Here, we present a study on agarose thin-film samples that represent a model system for the exopolysaccharide matrix of biofilms. Povidone-iodide (PVP-I) was selected as an antibacterial agent to evaluate our x-ray photoelectron spectroscopy (XPS)-based methodology to trace specific marker elements, here iodine, commonly found in organic matrices of antibiotics. The in-depth distribution of iodine was determined by XPS analyses with variable excitation energies and in combination with argon gas cluster ion beam sputter cycles. On mixed agarose/PVP-I nanometer-thin films, both methods were found to solve the analytical task and deliver independently comparable results. In the mixed agarose/PVP-I thin film, we found the outermost surface layer depleted in iodine, whereas the iodine is homogeneously distributed in the depth region between this outermost surface layer and the interface between the thin film and the substrate. Depletion of iodine from the uppermost surface in the thin-film samples is assumed to be caused by ultrahigh vacuum exposure resulting in a loss of molecular iodine (I2) as reported earlier for other iodine-doped polymers.

1.
See https://www.imi.europa.eu/projects-results/project-factsheets/nd4bb for more information about the IMI program ND4BB - New Drugs for Bad Bugs.
2.
See https://www.imi.europa.eu/projects-results/project-factsheets/translocation for more information about the project Translocation - Molecular basis of the bacterial cell wall permeability.
3.
See http://empir.npl.co.uk/metvbadbugs/ for more information about the EMPIR project 15HLT01 - MetVBadBugs.
4.
S.
Moulay
,
Recent Innov. Chem. Eng.
12
,
174
(
2019
).
5.
A.
Sa
,
S.
Sawatdee
,
N.
Phadoongsombut
,
W.
Buatong
,
T.
Nakpeng
,
R.
Sritharadol
, and
T.
Srichana
,
Acta Pharm.
67
,
169
(
2017
).
6.
T. A.
Gillam
,
C. K.
Goh
,
N.
Ninan
,
K.
Bilimoria
,
H. S.
Shirazi
,
S.
Saboohi
,
S.
Al-Bataineh
,
J.
Whittle
, and
A.
Blencowe
,
Appl. Surf. Sci.
537
,
147866
(
2021
).
7.
C. K.
Chiang
,
Y. W.
Park
,
A. J.
Heeger
,
H.
Shirakawa
,
E. J.
Louis
, and
A. G.
MacDiarmid
,
J. Chem. Phys.
69
,
5098
(
1978
).
8.
S. L.
Hsu
,
A. J.
Signorelli
,
G. P.
Pez
, and
R. H.
Baughman
,
J. Chem. Phys.
69
,
106
(
1978
).
9.
I.
Ikemoto
,
M.
Sakairi
,
T.
Tsutsumi
,
H.
Kuroda
,
I.
Harada
,
M.
Tasumi
,
H.
Shirakawa
, and
S.
Ikeda
,
Chem. Lett.
8
,
1189
(
1979
).
10.
W. R.
Salaneck
,
H. R.
Thomas
,
R. W.
Bigelow
,
C. B.
Duke
,
E. W.
Plummer
,
A. J.
Heeger
, and
A. G.
MacDiarmid
,
J. Chem. Phys.
72
,
3674
(
1980
).
11.
M. A.
Petit
,
A. H.
Soum
,
M.
Leclerc
, and
R. E.
Prud’Homme
,
J. Polym. Sci. B Polym. Phys.
25
,
423
(
1987
).
12.
E. T.
Kang
,
K. L.
Tan
,
K. G.
Neon
,
H. S. O.
Chan
, and
B. T. G.
Tan
,
Polym. Bull.
21
,
53
(
1989
).
13.
O. A.
Baschenko
,
M. A.
Tyzykhov
,
V. I.
Nefedov
,
G.
Polzonetti
,
M. V.
Russo
, and
A.
Furlani
,
J. Electron Spectrosc. Relat. Phenom.
56
,
203
(
1991
).
14.
J. R.
Ferraro
,
S.
Hill
,
P.
Stout
,
A.
Furlani
,
G.
Polzonetti
, and
M. V.
Russo
,
Appl. Spectrosc.
45
,
932
(
1991
).
15.
A.
Chilkoti
and
B. D.
Ratner
,
Chem. Mater.
5
,
786
(
1993
).
16.
M.
Ishihara
,
J.
Okumura
, and
K.
Yamaguchi
,
J. Polym. Sci. B Polym. Phys.
34
,
587
(
1996
).
17.
W.
Saenger
,
Naturwissenschaften
71
,
31
(
1984
).
18.
See the supplementary material at https://www.scitation.org/doi/suppl/10.1116/6.0001812 for additional SEM images, data, and core-level spectra.
19.
See https://eps.leeds.ac.uk/dir-record/facilities/3874/versatile-x-ray-spectroscopy-facility for more information about the Versatile x-ray spectroscopy facility, a multi-technique x-ray core level spectroscopy facility for the characterization of materials under natural environmental conditions located at the University of Leeds.
20.
P. M.
Dietrich
,
S.
Bahr
,
T.
Yamamoto
,
M.
Meyer
, and
A.
Thissen
,
J. Electron Spectrosc. Relat. Phenom.
231
,
118
(
2019
).
21.
H.
Bluhm
,
J. Electron Spectrosc. Relat. Phenom.
177
,
71
(
2010
).
22.
ISO 15472:2010
,
Surface Chemical Analysis—X-ray Photoelectron Spectrometers—Calibration of Energy Scales
(International Organization for Standardization,
Geneva
,
2010
).
23.
ISO 19318:2004
,
Surface Chemical Analysis—X-ray PhotoelectronSpectroscopy—Reporting of Methods Used for Charge Control and Charge Correction
(
International Organization for Standardization
,
Geneva
,
2004
).
24.
G.
Beamson
and
D.
Briggs
,
High Resolution XPS of Organic Polymers
(
John Wiley &Sons Ltd.
,
West Sussex
,
1992
), ISBN 0471935921.
25.
J.
Scofield
, “Theoretical Photoionization Cross Sections From 1 to 1500keV,” Technical Report, 1973, see http://www.osti.gov/servlets/purl/4545040/.
26.
S.
Tanuma
,
C. J.
Powell
, and
D. R.
Penn
,
Surf. Interface Anal.
20
,
77
(
1993
).
27.
ISO 14606:2000
,
Surface Chemical Analysis—Sputter Depth Profiling—Optimization Using Layered Systems as Reference Materials
(International Organization for Standardization,
Geneva
,
2000
).
28.
ISO 18115-1:2010
,
Surface Chemical Analysis—Vocabulary, Part 1: General Terms and Terms Used in Spectroscopy
(International Organization for Standardization,
Geneva
,
2010
).
29.
R.
Wilken
,
A.
Holländer
, and
J.
Behnisch
,
Surf. Coat. Technol.
116–119
,
991
(
1999
).
30.
B.
Finke
,
K.
Schröder
, and
A.
Ohl
,
Plasma Processes Polym.
5
,
386
(
2008
).
31.
32.
M.
Lorenz
,
J.
Zhang
,
A. G.
Shard
,
J.-L.
Vorng
,
P. D.
Rakowska
, and
I. S.
Gilmore
,
Anal. Chem.
93
,
3436
(
2021
).
33.
A. M.
Carabelli
 et al,
ACS Appl. Bio Mater.
3
,
8471
(
2020
).

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