RO132298B1 - Process for preparing composite materials based on zinc oxide with bacteriostatic and bactericidal properties - Google Patents

Description

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RO 132298 Β1

The invention relates to a process for obtaining materials with bacteriostatic and bactericidal activity, namely, zinc oxide-carbohydrate and / or polyol composites, respectively, zinc oxide obtained by calcination of these composites, by a method which uses as raw materials zinc salts and carbohydrates of the monosaccharide, disaccharide and polysaccharide type or polyol type alcohols.

Known from the article "Low-Temperature Wafer-Scale Production of ZnO Nanowire Arrays", Lori E. Greene, Matt Law, Joshua Goldberger, Franklin Kim, Justin C. Johnson, Yanfeng Zhang, Richard J. Saykally Prof., Peidong Yang Prof. Angew. Chem. Int., Vol. 42, 2003, pp. 3031-3034, a process for the synthesis of zinc oxide on silicon wafers in several layers, obtaining ZnO nanoparticles with a diameter of less than 30 nm, which can be efficient in the interaction with various cells bacterial.

It is also known from the article “Selective toxicity of ZnO nanoparticles towards Gram-positive bacteria and cancer cells by apoptosis through lipid peroxidation” - Mariappan Premanathan PhD, Krishnamoorthy Karthikeyan MTech, Kadarkaraithangam Jeyasubramanian PhD, Govindasamy Manivannic Biotech, Nanotech Medicine, Voi. 7, April 2011, pp. 184-192, the fact that the antibacterial activity of ZnO was tested against the gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, as well as the gram-positive bacterium Staphylococcus aureus.

The literature mentions two types of processes for the synthesis of zinc oxide: processes either in the vapor phase - deposition by sputtering [W. T. Chiou, W. Y. Wu, J. M. Ting, Diam. Relat. Mater. 12 (2003) 1841], chemical vapor deposition [S. C. Lyu, Y. Zhang, H. Ruh, H. J. Lee, H.-W. Shim, E. K. Suh, C. J. Lee, Chem. Phys. Lett. 363 (2002) 134, J. J. Wu, S. C. Liu, J. Phys. Chem. B 106 (2002) 9546,. H. Huang, S. Mao, H. Feick, H. Yan, Y. Wu, H. Kind, E. Weber, R. Russo, P. Yang, Science, 292 (2001) 1897, M. Satoh, N. Tanaka, Y. Ueda, S. Ohshio, H. Saitoh, Jpn. J. Appl. Phys. 38 (1999) 586], chemical vapor deposition of metal-organic compounds [W. I. Park, J. S. Kim, G. C. Yi,. H. Bae, H. J. Lee, Appl. Phys. Lett. 85 (2004) 5052, J. B. Baxter, E. S. Aydil, Appl. Phys. Lett. 86 (2005)], thermal evaporation [Y. G. Wang, C. Yuen, S. P. Lau, S. F. Yu,

B. K. Tay, Chem. Phys. Lett. 377 (2003) 329, W. L. Hughes, Z. L. Wang, Appl. Phys. Lett. 82 (2003), X. Y. Kong, Z. L. Wang, Nano Lett. 3 (2004) 1625], or in solution-precipitation [M.

I. Y. Cao, B. Liu, R. Huang, Z. Xia, S. Ge, Mater. Lett. 65 (2011) 160, Y. Wang, C. Zhang,

S. Bi, G. Luo, Powder Technol. 202 (2010) 130], sol-gel [Η. M. Cheng, H. C. Hsu, S. L. Chen, W. T. Wu, C. C. Kao, L. J. Lin, W. F. J. Hsieh, Cryst. Growth. 277 (2005) 192, V.

C. de Sousa, M. R. Morelli, R. H.G. Kiminami, Ceram. Int. 26 (2000) 561, A. K. Zak,. E. Abrishami, W. H. Abd Majid, R. Yousefi, S. M. Hosseini, Ceram. Int. 37 (2011) 393], hydrothermal method [Z. Fang, K. B. Tang, G. Z. Shen, D. Chen, R. Kong, S. J. Lei, Mater. Lett. 60 (2006) 2530, A. Eftekhari, F. Molaei, H. Arami, Mater. Sci. Eng. A 437 (2006) 446,

J. M. Wang, L. Gao, J. Cryst. Growth 262 (2004) 290] and solvothermal [S. K. N. Ayudhya, P. Tonto, O. Mekasuwandumrong, V.Pavarajarn, P. Praserthdam, Cryst. Growth Des. 6 (2006) 2446, J. Ma, C. Jiang, Y. Xiong, G. Xu, Powder Technol. 167 (2006) 49], the microemulsion method [D. Kaneko, H. Shouji, T. Kawai, K. Kon-No, Langmuir 16 (2000) 4086, X. Li, G. He, G. Xiao, H. Liu, M. Wang, J. Coli. Inter. Scie. 333 (2009) 465], ultrasonic irradiation [S. H. Jung, E. Oh, K.H. Lee, Y. Yang, C.G. Park, W. Park, S.H. Jeong, Cryst. Growth Des. 8 (2008) 265, P. Mishra, R. S. Yadav, A. C. Pandey, Ultrasound. Sonochem. 17 (2010) 560] and microwave [D. K., Nanoscale Res. Lett. 3 (2008) 31],

RO 132298 Β1

The disadvantage of steam methods is the use of sophisticated and complex equipment, which requires a high vacuum, high temperatures, the use of toxic gaseous compounds, which will ultimately lead to a substantial increase in manufacturing costs. 3 The advantages of the chemical methods that take place in the solution consist in their relative simplicity, a lower energy consumption and the ease of expansion to a medium and large scale production. 5 In addition, the processes in solution allow the use of additives as growth modifiers / inhibitors, which are usually compounds of an organic nature. Given that the size 7 and the shape of the materials greatly influence the properties of the materials, the presence of additives is a way to modify and / or improve the properties of these materials and, implicitly, to diversify 9 the applications [N. Lepot, Μ. K. Van Bael, H. Van den Rul, J. D'Haen, R. Peeters, D. Franco, J. Mullens, Mater. Lett. 61 (2007) 2624, T. L. Sounart, J. Liu, J. A. Voigt, J. W. P. Hsu, 11

E. D. Spoerke, Z. R. Tian, Y. Jiang, Adv. Function. Mater. 16 (2006) 335], These chemical methods have as an important disadvantage the toxicity of the raw materials of both precipitating agents 13 and solvents, as well as of the additives used.

The technical problem solved by the invention consists in obtaining a composite material based on zinc oxide with high bacterostatic and bactericidal activity, by a simple process, at temperatures up to 600 ° C. 17

The material consists of nanometric-sized zinc oxide crystallites, assembled into hierarchical structures, and various carbohydrates / carbohydrate fragments or 19 polyols / polyol fragments. The obtained material eliminates the disadvantages of using expensive raw materials, additives and solvents, of a complex apparatus, as well as of long thermal treatments, at high temperatures, being at the same time simple, fast, reproducible and applicable on an industrial scale. 2. 3

Although antibiotics have been and remain essential drugs for the prophylaxis and treatment of bacterial infections, the emergence of the phenomenon of antibiotic resistance has become a key public health issue globally. ZnO nanoparticles, with a diameter of less than 30 nm, can be effective in interacting with various 27 gram negative and gram positive bacterial cells. The stability of ZnO nanoparticles can be ensured by coating them with either natural or synthetic polymers or surfactants, such as decanoic acid, oleic acid or hexaldehyde. These processes lead to more stable colloidal suspensions, with small particles, high quality and good biocompatibility.

The use of carbohydrates in the synthesis of materials (metals, oxides, sulfides, nitrides, alloys, 33 composites) is a way to eliminate the use of toxic synthetic raw materials, and their replacement with bioregenerable raw materials, especially abundant, cheap and non-toxic. 35 The purity of the zinc oxide phase, the shape and the size of the crystallites strongly depend on the nature of the polysaccharide used, and on the synthesis parameters used. The use of polyalcohols in the synthesis of 37 materials (metals, alloys, oxides, sulfides and fluorides) is a way to eliminate the use of additional additives, the polyols acting both as solvents and as growth modifiers 39 of the nanoparticles, the resulting compounds having a high crystallinity and an organophilic surface. And in this case the purity of the zinc oxide phase, the shape and size of the crystallites 41 strongly depend on the nature of the polyol used and the synthesis parameters used.

The process for obtaining the composites zinc oxide - carbohydrate, zinc oxide - polyol 43 and zinc oxide, according to the invention, obtained by thermal calcination of the two types of composites, uses as a source of zinc its salts such as acetate, nitrate, acetylacetonate , 45 sulphate, chloride, etc., and as growth inhibitors or changes in morphology, carbohydrates such as monosaccharide, disaccharide and polysaccharide, or polyols such as 1,4-butanediol, 1,2-47 propanediol or diethylene glycol.

The production process according to the invention involves temperatures of up to 200 ° C, in the absence or presence of environmentally friendly precipitating agents, such as triethanolamine, urea, etc., and a reaction time of up to 72 h. The removal of the carbohydrate or polyol is carried out at temperatures less than or equal to 700 ° C.

RO 132298 Β1

The composites and oxides obtained have various morphologies (wire, rod, disc, perforated sphere, solid sphere, cylinder, flower, etc.) and crystallite sizes up to 300 Â. The compounds zinc oxide carbohydrate, zinc oxide - polyol, as well as the zinc oxide resulting from their calcination show high bacteriostatic and bactericidal activity against microbial cells in planktonic and adherent phase, developed in the form of biofilms, gram negative and gram positive.

The process according to the invention has the following advantages:

- the use as a source of zinc of its salts such as acetate, nitrate, acetylacetonate, chloride, sulphate, etc., which are cheap and non-toxic raw materials;

- use as a coordinating agent, precipitation, template and stabilization of triethanolamine, urea, etc. which are also cheap and non-toxic raw materials;

- use as growth inhibitors or changes in the morphology of carbohydrates or polyols, cheap raw materials;

- use of monosaccharide, disaccharide and polysaccharide carbohydrates;

- use of glucose, fructose, mannose, etc. as a monosaccharide;

- use of sucrose, lactose, maltose, etc. as a disaccharide;

- use of starch, methylcellulose, dextran, alginate, carrageenan, etc. as a polysaccharide;

- use of polyols as reaction medium, coordinating agent, template and stabilizer;

- use of 1,4-butanediol, 1,2-propanediol or diethylene glycol polyols;

- the development of the hydrothermal process and the hydrolytic decomposition process, which take place at low temperatures of up to 200 ° C, in a time varying between 10 min and 72 h;

- the production of zinc oxide from composites takes place at temperatures less than or equal to 600 ° C, following a calcination which varies between 1 h and 5 h;

- synthesis of zinc oxide - carbohydrate, zinc oxide - polyol composites and zinc oxide obtained by thermal calcination of the two types of composites with high bacteriostatic and bactericidal activity against planktonic microbial cells and in the form of biofilms, gram negative and gram positive;

- the process is simple, fast, cheap, reproducible and friendly, being applicable on an industrial scale.

The following are three embodiments of the invention.

Example 1 g of Zn (acac) ₂ was dissolved in 15 ml of 1,4-butanediol. The mixture was refluxed at 90 ° C and 140 ° C for 2/4 h, respectively, to give a white precipitate. The resulting product is zinc oxide, the precipitate being washed with ethanol and separated by centrifugation, and then dried at 70 ° C for 20 h.

Example 2

680 mg of sucrose, 219 mg of Zn (CH ₃ COO) ₂ · 2H ₂ O and 0.6 ml of triethanolamine are stirred by stirring for half an hour. The mixture is transferred to a Teflon container and placed in the oven at 90 ° C for 2 hours. The product obtained is washed by centrifugation with water and ethanol, then dried at 70 ° C for 10 h, obtaining the ZnO-sucrose composite. Calcination of this compound at 500 ° C for 1 h leads to the formation of ZnO.

Example 3

0.2 g of sodium alginate is dissolved in 20 ml of deionized water at a temperature of 90 ° C. Separately solubilize 1.5 g of Zn (NO ₃ ) ₂ · 6H ₂ O in 20 ml of deionized water. The sodium alginate solution is added with stirring at room temperature, over the zinc nitrate solution, when the formation of a tube-shaped hydrogel is observed. This hydrogel is washed with deionized water and separated by repeated centrifugation. The product obtained is dried at 75 ° C for 10 h, and then calcined at a temperature of 500 ° C for 1 h, when the zinc oxide is formed.

Claims (5)

Claims 1 1. Process for the production of zinc oxide composites, 3 characterized by a hydrothermal synthesis of zinc oxide carbohydrate or zinc-polyol oxide composites, with or without precipitators, with a reaction time of 5 up to 72 h, by a hydrolytic decomposition reaction occurring at temperatures up to 200 ° C. 7 Process for the production of zinc oxide-based composites according to Claim 1, characterized in that the acetate, 9 nitrate and zinc sulphate salts are used as zinc sources, and carbohydrates of the type are used as growth inhibitors. monosaccharide, disaccharide, polysaccharide or polyols such as diethylene glycol, 1,2-propanediol or 1,4-butanediol, and as precipitating agents - triethanolamine or urea. Process for obtaining zinc oxide-based composites according to claim 1, characterized in that the composites obtained have bacteriostatic and bactericidal properties against pathogens, in planktonic and adherent phase, developed as 15 gram-type biofilms negative as well as gram positive. Process for the production of zinc oxide composites according to Claim 1, characterized in that the zinc oxide is obtained by decomposing the zinc oxide-carbohydrate or zinc-polyol oxide composites at temperatures of less than or equal to 19 at 600 ° C, a time between 1 and 5 h. Process for obtaining zinc oxide-based composites according to claim 1, characterized in that the morphology of the composites obtained varies from one-dimensional structures to three-dimensional structures. 2. 3