selenium nanoparticle sols were investigated using the following reducing agents: Sodium borohydride (NaBH4), ascorbic acid (C6H8O6), thiourea (CH4N2S), hydrazine hydrochloric acid (N2H5Cl), L-cysteine (C3H7NO2S). The surfactant cocamidopropyl betaine was used as a stabiliser.
Figure 2 shows samples of selenium nanoparticle sols using ascorbic acid, sodium borohydride, L-cysteine, thiourea, and hydrazine hydrochloride as reducing agent.
To determine the optimal ratio of precursor and reducing agent, the dependences of the average hydrodynamic radius and light scattering intensity on the ratio of components were obtained by photon correlation spectroscopy. At this stage, ascorbic acid, sodium borohydride and thiourea were used as reducing agents, since the samples using these substances showed the highest stability.
Table 3 shows the values of average hydrodynamic radii of selenium nanoparticle sols as a function of precursor to reducing agent concentration ratio.
DISCUSSION
According to the results of the study of the influence of the type of reducing agent, it was determined that the most aggregatively unstable were the samples obtained using hydrazine, sodium thiosulfate and L-cysteine – these samples precipitated within 60 minutes after synthesis. No precipitation was observed in samples using ascorbic acid, sodium borohydride and thiourea and stable samples of nanoscale selenium were obtained. With the other reducing agents (sodium citrate, glucose, urea and urotropine) no reaction of selenium nanoparticles formation occurred.
As a result of analysing the obtained data, it was found that the nanoparticles synthesised using hydrazine and L-cysteine have the highest values of mean hydrodynamic radius of 385.5 nm and 157.8 nm, respectively. Selenium nanoparticles obtained using ascorbic acid have an average hydrodynamic radius of – 12.93 nm, using sodium borohydride – 23.16 nm, with thymourea – 21.85 nm, with sodium thiosulphate – 12.93 nm.
According to the results of the study of the optimum ratio of precursor and reducing agent according to the results of photon correlation spectroscopy of the samples, it was determined that in the series of experiments with sodium borohydride, the most optimal ratio of precursor and reducing agent was 1:2, and the size of the samples in this series was 17 nm.
In the series with ascorbic acid, the most stable samples were obtained with a ratio of 1:8, 1:4, 1:2. These sols have a size of 15, 14 and 15 nm, respectively. Samples with a reducing agent content greater than the 1:8 ratio are less stable and coagulate faster.
In the series using thiourea, samples with component ratios of 16:1, 8:1, 4:1 exhibited optimal mean hydrodynamic radii (26, 22, 22 nm, respectively) but were unstable over time and coagulated within 60 min of synthesis.
In the series of experiments using L-cysteine, the optimum size (42 and 40 nm) were samples with precursor to reducing agent ratios of 1:16 and 1:32, and in the samples where the reducing agent was hydrazine hydrochloric acid, the optimum mean hydrodynamic radius (21, 38 and 35 nm) were possessed by sols with precursor to reducing agent ratios of 32:1, 1:4 and 1:16, respectively. It is worth noting that the samples of selenium nanoparticles reduced using L-cysteine and hydrazine hydrochloride did not possess aggregation stability and coagulated for some time after synthesis.
It is important to note that when sodium borohydride, L-cysteine, thiourea and hydrazine hydrochloride are used as reducing agents, the reaction results in the release of gaseous reaction products (hydrogen, carbon dioxide, nitrogen), which prevent the formation of a homogeneous layer of stabiliser on the particle surface.
CONCLUSIONS
Thus, in the course of the work, the process of reduction of selenium nanoparticles was investigated. The analysis of the study showed that the most stable are the samples of selenium nanoparticles reduced using ascorbic acid and sodium borohydride. It is worth noting that the reduction did not occur in the samples where sodium citrate, glucose, urea and urotropine were used as reducing agents.
To determine the optimal precursor and reducing agent ratio, the dependences of the average hydrodynamic radius on the ratio of components were obtained by photon correlation spectroscopy. At this stage, ascorbic acid, sodium borohydride and thiourea were used as reducing agents. The data analysis showed that in the series with ascorbic acid the samples with optimum size were obtained at precursor to reducing agent ratios of 1:8, 1:4 and 1:2. The average hydrodynamic radius of the obtained sols is 15, 14 and 15 nm, respectively. In the series with sodium borohydride, a precursor to reducing agent ratio of 1:2 was determined with a size of 17 nm. In turn, the samples using thiourea as a reducing agent, although characterised by optimal size, coagulated within 60 min after synthesis.
After studying the reducing agent type on formation of selenium nanoparticles, it can be concluded that the optimal reducing agent is ascorbic acid, which does not produce gaseous reaction products.
ACKNOWLEDGMENTS
This study 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.
Selenium is an essential trace element, the biological role of which is widely studied and presented in a number of original publications and reviews [1, 2]. It has a significant influence on the processes of immune system functioning and also has pronounced antioxidant properties [3]. The main function of Se in the human body, is to participate in the formation and action of the organic molecule glutathione peroxidase – one of the most important antioxidant enzymes, which prevents oxidative processes of free-acting radicals [4]. In addition, sufficient selenium content in the human body helps to reduce the risk of cardiovascular diseases and stimulates metabolic processes in the body [5, 6].
Due to their unique properties, nanoscale forms of selenium find their application in various fields of science and technology. Thus, this nanomaterial is used as preparations in veterinary medicine and medicine, as well as a biologically active feed additive and antioxidant preparation for products of the perfume and cosmetic industry [7–11].
It is worth noting that nanosized selenium is characterised by low toxicity compared to inorganic selenium [12]. However, selenium nanoparticles do not exhibit aggregative stability in aqueous medium without the use of stabilisers and are prone to coagulation, which complicates their practical application [13]. In this regard, the development of methods for the production of selenium nanoparticles and the selection of optimal synthesis conditions is an urgent issue [14–16]. Thus, the aim of this work was to study the formation of selenium nanoparticles using different reducing agents.
RECEARCH METHODS
Selenium nanoparticles were synthesised by chemical reduction of selenium precursor in aqueous medium in the presence of stabilisers. Selenic acid (H2SeO3) was used as selenium precursor. In the process, selenium nanoparticle sols were investigated using the following reducing agents: sodium borohydride (NaBH4), ascorbic acid (C6H8O6), thiourea (CH4N2S), sodium thiosulfate (Na2S2O3), hydrazine hydrochloric acid (N2H5Cl), L-cysteine (C3H7NO2S), sodium citrate (Na3C6H5O7), glucose (C6H12O6), urea ((NH2)2CO), and urotropine (C6H12N4). The surfactant cocamidopropyl betaine was used as a stabiliser.
The synthesis of selenium nanoparticles was carried out as follows: at the first stage 0.036 M selenic acid solution was prepared in which the stabiliser suspensions were dissolved, then 0.088 M solutions of the used reducing agents were prepared. Finally, the solutions of reducing agents were added dropwise to the selenitic acid solutions and the obtained samples were stirred for 5–10 minutes.
The average hydrodynamic radius of the obtained samples of selenium nanoparticles was determined by photon correlation spectroscopy on the Photocor-Complex unit (Antec-97 Ltd., Russia). The ζ-potential of the obtained samples was determined by acoustic and electroacoustic spectroscopy on the DT-1202 unit manufactured by Dispersion Technology Inc., USA.
RESULTS
At the first stage, the synthesis of selenium nanoparticles was carried out using different reducing agents, samples of selenium nanoparticle sols were obtained, the images of which are presented in Fig.1.
The values of the average hydrodynamic radius and ζ-potential of the obtained samples are presented in Table 1.
To better visualise the reduction process, the selenium nanoparticle formation reactions are presented in Table 2.
In the second step, to determine the optimum ratio of precursor and reducing agent on the stability and size of selenium nanoparticles, the synthesis of selenium nanoparticles with different concentration ratio of reducing agent and selenium precursor selenic acid was carried out.Selenium nanoparticle sols were investigated using the following reducing agents: Sodium borohydride (NaBH4), ascorbic acid (C6H8O6), thiourea (CH4N2S), hydrazine hydrochloric acid (N2H5Cl), L-cysteine (C3H7NO2S). The surfactant cocamidopropyl betaine was used as a stabiliser.
Figure 2 shows samples of selenium nanoparticle sols using ascorbic acid, sodium borohydride, L-cysteine, thiourea, and hydrazine hydrochloride as reducing agent.
To determine the optimal ratio of precursor and reducing agent, the dependences of the average hydrodynamic radius and light scattering intensity on the ratio of components were obtained by photon correlation spectroscopy. At this stage, ascorbic acid, sodium borohydride and thiourea were used as reducing agents, since the samples using these substances showed the highest stability.
Table 3 shows the values of average hydrodynamic radii of selenium nanoparticle sols as a function of precursor to reducing agent concentration ratio.
DISCUSSION
According to the results of the study of the influence of the type of reducing agent, it was determined that the most aggregatively unstable were the samples obtained using hydrazine, sodium thiosulfate and L-cysteine – these samples precipitated within 60 minutes after synthesis. No precipitation was observed in samples using ascorbic acid, sodium borohydride and thiourea and stable samples of nanoscale selenium were obtained. With the other reducing agents (sodium citrate, glucose, urea and urotropine) no reaction of selenium nanoparticles formation occurred.
As a result of analysing the obtained data, it was found that the nanoparticles synthesised using hydrazine and L-cysteine have the highest values of mean hydrodynamic radius of 385.5 nm and 157.8 nm, respectively. Selenium nanoparticles obtained using ascorbic acid have an average hydrodynamic radius of – 12.93 nm, using sodium borohydride – 23.16 nm, with thymourea – 21.85 nm, with sodium thiosulphate – 12.93 nm.
According to the results of the study of the optimum ratio of precursor and reducing agent according to the results of photon correlation spectroscopy of the samples, it was determined that in the series of experiments with sodium borohydride, the most optimal ratio of precursor and reducing agent was 1:2, and the size of the samples in this series was 17 nm.
In the series with ascorbic acid, the most stable samples were obtained with a ratio of 1:8, 1:4, 1:2. These sols have a size of 15, 14 and 15 nm, respectively. Samples with a reducing agent content greater than the 1:8 ratio are less stable and coagulate faster.
In the series using thiourea, samples with component ratios of 16:1, 8:1, 4:1 exhibited optimal mean hydrodynamic radii (26, 22, 22 nm, respectively) but were unstable over time and coagulated within 60 min of synthesis.
In the series of experiments using L-cysteine, the optimum size (42 and 40 nm) were samples with precursor to reducing agent ratios of 1:16 and 1:32, and in the samples where the reducing agent was hydrazine hydrochloric acid, the optimum mean hydrodynamic radius (21, 38 and 35 nm) were possessed by sols with precursor to reducing agent ratios of 32:1, 1:4 and 1:16, respectively. It is worth noting that the samples of selenium nanoparticles reduced using L-cysteine and hydrazine hydrochloride did not possess aggregation stability and coagulated for some time after synthesis.
It is important to note that when sodium borohydride, L-cysteine, thiourea and hydrazine hydrochloride are used as reducing agents, the reaction results in the release of gaseous reaction products (hydrogen, carbon dioxide, nitrogen), which prevent the formation of a homogeneous layer of stabiliser on the particle surface.
CONCLUSIONS
Thus, in the course of the work, the process of reduction of selenium nanoparticles was investigated. The analysis of the study showed that the most stable are the samples of selenium nanoparticles reduced using ascorbic acid and sodium borohydride. It is worth noting that the reduction did not occur in the samples where sodium citrate, glucose, urea and urotropine were used as reducing agents.
To determine the optimal precursor and reducing agent ratio, the dependences of the average hydrodynamic radius on the ratio of components were obtained by photon correlation spectroscopy. At this stage, ascorbic acid, sodium borohydride and thiourea were used as reducing agents. The data analysis showed that in the series with ascorbic acid the samples with optimum size were obtained at precursor to reducing agent ratios of 1:8, 1:4 and 1:2. The average hydrodynamic radius of the obtained sols is 15, 14 and 15 nm, respectively. In the series with sodium borohydride, a precursor to reducing agent ratio of 1:2 was determined with a size of 17 nm. In turn, the samples using thiourea as a reducing agent, although characterised by optimal size, coagulated within 60 min after synthesis.
After studying the reducing agent type on formation of selenium nanoparticles, it can be concluded that the optimal reducing agent is ascorbic acid, which does not produce gaseous reaction products.
ACKNOWLEDGMENTS
This study 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.
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