Biophysical Measurements of Cells, Microtubules, and DNA with an Atomic Force Microscope

TL;DR

This paper reviews various atomic force microscope platforms and demonstrates their use in teaching laboratories to perform biophysical measurements on cells, microtubules, and DNA, including imaging and force quantification.

Contribution

It provides a comprehensive overview of accessible AFM platforms and details experimental protocols for biophysical measurements suitable for educational settings.

Findings

AFMs can image biological materials like cells, microtubules, and DNA.

Quantitative measurements of membrane tension, persistence length, and DNA tension are feasible.

Multiple AFM platforms are suitable for teaching biophysical experiments.

Abstract

Atomic force microscopes (AFMs) are ubiquitous in research laboratories and have recently been priced for use in teaching laboratories. Here we review several AFM platforms (Dimension 3000 by Digital Instruments, EasyScan2 by Nanosurf, ezAFM by Nanomagnetics, and TKAFM by Thorlabs) and describe various biophysical experiments that could be done in the teaching laboratory using these instruments. In particular, we focus on experiments that image biological materials and quantify biophysical parameters: 1) imaging cells to determine membrane tension, 2) imaging microtubules to determine their persistence length, 3) imaging the random walk of DNA molecules to determine their contour length, and 4) imaging stretched DNA molecules to measure the tensional force.