Competing ligand assisted aptamers and DNAzymes for nanomaterials

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Deoxyribonucleic acid (DNA) sequences that can bind to inorganic nanomaterials with high affinity and specificity are useful for biosensor development, biomineralization, and directed assembly of materials. However, strong nonspecific interactions make it difficult to obtain high quality DNA aptamers for surfaces. In addition, we are interested in exploring surfaces for supporting catalysis. The goal of the current proposal is to select DNA sequences (aptamers) that can selectively bind to inorganic surfaces and DNA-based enzymes (DNAzymes) using inorganic nanoparticles as cofactors for catalysis. Different from previous research, we will use ions and competing molecules to modulate the interaction strength so that nonspecific DNA adsorption is weakened to a degree comparable with the base pairing interactions between DNA. Under such conditions, we may obtain DNA sequences that can specifically recognize surface features. We will choose a few inorganic surfaces including iron oxide, graphene oxide and gold to perform aptamer selections using a large random DNA library. In addition, selection of DNAzymes will be performed in the presence of inorganic nanomaterials with the goal to use the surfaces as cofactors. The selected DNA aptamers and DNAzymes will be carefully characterized in terms of binding strength and catalytic efficiency. Their interactions with the target surfaces will be studied using various spectroscopic techniques, and their analytical and materials applications will be explored. This study will broaden our understanding of DNA/nano interfaces, generate specific DNA sequences for surface functionalization and recognition, and produce interesting biosensors and hybrid materials.