AFM: a versatile tool in biophysics

Here we review the applications of atomic force microscopy to the study of samples of biological origin. Emphasis is given to provide the reader with information on the broad range of different biophysical applications that, to date, such a technique can deal with. After recalling briefly the operating principles of an atomic force microscope, the broad field of bio-imaging applications is faced (DNA, DNA-protein interaction, proteins, lipid membranes, cells); thereafter, the use of the atomic force microscope to measure forces is introduced and force mapping on living cells is discussed. This section is followed by the description of the use of force curves in assessing single-molecule inter- and intramolecular interactions. A paragraph on the perspectives of the technique in biophysical applications concludes the paper. We hope that this review can help the reader in appreciating how atomic force microscopy contributes to the current explosive growth of nanobiosciences, where biology, chemistry and physics merge.