and toxicity of quantum dots of CdSe and PbSe on mice

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2 Νοε 2013 (πριν από 3 χρόνια και 5 μήνες)

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In vivo profiles of accumulation, elimination
and toxicity of quantum dots of CdSe and PbSe
on mice

Zikri

Arslan, PhD


Jackson State University

Department of Chemistry and Biochemistry



Colloidal semiconductor nanoparticles


The

term

"band

gap"

refers

to

the

energy

difference

between

the

top

of

the

valence

band

and

the

bottom

of

the

conduction

band
.


Nanometer size semiconductor particles (2
-
100 nm)


Synthesis
of colloidal semiconductors
nanocrystals
or quantum dots
have been studied since three decades
ago


Semiconductor
NPs exhibit electronic and optical properties
different from those of bulk solids
.


These properties arise from the increased number of surface atoms
that are often greater than those in the
core


These properties are
tunable by varying the particle size, surface
properties and
inter
-
particle integrations


CdSe

QDs possess important properties for
optoelectronics
and communications applications
within the
visible region


Fluorescent
(
brighter
and longer emission than
organic
dyes)

Cadmium
selenide

(
CdSe
) nanoparticles


Biomedical
imaging

Site
-
specific gene and drug delivery

Targeting specific biological and
cellular events

LED flat panel displays

Typical applications

Biomedical applications of
CdSe

QDs

QDs can be linked to
biological molecules,

such as peptides,
proteins, or nucleic acids.


CdSe

A
bility
to study genes, proteins, and
drug targets in cells, tissue
specimens, and live animals.


In vivo capabilities. Site
-
specific drug delivery

Ability to track cell and organ developments

over long periods of time.

PbSe QDs
possess important properties
for optoelectronic and communications
applications
within the infrared
region.


Narrow band
-
gap (0.27 eV),

Fast
response
time

UV
-
VIS
-
NIR
spectrum of
PbSe

QDs in hexane

Strong absorption ~
1430
nm

Stable and tunable
emission in the
NIR

Lead
selenide

(
PbSe
) nanoparticles


Telecommunications (1300
-
1600 nm)

Biological imaging (transparent tissue
windows
at

800
and 1100 nm)

Solar cells
& conversion (800
-
2000
nm
)

Photovoltaic applications

Typical applications

Toxicity of semiconductor NPs


CdSe

and
PbSe

NPs
are made up of heavy metals (
Cd,
Pb

and Se)


Cd and
Pb

compounds
are
toxic
even in low
concentrations


Selenium has both beneficial and harmful
effects


QD toxicity
depends on both their
properties



physiochemical
-

size
, charge, concentration, capping
material
and
functional groups, core stability



environmental
conditions

Oxidative, photolytic, mechanical stability, route of exposure


To investigate accumulation/distribution of
CdSe

and
PbSe

nanoparticles on in vivo on mice



To determine pathways of elimination



To determine toxic effects associated with exposure

Objectives

Materials & Methods

λ
max

= 548 nm,
d
ave

= 3.0 nm

CdSe

= 12.5 mg/mL

Thiol
-
capped CdSe NPs in water

[Cd] = 68
mM
, [Se] = 59
mM

Cd:Se

= 1.2:1

Aqueous solutions of CdSe were exposed to UV light
(365 nm) for 2 h to affect stability.

Silica
-
encapsulated
PbSe NPs

TEM image of TGA
-

PbSe bare
NPs

TEM image of PbSe
-
SiO
2

NPs ~ 25 nm

TGA
-
capped
PbSe
NPs
(left); silica
encapsulated PbSe
NPs
(middle); and
concentrated solution of PbSe
-
SiO
2

core
-
shell
NPs
(right) (~ 700
ppm).

Exposure to
CdSe

QDs


Single

injection

of

0
.
3

mL

of

NPs

(
12

mg/mL
)

via

tail

vein

(either

UV
-
exposed

(w/UV)

or

UV

unexposed

NPs

(
wo
/UV)
.



Three

animals

were

sacrificed

from

each

group

periodically

on

the

1
st,

7
th

and

14
th

day

of

injection
.



Organs,

intestine,

kidney,

liver,

lung,

heart,

brain

and

spleen,

were

collected
.



Urine

and

feces

were

collected

at

12

h,

24

h,

48

h,

and

on

the

7
th

and

14
th

day
.



Exposure to
PbSe

QDs

Single

injection

of

0
.
3

mL

of

NPs

(
700

ppm)

was

made

through

tail

vein
.


Five

animals

were

sacrificed

periodically

on

the

1
st
,

7
th
,

14
th
,

21
st
,

35
th

and

42
nd

day

of

injection
.

Intestine
,

kidneys,

liver,

lungs,

heart,

brain

and

spleen,

were

collected
.


Urine

and

feces

were

collected

at

12

h,

24

h,

48

h,

and

on

the

7
th
,

14
th
,

21
st
,

35
th

and

42
nd

day

of

injection
.


Procedures


Quantitative

analysis


Organs were digested in acid and analyzed for Cd and Se
content by ICP
-
MS.



Toxicity

(lipid

peroxidation)


Malondialdehyde

assay (MDA) was conducted on the
liver samples to determine oxidative stress.

Accumulation of
CdSe

NPs

Temporal accumulation of
Cadmium

Accumulation of
PbSe

NPs

Temporal accumulation of
PbSe

NPs

Fecal elimination of Cd and
Se

Urinary elimination of Cd and Se (µg/mL)

Toxic effects of CdSe NPs

Elimination of
PbSe

QDs

CdSe

NPs
-

Oxidative stress

PbSe

NPs
-

Oxidative stress