Biomedical Engineering Reference
In-Depth Information
Table 10.1
Nanoparticle Cytotoxicity to Mammalian Cells
Nanoparticles
Cytotoxicity Mechanism
TiO
2
ROS production
Glutathione depletion and toxic oxidative stress
Cell membrane disruption
ZnO
ROS production
Dissolution and release of toxic cations
Lysosomal damage
Inflammation
Ag
Dissolution and Ag
1
ion release inhibits respiratory enzymes and ATP production
ROS production
Disruption of membrane integrity and transport processes
Gold
Disruption of protein conformation
SiO
2
ROS production
Protein unfolding
Membrane disruption
Cu/CuO
DNA damage and oxidative stress
Adapted from Ref.
[25]
.
an increase in antimicrobial efficacy with a reduction in particle size. Again, gram-negative bacteria
were more affected than gram positive, which suggests that a membrane damage mechanism of
action rather than one involving the production of ROS is of overriding significance. Polyethylene
glycol-capped nanoparticles were found to be highly toxic to human cells with a very low
concentration (at 100
M) threshold for cytotoxic action, whereas the concentration for antibacterial
activity was 50 times greater (at 5 mM). It is hypothesized that the toxicity to eukaryotic cells
is related to nanoparticle-enhanced apoptosis by upregulation of the Fas ligand on the cell
membrane
[105]
.
An understanding of the interface between biological systems and nanomaterials should enable
design features to be used to control the exposure, bioavailability, and biocatalytic activities. A
number of possible approaches are now being identified
[25]
including changing the ability to
aggregate, application of surface coatings, and altering charge density and oxidative state.
However, this may well compromise the intended selective toxicity of antimicrobial nanoparticles.
It remains to be determined how potential mammalian toxicity issues will fully impact on the use
of nanotechnology in the control of oral biofilms.
μ
10.7
Conclusions
The application of nanoscaled antimicrobials to control oral infections, as a function of their
biocidal, antiadhesive, and delivering capabilities, is of increasing interest. Their use as constituents
of prosthetic device coatings, topically applied agents, and within dental materials is currently
being explored. Future developments are likely to concentrate on those nanoparticles with maximal
antimicrobial activity and minimal host
toxicity. Antimicrobial nanoparticulate metals have
