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Generation of radicals by doped TiO2 nanopowders in presence of visible and UV light and skin
protection from UV radiation by nanoparticles
A.P. Popov1,2, A. Sarkar3, K. Kordas3,4, M. Meinke5, J. Lademann5, A.V. Priezzhev2,6, R. Myllylä1, V.V. Tuchin1,7,8, J.-P. Mikkola3,
M. Darvin5
1Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Oulu, Finland
2International Laser Center, Moscow State University, Moscow, Rissia 3Technical Chemistry, Department of Chemistry, Umeå University, Umeå,
Sweden 4Microelectronics and Materials Physics Laboratories, Department of Electrical
and Information Engineering, University of Oulu, Oulu, Finland 5Center of Experimental and Applied Cutaneous Physiology, Department of
Dermatology, Universitätsmedizin Charité Berlin, Berlin, Germany 6Physics Department, Moscow State University, Moscow, Rissia
7Institute of Optics and Biophotonics, Saratov State University, Saratov, Russia 8Institute of Precise Mechanics and Control of RAS, Saratov, Russia
2
Outline
• Finland, Oulu, University of Oulu
• TiO2-nano, phototoxicity
• TiO2-nano in skin
• UV protection by TiO2-nano: simulations
• Conclusion
3
Facts about Finland
Independent: 1917European Union: 1995Euro: 1999
Population: 5.3 millionMarked area: 63% of populationHelsinki & beyond: 1 millionOfficial languages: Finnish, SwedishNeighbours: Russia, Sweden, Norway
HELSINKI
OULU
ROVANIEMI
4
Facts about Oulu
Founded: 1605 by King Karl IX of SwedenPopulation: 130.000 (No. 6 in Finland),180.000 (from 2013, No. 5 in Finland)Location: by Gulf of Bothnia Helsinki - 650 km, Arctic Circle – 200 km
5
FACULTIES
FACULTY OF HUMANITIES
FACULTY OF EDUCATION
FACULTY OF ECONOMICS AND BUSINESS
ADMINISTRATION
FACULTY OF SCIENCE
FACULTY OF MEDICINE
FACULTY OF TECHNOLOGY
BOARD RECTOR VICERECTORS
ADMINISTRATION
FOCUS AREAS
BIOCENTER OULU
LABORATORIES
INFOTECH OULU
THULE INSTITUTE
MATHEMATICS
ELECTRONICS
OPTOELECTRONICS AND MEASUREMENTS
MICROEL. & MATERIALS PHYSICS
INFORMATION PROCESSING
COMPUTER ENGINEERING
DEPARTMENTS
Architecture
Mechanical Engineering
Process and Environmental Engineering
Electrical Engineering
Industrial Engineering
TELECOMMUNICATION AND CWC
MICRO AND
NANOTECHNOLOG
Y CENTER
University of Oulu
Founded: 1958Students: 16.000 (No. 3 in Finland)Staff: 3000
6
Optoelectronics and Measurement Techniques Laboratory
Head: Prof. Risto MyllyläFinland Distinguished Professors (FiDiPro):• Valery Tuchin (Saratov State University, Russia), biophotonics• Ghassan Jabbour (King Abdullah University of Science and Technology, Saudi Arabia), printable electronicsStaff (researchers, teachers, students): 50
ResearchAreas: biophotonics (blood, skin), printable electronics (OLEDs, OPV)Biophotonics techniques: DOCT, OCT, Optical tweezers, PAS, TOF
Collaboration
Australia, Finland, Germany, Japan, Korea, Poland, Russia, Sweden, Taiwan, Saudi Arabia, USA
7
Solar spectrum
Absorption in stratosphereSolar spectrum
UV rangeUVC: 100 – 280 nm (absorbed by ozone layer)UVB: 280 – 315 nmUVA: 315 – 400 nmVisible range: 400-750 nm
Wavelength, um Wavelength, nm
reach Earth surface
8
280 300 320 340 360 380 400
0.000
0.001
0.002
0.003
0.004
0.005
0.006U VB U VA
Ha
rm
fu
l e
ffe
ctiv
en
es
s,
r.u
.
W avelength, nm
UV action spectrum
A.P. Popov at al., J. Phys. D: Appl. Phys. 38, 2564-2570 (2005).
200 400 600 800 1000 1200 1400
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8Solar spectrum
Sp
. ir
rad
ian
ce
, W
*m-2
*nm
-1
W avelength, nm
Although sun-protective factors are based on effect of UVB light, UVA and even visible lightproduce free radicals and are to be consideredin case of prolonged exposure to solar radiation.
10
EPR setup and samples
EPR setup (1.5 GHz, L-band)
EPR = Electron paramagnetic resonanceThe technique is capable for detection of free radicals
Samples with nanoparticles:1. Punch biopsies from porcine ears 2. Paper discs
Optical fiber transmittance spectrum
A liquid-filled optical fiber was used to guide light from the solar simulator to the samples. We used UV-VIS fiber (transmittance: 250-700 nm).Use of an optical filter (400-800 nm) allowed filtering out of UV part of spectrum.Light intensities: 77 mW/cm2 (UV+visible) and 55 mW/cm2 (visible). 12
13
TiO2 nanoparticles: SEM photos
TiO2 treatment 1 g TiO2 was heated in N2 atmosphere (s-025) or in 2% NH3 in N2 atmosphere (s-027) at 600 C, for 4 hours.The temperature was ramped at 20 °C/min so that 600 °C is attained in ~ 30 min.
s-027 TiO2s-025 TiO2
TiO2 nanoparticles: photoactivity
300 400 500 600 700 800
0
20
40
60
80
100U V
Ab
so
rpti
on
, %
W avelength, nm
T iO2 s-025
T iO2 s-027
s-027 (absorption in UV+vis.), 6 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16Time, min.
Am
pli
tud
e,
a.u
.
no light_averaged vis._averaged UV+vis._averaged
s-025 (absorption in UV), 4 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16Time, min.
Am
pli
tud
e,
a.u
.
no light_averaged vis._averaged UV+vis._averaged
Up: Absorption spectra of s-025 and s-027 TiO2 (measured by PerkinElmer Lambda 650 spectrometer equipped with an integrating sphere)
Right: Decrease of detected signal from PCA-marker indicated appearance of short-lived free radicals induced by light irradiation
15
s-028 TiO2s-026 TiO2
TiO2 nanoparticles: SEM photos
TiO2 treatment 1 g TiO2 was heated in N2 atmosphere (s-026) or in 2% NH3 in N2 atmosphere (s-028) at 600 C, for 4 hours.The temperature was ramped at 2 °C/min.
16
TiO2 nanoparticles: photoactivity
Up: Absorption spectra of s-026 and s-028 TiO2 (measured by PerkinElmer Lambda 650 spectrometer equipped with an integrating sphere)
s-026 (absorption in UV), 2 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
plitu
de
, a
.u.
no light_averaged vis._averaged UV+vis._averaged
s-028 (absorption in UV+vis.), 2 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
plitu
de
, a
.u.
no light_averaged vis._averaged UV+vis._averaged
Right: Decrease of detected signal from PCA-marker indicated appearance of short-lived free radicals induced by light irradiation
300 400 500 600 700 800
0
20
40
60
80
100
T iO2 s-026
T iO2 s-028
Ab
so
rpti
on
, %
W avelength, nm
17
ZnO and TiO2 anatase: SEM photos
TiO2 anatase, brand HOMBITAN (Sachtleben, former Kemira)
ZnO (Sigma-Aldrich)
18
300 400 500 600 700 800
0
20
40
60
80
100
Ab
so
rpti
on
, %
W avelength, nm
anatase
ZnO
ZnO and TiO2 anatase: photoactivity
Up: Absorption spectra of commercial anatase TiO2 and ZnO (measured by PerkinElmer Lambda 650 spectrometer equipped with an integrating sphere)
ZnO (absorption in UV), 2 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
pli
tud
e,
a.u
.
no light_averaged vis._averaged UV+vis._averaged
Right: Decrease of detected signal from PCA-marker indicated appearance of short-lived free radicals induced by light irradiationNote: UV+vis. curves are less steep (than in case of treated TiO2) due to localization on paper filter surface, no good penetration.
Anatase TiO2 (absorption in UV), 2 samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
pli
tud
e,
a.u
.
no light_averaged vis._averaged UV+vis._averaged
TiO2 anatase, s-025 and s-027 on pig ear skin in vitro: photoactivity
Anatase (absorption in UV) on pig skin, 2 samples
for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
pli
tud
e,
a.u
.
no light_averaged vis._averaged UV+vis._averaged
s-025 (absorption in UV) on pig skin, 2 samples for
each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
plitu
de
, a
.u.
no light_averaged vis._averaged UV+vis._averaged
s-027 (absorption in UV+vis.) on pig skin, 2
samples for each curve
0
0.2
0.4
0.6
0.8
1
1.2
2 4 6 8 10 12 14 16
Time, min.
Am
pli
tud
e, a
.u.
no light_averaged vis._averaged UV+vis._averaged
Existing difference between non-irradiated and irradiated with visible or with visibleand UV light is caused by contribution ofpig skin: it also gerenrates free radicals upon irradiation. Detection of particles effect is hardly possible in this case.
20
Skin structure
An OCT image of human skin in vivo (flexor forearm)
epidermis
Stratum corneumEpidermis
Dermisscale bar: 1 mm
Photograph of human corneocytes on a tape strip obtained by Ar+ laser scanning microscopy (λexcit = 488 nm); image size is 250 um x 250 um.
21
Pressing of the tape by a roller Removing of the adhesive film
Application of the emulsion Homogeneous distribution
J. Lademann at al., J. Biomed. Opt.. 10, 054015 (2005).
Tape stripping technique
22
Microscopy of corneocytes
Olympus BX51
Pure skin
Corneocytes + TiO2 (25 nm)
Corneocytes + TiO2 (400 nm)
Scale: 200 um
Courtesy Microel. and Mater. Phys. Labs (Univ. of Oulu)
23
0
0
Dep
th, u
m
Conc. TiO2 particles, ug/cm2
0
0
20
14
Volume concentration of TiO2:V
M
V
V
V
M
V
VNC
0
0
00
0
A.P. Popov et al., J. Opt. Technol. 73, 208-211 (2006).
In-depth particles distribution (by EDX technique)
TiO2 nanoparticles in horny layer
0 2 4 6 8 10 12 14 16 18 20
0
2
4
6
8
10
12
14
16
d = 100 nm
Co
nc
. T
iO2 p
arti
cle
s,
ug
/cm
2
D epth, um
24A.P. Popov et al., J. Biomed. Opt. 10, 064037 (2005).
Qs = s / ( d2) – scattering efficacy factor
s – scattering cross-sectionQa = a / ( d2) – absorption efficacy factor
a – absorption cross-sectiond – particle diameter
Opt. properties of TiO2
particles(rutile modification),
as an example
Calculations by Mie theory
, нм Re(n) – i·Im(n)
310 3.56 – i 1.720
400 3.13 – i 0.008
500 2.82 - i 0.000
40 60 80 100 120 140 160 180 200
0.00
0.01
0.02
0.03
0.04
= 500 nm
= 400 nm
= 310 nm
[Qa
+Q
s(1
-g)]
/d,
nm
-1
Diameter of TiO2 nanoparticle, nm
25
air
epidermis
Optical parameters for SC without nanoparticles
(adopted from V.V. Tuchin, 1998)
A = s(1)/( s
(1) + sm)
d
CQ
V
Nss
s5.1
)1( - scat. coef. of nanoparticles
d
CQ
V
Naa
a5.1
)1(- abs. coef. of nanoparticles
)()1()()( HGMie pApAp
hybrid phase function
2/32
2
)cos21(
1
4
1)(
gg
gp
HG - SC phase function
smss
)1(- scat. coef.
amaa
)1(- abs. coef.
Model of stratum corneum (SC) with nanoparticles
, nm sm, mm-1am, mm-1
310 240 60
400 200 23
Optical parameters for SC with nanoparticles
Attenuation curves of ZnO, TiO2 and Si nanoparticles
26A.P. Popov et al., JQSRT 112, 1891-1897 (2011).
0 20 40 60 80 100 120 140 160 180 200 220
0.00
0.01
0.02
0.03
0.04
0.05
0.06
= 310 nm
[Qa+
Qs*(
1-g
)]/d
, n
m-1
ZnO
Si
T iO2
D iam eter o f partic les, nm
(a)
0 20 40 60 80 100 120 140 160 180 200 220
0.00
0.01
0.02
0.03
0.04
0.05
ZnO
Si
T iO2
= 318 nm
[Qa
+Q
s*(
1-g
)]/d
, n
m-1
D iam eter o f partic les, nm
(b)
0 20 40 60 80 100 120 140 160 180 200 220
0.00
0.01
0.02
0.03
0.04
0.05
T iO2
S i
ZnO
= 360 nm
[Qa
+Q
s*(
1-g
)]/d
, n
m-1
D iam eter o f partic les, nm
(c)
0 20 40 60 80 100 120 140 160 180 200 220
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
= 400 nm
D iam eter o f partic les, nm
(d)
ZnO
TiO2
S i
[Qa+
Qs*(1
-g)]
/d,
nm
-1
Attenuation curves for = 310- (a), 318- (b), 360- (c) and 400-nm (b) radiation vs. particle size, according to the Mie theory; g – scattering anisotropy factor, d – particle diameter.
300 320 340 360 380 400
2
3
4
5
6
7
8
9
10
11
12 T iO2
S i
ZnO
pure skin
Ab
so
rpti
on
, %
W avelength, nm
(a)
300 320 340 360 380 400
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.4
T iO2
S i
ZnO
pure skin
Re
fle
cta
nc
e,
%
W avelength, nm
(b)
300 320 340 360 380 400
15
20
25
30
35
40
45
50 T iO
2
S i
ZnO
pure skin
Tra
ns
mit
tan
ce
, %
W avelength, nm
(c)
300 320 340 360 380 400
40
50
60
70
80
90
100
110
120
130
140
150
T iO2
S i
ZnO
Dia
me
ter
of
pa
rtic
les
, n
m
W avelength, nm
(d)
Absorption (a), reflectance (b) and transmittance (c) of light through stratum corneum. Calculations were performed for the following optimal sizes of TiO2, Si and ZnO particles, respectively: a) = 310 nm: 62, 55 and 45 nm, b) = 318 nm: 62, 58 and 52 nm, c) = 360 nm: 98, 64 and 92 nm, d) = 400 nm: 122, 70 and 140 nm. Section (d) corresponds to the optimal size-wavelength dependence.
27
Effect of optimal sizes
• Doping of TiO2 nanoparticles in 2% NH3 in N2 atmosphere causesappearance of absorption in visible spectral range.
• Upon irradiation with visible light (55 mW/cm2, 400-700 nm) freeshort-lived radicals formed by TiO2 particles are detected by an L-band (1.5 GHz) EPR spectrometer.
• Effect particles effect is hardly possible if they are localized on pigskin in vitro due to pronounced contribution of skin to radicalproduction.
• In addition, optimal sizes of ZnO, TiO2 and Si nanoparticles arecalculated and their effect on skin protection from UV light isestimated.
Conclusion