Nanomechanical Profiling of Aβ42 Oligomer-Induced Biological Changes in Single Hippocampus Neurons

Abstract

Understanding how Aβ42 oligomers induce changes in neurons from a mechanobiological perspective has important implications in neuronal dysfunction relevant to neurodegenerative diseases. However, it remains challenging to profile the mechanical responses of neurons and correlate the mechanical signatures to the biological properties of neurons given the structural complexity of cells. Here, we quantitatively investigate the nanomechanical properties of primary hippocampus neurons upon exposure to Aβ42 oligomers at the single neuron level by using atomic force microscopy (AFM). We develop a method termed heterogeneity-load-unload nanomechanics (HLUN), which exploits the AFM force spectra in the whole loading–unloading cycle, allowing comprehensive profiling of the mechanical properties of living neurons. We extract four key nanomechanical parameters, including the apparent Young’s modulus, cell spring constant, normalized hysteresis, and adhesion work, that serve as the nanomechanical signatures of neurons treated with Aβ42 oligomers. These parameters are well-correlated with neuronal height increase, cortical actin filament strengthening, and calcium concentration elevation. Thus, we establish an HLUN method-based AFM nanomechanical analysis tool for single neuron study and build an effective correlation between the nanomechanical profile of the single neurons and the biological effects triggered by Aβ42 oligomers. Our finding provides useful information on the dysfunction of neurons from the mechanobiological perspective.

Atomic Force Microscopy for the Study of Cell Mechanics in Pharmaceutics

“…While such experiments (Figure 10) can be more complex than elasticity measurements, the field of rheology is also already well established in other research areas [82]; therefore, a researcher can reapply this knowledge for cell rheology. One approach is to infer rheology from the regular force measurements as a function of time [79,83] (Figure 10a), and simply from the force-distance curve, one can calculate dissipated work due to the hysteresis between approach and retract [41] (Figure 2c). A different approach is to repeat the nanoindentation at different tip velocities [84].…”

“…In constant force mode, the feedback is turned on to keep the deflection of the cantilever constant. For a viscous sample, this necessitates that the One approach is to infer rheology from the regular force measurements as a function of time [79,83] (Figure 10a), and simply from the force-distance curve, one can calculate dissipated work due to the hysteresis between approach and retract [41] (Figure 2c). A different approach is to repeat the nanoindentation at different tip velocities [84].…”

“…The studies included in this review have used tip radii down to 2 nm (e.g., [ 40 ]), over 20 nm (e.g., [ 41 ]), to 60 μm (e.g., [ 42 ]), and even a flat wedge (e.g., [ 43 ]) which effectively has an infinite radius of curvature.…”

Near-Field Terahertz Morphological Reconstruction Nanoscopy for Subsurface Imaging of Protein Layers

“…Despite their utility, these methods struggle to provide three-dimensional (3D) nanoscale information, a crucial requirement for the precise characterization of protein adsorption. Atomic force microscopy (AFM) has been used to measure individual proteins and protein networks on solid surfaces at nanometer resolution. − However, its inherent limitation as a surface topography measurement technique hinders the elucidation of the morphological architecture of protein layers, as it precludes the acquisition of subsurface information. − Therefore, the development of a method capable of fully capturing the 3D nanoscale morphological structural information on proteins (from single molecules to networks and layers) remains a challenging task.…”

Optical Nanofiber-Enabled Self-Detection Picobalance

“…Developing ultrasensitive force (or masses) sensors capable of measuring force down to the piconewton level is of fundamental importance for a wide range of disciplines, including molecular biology, − cell biology, − micromanipulation, , and fundamental physics . For example, the mass fluctuations of cells, single-virus force spectroscopy, and optical forces can be precisely measured by specially designed microelectromechanical systems (MEMS) force sensors or advanced instruments (e.g., atomic force microscopy (AFM)).…”