AVS 46th International Symposium
    Applied Surface Science Division Friday Sessions
       Session AS-FrM

Paper AS-FrM7
Fundamental Studies of Polymer and Protein Cationization by ToF-SIMS

Friday, October 29, 1999, 10:20 am, Room 6A

Session: New or Improved Surface Related Analytical Techniques
Presenter: R Michel, University of Washington
Authors: R Michel, University of Washington
R. Luginbuehl, University of Washington
D.J. Graham, University of Washington
B.D. Ratner, University of Washington
Correspondent: Click to Email
Cationization of polymers, proteins and polypeptides is carried out on novel substrates with Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The surfaces consist of carboxylic terminated self-assembled monolayers with various metal ions such as Ag, Na, Li, Tl, and Cu substituting the terminal hydrogen. The resulting surfaces are used as carrier substrates for deposition and analysis of polymers, proteins and polypeptides. Low (1 kD) and high (400 kD) molecular weight polyethyleneoxide (PEO) was deposited via spincoating while the proteins were adsorbed to the substrates. Previously published results show that cationization of polymers was achieved with the various selected metal ions from the carboxylic terminated groups. Complementary experiments carried out on non-substituted and methyl terminated self-assembled monolayers suggested that metal ions which are desorbed from the gold surface and therefore not in close proximity to the polymer do not cationize polymers and their fragments. The intensity of the cationized fragments were observed to be dependent on the metal ion used. Both cationized fragments and whole molecular species were observed for the 1kD PEO while on 400 kD PEO chain fragments of up n = 25 monomer units were detected. For protein samples using our substrate, detection of whole low molecular weight proteins up to 2 kD could be achieved with additional peak patterns indicating a loss of peptide- and sidechains.