STM and AFM in biotechnology.

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are capable of providing atomic-scale images, as well as insights into functional characteristics, of surfaces. Biological materials can be studied by depositing them on appropriate substrates, and samples have been imaged with varying degrees of resolution. In this review, the principles of STM and AFM are summarized, and practical aspects of implementing them for studies relevant to biotechnology are discussed, with the emphasis on investigations of biological macromolecules such as DNA and proteins. Items covered include samples, surfaces, medium, tips, and typical operating conditions. Finally, prospects are discussed for potential future applications to biotechnology.