Thermoresponsive Dendronized Polypeptides Showing Switchable Recognition to Catechols

A new class of thermoresponsive dendronized polypeptides was prepared through highly efficient oxime ligation between oxyamino-substituted polylysines and aldehyde-cored oligo-ethylene glycol (OEG) dendrons. Their secondary structures and thermoresponsive behavior were investigated. Because of the dendritic structures and stable oxime linkage, these OEG-based dendronized polypeptides exhibited fast and fully reversible phase transitions in neutrally aqueous solutions, and their phase transition temperatures can be controlled around physiological temperatures. The effect of OEG dendronization on secondary structures of polypeptides were examined to check their prominent dendritic shielding effect, steric hindrance, and thermally driven phase transitions. To further extend the functions and potential applications of these stimuli-responsive dendronized polypeptides, phenylboronic acid moieties were introduced to achieve the corresponding dendronized copolymers, which were utilized to specifically recognize catechol-containing compounds such as alizarin red S or dopamine. These copolypeptides showed a significant enhancement to bind to catechols when comparing to monomeric phenylboronic acid. Furthermore, this enhanced binding can be switched surprisingly by thermally driven phase transitions or through addition of competitive catechols, which makes this class of dendronized polypeptides as unique scaffolds for selective and reversible recognition of catechols.