Analytical Sciences

DNA Terminal-Specific Dispersion Behavior of Polystyrene Latex Microparticles Densely Covered with Oligo-DNA Strands Under High-Salt Conditions

Hiroya NAKAUCHI,* Mizuo MAEDA,*,** and Naoki KANAYAMA*,**,***

*Department of Biomedical Engineering, Graduate School of Medicine, Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano, Nagano 380-8553, Japan
**Bioengineering Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
***Institute of Biomedical Science, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan

We prepared microspheres densely covered with oligo-DNA strands by immobilizing amino-terminated oligo-DNA strands on the surface of carboxylate polystyrene latex (PS) particles via the amide bond formation. The obtained microspheres (ssDNA-PS) stably dispersed in neutral pH buffer containing high concentrations of NaCl. For the ssDNA-PS ≥1 μm diameter, only 3 – 5% of surface-immobilized oligo-DNA could form a duplex with the complementary strands. Nevertheless, the resulting ssDNA-PS showed a distinct duplex terminal dependency in their dispersion behavior under neutral pH and high NaCl conditions; the microspheres with fully-matched duplexes on the surface spontaneously aggregated in a non-crosslinking manner. By contrast, the microspheres with terminal-mismatched duplexes remained dispersed under the identical conditions. These results suggest that the micrometer-scale particles covered with oligo-DNA strands also have high susceptibility to a duplex terminal sequence in their dispersion property, similar to previously reported DNA-functionalized nanoparticles. This property could potentially be used in various applications including analytical purposes.

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