Molecular recognition of proteins through quantitative force maps at single molecule level

This article belongs to the Special Issue Single-Molecule Protein Dynamics.Intermittent jumping force is an operational atomic-force microscopy mode that produces simultaneous topography and tip-sample maximum-adhesion images based on force spectroscopy. In this work, the operation conditions have been implemented scanning in a repulsive regime and applying very low forces, thus avoiding unspecific tip-sample forces. Remarkably, adhesion images give only specific rupture events, becoming qualitative and quantitative molecular recognition maps obtained at reasonably fast rates, which is a great advantage compared to the force–volume modes. This procedure has been used to go further in discriminating between two similar protein molecules, avidin and streptavidin, in hybrid samples. The adhesion maps generated scanning with biotinylated probes showed features identified as avidin molecules, in the range of 40–80 pN; meanwhile, streptavidin molecules rendered 120–170 pN at the selected working conditions. The gathered results evidence that repulsive jumping force mode applying very small forces allows the identification of biomolecules through the specific rupture forces of the complexes and could serve to identify receptors on membranes or samples or be applied to design ultrasensitive detection technologies.This research was funded by grant PID2019-103901GB-I00 funded by MCIN/AEI/10.13039/501100011033, grant QTP2103003 funded by CSIC, and grants E35_20R and LMP58_18 funded by the Government of Aragón-FEDER. The APC was funded by E35_20R.Peer reviewe