Force spectroscopy with electromagnetic tweezers

Force spectroscopy using magnetic tweezers (MTs) is a powerful method to probe the physical characteristics of single polymers. Typically, molecules are functionalized for specific attachment glass surface at one end and micrometer-scale paramagnetic bead other end. By applying an external field, multiple can be stretched twisted simultaneously without exposure potentially damaging radiation. The majority MTs utilize mobile, permanent magnets produce forces on beads (and molecule under test). However, translating rotating may require expensive precision actuators, limit rate which force changed, induce vibrations that disturb tether dynamics tracking. Alternatively, field produced with electromagnet, allows fast modulation eliminates motor-associated vibration. Here, we describe low-cost quadrapolar electromagnetic tweezer design capable manipulating DNA-tethered MyOne as high 15 pN. solid-state nature generated B-field modulated along two axes convenient accessing range torques relevant studying activity DNA motor enzymes like polymerases helicases. Our specifically leverages technology available increasing number university maker spaces student-run machine shops. Thus, it accessible tool undergraduate education applicable wide biophysical research questions.