Question

a) Why is it important to evaluate the effects of nanoparticles on bacteria?

b) How do nanoparticles cause nucleic acid damage?

Answer 1

a) It is important to evaluate the effects of nanoparticles on bacteria because:

Nanotechnology approaches using engineered nanoparti-
cles with biocidal properties (e.g. Ag, Zn, Cu, Ce and Ni)
offer novel applications, including control of unwanted
microbial colonization on diverse surfaces and prevention
of biofouling, improved waste-water treatment and drink-
ing water purification and the prophylaxis and topical
treatment of infectious diseases.

In contrast, the extensive use of engineered nanoparticles with antimicrobial properties and their increased release into the environment have raised major concerns due to potential (eco)toxicological effects and inappropriate testing methods.

At present, there are virtually no applicable standard meth-
odologies for evaluating the effects of exposure of micro-
bial biota to nanoparticles, regardless of whether these
are favourable effects (e.g. against pathogens) or adverse
impacts in the environment.

b) Nanoparticles cause nucleic acid damage.There are several different mechanisms that have been identified.

If nanoparticles are small enough, they can enter the nuclear pore and get transported into the nucleus, where they could interact directly with DNA. There, the particles may be binding to the DNA, and that potentially causes all kinds of havoc.

One of the predominant mechanisms is through nanoparticles also producing free radicals. Some nanoparticles, if they're based on certain metals, can interact with the hydrogen peroxide that is present in every cell, and convert it to a hydroxyl radical, which can enter the nucleus and can potentially damage DNA.

Some nanoparticles actually can enter cells through endocytosis, where they are engulfed by a vesicle in the cell membrane. If enough of them enter, they can increase the oxidative stress in the cell.

At that point, the cell recruits different types of neutrophils or macrophages to the spot, involving enhanced production of free radicals, which can travel throughout the cell. That's actually a natural response to an exogenous particle entering a cell.

But nanoparticles can exceed the natural antioxidant defense system of a cell. There's so much hydroxyl being produced that the cell can't handle the increased level causing oxidative burst that may overwhelm the cells.

Ps- An upvote would be highly appreciated

Thanks!