A DNA-Small Molecule Conjugate Modulates the Complexity of Multicomponent Supramolecular Polymerization in Biorelevant Environments

Aqueous multicomponent supramolecular systems hold great promise for designing synthetic biomaterials with tailored properties. Inspired by this notion, we explore the consequences of modulating the assembly behaviour of supramolecular polymers based on benzene-1,3,5-trixaboxamide (BTA) derivatives by the corresponding BTA-DNA conjugate. Our data demonstrate the divergence of the assembly mechanisms upon shifting from pure water to buffered solutions (pH=7) upon introducing the DNA conjugate. To follow the morphologic transitions, we developed a correlative spectroscopic-microscopic method suitable for the analyses of thermally controlled supramolecular copolymerization in aqueous systems. Using this approach, the structural origins of the cooperative transitions in water-soluble BTA systems were confirmed for the first time. Thus, at the macroscale, the elongation into micrometer-long supramolecular fibers occurs from globular aggregates, which exist at elevated temperatures. The acquired experimental data support the assumption expressed in the previous computational reports that nanoscale BTA ordering within the globules precedes the elongation phase. Furthermore, depending on the content of the DNA modulator, the globules derive two forms of supramolecular fibers, type I and type II, respectively. The latter type is stable within a short temperature window, transforming into the former one upon further cooling. Finally, the supramolecular copolymers were transformed in functional hydrogels via a DNA crosslinking strategy. Physical and mechanical properties of the hydrogels were assessed by microrheology.