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1. DNA drives the self-assembly of microspheres Arjun G. Yodh, University of Pennsylvania, DMR 1062638 Living systems assemble themselves from the ‘bottom up’ by relying on specific interactions between their molecular parts. The Crocker lab studies this fundamental process using plastic microspheres bearing DNA strands that form bridges only when the strands are complementary. This bridge formation causes the particles to associate, spontaneously forming a simple colloidal crystal having a body-centered cubic symmetry. Different DNA sequences should allow a wide variety of different structures to be grown from solution. 5 µm

2. DNA drives the self-assembly of microspheresArjun G. Yodh, University of Pennsylvania, DMR 1062638 Minna Chen, University of Minnesota, spent a 10-week REU fellowship in the Crocker lab, where she made DNA-directed microsphere crystals, performing the complete process from chemical synthesis, sample characterization, to crystallization and imaging. She formed the first crystals ever using polystyrene sulfate microspheres, and found that they were more stable than the particles in current use by the Crocker lab. This REU experience prepared Ms. Chen for a future research career in biomedical science by giving her hands on training in particle chemistry and advanced optical microscopy.