Atomic force microscope as a nano- and micrometer scale biological manipulator: A short review

Several types of AFM cantilevers developed for biological sample manipulation. A: an example of chemical modification of silicon or silicon nitride tip with MAL-PEG-NHS. B: a rectangular cantilever with a pyramidal tip at the end, C: triangular tip-less cantilever, D: cantilever with a glued colloidal bead, E: a sharpened tip using molecular beam epitaxy (MBE) technology, F: carbon nanotube tip, G: cantilever with a hooking capacity, H: scooping cantilever, (reproduced: A from [48], B from Olympus homepage, C from Bruker homepage, D from [64], E from [4], F from [5], G from [6], H from [7] with permissions). [Display omitted] •AFM as a manipulator for biological and nano-medical study is reviewed.•Various types of AFM cantilever have been developed.•Mechanical properties of single protein molecules have been studied by AFM.•Anchoring force of membrane proteins and lipids has been measured.•Wound healing processes of stress fibers and cell membrane can be studied by AFM. The amazing capacity of atomic force microscope to let us touch the molecular and cellular level samples with a sharp probe stimulated its application to bio-medical field among others. In addition to topographical imaging of the sample surface, a direct mechanical manipulation has attracted innovative minds to develop new methodologies aiming at direct handling of proteins, DNA/RNA, and cells. Measurement of their mechanical properties brought about a vivid picture of their physical nature. Direct handling of individual molecules and cells prompted development of nano-medical applications. This short review summarized recent application of AFM for measurement of mechanical properties of biological samples and attempts to perform direct manipulations of nano-medicine.