  We present a novel experimental setup in which magnetic and optical tweezers
are combined for torque and force transduction onto single filamentous
molecules in a transverse configuration to allow simultaneous mechanical
measurement and manipulation. Previously we have developed a super-resolution
imaging module which in conjunction with advanced imaging techniques such as
Blinking assisted Localisation Microscopy (BaLM) achieves localisation
precision of single fluorescent dye molecules bound to DNA of ~30 nm along the
contour of the molecule; our work here describes developments in producing a
system which combines tweezing and super-resolution fluorescence imaging. The
instrument also features an acousto-optic deflector that temporally divides the
laser beam to form multiple traps for high throughput statistics collection.
Our motivation for developing the new tool is to enable direct observation of
detailed molecular topological transformation and protein binding event
localisation in a stretching/twisting mechanical assay that previously could
hitherto only be deduced indirectly from the end-to-end length variation of
DNA. Our approach is simple and robust enough for reproduction in the lab
without the requirement of precise hardware engineering, yet is capable of
unveiling the elastic and dynamic properties of filamentous molecules that have
been hidden using traditional tools.
