Biomedical Engineering Reference
In-Depth Information
TABLE 8.6 % Cell Death from Exposure to IOMNPs
IOMNPs
Concentrations, mg/mL
IOMNPs w/
polymer~COOH
coating, 5 nm
0.2
0.1
0.05
% Cell death
2.04 ± 0.48
1.86 ± 0.36
0.50 ± 0.11
IOMNPs w/
polymer~COOH
coating, 10 nm
0.2
0.1
0.05
% Cell death
2.05 ± 0.97
2.77 ± 1.06
1.45 ± 0.47
Control
2.80 ± 1.26
to cause microorganism resistance than conventional antibiotics.
196,197
Because
of these antimicrobial characteristics, AgNPs are used for water purification
198
and wound dressing to disinfect microorganisms.
198-200
AgNPs can be coated
on common polyurethane foams through its interaction with the nitrogen atom
of the polyurethane.
199
The wound dressing with AgNPs exhibited better wound
healing capacity, improved cosmetic appearance, and scar-less healing in an
animal model.
200
A number of studies have shown that AgNPs have efficient antibacterial
activity compared with their bulk counterpart due to high surface-to-volume
ratio providing better contact with microorganisms.
201
TEM studies revealed
that the majority of AgNPs get localized on cell membranes that appeared
severely damaged as indicated by the presence of numerous pits and gaps.
202-204
AgNPs may also damage the permeability of bacterial membranes causing
efflux of reducing sugars and proteins and depletion of intracellular adenosine
triphosphate (ATP).
203,205
AgNPs can cause destabilization of the outer mem-
brane causing the plasma membrane potential to collapse.
206
It has also been
observed that expressions of several cell envelope proteins were stimulated
after a short exposure to AgNPs.
205
It has also been claimed that AgNPs inside
the bacterial cell attack the respiratory chain by interacting with thiol groups
of essential enzymes that lead to their inactivation and also dephosphorylate
peptides on tyrosine residues that could influence bacterial signal transduction
which eventually leads to cell death.
207
All these studies had focused on the
description of damage and mode of action of AgNPs on exposed bacteria, but
the primary reason for the induced antimicrobial effects remains unclear.
Silver NPs (AgNPs) are, due to their antimicrobial properties, the most
widely used NPs in commercial products. AgNPs are incorporated into medi-
cal products like bandages as well as textiles and household items.
208
AgNPs
are also known to induce toxicity in many different species
209
and in humans,
