pH-Responsive Self-Assembly by Molecular Recognition on a Macroscopic Scale

Macroscopic pH-responsive self-assembly is successfully constructed by polyacrylamide(pAAm)-based gels carrying dansyl (Dns) and -cyclodextrin (CD) residues, which are represented as Dns-gel and CD-gel, respectively. Dns-gel and CD-gel assemble together at pH 4.0, but disassemble at pH 3.0. The adhesion strengths for pairs of Dns-gel/CD-gel increase with increasing pH. The fluorescence study on the model system of pAAm modified with 1 mol% Dns moieties (pAAm/Dns) reveals that Dns residues are protonated at a lower pH, which results in the reduction in binding constant (K) for Dns residues and CD.