Fast imaging and fast force spectroscopy of single biopolymers with a new atomic force microscope designed for small cantilevers

Small cantilevers allow for faster imaging and faster force spectroscopy of single biopolymers than previously possible because they have higher reson ant frequencies and lower coefficients of viscous damping. We have used a n ew prototype atomic force microscope with small cantilevers to produce stab le tapping-mode images (1 mu mx1 mu m) in liquid of DNA adsorbed onto mica in as little as 1.7 s per image. We have also used these cantilevers to obs erve the forced unfolding of individual titin molecules on a time scale an order of magnitude faster than previously reported. These experiments demon strate that a new generation of atomic force microscopes using small cantil evers will enable us to study biological processes with greater time resolu tion. Furthermore, these instruments allow us to narrow the gap in time bet ween results from force spectroscopy experiments and molecular dynamics cal culations. (C) 1999 American Institute of Physics. [S0034-6748(99)02411-9].