Effect of Mono- and Divalent Metal Ions on Current–Voltage Features of a λ-DNA Solution Electrically Driven in a Microfluidic Capillary

Abstract

The interactions of DNA molecules and metal ions lead to changes in their configuration and conformation, which in turn influence the current characteristics of the solution as DNA molecules are translocated through a micro/nanofluidic channel and ultimately cause serious impacts on the practical applications of DNA/gene chips for precisely manipulating and studying the molecular properties of single DNA molecules. In this study, the current characteristics of λ-DNA solutions without or with metal ions (i.e., K + , Na + , Mg 2+ , and Ca 2+ ) were experimentally investigated when they were transported through a 5 μm microcapillary under an external electric field with asymmetric electrodes. Experimental data indicated some meaningful results. First, the current−voltage relations of the metal ion solutions were all linear, while those of λ-DNA solutions without or with metal ions were all nonlinear and followed power functions, of which the indices were related to the type, valence, and mobility of ions. Furthermore, as the concentrations of metal ions increased, the power indices of the λ-DNA solutions with monovalent metal ions increased, while those of the λ-DNA solutions with divalent ions decreased. Finally, the main reasons for the current characteristics were theoretically attributed to two possible mechanisms: the polarizations on the asymmetric electrodes and the interactions between λ-DNA and metal ions. These findings are helpful for the design of new biomedical micro/nanofluidic sensors and labs on a chip for accurately manipulating single DNA molecules.

Effect of mono-/divalent metal ions on the conductivity characteristics of DNA solutions transferring through a microfluidic channel

“…Interactions between λ -DNA molecules and metal ions alter the conformation or even break the strands of λ -DNA, which causes changes in the properties of charged particles in the mixed solutions thus affecting the conductivity. The λ -DNA solutions with or without metal ions are non-Newtonian fluids, and their I-U curves follow the nonlinear relationship [20]…”

“…Previous studies have found that there are several factors that affect the electrical characteristics of mixed solutions of DNA and metal ions as they pass through a micro-/nanochannel, such as the concentration and PH values of the electrolyte, the material and inner diameter of the micro-/nanochannel, etc. [17][18][19] Further research indicates that the interaction between DNA molecules and metal ions promotes or inhibits the concentration or mobility of the charged particles in the mixed solution, leading to different electrical characteristics, [20] however, how the interaction works remains unclear.…”