TY  - JOUR
A1  - Di Florio, G.
A1  - Bruendermann, E.
A1  - Yadavalli, Nataraja Sekhar
A1  - Santer, Svetlana
A1  - Havenith, Martina
T1  - Graphene multilayer as nanosized optical strain gauge for polymer surface relief gratings
JF  - Nano letters : a journal dedicated to nanoscience and nanotechnology
N2  - In this paper, we show how graphene can be utilized as a nanoscopic probe in order to characterize local opto-mechanical forces generated within photosensitive azobenzene containing polymer films. Upon irradiation with light interference patterns, photosensitive films deform according to the spatial intensity variation, leading to the formation of periodic topographies such as surface relief gratings (SRG). The mechanical driving forces inscribing a pattern into the films are supposedly fairly large, because the deformation takes place without photofluidization; the polymer is in a glassy state throughout. However, until now there has been no attempt to characterize these forces by any means. The challenge here is that the forces vary locally on a nanometer scale. Here, we propose to use Raman analysis of the stretching of the graphene layer adsorbed on top of polymer film under deformation in order to probe the strength of the material transport spatially resolved. With the well-known mechanical properties of graphene, we can obtain lower bounds on the forces acting within the film. Upon the basis of our experimental results, we can deduce that the internal pressure in the film due to grating formation can exceed 1 GPa. The graphene-based nanoscopic gauge opens new possibilities to characterize opto-mechanical forces generated within photosensitive polymer films.
KW  - Surface relief grating
KW  - optomechanical forces
KW  - photosensitive polymer films
KW  - multilayer graphene deformation
KW  - confocal Raman microscopy
Y1  - 2014
U6  - https://doi.org/10.1021/nl502631s
SN  - 1530-6984
SN  - 1530-6992
VL  - 14
IS  - 10
SP  - 5754
EP  - 5760
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Haase, Andrea
A1  - Arlinghaus, Heinrich F.
A1  - Tentschert, Jutta
A1  - Jungnickel, Harald
A1  - Graf, Philipp
A1  - Mantion, Alexandre
A1  - Draude, Felix
A1  - Galla, Sebastian
A1  - Plendl, Johanna
A1  - Goetz, Mario E.
A1  - Masic, Admir
A1  - Meier, Wolfgang P.
A1  - Thuenemann, Andreas F.
A1  - Taubert, Andreas
A1  - Luch, Andreas
T1  - Application of Laser Postionization Secondary Neutral Mass Spectrometry/Time-of-Flight Secondary Ion Mass Spectrometry in Nanotoxicology: Visualization of Nanosilver in Human Macrophages and Cellular Responses
JF  - ACS nano
N2  - Silver nanoparticles (SNP) are the subject of worldwide commercialization because of their antimicrobial effects. Yet only little data on their mode of action exist. Further, only few techniques allow for visualization and quantification of unlabeled nanoparticles inside cells. To study SNP of different sizes and coatings within human macrophages, we introduce a novel laser postionization secondary neutral mass spectrometry (Laser-SNMS) approach and prove this method superior to the widely applied confocal Raman and transmission electron microscopy. With time-of-flight secondary ion mass spectrometry (TOF-SIMS) we further demonstrate characteristic fingerprints in the lipid pattern of the cellular membrane indicative of oxidative stress and membrane fluidity changes. Increases of protein carbonyl and heme oxygenase-1 levels in treated cells confirm the presence of oxidative stress biochemically. Intriguingly, affected phagocytosis reveals as highly sensitive end point of SNP-mediated adversity In macrophages. The cellular responses monitored are. hierarchically linked, but follow individual kinetics and are partially reversible.
KW  - nanosilver
KW  - Laser-SNMS
KW  - TOF-SIMS
KW  - confocal Raman microscopy
KW  - oxidative stress
KW  - protein carbonyls
Y1  - 2011
U6  - https://doi.org/10.1021/nn200163w
SN  - 1936-0851
VL  - 5
IS  - 4
SP  - 3059
EP  - 3068
PB  - American Chemical Society
CY  - Washington
ER  -