Synthesis and applications of functional magnetic polymer beads; synthesis and mass spectrometry analysis of model peptides

The first part of the thesis describes the synthesis and application of functional magnetic polymer beads. The traditional suspension polymerization approach was used to synthesize polystyrene-iron oxide (Fe3O 4) based magnetic beads. The beads were coupled to different surface functional groups. The Fe3O4 particles were encapsulated into a polystyrene shell. The surface functional groups were generated by graft-polymerization with functional monomers. The average size of the beads was in the range of 100-500 mum. Chemical tests showed that the beads were stable in strong acid, strong base and polar solvent. The beads had a fast response to an external magnetic field. A self-emulsion-polymerization approach was developed to synthesize smaller magnetic beads with the - OH groups on the surface. A modified approach based on traditional suspension-polymerization was developed to synthesize acid-durable beads with more Fe3O 4 encapsulated inside the beads. A novel emulsion-suspension polymerization method was successfully developed to synthesize much smaller magnetic beads (<150 mum).;A new peptide synthesis approach was developed using functional magnetic beads as the resin for solid phase synthesis. In this application, synthesized magnetic beads were further modified by a two-step reaction. The amino group was anchored onto the surface of these beads, followed by coupling with the Rink amide linker. The resulting beads were used as the resin to synthesize several model peptides. The peptides were successfully synthesized, and the sequences were confirmed by mass spectrometry analysis. The yields of the peptides were comparable to those obtained from commercial Rink amide resin.;The second part of the thesis describes the synthesis and mass spectrometry analysis of two series of model peptides. One series has the linear (non-cyclic) structure, AnK, KAn, PnK, and AcAnK. The other series contains cyclic peptides, c-Ac-DAKAK and c-Ac-DADapAK. All peptides were synthesized using solid phase peptide synthesis. The relative proton affinities of the model peptides were measured using the collision induced dissociation experiments using a triple quadrupole mass spectrometer. It was found that the effective proton affinity of a cyclic peptide was significantly reduced compared to a linear analogue. The reduced proton affinity implies an increased lipophilicity of the peptide.