Sp Lab Report

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Possible antibacterial mechanisms of SNPs can be pointed to in 4 points:
a. Nanoparticles adhesion to the bacterial surface leading altering the properties of membrane. The small size and the large surface area of nanoparticles give power to form strong connection with the surface of microorganism (Wong and Liu, 2010). Now, the mostly popular understanding is that SNPs with diameters less than 20 nm get attached to proteins with sulfur group of the membranes of bacterial cell resulting in increasing the permeability of the membrane, which lead to bacterial death (Morones et al.,2005).
b. Internal penetration of the bacterial cell by SNPs, in the study of Choi and Hu, 2008 observed that SNPs less than 5 nm, which was more toxic than any
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Ag ions can also interference with DNA replication processes by interact with phosphorus group, which stops bacterial proliferation and decreases the number of cells over time (Wong and Liu, 2010) and (Cao et al., 2010). Moreover, Samberg et al., 2011 proposed that the antibacterial activity of Ag ions is caused by the synergistic effect between the binding of silver ions to the cell wall, their uptake and subsequent accumulation in the cell, and their interference with critical biomolecules within the cell. In contrast, Cao et al., 2011 mentioned that silver ions do not play an important role in the antimicrobial mechanism of metallic SNPs-modified films coated on titanium or titanium dioxide substrates.
We should also keep in mind, the formation of free radicals and induction of oxidative stress after uptaking of SNPs or silver ions Reactive oxygen species (ROS) can be generated outside the cell, in medium, or inside the cell, also as a consequence of cell damage/disruption (Wong and Liu, 2010), (Thannickal and Fanburg, 2000) and (Liu et al., 2010).According to (Choi and Hu, 2008) bacterial growth inhibition caused by all studied forms of silver was correlated with intracellular ROS levels but Photo catalytic ROS fraction
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