Microrheological Measurements on Soft Materials with Atomic Force Microscopy

_{KEYWORDS: AFM; NanoWizard; Biomaterial; Hydrogels; Tissues; Viscoelasticity; Microrheology; Life Science;}

A number of studies in recent years have emphasized the importance of viscoelasticity in various research fields, such as materials science and biophysics. Various techniques have been employed to measure the viscoelastic properties of biological and soft matter, including micropipette aspiration, optical stretching, and atomic force microscopy (AFM). Among these techniques, AFM is widely used due to its versatility in measuring materials with different geometries and at different scales.

This technical note presents a summary of microrheological measurements on hydrogels and biological tissues. It briefly details the theory behind evaluating the viscoelastic properties of materials and provides practical steps for calibrating an AFM system before conducting measurements. It describes the process of measuring polyacrylamide hydrogels with varying stiffness and evaluating their viscoelastic properties at different frequencies. The method is applied to assess the spatial variation in viscoelastic properties of a condyle tissue sample from a patient with osteoarthritis.

Readers can expect to learn about:

• Microrheological measurements on hydrogels and biological tissues, providing insights into the viscoelastic properties of these materials;
• The theory behind evaluating viscoelastic properties, along with practical steps for calibrating an AFM system to ensure accurate measurements; and
• A simple-to-apply method for performing and analyzing microrheological measurements on soft materials showcasing the benefits and potential of AFM for measuring viscoelasticity.