Open AccessRevisiting spontaneous silver nanoparticles formation: a factor influencing the determination of minimum inhibitory concentration values?
Author(s) -
Karolı́na Šišková,
Renáta Večeřová,
Hana Kubičková,
Magdaléna Bryksová,
Klára Čépe,
Milan Kolář
Publication year - 2015
Publication title -
aims environmental science
Language(s) - English
Resource type - Journals
eISSN - 2372-0352
pISSN - 2372-0344
DOI - 10.3934/environsci.2015.3.607
Subject(s) - silver nanoparticle , chemistry , amino acid , glutamine , composition (language) , minimum inhibitory concentration , covalent bond , nanoparticle , ion , nuclear chemistry , stereochemistry , nanotechnology , biochemistry , organic chemistry , materials science , in vitro , linguistics , philosophy
The present study gives evidence that silver nanoparticles (AgNPs) are spontaneously formed from Ag+ ions in Mueller-Hinton broth, which is frequently used as a standard cultivation medium for many types of bacteria. Silver ions often serve as a reference in the determination of minimum inhibitory concentration (MIC) values of engineered AgNPs. It is thus a question if the MIC values determined for engineered AgNPs are not influenced by the presence of spontaneously formed AgNPs. Furthermore, as shown here, the addition of augmented concentrations of selected amino acids, namely glutamic acid and glutamine, can change the growth and characteristic features of spontaneously formed AgNPs. For the sake of a direct comparison, the influence of the two selected amino acids on characteristics and MIC values determination of engineered AgNPs has been also investigated. The determined MIC values of all investigated systems (i.e., with and without the presence of engineered AgNPs) and their mutual comparison demonstrated that MIC values are slightly influenced by the actual composition of a cultivation medium for bacterial growth. On the other hand, the actual composition of a cultivation medium is crucial for the final characteristics of AgNPs. The changes in characteristic features of spontaneously formed as well as engineered AgNPs are most probably induced by the covalent bonding of amino acids to AgNPs surface which is proven by vibrational spectroscopic techniques