Dimensional precision in DNA affinity by layered double hydroxides with length and size selectivity

In this study, we demonstrated that deoxyribonucleic acid (DNA) strands selectively bind to the surfaces of size-customized layered double hydroxide (LDH) particles, driven by a distinct size-matching interaction between the adsorbate and adsorbent. High-purity LDHs with specific particle sizes – LDH-S (small) and LDH-L (large) – were synthesized, and their DNA adsorption behaviors were systematically examined. The LDH-S exhibited a higher specific surface energy and zeta potential than LDH-L; whereas LDH-L possessed a well-ordered crystalline structure along the crystallographic ab-plane compared to LDH-S. According to the adsorption isotherm, the DNA strands were adsorbed onto the LDH surface in a multilayer manner. The mathematical fitting indicated that LDH-S had a higher adsorption capacity and less cooperative adsorption than LDH-L. Electrophoresis using size-specific ladder DNA confirmed that LDH adsorbed DNA in a size-selective manner; ladder DNA below 800 base pairs selectively adsorbed on LDH-S, while DNA above 800 base pairs preferred adsorption on LDH-L. The binding assay using large plasmid DNA corroborated that LDH-L displayed superior adsorption efficiency for large DNA fragments. The distinctive preference of LDH-L for large DNA might be due to cooperative interactions among DNA strands on expansive surfaces with periodic electrostatic interaction sites.