Fig. 4From: Copper-free click chemistry for attachment of biomolecules in magnetic tweezersTether density as a function of PEG concentration. DNA tether density for different Azide-PEG concentrations. The number of tethers increases linearly with increasing PEG concentration. Inset shows an example of a reference bead (left) and three beads that signal 20Â kb DNA molecules tethered with click chemistryBack to article page