Cationization of polymers, proteins and polypeptides is being investigated with ToF-SIMS. The surfaces consist of a carboxylic terminated self-assembled monolayer with various metal ions such as Ag, Na, Li, Tl, and Cu substituting the terminal hydrogen. The resulting surface is used as a carrier substrate for deposition and analysis of polymers, proteins and polypeptides. To date, cationization of polymers has been 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 suggest 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 and quality of the cationized fragments are observed to be dependent on the metal ion used. Both cationized fragments and whole molecular species have been observed for 1kD PEO while on 4 00 kD PEO chain fragments of up n = 25 monomer units can be detected. Detection of whole low molecular-weight proteins up to 2 kD has been achieved with additional peaks indicating the loss of peptide- and sidechains.
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