Described herein are methods and devices for ligating nucleic acids or nucleic acid fragments as well as methods for transforming or transfecting cells with exogenous DNA. The methods and devices generally involve exposing the nucleic acids, nucleic acid fragments, and/or cells to an electromagnetic field, for example, a mini-current electromagnetic field, while performing the steps of ligation or transformation. The methods and devices provide numerous advantages over conventional ligation and transformation techniques and systems such as reduced reaction times, no heating requirements, and reduced amounts of reagents. Finally, as shown in the examples below, the methods and devices described herein are more effective compared to conventional ligation and transformation techniques and systems.