An Asylum Research MFP-3Dtm
top of a lab-made
inverted optical microscope. We use this instrument when we also need
optical access to our sample. Because the piezo scanners can be operated in closed loop the accuracy for height and stiffness measurements is optimal.
The optical microscope can be operated
both in brightfield and in total internal reflection fluorescence
(TIRF) mode. The AFM is mounted in an acoustic enclosure that is
equipped with an automatic temperature control to minimize thermal
Our second AFM
is a Nanotec Electrˇnica Cervantes. Because of its very compact design
is offers atomic resolution and scan withs speeds of up to 1 frame per
second. We use this instrument to obtain the highest resolution scans
of single proteins and to study dynamic samples.Vertical optical trap
vertical optical trap is built
around an upright optical fluorescence microscope. The traps uses a 300
mW 980 nm trapping laser and can exert forces of up to 100 pN. The
instrument is optimized to exert and detect forces in vertical
direction (so perpendicular to the microscope coverslip, like in AFM).
Compared to AFM a laser trap has the advantage that it can
and measure much lower forces, down to sub-pN. This is advantageous to
measure mechanical properties of very soft samples such as cells.
In addition to the combined
TIRF-AFM we also use several stand-alone optical microscopes, including
a TIRF microscope that can run with a 405, 488, 515 or 532 nm excitation diode laser and is
combined with a cooled EM-CCD to facilitate single molecule detection
at frame rates up to 500 s-1.
Finite element analysis
For the modeling of our mechanical
deformation experiments we use the Comsol Multipysics« package.
With our models we test the effects of the shape of our sample, the probe-sample contact mechanics, but also the
effects of heterogeneities of the used