The influence of physical-chemical characteristics of surface modified copper nanoparticles on E. coli cell population growth suppression and on electrostatic properties of their membranes
The biological activity of copper nanoparticles, able to suppress growth of E. coli cells population under contact interactions, was explored. Three types of samples with oxide layers of various sizes, thickness and composition were used in experiments. It was found out, that an increase in electron density on the external membrane of E. coli correlated with copper nanoparticles suppression capability and with lower activation energy of electron transfer on bacteria. The analysis of experimental data helps to correct conditions for obtaining nanoparticles with certain properties of their surface oxide layers. The character of temperature dependence of electron density reveals the electron type of conductivity in contact area of E. coli and nano-particles. These results help to find approach to understanding the nature of toxic influence of copper nano-particles on E. coli cells under contact interaction.
Environmental aspects of the use of ultrafine particles SiO2 (as exemplified by Solanum tuberosum)
The interest in the use of ultrafine particles in crop production and agricultural practice is associated with the unique properties of ultrafine particles (UFP). At the same time, it is obvious that artificial nanoobjects can have toxic properties. Therefore, for further development of nanotechnologies, a clearer understanding of both the properties of nanomaterials themselves and the mechanisms of their interaction is needed. The article presents studies on the effect of ultrafine particles of silicon dioxide on plants Solánum tuberósum. According to the results of research nano-silica at a concentration of 0.21 and 0.36 g/kg had a statistically significant effect on the number of cell integrity (a decrease to 17.1 % was observed). It was revealed that after processing potato tubers with UFP silicon oxide at a concentrations of 0.09 and 0.18 g/kg, they had a significant influence on the activity of peroxidase. The results of the studies revealed the toxicity of UFP SiO2 at a maximum dilution of 0.36 g / kg, which confirmed a decrease in the intensity of the luminosity peaks of DNA a temporally calculated linear profile. Therefore, assessing the impact of SiO2 use is of great importance for understanding the long-term environmental impact of UFP.
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.