Picturing polymers
SIMS can image novel devices
and biological tissue in both
2D and 3D, at an elemental
and molecular level. Images a–c
show 3D ToF-SIMS imaging
of polymer multilayer films
using argon cluster sputter depth
profiling (2), while d – a 3D
molecular image of a novel reference material – shows how
the “delta” layers – less than 2 nm thick – are sandwiched
between layers of another organic molecule (3). The depth
resolution of this technique is a remarkable 5 nm.(^40) Feature
Spot the difference
MS imaging (MSI) is a powerful tool for relating
molecular phenotype to tissue structure. Here, matrix
assisted laser desorption ionization (MALDI) MSI
was applied to “swiss roll” prepared colon samples with
genetic modifications and deletions to APC, KRAS,
and GPT2 genes. A machine-learning algorithm –
T-distributed stochastic neighbor embedding – allowed
us to visualize and interpret these highly dimensional,
complex data. Here, similar colors reflect the level
of similarly in the molecular composition of tissues,
highlighting how different the APC/KRAS model is
compared to the wild-type (WT) and other models.
IMAGING INNOVATION
Scientists from the UK’s National Centre of Excellence in Mass Spectrometry
Imaging (NiCE-MSI) showcase the potential for MSI in a wide range of fields.
Graphene graphics
By measuring carbon impurities in Cu foils before
graphene growth with time-of-flight secondary ion
MS (ToF-SIMS) and correlating this with graphene
nucleation density (GND) after graphene growth,
we can track how carbon distribution within the
untreated Cu foil impacts GND. Here, the surface ToF-
SIMS maps of C₂ ion signal (green) from the Cu foil
surface show how graphene nucleates along a preferred
direction. This corresponds to areas of high carbon
concentration located along rolling striations of the Cu
foi l (1).
a)
b)
c)
Credit: Rory T. Steven, Andrew Campbell, Alex Dexter, Spencer Thomas, Kenneth N.
Robinson, Alan M. Race, Rasmus Havelund, Ian S. Gilmore, Owen Sansom, Zoltan
Takats, Josephine Bunch (as part of the CRUK funded Rosetta consortium)
d)