Nanochemistry and biotechnology

Green synthesis and antimicrobial activity of silver nanoparticles
Kytsya A.R., Pokynbroda T.Ya., Bazylyak L.I., Karpenko O.V.
Department of Physical Chemistry of Fossil Fuels, InPOCC NAS of Ukraine. Naukova Str., 3a, Lviv, 79060, Ukraine.
E-mail: kytsya@nas.gov.ua

Silver nanoparticles (AgNPs) have been synthesized at 70 C via the mixing of 1 mL of 0.1 M AgNO3 solution with 100 ml of 1 g/L solutions of biosurfactants of microbial origin – rhamnolipids (RL) and rhamnolipid biocomplex (RBC) that were prepared as it is described in [1]. In our case used biosurfactants are both reducing agents and stabilizers due to their polyfunctionality. In all of cases the formation of stable AgNPs-containing sols were proved by UV/vis spectroscopy and using chloride test 100 % conversion of Ag+ ions were observed.
Antimicrobial activity of obtained sols have been evaluated according to their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) [2]. It was found (see Table) that the best antimicrobial activity is inherent for AgNPs modified by RBC.
Table. Antimicrobial activity of biosurfactants and their compositions with AgNPs against Agrobacterium tumefaciens
	RL	RBC	RL+AgNPs	RBC+AgNPs	
	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	
Dilution	1:50	1:25	1:100	1:50	1:200	1:100	1:800	1:400	
Probably, this fact can be explained by the higher affinity of RBC to the cell membrane which facilitates the interaction of silver with the microorganism. However, such an assumption requires more detailed investigations and will be considered in a separate article.

1.	Klosowska-Chomiczewska I. E., Medrzycka K., Hallmann E., Karpenko E., Pokynbroda T., Macierzanka A., Jungnickel C. Rhamnolipid CMC prediction // J Colloid Interface Sci.-2017.-488.-P. 10-19.
2.	Sotirova A., Avramova T., Stoitsova S., Lazarkevich I., Lubenets V., Kar-penko E., Galabova D. The importance of rhamnolipid-biosurfactant induced changes in bacterial membrane lipids of Bacillus subtilis for the antimicrobial activity of thiosulfonates // Curr Microbiol.-2012.-65.-P. 534-541.