Environmental Engineering Reference
In-Depth Information
surface presents a toxic environment for pathogens such that they will
be killed or rendered nonvirulent when present on the surface; therefore
resulting in reduced proliferation and amount of pathogens and reduced
risk of infection or illness due to the presence of pathogens. Hence, medi-
cal devices which may or may not be incorporated into the body, such
as needles or implants and the like, that have been modii ed to include a
surface characterized by selenium nanoparticles or selenium nanoclusters,
have antipathogenic properties.
12.6.3 Metal Oxides
Nanoparticulate metal oxides show antimicrobial activity against peri-
implantitis pathogens. Dental plaque accumulation may result in peri-
implantitis, an inl ammatory process causing loss of supporting bone that
may lead to dental implant failure. h e antimicrobial activities of six metal
and metal oxide nanoparticles and two of their composites against bac-
terial pathogens associated with peri-implantitis were examined under
anaerobic conditions. h e activities of nanoparticles of silver (Ag), cuprous
oxide (Cu
2
O), cupric oxide (CuO), zinc oxide (ZnO), titanium dioxide
(TiO
2
), tungsten oxide (WO
3
), Ag+CuO composite and Ag+ZnO compos-
ite were assessed by minimum inhibitory (bacteriostatic) concentration
(MIC) and minimum bactericidal concentration (MBC) determination
against
Prevotella intermedia
,
Porphyromonas gingivalis
,
Fusobacterium
nucleatum
and
Aggregatibacter actinomycetemcomitans.
Time-kill assays
were carried out to examine the dynamics of the antimicrobial activity
with ZnO nanoparticles. h e MIC and MBC values were in the range of
<100 μg/mL to 2500 μg/mL and <100 μg/mL to >2500 μg/mL, respectively.
h e activity of the nanoparticles tested in descending order was Ag>Ag+C
uO>Cu
2
O>CuO>Ag+ZnO>ZnO>TiO
2
>WO
3
. Time-kill assays with ZnO
demonstrated a signii cant decrease in growth of all species tested within
4h, reaching 100% within 2h for
P. gingivalis
and within 3h for
F. n u c l e a -
tum
and
P. i n t e r m e d i a
. Coating titanium surfaces of dental and orthopedic
implants with antimicrobial nanoparticles should lead to an increased rate
of implant success.
12.6.4
N-phenyl- and N-benzoylthiourea Derivatives
N-phenyl-and N-benzoylthiourea derivatives display selective antimi-
crobial activities against
Cladosporium cladosporioides, B. subtilis
and
Micrococcus luteus
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