The method provides for attaching nucleic acids to a surface at a controlled grafting density in a controlled conformation by contacting an immobilization solution of nucleic acids containing at least one block of adenine nucleotides to a surface for a sufficient period of time to allow attachment to the surface. Another aspect of the methods described provides for controlling the grafting density of immobilized oligonucleotides by coadsorption/displacement by oligo(dA). Another aspect provides for a method of immobilizing oligonucleotides in complex conformations by varying the number and position of the block(s) of adenine nucleotides in the sequence of said oligonucleotides. Another aspect provides for controlled immobilization of a functional unit, such as a ligand, a molecule, a macromolecule, an aptamer, a lectin, an immunoglobulin, an antibody, a biomolecule, a solid state particle, a vesicle, or a label to a surface via attachment to at least one block of adenine nucleotides.