Synthesis of spherical amorphous selenium nano and microparticles with tunable sizes
2016; Institution of Engineering and Technology; Volume: 11; Issue: 2 Linguagem: Inglês
10.1049/mnl.2015.0353
ISSN1750-0443
AutoresVilém Bartůněk, Jiřina Junková, Mario Babuněk, Pavel Ulbrich, Martin Kuchař, Zdeněk Sofer,
Tópico(s)Quantum Dots Synthesis And Properties
ResumoMicro & Nano LettersVolume 11, Issue 2 p. 91-93 ArticleFree Access Synthesis of spherical amorphous selenium nano and microparticles with tunable sizes Vilém Bartůněk, Corresponding Author Vilém Bartůněk vilem.bartunek@vscht.cz Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorJiřina Junková, Jiřina Junková Department of Food Analysis and Nutrition, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorMario Babuněk, Mario Babuněk Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorPavel Ulbrich, Pavel Ulbrich Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Technická 3, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorMartin Kuchař, Martin Kuchař Forensic Laboratory of Biologically Active Substances, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorZdeněk Sofer, Zdeněk Sofer Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this author Vilém Bartůněk, Corresponding Author Vilém Bartůněk vilem.bartunek@vscht.cz Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorJiřina Junková, Jiřina Junková Department of Food Analysis and Nutrition, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorMario Babuněk, Mario Babuněk Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorPavel Ulbrich, Pavel Ulbrich Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Technická 3, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorMartin Kuchař, Martin Kuchař Forensic Laboratory of Biologically Active Substances, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this authorZdeněk Sofer, Zdeněk Sofer Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6 Czech RepublicSearch for more papers by this author First published: 01 February 2016 https://doi.org/10.1049/mnl.2015.0353Citations: 11AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Spherical amorphous nano and microparticles of elemental selenium have been prepared by simple reduction method. For surface stabilisation, sodium dodecyl sulphate (SDS), polysorbate 80 and tryptone have been used. ZetaSizer and transmission electron microscopy measurements were used for characterisation of the size and shape of prepared particles and X-ray diffraction measurements to confirm their amorphous nature. The sizes of the nanoparticles stabilised by SDS can be controlled by varying of the surfactant concentration. Particles stabilised by tryptone have microdimensions and could be therefore applied where nanodimensions are not suitable. 1 Introduction Nanoparticle research shows a promising way to fight pathogenic microorganisms since the antibiotic resistance of bacteria is still very actual problem. The use of selenium nanoparticles (SeNPs) is the relatively new approach on this very important field [[1]-[4]]. Usage of nanomaterials raises also certain concerns, getting them also to the centre of attention. Some ultrafine nanoparticles can be cytotoxic or may accumulate or even aggregate in organs like brain or liver, causing there various unpredictable actions. Especially selenium has the advantage in comparison with currently widely used antimicrobial metal nanoparticles. Selenium is a micronutrient and thus SeNPs degrade in the human body over the time. With the proper dosage it could be even useful itself [[5]]. Selenium is also a part of some important nanoparticle systems like luminescent CdSe quantum dots [[6]] or other selenides [[7]]. Tryptone consists of a mixture of peptides prepared by the digestion of casein by the trypsin. These peptides can regulate the stability of biosynthetically prepared metal nanoparticles by capping, as was shown in the case of silver nanoparticles [[8]]. Surfactant and emulsifier polysorbate 80 (PS80) with full chemical name polyoxyethylene (20) sorbitan monooleate is a viscous yellow liquid, easily soluble in common solvents as water, ethanol or toluene. It can be used for effective preparation of various nanoparticles [[9]]. Since PS80 is non-toxic and biocompatible, it is especially useful for application of nanoparticles in medicine [[10], [11]]. Sodium dodecyl sulphate (SDS) is an anionic surfactant used in many cleaning and hygiene products. The salt is an organosulphate consisting of a 12-carbon tail attached to a sulphate group, giving the material amphiphilic properties. Derived from inexpensive coconut and palm oils, it is a common component of many domestic cleaning products and as such is very affordable. SDS was previously used for the stabilisation of selenium nanostructures using polyelectrolyte poly(2-acrylamido-2-methylpropanesulfonic acid) [[12]]. In this Letter, we used much simpler reduction method for the preparation of spherical SeNPs with various diameters controllable by the amount of added SDS. Synthesis using ascorbic acid as a reduction agent is very facile and do not need an elevated temperature nor the use of any dangerous compounds or biological systems as for example in [[1]]. 2 Experimental PS80 was purchased from Fluka Analytica, Ltd, SDS from Sigma-Aldrich, Ltd and Sodium selenite (Na2SeO3) from Schuchardt Ltd, Munich. Tryptone was bought from Oxoid Ltd. England (lot number 356832). All chemicals were used without their further purification. Typical sample was prepared by mixing 5.0 ml of 6 mM water solution of Na2SeO3 with the exact amount of the surfactant (water solutions of SDS, PS80 or tryptone). The reaction mixture was subsequently homogenised. A 1.0 ml of 30 mM ascorbic acid in water was added to this solution as a reduction agent. The mixture was kept on air for 2 h without stirring. Obtained SeNPs were purified from other reactants by several subsequent dialyses into demineralised water, followed by the solution centrifugation. X-ray powder diffraction data were collected at room temperature by X'Pert PRO θ-θ powder diffractometer using CuKα radiation (λ = 1.5418 Å). The samples for transmission electron microscopy (TEM) were prepared by the deposition of a 6 µl drop of studied solution onto carbon coated copper grid. Excess of solution was removed and grids were dried by Whatman filtration paper. The samples were observed by TEM JEOL JEM-1010 at an accelerating voltage of 80 kV. Pictures were taken by SIS MegaView III digital camera (Soft Imaging Systems) and analysed by AnalySIS v. 2.0 software. ZetaSizer Nano series instrument from Malvern Instruments Ltd was used for measurements of particle's sizes and ZetaSizer Software 6.32 Malvern Instruments Ltd for data processing. 3 Results and discussion We have used ZetaSizer measurements as the main characterisation method of the prepared selenium particles. These measurements revealed the possibility to control the size of prepared nanoparticles. The average sizes of prepared nanoparticles are summarised in Table 1. Prepared SeNPs were of spherical shape, which is apparent from TEM image shown in Fig. 1. This is quite important for the ZetaSizer measurements because the method presumes round shape of measured objects and therefore we consider the measurements more accurate. The size distribution of SeNPs follows the Gaussian curve and its typical shape and NPs size distribution are illustrated in Fig. 2. The distribution curve is quite broad but contains one peak and the vast majorities of all particles in all prepared samples are in their respective categories. TEM images confirmed the ZetaSizer measurements (Fig. 1). Fig. 1Open in figure viewerPowerPoint TEM images of prepared amorphous selenium particles a and b Nanoparticles stabilised by SDS c Nanoparticles stabilised by PS80 d Microparticles stabilised by tryptone Fig. 2Open in figure viewerPowerPoint Typical size distributions of prepared selenium micro and nanoparticles Table 1. Prepared samples and their sizes dependent on concentration of added surfactant Surfactant Concentration, g/l Average diameter, nm SDS 12.0 70 SDS 3.4 50 SDS 1.4 44 PS80 12.0 66 tryptone 7.1 650 The average size of particles prepared by using tryptone is particularly interesting, since the vast majority of particle diameters was over 100 nm (Fig. 2), thus over the size criterion for nanoparticle designation. This might be of high significance for the number of applications which need high particle surface, but where stricter legal rules are often applied for nanoobjects than for bigger entities. As far as we can observe, the sizes of the microparticles prepared by using the tryptone are not depending on tryptone concentration. Moreover, tryptone is used as a component of agars and as such is non-bactericidal. This could allow to perform some biological tests using micro-sized selenium. The amorphous structure of SeNPs was confirmed by X-ray diffraction (XRD) measurements and was compared with control crystalline sample prepared by reduction of sodium selenite by glucose (Fig. 3). Fig. 3Open in figure viewerPowerPoint XRD pattern of crystalline sample and prepared amorphous selenium SDS surfactant is a suitable reagent capable of changing average nanoparticles sizes (Table 1). With the increasing amount of added surfactant the average diameter also increases. We explain this phenomenon by reaction kinetics, when by increasing surfactant concentration the reaction proceeds slower and fewer, but larger particles are formed [[13]]. Samples stabilised by SDS also tend to form self-organised structures as shown in Fig. 1b. SDS as a strong anionic surfactant adds local negative charges to the surface of nanoparticles and therefore can cause repulsion of ball-like nanoparticles of selenium yet still bonded to dodecyl chains. This may lead to self-organising of the nanoparticles in some cases. This interesting property of SDS can be used in some future applications and researches. The possibility of using PS80 instead of SDS has also been examined. However, the sizes of obtained SeNPs were quite variable and relatively independent on PS80 concentration. Nevertheless, PS80 can be used in the case where the exact average nanoparticles sizes are not so important. In addition, PS80 can reduce unpleasant smell of selenium, similarly as PS20 [[13]]. All prepared nanoparticle samples (PS80 and SDS stabilised), were stable in colloid solution over few weeks of measurements. On the other hand, selenium microparticles prepared with tryptone tended to sedimentate in only few days due to their larger sizes. The mechanism of the formation of different sized nanoparticles prepared with the same surfactant and a certain degree of variability in their sizes can be explained by using concept of so-called coordination defects in amorphous selenium [[14]]. As these defects gather on the surface, various surfactants influence the extent and amount of the defects resulting in diverse sizes of the objects. 4 Conclusion Spherical nano and microparticles of amorphous selenium were prepared by facile reduction method. Tryptone and PS80 were used for the first time for stabilisation of SeNPs. SeNPs with tunable sizes were prepared by using SDS and PS80 as stabilisation agents. Selenium microparticles were prepared using tryptone. Samples were characterised by ZetaSizer measurements and TEM; the amorphous nature of prepared selenium was confirmed by XRD measurements. Our method enables quick preparation of SeNPs with tunable sizes usable for further research and applications. 5 Acknowledgments This work was supported by the Ministry of Interior of the Czech Republic (project VG20122015075). 6 References [1]Beheshti N. Soflaei S. Shakibaie M. et al.: 'Efficacy of biogenic selenium nanoparticles against Leishmania major: in vitro and in vivo studies', J. Trace Elem. Med. Biol., 2013, 27, (3), pp. 203– 207 (doi: 10.1016/j.jtemb.2012.11.002) [2]Kheradmand E. Rafii F. Yazdi M.H. et al.: 'The antimicrobial effects of selenium nanoparticle-enriched probiotics and their fermented broth against Candida albicans', Daru-J. Pharm. Sci., 2014, 22, (48) [3]Shakibaie M. Forootanfar H. 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