Atomic force microscopy applied to interrogate nanoscale cellular chemistry and supramolecular bond dynamics for biomedical applications

Abstract

Understanding biological interactions at a molecular-level grants valuable information relevant to improving medical treatments and outcomes. Among the suite of technologies available, Atomic Force Microscopy (AFM) is unique in its...

Single-Molecule Analysis of SARS-CoV-2 Binding to C-Type Lectin Receptors

“…Here we utilize atomic force microscopy (AFM) 29 and employ single-molecule force spectroscopy (SMFS) 30 , 31 to probe this interaction and shed unique insight on the behaviors exhibited. 32 We demonstrate that the SARS-CoV-2 S1 specifically binds DC and L-SIGN, likely through the glycans of the RBD. Further, we discern the kinetic parameters associated with this interaction.…”

“…By coating gold surfaces with either L-SIGN or DC-SIGN, and functionalizing the AFM tip with S1 or RBD, we were able to assess the binding probability (BP) and ability of antibodies to interfere with binding behaviors. Using force–distance AFM (FD-AFM), the tip was cyclically approached and retracted as the cantilever raster scans the surface, while the signal was collected from the reflection of a laser from the back of the tip into a photodiode, with the displacement of the signal indicating the forces associated with adhesion . The retrieved force–distance (FD) curves were then used to categorize pixels that contain no binding and specific binding, and consequently the proportion of the curves displaying adhesion events were used to calculate BPs for each interaction (Figure E) …”

“…While binding and infectivity behaviors associated with the SARS-CoV-2 interaction with DC-SIGN and L-SIGN have been strongly evidenced, direct single molecule-based examination of crucial elements such as specificity and kinetics of this interaction remains underdeveloped. Here we utilize atomic force microscopy (AFM) and employ single-molecule force spectroscopy (SMFS) , to probe this interaction and shed unique insight on the behaviors exhibited . We demonstrate that the SARS-CoV-2 S1 specifically binds DC and L-SIGN, likely through the glycans of the RBD.…”

“…Using force− distance AFM (FD-AFM), the tip was cyclically approached and retracted as the cantilever raster scans the surface, while the signal was collected from the reflection of a laser from the back of the tip into a photodiode, with the displacement of the signal indicating the forces associated with adhesion. 32 The retrieved force−distance (FD) curves were then used to categorize pixels that contain no binding and specific binding, and consequently the proportion of the curves displaying adhesion events were used to calculate BPs for each interaction (Figure 1E). 34 When tips were functionalized with either S1 or RBD, L-SIGN exhibited a higher BP (9.8 ± 1.4%) than did DC-SIGN (6.3 ± 1.4%).…”

Advances in probing single biomolecules: From DNA bases to glycans

“…Moreover, AFM can also be applied to soft systems, such as synthetic biology and oncology. [19,[42][43][44][45][46][47][48][49] Nowadays, many new AFM imaging modes have been developed. [19,33,[50][51][52][53] Contact mode, the primary imaging mode of AFM, has been widely used for decades.…”