AVS 46th International Symposium
    Biomaterial Interfaces Group Wednesday Sessions
       Session BI-WeA

Paper BI-WeA10
Probing the Nano-environments of Peptides on Solid Surfaces by Advanced Secondary Ion Mass Spectrometry

Wednesday, October 27, 1999, 5:00 pm, Room 613/614

Session: Biology at the Nanoscale
Presenter: T. Schenkel, Lawrence Livermore National Laboratory
Authors: T. Schenkel, Lawrence Livermore National Laboratory
K.J. Wu, Charles Evans & Associates
A.V. Barnes, Lawrence Livermore National Laboratory
M.W. Newman, Lawrence Livermore National Laboratory
J.W. McDonald, Lawrence Livermore National Laboratory
A.V. Hamza, Lawrence Livermore National Laboratory
Correspondent: Click to Email
The interaction and bonding of peptides and proteins in the solid phase and on solid surfaces is of central importance in biotechnological research. Embedding of analyte molecules in special matrix solutions (such as 2,5 dihydroxybenzoic acid) has been shown to produce enormous increases in yields of intact molecules both for laser and single charged ion induced ablation. The mechanisms responsible for this enhancement are however not well understood. Both the binding of matrix and analyte molecules in the solid and collisional ion formation processes have been suggested to play important roles. We have investigated the effect of sodium and potassium impurities on secondary ion emission from gramicidin S by time-of-flight secondary ion mass spectrometry (TOF-SIMS) with highly charged projectiles.@footnote 1@ Highly charged ions like Xe@super44+@ or Au@super69+@ increase secondary ion yields by over two orders of magnitude as compared to singly charged ions. Each highly charged projectile emits secondaries from an area of only about 10 nm^2. Analysis of coincidences among secondary ions detected following the impact of a single projectiles allows for the characterization of the nano-environment of e. g. a peptide molecule in a matrix solution. For the gramicidin S, we found that emission of Na@super+@ and K@super+@ ions was strongly correlated with emission of sodium and potassium adduct ions, [M+Na]@super+@, [M+K]@super+@. This correlation indicates the nestling of sodium impurities around peptide molecules. In our presentation we will discuss the potential of coincidence analysis in TOF-SIMS for the probing of nano-environments on surfaces of biomaterials. @FootnoteText@@footnote 1@A. V. Hamza et al., J. Vac. Sc. Technol. A 17, 303 (1999) Acknowledgement: This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.