DNA condensations on mica surfaces induced collaboratively by alcohol and hexammine cobalt

▶ We systematically studied the λ-DNA condensations on mica surfaces induced by alcohol and hexammine cobalt (III) [Co(NH3)63+] with atomic force microscopy (AFM). And we measured the critical condensation concentrations for Co(NH3)63+ and alcohols. ▶ We investigated the collaborative condensation by both alcohol and Co(NH3)63+ and found that DNA condensation patterns can be observed even when the concentration of the two condensation agents are lower than their critical values. ▶ We explained the observation by electrostatic interaction and concluded that the collaborative condensation phenomenon might be ascribed to the electrostatic interaction due to the lowering dielectric constant by adding alcohols.