Melamine-DNA encoded periodicity of quantum dot arrays

Formation of QD-array in solution phase guided by the self-assembly with DNA-melamine hybrid molecules is reported here. Melamine was conjugated with ssDNA using phosphoramidate chemistry. Aqueous soluble ZnSe/ZnS QDs conjugated to complementary ssDNA was self-assembled with the DNA-melamine hybrid molecules by DNA-hybridization. The self-assembly leads to the precise positioning of the QDs in QDs array where the inter QD distance is being maintained by the DNA sequence length. The QD array was characterized by gel electrophoresis, UV-visible and fluorescence spectrophotometry and circular dichroism. Direct visualization of the DNA-melamine hybrid molecule mediated QD array was made possible by atomic force microscopy (AFM) and transmission electron microscopy (TEM) analysis. Substantial increase in the fluorescence intensity and lifetime of the QDs was observed on array formation by DNA self-assembly.