Single molecule force spectrometer with magnetic force control and inductive detection

Mechanical investigations with single molecules have opened a rich spectrum of new experiments, ranging from molecular recognition over polymer elasticity and DNA unzipping to protein unfolding. Here we present the design of a novel instrument, where the force is applied to the molecule via magnetic fields acting on a magnetic cantilever for atomic force microscopy. The performance of this instrument was demonstrated by measuring the binding force of biotin/avidin complexes. A new and technically very appealing detection scheme for measurements of unbinding forces was introduced, which consists of picking up the induced voltage pulse caused by a discontinuous change of the magnet position upon bond rupture. (C) 1999 American Institute of Physics. [S0034-6748(99)02602-7].