This is an author version of the contribution published on:

Questa è la versione dell’autore dell’opera:

Turci et al., Chem. Res. Toxicol., 2013,

26 (10), pp 1579–1590

The definitive version is available at:

La versione definitiva è disponibile alla URL:

http://pubs.acs.org/doi/abs/10.1021/tx400285j

Crystalline phase modulates the potency of nanometric

TiO2 to adhere and perturb the stratum corneum of

porcine skin under indoor light.

×

ca.

ζ potential was evaluated by means of electrophoretic light scattering (ELS) (Zetasizer Nano–ZS,

Malvern Instruments, Worcestershire, U.K.). In this technique the velocity of particle in an oscillating

electric field, which is proportional to its ζ potential, is measured by light scattering. The ζ potential was

measured suspending the nano-TiO2 in the delivery medium without altering the pH, in order to gather

indications on the real surface charge exhibited by the three powders during the skin-interaction

experiments. The ζ potential was measured also at several pH values, adjusting the pH of the dust

suspension with 0.1 M HCl or 0.1 M NaOH and a plot of ζ potential values versus pH was obtained. The

set of experimental points was fitted with a sigmoidal curve (Boltzmann equation) with OriginPro8.0

software suite (

dxxx

e

AAAy

)0(

1

212 ,

where A1 and A2 are the lower and upper horizontal respectively, x0 the

and dx the curve rate, i.e.

were carried out under controlled indoor

illumination with a very low content of UV light. The light irradiance was measured by a portable

photoradiometer (Deltahom, Caselle di Selvazzano, Padova, Italy) equipped with two detectors

operating in the Vis−NIR range (400–1050 nm) and in the UVA range (315–400 nm). An irradiance of

ca. 750 mW/m2 (Vis-NIR range) and < 1 mW/m

2 (UVA) was measured during all experiments. It is

worth noting that experiments of TiO2-induced photodegradation of skin are commonly carried out with

an UVA irradiance >10 outdoor summer sunlight)

×

100)1(%blank

sample

H

HH

under controlled indoor

illumination

http://pubs.acs.org/doi/full/10.1021/tx400241c#notes-1

50 nm

a)

100 nm

b)

100

101

102

103

104

*

DL

S in

ten

sity (

%)

Size (nm)

c)

100

101

102

103

104

*

DL

S in

ten

sity (

%)

Size (nm)

101

102

103

104

DLS

inte

nsity (

%)

*

Size (nm)

0 1 10 100 10000

20

40

60

80

100

120

140

160

180

Par

ticl

e n

um

be

r

Average diameter ( m)

0

25

50

75

100

Cu

mu

lati

ve d

istr

ibu

tio

n,

%

0 1 10 100 10000

100

200

300

400

500

600

700

Par

ticl

e n

um

be

r

Average diameter ( m)

0

25

50

75

100

Cu

mu

lati

ve d

istr

ibu

tio

n,

%

0 1 10 100 10000

20

40

60

80

100

120

140

160

180

Par

ticl

e n

um

be

r

Average diameter ( m)

0

25

50

75

100

Cu

mu

lati

ve d

istr

ibu

tio

n,

%

Anatase Hombikat UV100

Sachtleben, DE

Rutile MT500 B

LCM Trading, IT

Anatase / Rutile Aeroxide P25

Evonik, DE

2 3 4 5 6 7 8 9 10

-30

-20

-10

0

10

20

30

- p

ote

nti

al, m

V

pH

2 3 4 5 6 7 8 9 10

-30

-20

-10

0

10

20

30

pH

2 3 4 5 6 7 8 9 10

-30

-20

-10

0

10

20

30

rutileanatase anatase/rutile

pH

100 µm 100 µm

100 µm 100 µm

100 µm 100 µm

A A’

B’ B

C C’

c)

b)

a

A

B

2700 2800 2900 3000 3100

No

rma

lize

d R

am

an

in

ten

sity, A

U

a,b

c,d

Raman Shift (cm-1)

2719

28832974

3060

2937

2852

-100

-80

-60

-40

-20

0Negativ

e Ctrl

A R A/R H 2O 2

b

bc

c

bc

%H

of

lipid

tra

nsi

tio

n

a

carboxyl radical

Such radical can be detected via the spin trapping technique and EPR spectroscopy, provided that

concentrated HCO2– and neutral buffered solutions are employed. Despite its slower kinetics, due to the

low molar concentration of

330 331 332 333 334 335 336 337

A/R

A

R

field, mT

A

A R A/R0

50

100

150

200

250

300

350

400

450

500

sign

al in

ten

sity

, A.U

.

B

blank A R A/R0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

*

*#

Absorb

ance

= 5

35 n

m,

A.U

.

*

Absorbance ( 535 nm) recorded on

the supernatant after incubation of the suspended in a 1

mM suspension of linoleic acid in 5 mM phosphate buffer (pH 7.4) for 72 h under indoor illumination.

A linoleic acid suspension without dust was employed as blank. The data are expressed as the mean

value of three separate determinations ± SD. Vs blank: *p < 0.05; R vs. A and R vs. A/R: # p < 0.05.

http://pubs.acs.org/

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