Civil Engineering Reference
In-Depth Information
UV
Electron-donar/acceptor
active group
O
2
Example:
HO OH
CCR
O
2
•
-
O
2
e
-
O
h
+
Material
composition, e.g.,
discontinuous crystal
planes and defects,
generating active
electronic
conigurations
e
-
O
2
•
-
UV activation of
electron hole pairs
leading to bond
splitting and radical
formation
HO
CR
O
Redox cycling and
catalytic chemistry
via coating metals
(e.g., Fe)
and organics
(e.g., quinones)
e
-
Media interactions by
particle dissolution,
coating, passivation
and hydrophobicity/
hydrophilicity
Disslolution
Coating may protect the
surface, change cellular
uptake or could lead to
release of toxic chemicals
Q
+-
Q
Fe
++
O
2
O
2
•
-
Passivation
H
2
O
Q = quinone
Q
•
-
= semiquinone
H
2
O
2
H
2
O
OH
•
Hydrophobicity
→
interactions with
cell membranes, determining uptake
hydrophilicity
→
water suspendability
Fenton chemistry
16.9
Effect of reactive oxygen species in cells (adapted from Wani
et al.
, 2011).
DNA strand breaks,
covalent modiication of DNA
Metallothionein induction
Protein
oxidation
Nanoparticles
or metals
•
OH + OH
-
Liqid
peroxidation
Redox cycle
Superoxides
O
2
•
-
SOD
Catalase
H
2
O + O
2
H
2
O
2
O
2
Intermediate from
oxyradical attacks
RH
•
GPx
RH
2
+ GS
•
GSH
GSH
reductase
H
2
O + O
2
GSSG
•
-
+ O
2
GS
-
GSSG
16.10
Interaction and the adverse effects of nanoparticles on
biological systems (adapted from Wani
et al.
, 2011).
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