Time-of-flight secondary ion spectrometry (ToF-SIMS) is a rare but very powerful characterization technique for many different kinds of biomaterials. Being available from several specialized analytical service labs across Europe, clustered in the NFFA (KIT/Germany, Uni-Namur/Belgium, JRC-Ispra/Italy, and CEA-LETI/France), this technique allows for example the chemical characterization of (bio-) polymer layers, protein adsorbates, metallic biomaterials. Being more destructive as compared to MALDI but still providing molecular information when needed, SIMS provides also surface mass spectra and can be quantitative when reference samples are used and achieves ppm sensitivity. SIMS can be applied to visualize chemical patterns with a lateral resolution down to the sub-µm range. Furthermore, SIMS with dual beam depth profiling allows for chemical contrast tomography showing three-dimensional structures being up to 500×500 µm2 wide and usually some 100 nm thick.
Some examples of biomaterials analyzed the SIMS lab at KIT within the last few years will be provided:
Tracing the size dependent uptake of zirconia nanoparticles by human primary osteoblasts (implant coatings in dentistry, DOI: 10.3390/nano12234272);
analyzing the coverage of lactose particles with magnesium stearate acting as flow enhancer (dry powder inhalers, DOI: 10.1016/j.ijpharm.2023.123503);
the development of a compound interaction screen on a photoactivatable cellulose membrane (CISCM) for the identification of drug targets / SIMS amino acid fingerprinting signal of N-methylated Leu (DOI: 10.1002/cmdc.202200346);
nitroxide functional surfaces controlling biofilm formation / SIMS tomography of polymer spots on titanium substrates (DOI: 10.1039/c9py00690g);
and magnesium/gadolinium alloys for implantology / showing local iron inclusions affection the corrosion behavior (DOI: 10.3390/met9020117).
These examples are spanning a broad range of metallic, ceramic and polymeric substrates and comprise patterned surfaces as well as particles. Strengths and limitations of ToF-SIMS will be discussed.