DNA-Coated Microspheres with Base Mismatches for Stepwise Programmed Assembly

Through the strategic design of base sequences in DNA brushes, it is possible to adjust the interaction parameters between DNA-coated colloidal microspheres in tandem with their DNA grafting density and buffer conditions, resulting in a shift in their melting temperature. Multiple DNA-coated colloids can be assembled into hierarchical colloidal superstructures in a stepwise manner by tuning their respective melting temperatures. Here, the controlled introduction of mismatched base pairs into complementary DNA brushes provides an additional means of tuning the interparticle interactions. We find that precise control over the melting temperature can be achieved by strategically designing the type, position, or number of mismatched base pairs introduced in otherwise self-complementary DNA brushes. The use of two sets of particles coated with self-complementary DNA with dissimilar mismatched bases enables the realization of temperature-dependent binding with distinct melting temperatures. Using self-complementary DNA brushes with mismatched base pairs, two sets of colloidal particles are programmed with temperature-dependent orthogonal interactions to promote the stepwise assembly of the FCC-crystalline core-shell superstructures. Furthermore, to demonstrate the versatility of manipulating DNA sequences to engineer precise control over colloidal assembly, we demonstrate that CsCl-crystalline core-shell superstructures can be assembled from a ternary colloidal mixture by using complementary DNA brushes without or with mismatched bases.