Thermoresponsive dendronized polyprolines via the 'grafting to' route

摘要

The first and second generations of dendronized polyprolines P3G1, P3G2, and P4G1 are prepared via the "grafting to" route, and their thermoresponsive properties and helical conformations investigated. High molar masses of polyproline main chains carrying azido groups are achieved first by polycondensation of peptide precursors through activated ester strategy. Oligoethylene glycol dendrons cored with alkyne are then attached onto the main chains through click reaction. These polymers are found to be thermoresponsive. Circular dichroism spectroscopy investigation indicates, in contrast to P3G2 and P4G1 which adopt the expected PPII conformation in aqueous conditions, P3G1 prefers to adopt PPI helical conformation, and this conformation is stable within the measured time period and temperature range. Dendronization of polyprolines with three-folded oligoethylene glycol dendrons via post-modification through azide-alkyne "click reaction" affords the polypeptides thermoresponsiveness and tunable secondary structures. The thermoresponsive properties and perference of the ordered structures for these dendronized polypeptides are dependent not only on the dendron generation, but more criucially also on the spatial arrangement of the dendrons along the peptide backbone.