Force-clamp spectrometer with functionalized cantilever tip
The disclosed subject matter relates to a force-clamp spectrometer that enables operation in constant force mode and allows for automated data acquisition and analysis, using feedback electronics and software. The disclosed subject matter also relates to methods of using the force-clamp spectrometer for the measurement of the dynamics of chemical reactions. The methods may include, but are not limited to, the measurement of the dynamics of substrate folding and unfolding, as well as bond cleavage and bond formation.
1. A force-clamp spectrometer comprising:
a cantilever extending from a cantilever chip, the cantilever comprising a functionalized cantilever tip for attaching a first end of a molecular substrate;
a functionalized coverslip adjacent to the cantilever chip and mounted on a piezo-electric positioner for attaching a second end of the molecular substrate;
a laser configured to focus a laser beam on the cantilever to form a laser beam focal spot;
a split photodetector configured to detect a reflected beam;
a camera for monitoring the laser beam focal spot; and
a first movable flip mount for controlling a position of the camera, wherein the camera is positioned on the first movable flip mount, the first movable flip mount being switchable between a first camera position and a second camera position, wherein the cantilever is in focus of the camera in the second camera position; and
a second movable flip mount for controlling a position of the piezo-electric positioner, wherein the piezo-electric positioner is positioned on the second movable flip mount, the second movable flip mount being switchable between a first piezo-electric position and a second piezo-electric position, wherein in the first piezo-electric position, the cantilever is accessible for placement of a sample comprising the molecular substrate thereon and in the second piezo-electric position the cantilever is in a position for measuring the molecular substrate dynamics.
2. The force-clamp spectrometer of claim 1 , wherein the molecular substrate is suspended between the cantilever and the coverslip.
3. The force-clamp spectrometer of claim 2 , further comprising an electronically controlled feedback system configured to adjust the extension of the suspended molecular substrate between the functionalized cantilever tip and the functionalized coverslip.
4. The force-clamp spectrometer of claim 3 , wherein the electronically controlled feedback system is further configured to allow the force-clamp spectrometer to maintain a desired force exerted on the cantilever.
5. The force-clamp spectrometer of claim 1 , further comprising a magnetic-orientable prism configured to steer the reflected beam to the split photodetector, wherein the magnetic-orientable prism is mounted on magnets to eliminate mechanical drift.