From Design Rules to Crystal Structures: A Research-Style DNA-Programmed Colloidal Crystal Laboratory for Upper-Division Chemistry Students

Undergraduate laboratory curricula often provide limited opportunities for students to engage with advanced nanoscience techniques, develop predictive reasoning, and participate in research-style scientific inquiry. To address these gaps, we developed a research-style laboratory module for upper-division undergraduate students centered on colloidal crystal engineering with DNA, a rapidly advancing field in nanoscience governed by design rules that connect nanoscale DNA bonding interactions to emergent crystal structures. Students synthesized programmable atom equivalents (PAEs), composed of gold nanoparticle core and a DNA shell, and assembled them into one of six distinct crystal structures, including three body-centered cubic (BCC) lattices, two face-centered cubic (FCC) lattices, and one CsCl lattice. Class-wide data sharing enabled comparison of structural outcomes and reinforced the design principles underlying colloidal crystal engineering with DNA. Students characterized nanoparticle size, surface charge, and crystal habit and structure using contemporary techniques, including dynamic light scattering (DLS) and zeta potential, UV–Vis spectroscopy, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). They also interpreted SAXS diffraction data, assigned crystal symmetry, and determined lattice parameters. Analysis of laboratory reports demonstrated that students applied design rules to predict how nanoscale interactions translate to macroscopic crystal symmetry, while survey responses indicated gains in understanding of colloidal crystal engineering with DNA and appreciation for research experiences. This module provides a scalable, replicable approach for integrating programmable nanomaterials, crystallographic reasoning, and research-aligned practices into upper-division chemistry curricula. More broadly, it offers a framework for laboratory experiences that combine collaborative learning, advanced instrumentation, data-driven analysis, and contemporary materials research.