| AVS 63rd International Symposium & Exhibition | |
| Biomaterial Interfaces | Tuesday Sessions |
| Session BI+PB-TuP |
| Session: | Biomaterial Interfaces Poster Session (preceded by Oral Flash Presentations) |
| Presenter: | Martin Körsgen, Universität Münster, Germany |
| Authors: | M. Körsgen, Universität Münster, Germany A. Pelster, Universität Münster, Germany M. Heeger, Universität Münster, Germany B.J. Tyler, Universität Münster, Germany K. Dreisewerd, Universität Münster, Germany H.F. Arlinghaus, Universität Münster, Germany |
| Correspondent: | Click to Email |
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful technique for the nanoanalysis of biological samples, but improvements in sensitivity are needed in order to detect large biomolecules, such as peptides, on the individual cell level at physiological concentrations. An increase in the detection efficiency for larger molecules and reduced fragmentation rates could be obtained by a) the use of cluster ion beams such as Aun+ , Bin+ , C60+ , or even large Arn+ clusters in order to maximize the energy deposited close to the surface or b) by modifying the surface by organic matrices in the so-called matrix-enhanced SIMS (ME-SIMS). This approach is based on embedding analyte molecules in low weight organic matrices, like common MALDI matrices, prior to ion bombardment
We used dual beam ToF-SIMS to image the incorporation of three peptides with different hydrophobicities, bradykinin, substance P, and vasopressin, into two classical MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA) prepared with dried droplet sample preparation method. For depth profiling, an Ar cluster ion beam was used to gradually sputter through the matrix crystals without causing significant degradation of matrix or biomolecules. A pulsed Bi3+ ion cluster beam was used to image the lateral analyte distribution in the center of the sputter crater. Using this dual beam technique, the 3D distribution of the analytes and spatial segregation effects within the matrix crystals were imaged with sub-µm resolution.
Combining cluster ion beams and ME-SIMS we were able to investigate the molecular yield of two peptides (bradykinin and melittin) under various primary ions and preparation methods. Large argon clusters in the mass range between 1000 and 2500 atoms per cluster and several bismuth primary ions were used to determine molecular yields. Preparation utilized spin coating of pure peptide solutions and spray coating of matrix-peptide mixtures on silicon wafers. With the data obtained we were able to describe the molecular yield of the analyzed peptides. For bismuth primary ions the yield obtained by the use of cluster primary ions is nearly constant in the case of ME-SIMS, whereas for the neat sample an increase of the molecular yield is observable. In contrast to the molecular yield decrease with larger argon clusters for neat samples, an increase of the molecular yield is observable for larger argon clusters in the case of ME-SIMS.