Miniaturised magnetic bead actuator-based atomic force microscope for single-molecule measurements

Abstract

Single molecular techniques have been providing researchers powerful tools to reveal the mechanisms of bioprocesses by investigating the behaviours and properties of individual molecules. It’s also an essential way to study the functional differences and accesses the parameters of individual molecules. Atomic force microscopy (AFM) is one of the most popular technologies to probe into individual molecules and has provided insights into structure, kinetics and dynamics of many molecules. However, the conventional AFM use cantilever-based sensors and piezo-based actuators which are relatively large in dimension and prone to drift and noise. This thesis focuses on the development of a customised AFM for single molecule force spectroscopy experiments which is capable of both magnetic and piezo actuation. The magnetic actuation method unitises miniaturise magnetic beads as actuators reduces the actuator size significantly and performs experiment in non-contact way, thus reduces the impact of noise and drift. The resolution of the setup is verified experimentally and comparable to commercial AFM in single molecule force spectroscopy applications. Single molecule force spectroscopy experiments using both varying loading rates and force clamp methods have been performed using biotin-streptavidin and heparin-FGF2 molecule pairs. The energy landscapes of their bonds have been studied