Atomic Force Microscopy in Mechanical Characterization of Soft Biological Materials

Atomic force microscopy (AFM) has established itself as a pivotal tool for probing the mechanical properties of soft biological tissues, cells and extracellular matrices at nanometre resolution. By employing a cantilever with a sharp or spherical tip to indent samples under physiological conditions, AFM can map variations in stiffness, elasticity and viscoelastic response across heterogeneous structures. This technique integrates force spectroscopy with high-resolution imaging, enabling simultaneous characterisation of topographical features and mechanical behaviour. The resulting force–indentation curves can be interpreted through contact mechanics models to extract quantitative metrics such as Young’s modulus, viscosity and adhesion forces. Applications span from elucidating mechanical heterogeneity in healthy and diseased tissues to monitoring changes in cellular compliance during development, pathology or therapeutic intervention. Recent methodological advances in probe calibration, automated contact point detection and theoretical corrections for large deformations and surface tension have significantly improved measurement accuracy and reproducibility. AFM-based mechanobiology is now instrumental in understanding how mechanical cues regulate cellular function, tissue homeostasis and disease progression, with direct implications for biomaterial design, diagnostic markers and mechanotherapeutics.

Research from Nature Portfolio

Recent studies have leveraged micro-scale indentation to reveal mechanical heterogeneity within complex tissues. Investigations of the rat bladder wall uncovered stiffness gradients spanning the urothelium to muscle layers and detected stiffness alterations associated with fibrotic and neoplastic conditions, thereby demonstrating the capacity of AFM to map disease-related micromechanical fingerprints. Foundational work on standardised procedures has introduced protocols to calibrate cantilever sensitivity and spring constants across laboratories, markedly reducing variability in Young’s modulus measurements of hydrogels and living cells. Complementary theoretical modelling has refined the interpretation of force–indentation data by incorporating neo-Hookean hyperelastic behaviour and surface tension effects, enabling more accurate characterisation of cellular mechanics under large deformations and improving upon classical Hertzian analyses.

Atomic Force Microscopy in Mechanical Characterization of Soft Biological Materials publication trend

The graph below shows the total number of articles in atomic force microscopy in mechanical characterization of soft biological materials across all publications each year (not limited to Nature Index journals).

Technical terms

Atomic Force Microscopy (AFM): A high-resolution technique that measures forces between a probe tip and a sample surface to map topography and mechanical properties.

Young’s modulus: A measure of elastic stiffness, defined as stress divided by strain in the linear elastic regime.

Viscoelasticity: The combined viscous and elastic response of materials, characterised by time-dependent deformation under load.

Contact mechanics model: A theoretical framework (e.g. Hertz or Oliver & Pharr) used to relate force–indentation data to material properties.

Nanoindentation: A method where a rigid tip indents a material surface to measure mechanical properties at small scales.

References

1. Atomic force microscopy-mediated mechanobiological profiling of complex human tissues. Biomaterials (2023).
2. Micro-mechanical fingerprints of the rat bladder change in actinic cystitis and tumor presence. Communications Biology (2023).
3. Standardized Nanomechanical Atomic Force Microscopy Procedure (SNAP) for Measuring Soft and Biological Samples. Scientific Reports (2017).
4. Combined strategies for optimal detection of the contact point in AFM force-indentation curves obtained on thin samples and adherent cells. Scientific Reports (2016).
5. Hertz model or Oliver & Pharr analysis? Tutorial regarding AFM nanoindentation experiments on biological samples. Materials Research Express (2020).
6. Indentation and Adhesive Probing of a Cell Membrane with AFM: Theoretical Model and Experiments. Biophysical Journal (2005).
7. Atomic Force Microscopy on Biological Materials Related to Pathological Conditions. Scanning (2019).