Search

Atomic force microscopy (AFM) is a powerful tool in Biology due to the possibility of identifying and locating single molecules at a subnanometer scale. Performing these experiments requires the usage of functionalized AFM tips to which sensing molecules can be attached. In this work the possibility of functionalizing AFM cantilevers and tips using the activated vapour silanization (AVS) process is explored. Functionalized thin films are deposited on commercial silicon nitride chips and their presence is assessed by measuring the variation in the resonance frequency of the cantilever. Subsequently, the presence and functionality of the films is studied through the covalent immobilization of a fluorescein-derived molecule to the amine reactive groups on the surface. With regard to its sensing ability, the functionalized tips are shown to sustain repetitive interactions with a model graphite substrate (HOPG) under relatively harsh conditions, while no apparent damage is observed in the tip. It is also found that the substrate-tip interaction may be modified by covalently attaching a molecule to the latter. Consequently, AVS functionalized AFM tips are found to be robust and reliable candidates for their use in the affinity (or chemical) atomic force microscopy (AF-AFM) mode. Unlabelled Image • Atomic force microscopy (AFM) cantilevers and tips were functionalized by activated vapor silanization (AVS). • The deposition of the functionalized layer was assessed through variations in the resonance frequency of the cantilever. • The reactivity of the amine groups in the functionalized layer was checked by forming covalent bonds with a fluorophore. • The stability of the functionalized film upon repeated interactions with a model HOPG substrate was established. • AVS functionalized AFM tips appear as promising candidates for their usage in affinity atomic force microscopy experiments. [ABSTRACT FROM AUTHOR]