Synthesis, characterization and property exploration of the biomimetic poly beta-alanine dendrimers.

摘要

This thesis described the development of a new and convenient synthetic scheme for the preparation of poly(beta-alanine) dendrimers. A combination of analytical methods, e.g. NMR spectroscopy, mass spectrometry and laser light scattering technique, were used to characterize their chemical structures. After the structural elucidation, we have studied some physico-chemical properties of these dendrimers e.g. solution phase aggregation behavior and electrophoretic mobility.;The first half of this thesis was focused on the synthesis and characterization of poly(beta-alanine) dendrimers. By utilizing the classical convergent and divergent growth strategies together with solution phase peptide chemistry, a convenient and effective synthetic route for a series of biomimetic poly(beta-alanine) dendrimers was developed. Purity of all the synthesized products were scrutinized by gel permeation chromatography (GPC).;The second half of this thesis was concentrated on the investigation of the properties of the poly(beta-alanine) dendrimers. The presence of numerous polar amide and carbamate groups in the dendrimers facilitated a self-assembling process leading to aggregate formation. By dynamic light scattering, the solution aggregation behavior of the G2-poly(beta-alanine) dendrimer at different temperatures and in different solvent conditions were investigated. The results showed that a self-assembling aggregate of average hydrodynamic radius ⟨Rh⟩ of 16 nm was identified which was ten times the size of the average hydrodynamic radius of the monomeric dendrimer. Finally, we also explored the electrophoretic property of the deprotected G2-, G3- and G4-poly(beta-alanine) dendrimers by polyacrylamide gel electrophoretic method in acidic condition. The results showed that the poly(beta-alanine) dendrimers possessed electrophoretic property similar to small native peptides and their mobility were governed by molecular sieving effect of polyacrylamide network.;This thesis has demonstrated the feasibility of designing biomimetic molecules with the dendritic architecture. The results of the product characterization and property exploration have laid down the groundwork for further investigation and application of these new biomimetic materials.